China 12ax7B - low gain?

[stef]

I bought set of 5 - bulk. 2 went to vox ac15 blue and 3 in 1978 SL NMV. Both amps have less gain with them!

Vox sounds a lot better with them - darker, fuller, bassier and a lot cleaner. Sovtek and Tung-sol were 2 stock factory pre tubes - shrill, fizzy sounding and died quickly


China 12ax7B should be high gain tubes and bright sounding - right? Did they change something recently?

[robertmendeziii]

The chinese 12ax7-b should be more gain and lower noise than the chinese 12ax7-B. But maybe the reason why they have lower noise is because really the gain was lowered? I have chinese 12ax7-a in my marshall dsl and have plaenty of gain to spair. Along with the lower gain, is your amp quieter also?

[stef]

The chinese 12ax7-b should be more gain and lower noise than the chinese 12ax7-B. But maybe the reason why they have lower noise is because really the gain was lowered? I have chinese 12ax7-a in my marshall dsl and have plaenty of gain to spair. Along with the lower gain, is your amp quieter also?

These are the tubes i bought http://www.tube-town.net/ttstore/produc ... tubes.html" onclick="window.open(this.href);return false;

Quieter-yes, the vox ac15ccx is a lot quieter even with the BSM BM treble booster in front and mastervol and gain on 12 o'clock.
My SL is also quieter but the pre tubes that came with the amp were very old (I think long plates, with just ecc83 on them - they flash really bright when turning the amp on) and made strange cranking noisies and microphonic noise - but they used to give a little more gain (dirt - overdrive). I own the amp just a couple of months and have used it on just one live gig.
I was told the power tuber were N(almost new)OS siemens el34 but there's no sign on them - nothing written on the glass.
Maybe I should check the bias... on the other hand, my question is about the preamp gain and tubes..
I like the tone from both amps, but vox has a master volume control just like your dsl so it's easy to compensate..
I didn't know there was a difference between 12ax7b and12ax7 B I've heard about a and b series - b's with even higher gain..

[demonufo]

I thought B's were low noise. Which in my mind would suggest lower gain.

[robertmendeziii]

I have to agree with demonufo. Lower noise usually means less gain also. Even though the description of them says otherwise. You should email thetubestore.com and see what they have to say. Thats were i always go when i get stumped.

[Guitar-Sam]

I heard the best chinese 12ax7s to get were the 80s and 90s with the silver thingy in them(silver dragon??).