V1 Noise with JJ 12ax7's

[mauiboy81]

I just finished a build that is kind if a cross between dumb le clean channel and blackface reverb. When I have jj ecc83s in v1 it is super microphonic and noisy. When I tap the cassis or ground buss or anything it makes lots if noise(clang, thunk, scratch, pop). The noise goes away when the bright switch is turned on but then comes back if the treble and mid are turned down completely. Conversely when the bright switch is off it is noisy but it goes away when the treble and mid are turned all te way down. I tried three separate JJ's and they all have te same issue. I also tried eh, ruby, tung sol ri, old 7025, and they are fine in v1. The same JJ's are fine in the reverb recovery/mix position. What's up with that?

Edit: photos added

[martin manning]

The input stage has the highest sensitivity to noisy tubes because the signal to noise ratio is low, and any noise introduced there is amplified along with the signal through the rest of the amp. Since it is mostly high frequency, any EQ thàt reduces HF will reduce it, but of course that is at the expense of reducing all HF content. Your bright switch effect sounds backwards, but caps can be noisy and microphonic too. The solution is finding a quiet tube for that position.

Microphonic is a different problem, and you can find quiet tubes that you have to reject for that reason. Sounds like these JJ's you have are just not up to it on either front.

[mauiboy81]

It's not the normal high frequency noise that a bright switch would let through. The whole thing goes live and crazy and unstable.

The bright switch works normally with other tubes.

[steveneddy]

When I was in the amp repair business I grew a disdain for JJ tubes.

Some guys like 'em - but I hate 'em. Faulty, noisy, junk tubes IMHO.

YMMV - but I'm a Sovtek, Gold Lion and EH user and my tube issues are almost non-existent.

Maybe you can go get your money back or trade them for others from your preferred vendor.

[mauiboy81]

I have had lots of issues with JJ's in the past as well. I had decided not to buy them any more but I have had these in a drawer for a while and am trying to use them up. I was surprised that all of them have issues in this amp.

Could it be a problem in the amp that for whatever reason the JJ's are more sensitive to? It's not high gain and I thought it would be real stable.

[Jana]

Add me to the JJ AX7's suck list. Every one of them I have tried has a lot of hiss and noise. Maybe they do have a good tone--I don't know. I couldn't get past the noise issue.

[pops]

A few years ago i bought 10 jj 12AX7's, all were bad. Noisy, inconsistent tubes, i won't use them.