BTB - FAQs

With AVM, the sound can be specifically refined, especially in units with a tube stage. These include, for example, OVATION CS 8.3, CS 8.3 S, A 8.3, PA 8.3, as well as EVOLUTION CS 5.3, AS 5.3 or MP 5.3. If you want to achieve better sound here, you should not simply use standard tubes, but pay attention to a carefully selected and tonally suitable tube configuration. For many AVM units, we offer suitable selected tube solutions.

With T+A, it depends strongly on the respective device. A well-known example is the V10, which works with EL509S / EL509-II, ECL82 / 6BM8, ECC83 / 12AX7 S4A and ECC99; Radiomuseum and Stereophile list exactly this configuration for the V10. For older or special concepts around T+A, depending on the device, 6SN7 or 12AX7LPS are also sought after. Anyone who wants to preserve such T+A tube devices or make them operational again therefore needs the correct tube for the exact model. For older T+A loudspeakers, T+A also still offers replacement chassis in its own shop, which is also important for many owners. Many suitable tubes for T+A classics are available from BTB in carefully selected quality. 

For VOX tube devices, suitable and robust replacement tubes are especially important, particularly EL84. This applies especially to the legendary AC30 with EL84 and 12AX7 / ECC83, to the AC15, but also to other models such as AC10, AC30S1, Night Train or Hand-Wired versions. For VOX effects units and modeling concepts with a real tube, devices such as ToneLab EX, ToneLab ST or Valvetronix are also interesting, as they work with a 12AX7 / ECC83 in the Valve Reactor circuit. All these types are also available from BTB as suitable tubes, which is important for older AC30 models, and on request as premium matched tubes.

For ENGL guitar amps, suitable and robust tubes for high-gain applications are especially important. This applies in particular to classics such as Fireball, Powerball, Savage, Invader or Ironball, which ENGL itself clearly positions in the rock and metal sector. For heavy metal, 12AX7 / ECC83 high-gain preamp tubes are especially interesting when a lot of gain, pressure and stable performance are required. In the power stage, depending on the model, 5881 or EL34 also play an important role. Suitable 5881 S4GB and 12AX7GB High Gain are therefore a very good choice for many ENGL amps. Many of these types are also available from BTB in selected quality and, on request, matched.

With LEAK, a targeted tube selection is often more worthwhile than a simple replacement. This applies especially to classics such as Stereo 20, TL/12 Plus, TL/12.1 Point One or the Varislope preamplifiers. In the Stereo 20, EL84 and ECC83 are particularly interesting; in the TL/12 Plus, rather EL84 with EF86 and ECC81; and in the TL/12.1 Point One, the KT66 plays a central role. These well-known LEAK units in particular often respond very well to a carefully selected tube configuration. 

classics such as SVT, V4, V4B, B-15 or Heritage SVT-CL. Depending on the unit, typical types include 6550, 7027A, 6L6GC, 12AX7 / ECC83, 12BH7A, 12AU7 / ECC82, 12DW7 / 7247 or the rare 6K11. Especially in powerful bass amplifiers such as the SVT, carefully selected and matched power tubes are very important. Many suitable Ampeg tubes are also available from BTB in premium matching quality.

We supply suitable replacement tubes and upgrade tubes for many Canor units from Slovakia. These include, for example, the Canor Virtus I2 and AI 1.10 with KT88 configuration, as well as the TP101 A30 with 4 x EL34. We also offer suitable tubes for tube phono stages such as the Canor PH 2.10 with 2 x ECC81 / 12AT7 and 2 x ECC83 / 12AX7. Many common types for Canor units are available in selected quality and, on request, matched. 

With Cayin, the range extends from classic KT88 / 6550 push-pull concepts to large 805 and 300B single-ended amps. According to the manufacturer, the CS-88A uses KT88 / 6550EH as well as 6SL7 and 6SN7 in the preamp stages, while the CS-805A combines 805A with original Western Electric WE300B as an upgrade and Linlai 6SN7 as an upgrade. This means that the right choice does not only depend on the brand, but very strongly on the specific model and its circuit. Many suitable Cayin tubes are available from BTB selected, as matched pairs or, for power tubes, as premium-matched quartets and pairs.

With Jadis, a targeted tube selection is often more worthwhile than a simple replacement. This applies especially to popular units such as DA50S, DA88S, Orchestra Reference, JA80 MkII and JA120. Depending on the model, KT90, KT88, 6550, KT120, EL34 / 6CA7 as well as ECC82 and ECC83 are particularly interesting. According to Jadis, the DA88S can be operated with KT88, KT90, KT120 or 6550, the Orchestra Reference uses EL34 and ECC83, and for JA80 MkII and JA120, Jadis also lists several compatible power tubes plus ECC82 / ECC83 in the driver stages. 

For Laney tube amplifiers, suitable and robust replacement tubes are especially important. This applies, for example, to CUB models such as CUB12R and CUB-SUPER12 with EL84 and ECC83, to the Lionheart series such as L20H with EL84 and ECC83 configuration, to GH classics such as GH50R / GH50L with EL34 and ECC83, as well as to Ironheart models such as IRT60H or BCC-IRT60H, which run with 6L6GC from the factory and, according to Laney, are also designed for EL34 as an alternative. It is always important to select the tubes to match the respective model and circuit. All these types are also available from BTB in premium matching and V1 quality. 

For Line 6 tube amplifiers, the tube types suitable for the respective model are especially important. This applies in particular to the DT25 with EL84 and 12AX7 / ECC83, to the DT50 with EL34 and 12AX7 / ECC83, as well as to Spider Valve models with 6L6 and 12AX7 / ECC83. Line 6 also expressly points out for the DT models that suitable matched power tubes are important. Many of these types are also available from BTB in premium matching quality. 

With Lyric Audio, the situation is somewhat different, because in addition to distributing other brands, its own Lyritech electronics now also appear. Current examples are the Lyritech Pulse as a tube phono stage and the Lyritech Timeless as a 300B-based mono-dual power amplifier. Especially with such devices, the tube configuration should always match the respective concept exactly, because here it is not a broad product family, but rather individual, clearly defined tube models that make sense as a sonic upgrade. Many suitable tubes for Lyric devices are available from BTB in selected quality, with power tubes also available on request as matched pairs and quartets. 

Due to the currently frequent inquiries about the China clone, we have dealt extensively with the EAR834 and tried many options. The best tube is the ECC83 Premium 12AX7 S4A, followed by the 12AX7G ECC803S Tung-Sol Gold Pin and the ECC83 Genalex Gold Lion. The S4A plays with good resolution, pleasant spatiality and many details, but not analytically. It remains pleasant and you can still tell that it is a tube preamp. The Tung-Sol is similar, but plays warmer, with a slightly smaller soundstage. The Genalex sounds a little more forward and open, but has slightly more noise than the other two. In our setup, the PSVANE Art and JJ ECC83S were not a good match. 

With Fender, selected V1 tubes plus cleanly paired power tubes often pay off more than unnecessarily high preamp gain. This fits especially well with models such as Deluxe Reverb, Princeton Reverb, Twin Reverb, Vibrolux Reverb, ’59 Bassman, Hot Rod Deluxe, Blues Junior or Vibro-King, where, depending on the amp, mainly 6V6GT, 6L6GC, EL84, 12AX7 / ECC83, 12AT7 / ECC81, partly 12AU7 / ECC82, 5AR4 / GZ34 and, in individual concepts, also KT66 are relevant. For an independent BTB line, this means: in V1, a selected 12AX7 with normal gain (S4GB), the 7025 or 12AX7WB often work particularly well, while in the power stage S4GB Highgrade power tubes for 6V6GT, 6L6GC or EL84 are useful for stability, matching and a reliable Fender-typical basic character. All tubes suitable for Fender are available from BTB in selected quality, on request also as S4GB handselected / matched power tubes. 

For Hiwatt tube amplifiers, the tube types suitable for the respective model are especially important. This applies in particular to classics such as the DR103 with EL34, ECC83 / 12AX7 and ECC81 / 12AT7, but also to models such as Custom 20 / Little Rig with EL84 and ECC83, as well as the Tube Series T20/10 and T40/20 with EL84, ECC83 and ECC82 / 12AU7. With Hiwatt, cleanly selected sextets and quartets of power tubes such as KT88 are especially important, so that headroom, dynamics and reliability match the respective circuit. All these types are also available from BTB in hand-selected matching quality (S4GB V1 and power tubes). 

With Luxman, the tube choice should always closely follow the respective model. A good example is the MQ-88uC with KT88, the compact SQ-N150 with ECC83 and EL84, as well as the MQ-300 with 300B and 6SN7GTB. Especially with Luxman, it is usually less about experimenting and more about a coherent, high-quality tube configuration that preserves the character of the device. Many suitable types are available from BTB in selected quality, with power tubes also available on request as matched pairs or quartets, as well as rare types such as 6240G or 6336. 

For Orange tube amplifiers, suitable and robust replacement tubes are especially important. This applies, for example, to Rockerverb 50/100, AD30, TH30, OR15 and Rocker 15. Depending on the model, EL34, EL84, ECC83 / 12AX7, ECC81 / 12AT7, 12AU7 or, in some series, also 6V6 are particularly interesting. Orange explicitly describes the AD30, TH30, OR30 and Rocker 15 as all-valve amps with EL84 power stages; in the Rockerverb, EL34 are among the classic power tubes. With Orange, matched power tubes are especially useful so that output, matching and reliability suit the respective power stage. This is particularly important for models with EL34 or EL84 configuration if the amplifier is to run reliably and remain tonally coherent. Many of these types are also available from BTB in premium matching quality. 

For Peavey tube amplifiers, suitable and robust replacement tubes are especially important. This applies in particular to Classic 30 and Classic 50 with EL84 and 12AX7 / ECC83, but also to other models such as Delta Blues, 6505, 6505 MH, ValveKing or JSX. Depending on the series, EL84, EL34, 6L6GC, 12AX7 / ECC83 and partly 12AT7 / ECC81 are typical. In power stages with several power tubes, cleanly matched sets are especially useful. Many of these types are also available from BTB in premium matching quality. 

With Thivan Labs, the overall picture is mainly shaped by classic single-ended Class A concepts. The Flamingo 300B uses 300B, 811A, 572B, 12AU7, 6SN7 and 6V6, while the Eagle 845 uses 845, 12AU7, 6SN7 and 6V6. Especially with these amplifiers, it makes sense to consider the power tube and the preceding driver stages as one coordinated whole. Many suitable tubes for Thivan Labs devices are available from BTB selected, and power tubes are also available on request as matched pairs or quartets. 

With Copland, a carefully selected tube configuration can often bring out even more sound quality. This applies, for example, to models such as CTA407, CTA408, CTA405A, CTA402, CTA506, CTA305 or CTA301. Instead of simply using standard tubes, the sound can be specifically improved with selected Genalex or hand-selected S4A tubes toward more quietness, fine detail and musical naturalness. It is always important to choose the tubes to match the respective unit and the desired tonal tuning.

With jukeboxes, the correct tube configuration is often decisive for preservation and reliable operation. This applies, for example, to amplifiers and jukeboxes from Wurlitzer, Seeburg, Rock-Ola, AMI or NSM. Typical tubes in this field include 6973, 7189 RSD, 7868, 0C3, 6L6GB, 7199, 12AX7 and other classic audio and regulator tubes, as used in many jukeboxes from that period. Since these units have often been running for decades, suitable replacement tubes are especially sought today in order to preserve the amplifier, sound reproduction and function of the jukebox. The decisive factor is always to choose the correct tube for the exact model and the installed amplifier. 

For Soldano tube amplifiers, the tube types suitable for the respective model are especially important. This applies in particular to the legendary SLO-100, to SLO-30, Astro-20, Hot Rod 50 and other classic Soldano amps. Typical here are mainly 12AX7 / ECC83 in the preamp stage and, depending on the model, 6L6, 5881, EL34 or 6V6 in the power stage. Soldano explicitly describes the Astro-20 as an all-tube amp, and around the SLO-100, exactly these tube families have been listed for years as typical configurations. Many suitable types are also available from BTB in premium matching quality. 

With Vincent, or the SV series distributed by Sintron, tube selection should always be based on the exact model, because the hybrid amplifiers use different tube stages depending on the version. Typical examples are the SV-200 with 2 x 6N1, the SV-237MKII with 2 x 6N1P NOS in the preamp stage, and the SV-700 with an elaborate tube preamp stage using 3 tubes per side. The SV-737 is also one of the important current SV models. Anyone who wants to preserve a Vincent amplifier or equip it correctly again therefore needs the right tube for the exact device. Many suitable types for Vincent SV amplifiers are available from BTB in carefully selected, tested or matched quality.

We supply suitable replacement tubes and upgrade tubes for many Air Tight units. These include, for example, the ATM-1 2024 with 1 x 12AT7 / ECC81, 2 x 6CG7 / 6FQ7 and 4 x EL34, the ATM-2Plus with 2 x 12AX7, 4 x 6CG7 / 6FQ7 and 4 x KT88 / 6550, as well as ATM-300 / ATM-300R models with 300B and 5U4GB as rectifier tube. Other Air Tight amplifiers such as ATM-1S, ATM-2211 or ATM-3211 are also covered. Many common types for Air Tight units are available from us in selected quality and, on request, matched.

We supply suitable replacement tubes and upgrade tubes for many Audiomat amplifiers, for example Aria, Opéra Référence 12, Adagio or Récital MKIV. Depending on the model, types such as ECC83S, EL34 / E34L, 12BH7A, ECC99 and KT88 are used. Many common tubes for Audiomat units are available from us in selected quality and, on request, matched. Since, according to your information, we also supply manufacturers and distributors, Audiomat is a particularly familiar brand for us.

With Marshall, it is worth choosing the tubes to match the respective amp concept instead of simply using any standard configuration. For many classics and modern series such as JTM45, Plexi, JCM800, JCM900, JCM2000 DSL/TSL or JVM, mainly EL34 are relevant, depending on the model also 5881 / 6L6, with the JTM45 the KT66, and in the preamp stage 12AX7 / ECC83. Especially with Marshall, the first preamp tube has a major influence on response, noise and the clean structure of the overdrive sound. That is why a selected 12AX7 with normal gain (S4GB) is often the more sensible choice for V1 than the most aggressive possible preamp tube. In the power stage, S4GB Highgrade power tubes are particularly interesting when durability, stability and reliable stage and studio operation are required. Many suitable Marshall replacement tubes are available from BTB in selected quality, on request also as premium-matched power tubes (S4GB). 

Yes, with the right tubes, the sound of many McIntosh units can be specifically refined. Especially with classics such as MC275 and MC1502, but also with tube preamplifiers such as C22 Mk V, C2700 or C8, as well as hybrid amplifiers such as MA252 and MA12000, many users pay attention not only to suitable replacements, but to a tonally coherent selection. Particularly interesting are S4A tubes, hand-selected audio tubes with very clean reproduction, low microphonics and low noise and hum. Depending on the device, types such as KT88, 12AX7 / ECC83 and 12AT7 / ECC81 play an important role. With selected and cleanly matched quality, many McIntosh units can deliver more sound quality than with a simple standard configuration. 

For DIY single-ended power amplifiers and classic SET projects, high-quality directly heated triodes are especially sought after, for example 300B, 2A3, PX4, PX25, 45 and AD1. Such types are the heart of many self-build concepts, whether classic 300B SE, 2A3 monos or more elaborate projects with PX4, PX25 or AD1. At BTB, suitable tubes from Linlai, KR-Audio (Kron), Emission Labs and PSVANE are available for this. EML currently explicitly lists these families in its range, including 320B XLS (AV32BSL), 520B XLS as a replacement for AA52bsl, 300B Mesh or 300B XLS (AA300B), 2A3 Mesh and 45 Mesh. PSVANE offers, among others, 300B and 2A3, and KR continues to position itself as a manufacturer of high-quality audio tubes. 

For Aesthetix, the right tube set depends on the specific model. The Rhea mainly uses 12AX7 / E83CCS and 6922, while the Io also uses these types plus 6SN7. In the Atlas, one 6SN7 per channel is used as the tube gain stage. Across models such as Janus, Calypso, Pandora and Romulus, 12AX7, E83CCS, 6922 and 6SN7 are therefore key tube families. Since Aesthetix refers to matched tubes and correct socket positions, replacement should always be model-specific. BTB offers many suitable types in selected quality, also as matched pairs or quartets depending on the unit.

With Fezz Audio, the device families should be clearly distinguished: Mira Ceti and Lybra 300B represent the 300B world, Silver Luna and Luna Mini stand for EL34, Titania for KT88 and Olympia for the more powerful double-mono concepts. In addition, units such as Alfa Lupi, Omega Lupi or Sagita expand the range upward and into special areas. Our earlier assessment therefore referred only to the 300B models and not generally to all Fezz amplifiers. For Mira Ceti 300B and Lybra 300B, we looked at the topic more intensively: very high on our list is the Linlai WE300B, because sonically it moves in the direction of the great American original, musical, pleasant and with a beautiful soundstage. Also very strong is the Linlai 300B-D Dream Series with high resolution, clean bass and plenty of dynamics. The Genalex Gold Lion 300B is a very good all-round tube with a rather warm tuning, and the JJ 300B does a lot right for its price level with a tight, fast playing style. With Silver Luna or Luna Mini, however, the EL34 is the focus, and with Titania the KT88. Many suitable tubes for Fezz Audio are available from BTB in selected quality, with power tubes also available on request as matched pairs and quartets, as well as suitable upgrade solutions for the preamp tubes. 

With Music Man, it is important to pay close attention to the respective amp version, because many models are designed as hybrid amplifiers with transistor preamp and tube power stage. This applies especially to classics such as HD-130, 65 112, 65 210, RD50 or RD112. Typical here are mainly 6CA7 / EL34 in the power stage; in early versions, a 12AX7 / 7025 was sometimes also used as a phase driver, while later versions may be built differently. Therefore, the tube selection for Music Man should always follow the exact model and circuit. Suitable tubes for many of these amplifiers are available from BTB in carefully selected quality, on request also as premium-matched power tubes. 

Most Pro-Ject tube devices use the following tubes.

Suitable for: Tube Box S2, DS2, DS3 B, RS2, as well as the classics Tube Box S, DS and SE II.

Our top recommendations:

Favorite: ECC83 Premium S4A with optional balanced selection. Very spacious, musical and extremely low-noise. Our best recommendation for a balanced sound.

12AX7 Tung-Sol with optional balanced selection. Warm, rounded sound – ideal for relaxed long-term listening and more analytical systems.

Genalex ECC83 Gold Lion (BTB V1 Set). Outstanding resolution and dynamics. Brings out the finest details perfectly, with slightly higher self-noise than S4A.

Why buy from BTB? Phono preamps do not forgive weak selection. We test our tubes specifically for low noise and freedom from microphonics, so your records sound interference-free. 

With PrimaLuna, tube selection is particularly interesting because the units usually work with EL34 or KT88 from the factory, but the manufacturer also explicitly approves alternatives such as 6550, KT66, 6L6GC, 7581, KT90 or EL37. In the small-signal stages, 12AX7 and 12AU7 also play an important role; PrimaLuna itself points out that noise often comes especially from these tubes. For models of the EVO series, therefore, not only the correct power tube is important, but also a clean selection of the preamp tubes. Many suitable tubes for PrimaLuna are also available from BTB selected, as matched pairs or as premium-matched quartets. 

With Synthesis, the suitable tube configuration depends strongly on the series. The Roma 753AC uses 12AU7 and EL34 / 6CA7, the Roma 37DC+ uses a 6DJ8 input stage, and in more powerful models such as Action A100 Titan or Metropolis NYC100i, KT66 concepts are used. Therefore, the tube choice for Synthesis should always be model-specific and not based only on the brand. Many suitable tubes for Synthesis are available from BTB in selected quality, with power tubes also available as matched pairs or quartets. 

For Wehrmacht equipment and historic military radio technology, the correct type and a technically clean selection are especially important. Tubes such as RV12P2000, RL12P35, P800, LG1 and T15 are particularly sought after here. The RV12P2000 was used as a versatile army tube in many devices, while the RL12P35 was used as a 35-watt transmitting pentode in the shortwave range. Types such as LG1 also explicitly appear in test and radio technology of the German Wehrmacht. Anyone who wants to preserve or restore such devices should therefore specifically look for suitable and tested tubes for the exact respective device. 

For car radios and battery-powered devices, suitable tubes are mainly sought for preservation and restoration. This applies, for example, to classic Becker Europa, Becker Mexico, Blaupunkt Köln, Blaupunkt Frankfurt or Philips car radios, as well as portable battery receivers and suitcase radios of that period. Typical low-voltage tubes in this field include EF97, EF98, ECH83, ECF83, EBF83 and ECC86. The ECH83 was designed specifically for 6 V and 12 V car radios. Suitable tubes for car radios and battery devices are available from BTB. 

For tube televisions, suitable replacement tubes are mainly sought for preservation and restoration. This applies to many units from Grundig, Philips, Telefunken, Saba, Nordmende, Loewe Opta or Schaub-Lorenz. Typical P-series tubes from black-and-white and color televisions are especially in demand, for example PCL82, PCL84, PCL85, PCL86, PCL805, PCF80, PCF86, PCF802, PCC88, PCH200, PFL200, PL36, PL500, PL504, PY88, PY500A or PD500. Picture tubes themselves are not part of our range, but many of the other tube types for TV chassis and signal stages are available. Anyone who needs the right tube for their tube television will find it at BTB. 

With Trafomatic Audio, tube selection depends strongly on the respective device, because the brand ranges from classic 300B SET concepts to powerful KT120 and 6550 / KT88 amplifiers. This applies, for example, to Experience Two MK II and Evolution Two with 300B, to the EOS with KT120, and to the Evolution Elegance with 6550 / KT88. Especially with Trafomatic, the tubes are not only part of the configuration, but also significantly shape the character of the amplifier. Anyone who wants to preserve such a device or equip it correctly again therefore needs the right tube for the exact model. Many suitable types for Trafomatic are available from BTB in carefully selected quality. 

With Tsakiridis Devices, the correct tube choice depends strongly on the respective amplifier concept. This applies, for example, to the Aeolos with EL34 and 12AT7, to the Theseus as a flexible Class A concept with power tubes from EL34 up to KT170, as well as to the Achilles as a 300B monoblock. Models such as Apollon or Artemis also belong to this device family. Anyone who wants to preserve a Tsakiridis amplifier or equip it correctly again should therefore always pay attention to the exact model and the intended tube configuration. Many suitable tubes are also available from BTB selected, as matched pairs or, for power tubes, on request as premium-matched quartets. 

For AC/DC tube radios, the correct U-series tubes and a technically suitable selection are especially important. This applies, for example, to models such as Grundig Musikgerät 87, Grundig Musikgerät 95GW, Grundig Musikgerät 3028 AC/DC, Schaub-Lorenz Touring T50 Automatik or similar AC/DC receivers from that period. Typical tubes include UABC80, UY85, UCH81, UF89, UL84 and, depending on the unit, other U-types. Especially with AC/DC devices, it is important not to use just any substitute, but to choose the tube set that matches the specific device.

The high-end manufacturer Audio Valve from Kassel, led by Helmut Becker until his passing in March 2022, set standards worldwide. As a long-standing tube supplier, we know the specific requirements of his innovative circuits, including the famous ABR autobias control, in detail. Whether Challenger, Baldur, the Assistent series, Luminare or Solaris: we know which tubes deliver the best sound. Electro Harmonix and JJ often form the basis, while Genalex Gold Lion or selected NOS tubes such as 6AS7G RSD, PCL805 or QQE03/12 are used for fine tuning.

For Mesa Boogie, suitable tubes with the correct color code and in STR quality are especially important. Typical Mesa colors are Green, Yellow, Red, Blue and Gray; according to Mesa, they are used to classify power tubes within the intended operating range of the respective circuit. In addition, there are Mesa-specified STR types such as 6L6 STR-445, 6L6 STR-448, 5881 STR-425, EL34 STR-447 or KT-88 STR-488. For high-gain and heavy metal applications, 12AX7 / ECC83 high-gain preamp tubes are also particularly interesting; Mesa describes its own 12AX7 as very high-gain, stable, low-noise and low-microphonic, corresponding to our 12AX7 S4GB High Gain. Many suitable Mesa-compatible tubes in highly selected quality are available from BTB. 

For music cabinets, concert cabinets and classic tube-based audio furniture, suitable tubes are mainly sought for preservation and restoration. This applies, for example, to units such as Grundig Musikschrank 9080, Konzertschrank 9072, Konzertschrank 9079, Stereo-Konzertschrank SO124/60 or SO181, as well as similar furniture-style units from Saba, Nordmende, Loewe Opta, Telefunken or Philips. Typical tubes, depending on the chassis, include EC92 / 6AB4, ECH81, EF80, EAA91, EAF42, ECC81, EL95, EL84 or EM34 / EM35. Anyone who wants to make such devices operational again or preserve them in original condition will find suitable tubes and magic eyes, such as EM84 RSD or EM34E, at BTB Elektronik. 

For OTL projects and transformerless tube power amplifiers, powerful and proven tube types are especially sought after. These include 6336, 6C33C-B, EL509, EL519, 6C41C and 6080 / 6082. Especially 6080 / 6AS7G are considered classic OTL tubes; Atma-Sphere explicitly describes the 6AS7G as a particularly suitable type for OTL amplifiers. 6C33C-B and 6C41C have also been well-known power tubes in the OTL field for years, while EL509 and EL519 repeatedly appear in special OTL and high-current concepts. Anyone who wants to replace defective tubes or build a new OTL project should therefore look for suitable types for the exact circuit and load. 

For post office tubes, authority tubes and professional telecommunications, measuring and amplifier technology, suitable types are mainly sought for preservation, restoration and high-quality special applications. These include sought-after classics such as C3c, E180F, E180CC / 18046, EF860 / EF800, EL861 / E81L, C3m, C3g and D3a. Many of these tubes come from the field of post office, telecommunications and studio technology; E180F and E81L are documented as special pentodes, EF800 expressly for professional telecommunications technology, and C3G / C3m / D3a are considered typical German post office tubes with particularly high-quality electrical data. Anyone who needs the right tube for such applications will find many of these types at BTB. 

The amplifiers from Thomas Reußenzehn are legendary. Since we supplied Mr. Reußenzehn with tubes for a long time, we know the technical requirements of his circuits very well.

In the factory configuration, he preferred to use Sovtek; for upgrades, Tung-Sol or special Russian NOS preamp tubes were often used. After his passing in February 2022, we continue to advise you in finding the right tubes such as 5881, 12AX7, 6550 or others for preserving and optimizing the sound of your Reußenzehn classics. 

For tube pedals, tube distortion units and rack effects units, suitable and cleanly selected preamp tubes are especially important. This applies, for example, to classics such as the B.K. Butler Tube Driver, the Mesa/Boogie V-Twin, the Blackstar HT-Dual or units such as the Damage Control Demonizer. The most requested types here are mainly 12AX7 / ECC83, and depending on the desired tuning also 12AT7 / ECC81 or 12AU7 / ECC82. Especially with such devices, not just any standard tube should be used, but a technically clean and tonally suitable selection. The S4GB tubes with different gain options are particularly suitable for this. 

For portable radios, kitchen radios and battery radios with tubes, suitable and tested replacement tubes in good quality are especially important. This applies, for example, to classics such as Philips Philetta, Philips L3D23T, Philips BX220B, Braun Koffersuper 100B, Telefunken Portable Hi-Fi and similar portable devices from that period. Types such as DAF91, DF91, DAF96 and DL96 are particularly sought after, depending on the device also DK91, DK92, DF96, DL94 or DM71. 

Anyone looking for good branded tubes for a tube radio should pay attention not only to the correct type, but also to quality, origin and a technically clean condition. This applies especially to classic units from Saba, Nordmende, Grundig, Telefunken, Loewe Opta, Blaupunkt, Graetz, Schaub Lorenz, Philips or Siemens. Especially with historic radios, reliable and proven tubes are often more important than just any quick replacement. Depending on the device, a good branded tube can contribute to better operating reliability, clean reception and an overall more coherent sound reproduction. It is therefore worth paying attention to suitable and carefully tested tubes.

For HiFi tube tuners, suitable and tested replacement tubes in good quality are especially important. This applies particularly to sought-after US units such as McIntosh MR65, MR67 and MR71, Fisher FM-100B / FM-200B as well as H.H. Scott LT-110. Especially with such classics, not only the audio tubes but above all the RF tubes are important. Depending on the device, these include 6DS4, 6AQ8 / ECC85, 6AU6, 6AN8, 6BS8 or 6U8. Anyone who wants to preserve such a tube tuner should therefore specifically look for suitable and technically clean tubes for exactly this device. 

For boutique amps and small-series amps, careful tube selection is especially worthwhile, because many of these amplifiers react strongly to response, dynamics and the fine-tuning of the preamp stage. This applies, for example, to Koch models such as Twintone, Powertone or The Greg, to Diezel classics such as VH4, Herbert, Hagen or Einstein, to Bugera series such as 1960, 333, 6262 or Trirec, as well as to Madamp kits and similar concepts. Typical tubes in this field are mainly EL34, 12AX7 / ECC83 and 6L6GC. In many of these amps, high-quality S4GB tubes are particularly interesting when stable, lower-noise and tonally balanced performance is required. Many suitable types for these amplifiers are also available from BTB in selected quality and, on request, as premium-matched power tubes. 

With Line Magnetic, the range extends from classic 300B and 845 concepts to powerful 805 single-ended amplifiers. Typical examples are the LM-845 Premium with 845, 300B, 310A and 12AX7, as well as the LM-805IA as a pure 805 Class A amplifier. This makes Line Magnetic a brand where often not just one single tube, but a complete combination of driver and power tubes is important. Many suitable types for these device families are available from BTB in selected quality, on request also as matched pairs for the power stage. 

For tube radios, vintage amplifiers and many other tube devices, suitable dual electrolytic capacitors, high-voltage electrolytic capacitors and electrolytic capacitors with central mounting are often indispensable. Classic types with 18 mm central mounting are sought, for example, as well as dual versions such as 32+32 µF, 50+50 µF, 3x50 µF or other typical values such as 16 µF for power supply and filtering. Modern replacement types also require the correct capacitance, voltage rating, construction type and clean technical design. For such applications, brands such as Mundorf, JJ and F+T are available from BTB. 

For early video technology with tubes, suitable tubes are mainly sought for preservation and restoration. On the private or semi-professional side, this includes devices such as the Philips EL3400, and in the studio / broadcast sector early systems such as Ampex VR-1000 or RCA TR-22. For the Philips EL3400, types including ECC89, ECF80, EM87, ECC85, ECC88, ECC83, EL95, EF184 and ECL84 are documented. For the studio machines mentioned, I was able to find reliable device sources quickly, but not a clearly readable complete tube list; therefore, I would prefer to mention only the devices in the FAQ. Anyone who needs the right tube for early video technology will find many of these types at BTB for the exact respective application.

With Audio Research, the sound can often be improved further when the tubes are not only technically suitable, but also carefully selected. In high-end units such as Reference 6SE, Reference 10, Reference Phono 3SE, PH9 or Reference 160M MkII, types like 6H30Pi, 6550, KT120 or, depending on the generation, E88CC / 6922 play an important role. For better sound, selected tubes with high stability, low noise and a balanced tonal character are recommended. S4A tubes are especially interesting for clean reproduction, a quiet soundstage and fine resolution.

With Conrad-Johnson, the correct tube configuration depends strongly on the respective series. In the power amplifiers, models such as Classic 62 and Classic 120 are good examples of EL34 concepts; Conrad-Johnson describes the Classic 62 output stage with one pair of EL34 per channel, and the Classic 120 accordingly with two pairs. In addition, there are many well-known tube preamplifiers and phono stages from the current and vintage lines. Anyone who wants to equip a c-j unit correctly should therefore always follow the specific model closely. Many suitable tubes are available from BTB in selected quality, and power tubes are also available on request as matched pairs or quartets.

With Symphonic Line, the main focus is on specifically optimizing the tube stages that are truly decisive for the sound. This applies especially to devices such as Erleuchtung, Erleuchtung Reference MK3 HD, Phono Preamplifier and Phono Reference HD. Especially here, a very careful selection is more worthwhile than a simple standard configuration. Anyone who wants to further improve the sound should above all pay attention to quiet, selected and tonally coherent tubes. This can often achieve more quietness in the soundstage, finer resolution and more natural reproduction. 

For classic reel-to-reel tape recorders with tube technology, suitable tubes are mainly sought for preservation and restoration. This applies, for example, to the Revox G36, professional Studer machines such as the C37, as well as popular Grundig units such as TK 20 or TK 45 and many models from Philips. In such tape recorders, depending on the model, tubes such as EF86, ECC83, ECL82, EM80, EM84 and EZ80 play an important role. Anyone who wants to make such a machine operational again or preserve it in original condition will find these at BTB Elektronik. 

For vintage audio classics, suitable replacement tubes in good quality are especially important. This applies to brands such as The Fisher, EICO, Harman Kardon, Klein + Hummel / Telewatt and Pioneer, as well as classics like Scott, Sherwood, Sansui, Dynaco or Leak. Typical audio tubes such as 7591, 7868, 6973 and ECL82 are often in demand. To keep these amplifiers, receivers or power amps reliable, carefully tested tubes should be used to preserve operating safety, sound quality and the classic character.

For speakers with ion tweeters or plasma tweeters, suitable tubes are mainly sought for preservation and repair. This concerns well-known manufacturers such as Acapella Audio Arts and Lansche Audio. Typical tube types in this field are EL509, EL519, PL509, PL519 and other related high-voltage tubes, as used in such high-frequency systems. Anyone who wants to make a speaker with an ion or plasma tweeter operational again or preserve it will find what they need at BTB Elektronik. 

For Tesla generators, VTTCs and other high-voltage experiments, the tubes sought are often exactly those that have been typical for such setups for years. These mainly include 811A, 572B, 833A or also 810. The 811A in particular is considered a very popular entry-level type in the VTTC scene, because it is widely used and has proven itself in many classic setups; 572B and 833A tubes also appear regularly in such projects. Anyone who wants to replace defective tubes or preserve a historic setup should therefore look for suitable types for the exact generator or experimental setup. 

With Unison Research amplifiers such as S6, Sinfonia, Triode 25, Simply Italy and Simply Two, a tube upgrade depends especially on robustness, clean matching and the right tonal tuning. Depending on the model, types such as EL34, KT88, ECC82 and ECC83 are used. Since many of these units put considerable stress on their tubes during operation, not only the correct type should be chosen, but also a quality that proves itself over the long term. This is exactly what we pay attention to when selecting our upgrade tubes. 

For Volksempfänger and similar radios from the Second World War era, suitable and carefully selected replacement tubes are especially important. This concerns devices such as VE301, VE301 Dyn, DKE38, Olympia-Koffer or similar receivers from this period. Typical tubes include RGN1064, RES164, VCL11 and V301, as well as A-series tubes such as AF3, ABC1, AL4, AK2, AZ1 or UCL11. In the VE301 Dyn, for example, AF7, RES164 and RGN1064 are documented; in the DKE38, among others, VCL11. Anyone who wants to preserve or restore such devices should pay attention to the tube configuration suitable for the respective model and to replacing the capacitors. 

For Hughes & Kettner, suitable and robust tubes for the respective model are especially important. This applies in particular to TubeMeister Deluxe 20/40, GrandMeister Deluxe 40 and TriAmp Mark 3. The amps are especially popular for their great sound variety, modern high-gain sounds, recording suitability and practical features such as Power Soak, Red Box and, in some cases, MIDI. Depending on the model, EL84, EL34 and 12AX7 / ECC83 are especially typical. For many applications, S4GB tubes are also interesting when a particularly stable, low-noise and gain-resistant behavior is required in the preamp stage. Many suitable types are also available from BTB in selected quality and, on request, matched. 

BTB supplies high-quality and selected tubes for many tube microphones and tube preamps, for example from Neumann, Microtech Gefell, AKG, Brauner, ADK and Telefunken. Especially in such applications, low noise, low microphonics, stable behavior and clean selection are particularly important. Typical tubes here include EF86, EF806s S4GB, AC701, 5840, EF732, EF95, ECC83 / 12AX7 S4GB Clean and other selected microphone tubes. This is exactly what we pay attention to at BTB. 

The Italian high-end classics from GRAAF are technically brilliant, but demanding. Since BTB was the tube supplier for Giovanni Mariani for many years, we know his units very well and know exactly which selections are necessary for stable operation.

Our expertise for your GRAAF classics:

OTL models (GM 200 & GM 20): For the Russian 6C33C triode, we supply specially selected, precisely matched sets that are essential for the thermal stability of these OTL circuits.

Special case GM 100: This unique unit requires a perfectly homogeneous matrix of 32 pieces 12AX7 (ECC83). We put together precisely matched large sets for this purpose.

Preamps & upgrades: Whether 6922 / E88CC, 12AX7 or 5751 – from the solid Sovtek basis to S4A or Genalex Gold Lion, we carry exactly what fits these concepts.

Giovanni Mariani sourced the tubes for his production from us for a long time. We know the requirements for the tube values of his models and help you secure the longevity of your units. 

We supply suitable replacement tubes and upgrade tubes for many Leben amplifiers. These include, for example, the Leben CS-300 and CS-300XS with 4 x EL84 / 6BQ5 and 2 x 12AX7A, as well as the Leben CS-600 with 4 x 6L6GC or optionally 4 x EL34 / 6CA7, plus 4 x 6CS7 and 1 x 6CJ3. We also carry suitable tubes in selected quality and, on request, matched quality for other popular Leben units such as RS-28CX, RS-30EQ or CS-1000P. Many of these tubes are available from stock in premium matching quality. The official Leben product pages also list these configurations for the models mentioned. 

For historic radios and pre-war devices, it is especially important to find the tube series and version that matches the respective unit. Older series such as RE, RES and RENS are particularly sought after, supplemented by some early A-series tubes. This applies to many classic units from Telefunken, Saba, Mende, Blaupunkt, Lorenz, Philips, Graetz or Loewe. Especially with such radios, a suitable and carefully selected replacement is more important than just any tube, because construction type, base and technical design must match the respective device series. 

For measuring instruments, tube voltmeters and oscilloscopes, many tubes are mainly sought for preservation and restoration. This applies, for example, to classic Tektronix oscilloscopes such as 535, 545 or 545A, to Heathkit tube voltmeters such as IM-11 and similar VTVM models, as well as to laboratory instruments from HP such as the 410B. What is needed here are not the picture tubes / CRTs, but the other functional tubes in the measuring and amplifier sections. Typical tubes in this field include, depending on the device, 12AU7, 6AL5, 6DJ8 / ECC88, 6CL6, 6CB6, 6DK6, 6AU6, 6U8, 5651 or high-quality types such as E80F for precise measuring and amplifier applications. In the Heathkit IM-11, the combination of 12AU7 and 6AL5 is explicitly described, and in the large Tektronix 545 units, 6CB6 and 6DK6, among others, are typical tubes of the vertical amplifiers. 

For classic ELA amplifiers and older public address systems, the exact tubes that are really required for operating the unit are often decisive. This applies, for example, to equipment from Siemens, Telefunken, Dynacord, Electro-Voice, Telewatt / Klein + Hummel and similar amplifiers from that period. Typical tubes in this field include EL500, EL504, EL12, EL34, ECC83 and, in the case of Klein + Hummel, also EL5000. For Siemens, for example, the 6S Ela 2524 with EL34 and ECC83 is documented; in many ELA, studio and public address amplifiers from these years, exactly these types appear again and again. Anyone who wants to preserve such equipment or make it operational again will find the desired tube, also premium matched on request, at BTB. 

For tinkering, experimenting and unusual DIY projects, the less obvious tubes are often especially interesting. Affordable sleeper types include, for example, EL12N, EL861 / E81L, EF860 / EF80, EF183, E180F, 5678 and 1J24. Many of them originally come from RF, industrial or special applications and are now excellently suited for creative preamps, small power amplifiers, headphone amplifiers or laboratory and hobby setups. The EL12N, for example, also appears in DIY audio projects as a power tube, EF80 / EF860 and EF183 are popular as versatile pentodes, E180F is considered a particularly interesting quality type, and 5678 as well as 1J24 are interesting candidates for compact or unusual circuits. Many of these tubes are available from us at particularly attractive prices. 

With Octave, the tube choice is particularly interesting because many amplifiers are not limited to one single power tube type and therefore deliberately offer room for a suitable new configuration. This applies, among others, to V 40, V 40 SE, V 70 SE, V 70 Class A, V 80 SE, V 110 SE, MRE 130, MRE 220, MRE 220 SE, HP 300, HP 300 SE and HP 500. Especially with used units, it often makes sense to first follow the previous or original tube configuration and then decide specifically in which direction the amplifier should perform. In many Octave models, 6550, KT120, KT150 and KT170 are used; for example, 6550 JJ, KT88 Genalex or also the KT88 Carbon S4A have proven themselves very well here and perform very coherently in many Octave amplifiers. With the Jubilee models, however, the selection should always be matched more precisely. Many suitable tubes for Octave are available from BTB in selected quality, with power tubes also available on request as premium matched pairs or quartets. 

For portable record players with tube technology, suitable replacement tubes are mainly sought for preservation and restoration. This applies to many portable record players and compact music cabinet units from Dual, Philips, Grundig, Perpetuum Ebner, Telefunken or similar manufacturers. Typical tubes in this field include, depending on the device, ECL82, ECL86, UL84, UY85, UCL82 or ECC83. Anyone who wants to make a portable record player operational again or preserve it in original condition should therefore look for the correct tube for the exact model. 

BTB supplies high-quality and selected NOS tubes for many classic tube-based studio devices, for example for Telefunken V72, V76 and V78, Fairchild 660 / 670, Pultec EQP-1A or Klein + Hummel UE 100. The most sought-after types include EF804S, ECC81 / 12AT7, ECC83 / 12AX7, ECC82 / 12AU7, 6386, 6973, 6BC8 or 6X4. Especially with vintage studio technology, low microphonics, clean premium matching and careful selection are essential. This is exactly what we pay attention to. 

RSD stands for Röhren Schnell Dienst. In 1951, its inventor Germa Weiss from Frankfurt established it as a brand based on a marketing idea. RSD tubes have been found for decades all over the world in radios, tube amplifiers, historic televisions, radio equipment and all kinds of tube devices. RSD tubes offer a very good price-performance ratio; they are double-tested, come with a 6-month warranty from the brand owner BTB Elektronik, and are very reliable. In earlier days, these tubes mostly came from the GDR, as Germa Weiss, later Gert Müller, were the only importers of these tubes and held the license for Eastern tubes for “brown goods” in the West. Later, Tesla, Ei, Polamp, Tungsram, Russian and Western tubes were also used for RSD tubes. 

S4A stands for selected for audio. This means that these tubes are specifically intended for audio applications. The special characteristics of these tubes are extremely clean and low-distortion reproduction, with very low background noise in terms of microphonics, noise or hum. These tubes are mainly used for music reproduction in audiophile tube devices, for example tube preamps and power amplifiers, DAC outputs, CD players, phono preamps and tube filters, but also in the studio and microphone sector for recording and playback, for example tube microphones, mixing consoles, tube compressors, amplifier modules, EQs and preamps. The tubes are hand-selected at the factory by BTB Elektronik for low distortion and low noise. The matched / balanced option makes sense in all multi-channel systems, such as stereo or surround, differential amplifiers and phase inverter stages. 

For many vintage DIY and self-build amplifiers, suitable replacement tubes in good quality are still in demand today. This applies, for example, to classic ELRAD projects, well-known Elektor concepts such as Williamson variants, the designs by Mr. Haas from Experience Electronics, Welter Electronics, later Raphael, Bubeck 300B projects, as well as Heathkit classics such as W-5M and AA-100. Typical tubes in this field include EL34 / E34L, KT88, 300B, ECC83 / 12AX7, ECC82 / 12AU7 and, depending on the circuit, also EF86 or 6550. These are available from BTB in premium matched quality. 

LUA units are popular and widely used. Unfortunately, Mr. LUA has since passed away. Since we supplied the tubes to Mr. Lua, we know his devices well and know what works well here. As a basis, he often purchased Electro-Harmonix tubes from us, but also liked to use Genalex Gold Lion tubes, and in some cases also NOS preamp tubes. For the reasons mentioned, it makes sense to call us for advice. 

S4GB stands for selected for Guitar and Basses. These tubes are intended for amplification in guitar, bass and effects devices, as well as all musical instrument amplifiers. Unlike S4A tubes, they are not selected for low distortion, but for good dynamic playability, openness of sound, with different levels for different amps and sound directions in the 12AX7 range, and robustness in mobile use. All tubes are hand-selected at BTB Elektronik for low microphonics, low noise and low hum, so that the amp works quietly on stage, at home or in the studio. For preamp tubes, we offer the matched / balanced option. This is particularly advantageous for the phase inverter stage and clean operation. This option can also be beneficial when used in the studio, for example in a compressor, or in multi-channel effects devices. 

For older guitar and bass amplifiers, rare tube types are often not only interesting, but simply necessary for continued operation if the original configuration is defective. These include, for example, 6C10 and 6K11 in various Ampeg circuits, 7247 / 12DW7 for example in the Ampeg B-15, 7581A as a robust variant in stronger 6L6GB concepts, as well as EL503 and PL84 in rarer European amplifiers such as certain Hohner units. Unusual types such as EL12 also appear again and again in older individual concepts and modifications. In such cases, what is needed is not just any standard replacement, but a suitable tube for the exact device and its circuit. 

The many different 300B tubes offered, meaning WE300B, sometimes differ enormously. If you want to replace them, you should therefore ask yourself a few questions before buying:

Do I want a replacement or an upgrade?

Are there any sonic goals or wishes?

What budget am I aiming for?

Can I live with using an exotic type that may no longer be available later?

Once you are aware of this, we at BTB look forward to your specific inquiry.

As a small tip in advance, in the lower price segment the 300B from JJ and PX300B from Genalex are excellent tubes. The entry into real WE300B starts with us with the WE300B from RSD, the price-performance winner is the WE300B from Linlai, and as a top product we naturally see the royal class from the USA: the WE300B from Western Electric with a 5-year factory warranty and a very stable resale value. 

Replacement tubes for tube amplifiers are compatible tubes, for example 12AX7 = ECC83, that replace worn or defective tubes. Since tubes are wear parts, replacing them is part of regular maintenance. It is important that the replacement tube fits the amplifier electrically, mechanically and operationally in order to ensure safe operation and the desired sound, especially in a guitar tube amp.

A distinction is made between preamp tubes, power tubes, rectifier tubes and RF tubes in tube radios. Preamp tubes such as ECC83 or ECC82 amplify small signals and can usually be replaced without problems by the same type, for example 6922 = E88CC. Power tubes such as EL34, EL84, 6L6 or KT88 provide the output power and often require checking or setting the idle current (bias). In push-pull amplifiers, they are usually used matched. Preamp tubes in the input stage should be selected for V1, meaning low microphonics and low noise, and in multi-channel devices they should also be matched plus balanced. Rectifier tubes must of course also match in terms of type designation. If further replacement types are approved, there is nothing against using them for sonic, price-related or aesthetic reasons. 

When it comes to making a setup with ECC83 / 12AX7 move forward, so that it really hits you in the stomach and delivers attack, these types should be considered:

ECC83 S4A Dynamic – this tube provides speed, remains balanced, low-distortion and is a lot of fun

12AX7B Shuguang – this tube delivers attack, pressure and real fun with rock and fast beats – price tip

12AX7LPS Sovtek – great attack, good detail, a slightly brighter and more open tone, with well-controlled bass

If you want to spend a little more here, you can also look at NOS types; however, these can sometimes be difficult to obtain. We recommend buying from a specialist dealer, for example BTB Elektronik.

ECC83 Telefunken with Ribbed Plates – sound fast, open, precise, dynamic and tight in the bass

ECC83 RFT – this one makes music and can really kick – anyone looking for fun should have tried it

12AX7WA JAN USA – a robust tube that is a lot of fun and sounds powerful and tight 

The first answer is the basic application – whether it is a HiFi amplifier or a guitar amplifier. Here we distinguish between S4A tubes for audio, HiFi and studio equipment and S4GB tubes for musicians’ amplifiers such as guitar amps or bass amps. 

This is probably the top class among ECC83 tubes, because they are intended above all to work cleanly and precisely:

ECC83 Premium S4A – sounds very clean and spatially structured, rich in detail, but not analytical – BTB tip

ECC803S Tung-Sol GOLD – sounds precise, clear, slightly tighter in the bass, and never becomes annoying

ECC803S JJ – clean, clear, honest, but slightly rounder in the highs

Unfortunately, the cleanest NOS tubes now cost a lot of money and have become rare, as there is naturally high demand here. To avoid unpleasant surprises, these should be purchased from a specialist dealer such as BTB Elektronik:

ECC803S Telefunken – the finest of the ECC83 tubes – the best, without ifs or buts

E83CC Siemens – without any doubt outstanding – everything is there, it does not become annoying, sounds like a tube – our NOS tip 

Among newly produced tubes, these are:

ECC83 S4A Smooth – pleasant, smoother and unobtrusive tube sound with good resolution

12AX7 Tung-Sol – subtle, warm, good for voices and smaller ensembles

5751 Tung-Sol – usually interchangeable; the slightly lower gain can be useful, good for full-range drivers and horns

ECC83S from JJ – very well suited for rock and pop, but also classical music – the price hit in this category

ECC83 Mullard / 12AX7 Mullard Reissue from Russia – sounds warm, but does not come close to the original

12AX7-S PSVANE – can also be tested in this context

When it comes to NOS tubes, it can become very expensive, or the type may already be sold out. It is advisable to always buy such NOS tubes from a specialist dealer, for example BTB.

ECC83 Valvo – the warm-sounding all-rounder; everything is simply right here

ECC83 Mullard NOS (not reissue) – warm, many details, but also slightly more open than Valvo

ECC83 Tungsram – rare, high quality and well suited for frequent listeners 

When it comes to charm and musicality, it is usually hard to get around these tubes:

ECC83 S4A Performance – musical, open, natural, audiophile sonic characteristics, the best all-rounder for tube amplifiers

ECC83 Genalex Gold Lion – similar to ECC83 S4A Performance, but not highly selected

ECC803S JJ – open, but never intrusive, good for frequent listeners – our price tip

Of course, there are also recommendations for musical-sounding NOS ECC83:

ECC83 Telefunken Smooth Plate – lots of warmth, musical, slightly brighter, not intrusive

ECC83 Philips from NL – excellent tube, shows a lot of space and aura and sounds pleasantly musical

ECC83 RSD – affordable NOS tube that plays very musically, openly and naturally 

Tubes that are intended to amplify phono signals must above all be low-noise, low-distortion and well selected, meaning matched and balanced, because these devices often have very little negative feedback; therefore, the characteristics of the tube have a strong effect here:

ECC83 Premium S4A – low-noise, low-distortion, sounds excellent, detailed, pleasantly spacious and sounds like a tube – currently the best choice when it comes to phono preamps.

ECC803S Tung-Sol GOLD – tends toward warm sound, good S/N ratio, a good alternative for experimenting.

ECC83MG JJ – relatively unknown, comparatively low-noise, sounds pleasant and has excellent resolution – this tube is the tip when it comes to price-performance in vinyl playback.

With NOS tubes, special attention should be paid to acoustically tested tubes because of background noise; therefore, it is better here as well to buy from a specialist dealer:

E83CC Tesla NOS – sounds warm, pleasant and musical, with low noise.

E83CC Siemens – sounds musical, structured and precise. 

First, you have to check whether the tube type you are looking for is available as new production. For most HiFi tubes, for example EL34 or KT88, high-end audio devices, for example 300B or 845, as well as guitar and bass amps, for example 12AX7 or 6L6GC, tubes from current production, such as JJ or Tung-Sol, can be purchased. Typical radio tubes, for example ECH81 or EF85, are usually only available as NOS stock, so the question does not really arise there. Newly produced tubes are cheaper and can be matched or selected much better, because large quantities can be measured. With NOS tubes, availability is limited and demand is high, so the price is significantly higher. Sonically, NOS tubes are not automatically better. It is best to buy selected quality tubes, for example S4A or S4GB tubes, or high-quality branded tubes, for example Genalex or Linlai, plus selection where available. 

Lundahl output transformers, unlike standard output transformers, have a high-quality dual-coil C-core design made of grain-oriented silicon iron strip-wound core material (VM111) and are suitable for both single-ended and push-pull tube amplifiers. Different core air gaps and configurable primary and secondary impedances allow flexible impedance matching while making maximum use of the windings. This significantly improves coupling and therefore bandwidth and impulse response quality. Optional amorphous cores are available, which can offer sonic advantages, but have around 30% lower signal handling capability. 

Lundahl transformers are very high-quality audio transformers from Sweden and are used for galvanic isolation, balancing and impedance matching. Typical applications include output transformers for tube amplifiers, either single-ended or push-pull, MC step-up transformers for high-quality phono systems, line input and output transformers, balanced or unbalanced, and interstage transformers.

Depending on the circuit, Lundahl transformers are used to improve sonic characteristics, reduce hum and, of course, for matching. 

In the context of our tube-related topics, line transformers are used to transmit high-level audio signals in balanced or unbalanced form, to match input and output levels or impedances, to avoid ground loops and to safely isolate devices from each other. They are often used in preamplifiers, studio equipment, DIY solutions and DAC outputs. A correctly selected transformer ensures proper matching, clean levels, low distortion and high bandwidth.

Typical products include, for example, the Lundahl LL1545, LL1676, LL1680 and the price tip LL1930. Correct impedance matching is important in this context. If in doubt, please send us an inquiry. 

We offer single-ended and push-pull output transformers for DIY HiFi, Lundahl audio high-end, replacement transformers for many Hammond guitar amplifiers, low-cost OPTs, transformers for headphone amplifiers, DI transformers and output transformers for tube preamps from stock. 

For moving-coil (MC) cartridges, Lundahl step-up transformers (SUT) are used to raise the very small signal to MM level. Important factors are the turns ratio, input impedance and the desired gain. The selection depends on the internal resistance of the cartridge and the phono input. For optimal results, the transformer should be matched according to the data sheet and the system data.

The most popular models for normal impedance are the LL1931 and LL1933. For systems with low impedance of just a few ohms, the LL1941 is suitable, while the LL1681 is our price tip. 

With most Lundahl output transformers, there is no way around the data sheets, as most types offer several connection options and therefore a larger number of transformation ratios. This allows the windings to be used as effectively as possible and improves coupling. The data sheets can be found from the manufacturer or in the BTB Elektronik online shop under Downloads for the respective product. Please note that both sides, meaning the primary side and the secondary side, must always be wired. In many cases, bridges also have to be soldered according to the diagrams.

The star in the circle in the data sheet always marks the beginning of the winding and is therefore important for polarity, meaning the phase position. V+ is the transformer input on the primary side, coming from the power supply. Tube Anode is the anode connection. The secondary connection is usually optimized for a specific load impedance.

For example, if you look at the data sheet for the Lundahl LL1620, LL1623, LL1627 or LL902, you will find a three-column table. Depending on the desired primary impedance (Ra or Raa), the secondary side is then wired accordingly, for example B/C/D for 4 Ω / 8 Ω / 16 Ω or C/D/E for 4 Ω / 8 Ω / 16 Ω.

Example 1:

Single-ended operation with Ra = 3 kΩ and Rl = 8 Ω, selected transformer LL1623 (90 mA), then the following applies:

• “Primary Connections”: right column, lower diagram

• “Secondary Connections”, meaning secondary: middle row, left diagram (C)

Example 2:

Push-pull operation with Raa = 3.3 kΩ and Rl = 8 Ω, selected transformer LL1620 (PP), then the following applies:

• “Primary Connections”: diagram at the top far left

• “Secondary Connections”, meaning secondary: middle row, right diagram (D)

Tip: If oscillation or whistling occurs in push-pull circuits, it may be necessary to swap the two anode connections and, if necessary, G2 as well. 

Connection is carried out according to the data sheet: windings can be connected in series or in parallel for different step-up or step-down ratios. Important factors are the correct phase position, grounding and the desired operating mode, either balanced or unbalanced. Incorrect wiring can lead to level loss, hum or incorrect channel phase. If you are unsure, the Lundahl data sheet will help; it can be found in the BTB online shop under Downloads for the respective product.

Example:

Line transformer LL1680 as a single-ended output transformer for the ECC82 – idle current is max. 5 mA, Ra = 15 kΩ, Rl = 600 Ω.

For an unbalanced output (RCA), diagram B applies; for balanced operation (XLR), diagram A applies accordingly. 

When selecting an output transformer for EL34 push-pull operation at BTB Elektronik, the first question is the matching, meaning the Raa. According to the Telefunken data sheet (see image on the right), the desired anode voltage provides good orientation. With the usual 350 volts to 500 volts, you will usually end up between 3 kΩ and 5 kΩ. This is also not overly critical, as most loudspeakers are not impedance-linearized. It seems sensible to choose around 3 kΩ – 4 kΩ at lower anode voltage and rather 4 kΩ – 5 kΩ at higher voltages from 450 V – 500 V.

The second question is whether you can live with only one secondary impedance without rewiring, but in return make use of the better audio characteristics of the transformers. Further questions concern the budget, the size, and whether you want to use ultralinear and/or cathode feedback (CFB).

Here is a list of suitable transformers:

Lundahl LL1623 PP Raa = 3.3 kΩ → very wide-bandwidth, very low-distortion, sounds excellent, one load impedance each

Lundahl LL1679 PP Raa = 4.5 kΩ → very wide-bandwidth, very low-distortion, sounds excellent, one load impedance each

Lundahl LL3723 PP Raa = 4.3 kΩ → the finest among high-end push-pull EL34 output transformers. This type has UL taps at 33%, goes up to 160 Wout (@30 Hz) and covers 5 Hz – 60 kHz (−1 dB)

Hammond 1650NA Raa = 4.3 kΩ – good for DIY tube amplifiers with 4 Ω, 8 Ω and 16 Ω connections plus UL up to 60 Wout

Hammond 1750N Raa = 3.2 kΩ – the ideal transformer for guitar amps based on the Marshall JCM800 / 2204 specification

Hammond 125E Raa = 3 kΩ – 6 kΩ – the small entry-level transformer for experiments with lower power up to 15 W 

Lundahl uses this to optimize its transformers for the specified nominal current (bias). At this current, the core is still far from saturation, providing more headroom. The number of windings and the air gap are optimized so that ohmic losses, leakage inductance and winding capacitance remain low, while the primary inductance is as high as possible for the available construction size. All of this together guarantees optimized bandwidth, low distortion and lower transformer losses than with conventional output transformers.

If you are planning a small series, you can also specify your desired nominal current at BTB if it is not already available, and we will offer you the matching Lundahl transformer.

Info:

Of course, Lundahl transformers can also be operated with a lower current than the specified value. 

First, please clarify whether it is a single-ended or push-pull output stage. After that, the primary impedance, power rating or the power tube type must be known in order to make the correct selection:

For low-output and low-impedance cartridges, for example Ortofon SPU, the LL1941 is often the best choice, as it can provide both 1:16 and 1:32 step-up ratios. If the solution should be more affordable, the proven LL1681 and also the LL9226 are good alternatives. For low-impedance matching, it is important to choose the higher step-up ratio.

From experience, an LL1941 set to 1:16 sounds more airy and homogeneous than an LL1931 at 1:16. For very low-output systems and less sensitive inputs, the 1:32 step-up ratio is preferable.

If the phono input is not terminated with 47 kΩ, as is usually the case, a parallel resistor should be connected to the transformer output so that the transformer can work cleanly and the system sees a sensible load for damping.

The LL1943 would also be conceivable, as it may offer advantages in the bass range; however, in terms of dynamics, the LL1941 has the edge. 

With most Lundahl output transformers, this is unfortunately not possible without reconfiguration. Lundahl has usually chosen a fixed configuration in favor of better coupling and better utilization of its individual windings. This results in significantly better bandwidth and lower distortion, which benefits the sound. For the LL1620, LL1623, LL1627 and LL9202, we have attached an extra PDF datasheet showing how to switch between two impedances with three jumpers or three relay contacts per channel. If you want to commit to one setting in your DIY project, you should usually choose the lowest impedance for tube amplifiers, in this case 4 ohms, as this is often more advantageous sonically and the difference in power is negligible in most cases. 

We have merged our blog with Jogis Röhrenbude, which we continue to run after the death of Joachim Gittel. There you will find vintage circuit diagrams for tube devices, customer circuits, free reading material on the subject of tubes, descriptions of tubes and devices for tinkering, DIY and amplifier building. Have fun browsing, yours, Michael Kaim 

In amateur radio and CB radio, robust transmitting tubes matched to the specific equipment are especially important. Typical examples are 811A and 572B in classic linear shortwave amplifiers such as the Ameritron AL-811 or AL-572, 3-500Z in powerful HF linear amplifiers, 6146B in transceivers such as the Yaesu FT-101ZD, 4CX250B in amplifiers like the Dentron MLA-2500 and QQE06/40 in 2 m HF stages. EL509 and EL519 are also used, especially in older or modified linears. In such amplifiers, technically suitable tubes are essential.

With organs and Leslie amplifiers, a technically clean and robust replacement is especially important. This applies, for example, to classic Hammond models such as B3, C3, A-100 or RT3, as well as popular Leslie cabinet systems such as 122, 145, 147 or 251. Especially in Leslie amplifiers, the 6550 plays a central role; Hammond Organ explicitly names it as the standard for most Leslie tube amplifiers and points out that it should be used in matched pairs. In many Leslie amps, 12AU7 and, depending on the model, also 0C3 are used; in classic Hammond organs, 12BH7, 12AU7 and, depending on the model, other types are also relevant. 

Especially in phono preamps and sensitive tube preamplifiers, particularly low-noise, low-microphonic, low-distortion and low-hum tubes are important. That is exactly why S4A tubes are often especially interesting here: they are very well suited for applications where a lot of gain is required and, at the same time, quietness, stability and clean reproduction are crucial. Especially in phono stages, a carefully selected tube can bring more sound quality than a simple standard replacement, because even small differences in noise, microphonics and matching become clearly audible. This applies, for example, to popular units such as the Pro-Ject Tube Box DS2 and Tube Box DS3 B, which Pro-Ject explicitly positions as tube phono preamplifiers, or to classics such as the EAR Yoshino 834P. Models such as the PrimaLuna EVO 100 Tube Phono Preamplifier or Manley Oasis also show how important a clean tube stage is in high-quality phono preamps for noise behavior, dynamics and fine resolution. 

BTB comes from the names Ballwieser – Thomanek – Bergbauer. They were the second generation from 1981 onward, following the Eugen Queck engineering office. For a time, the former managing directors also used the abbreviation BTB for marketing purposes for our wholesale business as Business To Business. 

With high-quality coupling capacitors, the sound of many tube devices can be improved further. This applies, for example, to units such as the Musical Paradise MP-701 and MP-301 tube preamplifier, older Experience Electronics concepts, many imported tube devices from the Far East, as well as some tube DACs or Dynavox preamplifiers. For such applications, high-quality film capacitors such as Mundorf MCap Supreme EVO Silver Gold Oil are particularly interesting. Mundorf itself describes the Supreme EVO series as a combination of very good impulse response and pronounced spatial imaging. In suitable devices, this can contribute to more fine detail, better quietness and a more coherent reproduction. 

The best and most well-known link we know is Frank Pocnet, to whom we are very grateful for the enormous effort! 

For tube radios and many vintage devices, suitable replacement capacitors are often just as important as the correct tube. Particularly sought after are axial film capacitors, for example Mundorf MCap or MKT 72, when old paper or tar capacitors need to be replaced reliably. Equally important are suitable electrolytic capacitors, such as classic types with 18 mm central mounting in dual versions like 50+50 µF, but also older values such as 4 µF or 20 µF, as found in many historic devices. The decisive factors are always capacitance, voltage rating and construction type, so that the replacement fits the device electrically and mechanically. We also offer a unit calculator that quickly converts values from cm to uF. 

Electron tubes have different designations because they were named according to different standard systems in different countries. There are often European type names, for example ECC83 or EL34, and American type names, for example 12AX7 or 6L6, for the same tube. Common examples of identical tubes with different designations:

ECC83 = 12AX7
ECC82 = 12AU7
ECC81 = 12AT7
E88CC = 6922
EL34 = 6CA7

In addition, there are often industrial, military or selected variants with their own type numbers, for example especially low-noise or longer-lasting versions. Manufacturer labels and rebranding also mean that identical tubes are offered under different names.

Tip: It is best to buy from the BTB specialist trade to check and make sure that it is a genuine equivalent in terms of socket, heater data and electrical values – because similar tubes are not always interchangeable 1:1. 

Whether tubes are defective can only be partially recognized visually. Some specific damage is visible, but many defects are not. A clear sign of a defective tube is a whitish coating inside the glass bulb, which indicates lost vacuum. Cracks in the glass, a loose base or damaged pins also mean that the tube must no longer be used. Unusual glow behavior, e.g. a purple glow, can also indicate problems. If the tube does not glow at all, the heater filament may be interrupted, although some tubes also glow very darkly. If the anode glows red, there is acute danger, e.g. bias too high due to grid current. A slight blue shimmer is usually not critical. In some tubes, a brown or gray coating appears on the glass; in others, the getter mirror fades. However, these signs are not a direct indication of tube wear. Only an electrical tube test by a specialist dealer can provide clarity. 

The white top of a tube is a clear sign that the tube has drawn air and lost its vacuum. The tube is defective and must be replaced. Such defects can be caused by dropping the tube, for example when the pump tip breaks off, by overload, poor tempering during production, faulty contact feedthroughs and, especially with Noval and miniature tubes, when the PCB socket was not properly centered during circuit board assembly. Due to the asymmetrical arrangement of the contacts, mechanical stress occurs in the tube. The tube then breaks at the glass base and turns white.

Remedy: insert a sample tube and, with the tube inserted, resolder the tube socket on the board. 

Strictly speaking, the tube base is the part attached to the foot of the tube with the contact pins, the male part, in order to be connected to the tube socket, the counterpart or female part. The tube socket is located in the device, while the tube base is on the tube. Colloquially, customers often order tube bases when they actually mean chassis-mounted sockets. PCB versions are mounted on a circuit board, while versions for chassis mounting are used in devices with wire connections or solder lugs.

This depends on the intended application. Tulip spring sockets have higher insertion force, but fewer plug-in cycles. They are intended for suspended applications, for example in guitar amplifiers, or for tubes that require a high heater current, such as KT170 or 5U4G. Fork spring contacts, on the other hand, have lower insertion force and allow more plug-in cycles. This makes them well suited for tube testers or for users who like to change their tubes frequently (tube rolling). If you want both properties together, Teflon sockets with gold-plated collet contacts are the best choice. 

Mundorf film capacitors (e.g. Supreme, EVO, TCAP) are generally not polarized and can therefore be installed in either direction. Only Mundorf electrolytic capacitors have a real polarity (+/–). However, some Mundorf models have a marking for the outer foil – this can be aligned toward the lower-impedance side or toward the signal source for better interference immunity. The input is then usually the shorter wire. 

Both “LPS” on the 12AX7LPS and “WXT” on 6L6 and 5881 types are so-called suffix designations, just like with 5U4GY, 6L6WGC or 6SN7GTB. In addition to the standard properties, these suffixes describe further details. Examples:

LPS = long plate spiral heater; robust, bifilar heater for low hum

WXT = ruggedized; robust version, higher voltage rating with the 5881WXT

WGC = ruggedized, glass version C, stable and update version C

GTB = glass container, straight construction, update version B

GA = G, coke bottle version, first update A

Y = metal version

S = with JJ spiral heater, bifilar heater = low hum

In most cases, especially with current tube audio devices, the suffix only plays a minor role. Taking the datasheets and operating manuals into account, the tubes can usually be exchanged. If in doubt, please ask. 

You need to know which tube the socket, correctly called a tube holder, is intended to be used for. If you know the European tube designation, you can use the table as a guide. The first number after the letters indicates the socket type, for example the 8 in ECC82 indicates Noval: