Tube amps and background static

[pbman1953]

All my gear has been preforming well, but when its quiet some of mine have background static.


For example ,The Super Twin. This one has a master and volume. The static exhibits this when the master is up far for a clean setting, The  master is on 7-8 and I use the volume control as the main control of the volume. At that setting you hear the static
 
When I want a grittier sound , I set volume up to 6-9 and master as the main control, For this there's no static.




Also, there's some hum that goes up and down with the master. It's a tube amp ,I can't expect it to be whisper quiet but was wondering if there's something I should look at


Thanks

[Willabe]

And? 

[Willabe]

For example ,The Super Twin.

Is that 6 x 6L6GC, 180w? 

[pbman1953]

For example ,The Super Twin.

Is that 6 x 6L6GC, 180w?

Yes

[tubeswell]

background static.

hissy or crackly?

[pbman1953]

hissy or crackly?

Crackling


Edit; untangled quote, Willabe

[tubeswell]

How old are the output tubes?

[stratomaster]

Pull your PI and see if the noise goes away.

If so, then put it back and pull your reverb recovery/3rd stage tube (I'm not sure what tube this is on this exact model but usually v4).  If the noise goes away again, then the problem is somewhere in your vibrato channel (90% or more of the time, I find it's in this area).  The good news is that you can try swapping in a new tube for V2/V4 and see if it was just a tube problem.  My money would be on that. 

[pbman1953]

How old are the output tubes?

Bought within the last 2 years

[pbman1953]

Pull your PI and see if the noise goes away.

If so, then put it back and pull your reverb recovery/3rd stage tube (I'm not sure what tube this is on this exact model but usually v4).  If the noise goes away again, then the problem is somewhere in your vibrato channel (90% or more of the time, I find it's in this area).  The good news is that you can try swapping in a new tube for V2/V4 and see if it was just a tube problem.  My money would be on that.

This is the first model without Reverb. Before leaving to work I tried swapping.  I'm not sure if it was warmed up enough to exhibit the noise. There was a GE 5751 in the inverter spot and it was slightly noisy. I took it out and installed a GE Ecc81 and it seems to be quieter but I'll know better when I have it on for a while later.

[pbman1953]

That tube was it, whisper quiet


Thanks!

[tubeswell]

How old are the output tubes?

Bought within the last 2 years

How much use have these had?

[pbman1953]

How old are the output tubes?

Bought within the last 2 years

How much use have these had?

It's at home and not taken out much so  it's light

[pbman1953]

Since the Ecc81/12at7 seemed to solve the issue, do I need to re-bias?





Thanks

[pbman1953]

Did anyone see my last message?

[shooter]

my "rule of thumb"
I never "button up" an amp til I have a full set of voltage readings, AND have verified bias

[pbman1953]

my "rule of thumb"
I never "button up" an amp til I have a full set of voltage readings, AND have verified bias

You're probably right but all i did was to replace the tube. But I can certainly check the bias , thanks!


Just to mention, on my Sunn 2000, with an 6AN8A, the amp starts up with that same crackle but goes away in 10 seconds. Could that be the difference of the "A" version vs. the non-A or could the tube be bad? I installed a non-A version and there wasn't a peep.

[pbman1953]

Can anyone chime in my last question if you know the 6An8 tube?


Just to mention, on my Sunn 2000, with an 6AN8A, the amp starts up with that same crackle but goes away in 10 seconds. Could that be the difference of the "A" version vs. the non-A or could the tube be bad? I installed a non-A version and there wasn't a peep.