Where can I find suitable replacement tubes for music cabinets, concert cabinets and tube-based audio furniture?

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.