1.0 General Description
Almost all of the products for sale on www.oldsound.it come from our “past”, popularly referred to as “ D'EPOCA (VINTAGE) ”; certainly dated and almost always no longer in current production.
We will always do our best to describe each item in the most detailed way possible so as to provide the interested buyer with all the necessary information so that he can purchase with the highest awareness. We are always and in any case at your disposal for any information you wish to have: email@example.com.
Furthermore, it should be noted that all the items proposed will be identified in two large macro areas : " Working" and "Not Working / to be restored " ; this aspect will always be clearly stated in the product sheet. In the "functioning" area we will distinguish in turn as follows:
· NOS / NIB (New Old Stock / New In Box) or "New of old production and in their original packaging".
· NOS (New Old Stock) or "New and re-packaged or without original box".
· USED but “tested and guaranteed”.
The above is valid for all products offered in our shop.
1.1 Instrumentation for tube checking
Particular attention is paid to valves (vacuum / electronic / thermionic tubes), which are ALWAYS checked under every aesthetic, mechanical and functional aspect. Subsequently tested in the laboratory with the appropriate and best possible instrumentation in our possession, ie professional "laboratory" and / or professional "military" valve testers (Tubetesters) always with a high level of precision. We normally use the following test instruments: METRIX U61b - METRIX L109A - AVO VCM163 - AVO MK4 - AVO CT160 - FUNKE W19S - HICKOK TV-7D / U, NEUBERGER RPM375, etc ... All measuring instruments are regularly checked and subjected, where necessary, for maintenance checks in order to have the most truthful results possible. At our discretion, if necessary, comparative tests may also sometimes be carried out.
1.2 Testing of the thermionic valves
In compliance with their data sheets, by applying the appropriate parameters and scrupulously following the user manuals of the instruments, the following tests are performed:
- Plate or anodic current (Ia - mA).
- Voltage gain / Gain (Mu - µ) and / or Transconductance / Slope (Sg / GM - mA / V mhos = micromohms).
- Anodic or Plaque Resistance (Ra - ohm); if necessary.
- Insulation and short circuit between all electrodes both hot and cold (Mohm).
- Presence of abnormal gas and any leaks.
- Efficiency / Emission (Overall judgment).
- Where possible, tests are also carried out on real circuitry in order to provide a concrete confirmation of good functioning and verification of any microphonics.
1.3 Matching and Balancing
All tubes offered for sale by OldSound, where possible, can be " coupled " (preamplifiers, power amps, other ...) in PAIR, TRIO, QUAD or multiples, always based on current availability. Once all the aforementioned ritual tests have been carried out, all the necessary reference parameters by type of valve will be available for the purpose of this operation; substantially Mu, Ri for the double triodes and Gm for the final power pentodes / tetrodes, as well as Ia (anode current).
Of course, a series of cross-checks will also be made, using all the results obtained, always in order to ensure the most “ideal” result possible. By “ideal”, on average, we mean in a percentage range of 5-8%, sometimes even less, depending on the type of valve and its use and application.
Many suppliers of “vintage” tubes promise miracles (under or far below 5%!) But, beware, with the generally limited quantity typical of the vintage tube, obtaining this result is very rare.
All test results are uniquely noted and certified for that item with reference (where possible) to production date, specific descriptive characteristics, etc…; moreover, if made upon request, also with reference to the requesting Customer.
OldSound reminds and is keen to highlight that: considering the dating and the intrinsic high level of risk to develop problems, even accidentally, of the electronic component in question (NOS / NIB, NOS and USED valves tested); any type of control, even if it verifies 99% correct operation, CANNOT guarantee absolute certainty or the exact duration of life over time .