5647 subminiatur Pentode
Stable characteristics, useful for audio projects
Popular in DIY hifi as driver or preamp stage
6.3V heater, 7 pin miniature base, rugged design
5647 / CV3916 subminiature diode for level detection and studio DIY
The 5647 is a compact, indirectly heated vacuum signal diode with wire leads. Its approximately 460 V peak inverse rating and 10 mA rectified-current capability make it useful for signal rectification, level detection and fast measurement circuits.
In audio and studio equipment, it is particularly interesting for compressor sidechains, peak detectors, limiters and level indicators. It has no control grid and cannot operate as a preamplifier or driver valve.
Useful applications
- Rectification in tube-compressor sidechains
- Audio level, envelope and peak detectors
- Limiter, control and indication circuits
- RF probes, demodulators and compact test equipment
Technical specifications
- Valve type
- Single indirectly heated subminiature signal diode
- Equivalent designation
- CV3916
- Connection style
- Subminiature construction with four wire leads and no conventional base
- Heater
- 6.3 V at 150 mA
- Peak inverse voltage
- Approximately 460 V
- Maximum rectified current
- Approximately 10 mA
- Frequency capability
- Specified as a signal diode for operation up to approximately 900 MHz
Audio and measurement design notes
The 5647 can rectify an audio signal to create a control, display or measurement voltage. The associated resistance, capacitance and filtering determine whether the circuit responds to peaks, average level or a slower envelope.
The four wire leads should be identified from the applicable data sheet or the marking of the supplied valve. Existing descriptions of the 5647 as a pentode or a 7-pin valve should be corrected.
Questions about selection and audio use
Is the 5647 suitable for a tube-compressor sidechain?
Yes, the vacuum diode can rectify the audio signal to generate a gain-control voltage. A suitable RC network can then define the attack and release behaviour of the sidechain.
Can the 5647 operate as an audio level or peak detector?
Yes, it is suitable for valve-based level indicators, envelope detectors, limiters and measurement circuits. Its substantial peak inverse voltage provides useful headroom in conventional tube equipment.
Is the 5647 useful for compact RF and audio test equipment?
Yes, its subminiature construction and documented high-frequency capability make it attractive for probes, demodulators and compact signal rectifiers. It can also be integrated unobtrusively into detector and control sections of audio equipment.
Note: All brand names mentioned, such as Marshall, Fender, etc., are registered trademarks of their respective owners and are used here for descriptive and compatibility purposes only.
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The EU Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (2011/65/EU = "RoHS 2") aims to exclude certain hazardous substances from electrical and electronic equipment or to restrict the use of certain substances in electrical and electronic equipment. These include substances such as lead, mercury, cadmium, and chromium, as well as certain brominated flame retardants and plasticizers. These substances may only be used in electrical and electronic equipment up to a maximum concentration limit, unless exemptions in the annexes to the directive permit their use under certain conditions. This can reduce and eliminate harmful substances and improve the recycling of waste electrical and electronic equipment. To find out whether the component you purchased from us is permitted in your device, please refer to the current directive or the current law applicable to your country. If you are a manufacturer, please feel free to contact us to find out whether the component you require can be tested and approved according to the current directives. We would be happy to assist you.
Fact sheet on EU Directive 2011/65/EURestriction of the use of hazardous substances in electrical and electronic equipment (PDF, not accessible, 2 MB)
Source: IHK Mittelfranken
Tariff Number: 85408100900
Country of Origin: DE