• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Choosing a brand as a standard

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I have been working on a few designs for preamps. I have worked hard to choose manufactures that produce quality parts. I am very suprised that there is not a prefered supplier of tubes. After all, I can not belive that Boulder audio just picks an NOS tube off a web site
Have I missed something here or is it as much of a crap shoot as it appears?
There is no such thing as one best manufacturer for all tube types. Here’s why:

1. Time: Tubes were made for decades by many manufacturers. Tube designs often evolved, as did manufacturing techniques, materials and methods. A given tube from a given manufacturer might have changed throughout its production lifetime. What was great from Brand A in 1940 might have been bettered by Brand B in 1960.
2. Brand versus Manufacturer: Tubes from any one brand could have been made by various manufacturers, as subcontracting and rebranding was commonplace.
3. Incomplete line offering: Not every tube manufacturer made every tube. You might have to pick tube type A from one set of brands, and type B from another set of brands.
4. De Facto Specialization: Even if one brand offered every tube of interest, it might not be the best choice for all types offered. A given manufacturer might be known for its great 6DJ8s, but not as well regarded for its 12AX7s for example.
5. Present day supply: For an amplifier manufacturer, (except for a few boutique houses) hunting down NOS tubes is not practical since supply is not assured for any significant production quantity, quality and past use is not known, and prices are variable and usually high. That is why many modern amplifier makers are using only tubes types currently being made in Russia or China (such as the 6N1P).
6. No standard for “best”: People often disagree about whether Brand A or Brand B of the same type is better. There is even disagreement about Brand A with the black plates or Brand A with the gray plates. And what does “better” or “best” mean? What subjective parameters are considered? Does everyone agree on those parameters? Noise? Reliability? Microphonics?
7. How a tube is used: Any one type from a given brand may have strengths and weaknesses relative to the same type from other brands. How it is used in a circuit design will influence how strengths and weaknesses are expressed. For example, in the front end of a phono preamp, a 6DJ8 from Brand A might be preferred for its low noise. However, for a 6DJ8 used in a higher-level gain stage later in the signal chain, another Brand B’s superior linearity might be advantageous.

PS: The Boulder I know of doesn't even make tube amps.
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