If your equipment uses 6922 tubes, there is a lot to choose from, and sometimes this can be confusing. Here's the "411" on the 6DJ8 family from Uncle Kevvy:
Sometimes you will see “CV” numbers. This means "Common Valve" for people in the military (typically Europe NATO forces) so they easily know what parts is what. So in 6922 types you have CV5358, CV2492, and CV2493. The more common numbering system would be 6DJ8/ECC88, 6922/E88CC, and 7308/E188CC. The 6922 is supposed to be lower in microphony than the 6DJ8, and the 7308 even better still. History, as well as our own testing, proves that's not always the case. For example, the U.S. production Sylvania 6922, also sold as Philips ECG, does not test as good as a German or Japanese 6DJ8 and can fail in difficult products, such as the Audible Illusions Modulus 3A. Most 6DJ8 types will test better than this tube for microphony.
We help you by giving a description of the tubes sonic characteristics, and microphony issues. You will see us mention at times that a 6DJ8/6922/7308 may go "ting" for a moment when you flip a switch. This is not "microphony" be definition. It is not a big deal so don't sweat it.
When you order, make sure to tell us what you are using it in. If we see a problem we will let you know.
The 6922 family has some other aliases as well. The CCa tube, produced by Siemens and Telefunken, is just a factory-selected 6922. Siemens produced a tube called the E288CC, which is also a 6922 variant, though they must be tested to assure low microphony.
The PCC88 / 7DJ8: Deal of the century? A PCC88 is a 7-volt filament version of the 6.3-volt filament ECC88. Aside from the difference in filament voltage, the two tubes are the same. That means, no problem-o, bitchin’ sound, and less money. There is never an issue substituting these into any 6DJ8/6922 position. Uncle Kevvy recently found a stash of vintage Matsushita PCC88 in Japan National boxes (Not the Jive-Ass U.S.A. National that can be anything in the box). Man they are sweet!
Here is a story for you. Back in the 1980's, I found these Japanese 6DJ8 tubes marked "Made in Gr Britain" and plugged them into my Audio Research preamp. They sounded so organic it made my head spin. I went to every old electronics store in Southern California looking for them, to no avail. I thought they must be Mullard. But through research I learned how to identify tubes by internal structure and small etched codes, and found these were Japanese. This tube was the one that started my tube-rolling hobby, and that passion for better sound eventually launched Upscale Audio.
The point is, look at 7DJ8/PCC88 as a way to get into the $100-$250 type of stuff for $30-$90 each.
So what not to use?
This is a big one because if you use an incompatible tube, you could damage the tube, or even your equipment!
Do not use a 6N1P in a 6922 position. But you can almost always use a 6922 in a 6N1P position in products like Peachtree Audio and others.
Do not use a 6H30. The 6H30 is a completely different tube. You also cannot use a 6922 in a 6H30 position except for a couple rare preamps, check with the manufacturer.
Do not use a 6ES8; It is a variable-mu tube. It may work as an output buffer, but don't put it in preamp gain stages But people are trying to sell them as a 6DJ8 type. Not true.