And who does this? I recently bought some Psvane and some of them were all over the place. I found one I could use but the plate voltage was 220V for both sides vs the 235V seen on both sides of the GE 6679. The other Psvane was something like yours on one side 257V and 210V on the other side.
Most shops sell factory matched tubes (and I would not trust them) but few shops (mostly focusing on the guitar amp market) offer their own matching service. For instance www.tubeampdoctor.com and www.thetubestore.com to choose an example for either sides of the pond.
For Europe I have few more suggestions. And in the past I found privates buying NOS stocks and matching what you ask for.
For Europe I have few more suggestions. And in the past I found privates buying NOS stocks and matching what you ask for.
Looks like a good spectrum. As long as odd Hs are below 1%, and falling, you are good to go. I bet it sounds great. Here is my garage amp, a JFET-5881/6L6 hybrid, THD is ca 0.6% at 1W, it clips at ca 2.6W. Sounds sweeeet:
Indeed I like what I am hearing (triode no feedback for now). Third harmonic is below 0.05% at 1W and it is 20 dB further down with EL34.
Get some KT-88's and bias the amp for those tubes and you will be pleasantly surprised at what you hear. I am really enjoying some reasonably priced JJ KT-88's.