Low background distortion/fizz - seems to be connected to V1

[sirshackleton]

Good evening, all!

I recently purchased a used 3rd Power Wooly Coats Extra Spanky. It's my second Wooly Coats, and I love these amps.

This amp has clearly been used and needed a little TLC at the outset. Not sure how old it is, but definitely no more than ten years. Anyways, here's the issue plaguing me right now:

This is a very clean, high headroom amp, but I can hear a bit of background distortion when playing. On a scale of 1-10 in terms of severity (10 being the worst), I'd put it around a 3. It's particularly prevalent on the low E string. A couple of things I've noted when working to diagnose:

1) I've changed all power and preamp tubes (it's solid state rectified) and rebiased as appropriate. No change. I've changed V1 three times with the same results. Did the chopstick tap and all tubes are quiet. Sound occurs whether tube shields are installed or not.
2) The V1 socket holds the tube firmly but the tube is pretty wiggly, way more wiggly than I'm used to.
3) The Wooly has a Volume and what's called a Hybrid Master, which is a master volume meant to keep tone consistent at any volume. I'm not sure exactly how it works...maybe part attentuator, part post-phase inverter master? Anyways, there's a little bit of noise at the end of the Hybrid Master travel, but nothing crazy. Probably normal. All the other pots are quiet.
4) I've noticed that the higher the "normal" volume is, the more apparent the fizz/distortion is (though still in the background). These amps stay pretty clean until the volume gets around one-clock mark, but the fizz is showing up much earlier. But, if I turn the normal volume down and turn the Hybrid Master up to compensate, the fizz/distortion begins to reduce noticeably. Eq settings seem to make no difference, though adding mods brings out the fizz a bit more.
5) At one point, when idling, I got some low frequency crackle through the amp. In another amp, this ended up being caused by a cold solder joint...but that was much more constant and louder. This was maybe eight or ten seconds and I had never heard before or since. Maybe it was a little bit of moisture burning off? We've been super humid and rainy lately. Still, thought it important to note this.

So, I feel like there's something going on around V1. Maybe it's wiggling/vibrating in the socket and I should look a re-tensioning or a new socket altogether? Appreciate any thoughts!!! Thanks!!

 

[Jasonpatrick]

Is it the guitar? The cable? Speaker connection? Input jack need cleaning?

 

[Jasonpatrick]

This amp have reverb? Does it do it when the verb is all the way down or off?

 

[sirshackleton]

I think I figured it out: operator ignorance.

The Volume and Hybrid Master are pretty interactive, and I just needed to get a feel for how they do their things individually and collectively. Turns out the Hybrid Master is a dual-ganged pot that behaves like a normal master volume in the first half of the sweep and then controls the headroom of the phase inverter in the second half of the sweep. I was trying to dial things in the way I dial my other Wooly Coats, which doesn't have a Hybrid Master. Figured out this one needs a different approach. But it sounds fantastic, so I can live with that

 

[sirshackleton]

Nevermind, it's back

I've posted an audio clip:
.

This seems to be the setting where it's most apparent: Volume at 12 o'clock, Hybrid Master about 10 o'clock. The lower the volume gets the less fizz there is. If it up the Hybrid Master with the Volume that also seems to quell the fizz a bit.

It's a very light crackle/fizz/distortion. It's not super apparent, but I can hear it. The closest to the way it sounds in the room is on the second chord as it rings out. Appreciate any ideas! I've replaced all the tubes, tried different speakers, different guitars, etc. It's definitely happening with the amp.

 

[sirshackleton]

After a little more research, I think it may be in the power section. The amp has a tube-driven effects loop, and when I plug it in I still get the fizz. I'm going to re-check the tube for the loop. I'm pretty confident it's not a power tube as I've tried a couple different sets already with re-biasing and everything.

 

[GotA24Fretter]

Make sure it's not something else in the room. I spent an afternoon and a few taxi fares to a tech chasing a rattling fizzy sound in one of my amps back when I was completely clueless about how they worked. When I brought the amp back home and accidentally kicked a nearby drawer while moving the amp back to its spot I heard the rattle... it was some loose screws and nuts at the bottom of said drawer.

 

[sirshackleton]

Make sure it's not something else in the room. I spent an afternoon and a few taxi fares to a tech chasing a rattling fizzy sound in one of my amps back when I was completely clueless about how they worked. When I brought the amp back home and accidentally kicked a nearby drawer while moving the amp back to its spot I heard the rattle... it was some loose screws and nuts at the bottom of said drawer.

Ah, good tip...but yeah, I gave it a whirl and it's definitely coming through the speakers. Finding now that increasing the Mids brings it out a little more. Has a sound almost like someone is going "shhh..."

 

[peteb]

Has a sound almost like someone is going "shhh..."

Your video is a good reference point.

That helps a lot.


I listened expecting to hear distortion.

The signal comes thru clean.

I hear white noise behind the signal.

It is a slightly complex amp. Maybe more than slightly.

It sounds good.


If the only difference between this and previous models you have had is the hybrid master volume, maybe that is the source.

You did say the HMV affected the problem, and it needed to be considered when dialing in.


Best of luck.


They look like nice amps.

 

[Pete Farrington]

This seems to be the setting where it's most apparent: Volume at 12 o'clock, Hybrid Master about 10 o'clock. The lower the volume gets the less fizz there is.

Nothing you've described or recorded in that clip indicates a technical problem to me.
What makes you think this isn't just regular preamp clipping, exactly what the master volume is there to facilitate?
If preamp clipping is desired, then turn the volume up, eg above noon.
If a clean preamp tone is preferred, then turn the volume down, well below noon.
Use the master volume to set the desired SPL level that the amp generates, eg for clean and loud, turn the volume low and the master up full.

If the tone controls are after the final clipping stage, eg Marshall 2204, then they'll affect the tone of any preamp clipping but not the depth of it.

Whereas if the tone controls are prior to the final clipping stage, eg Mesa MkIV, Fender HRD, the tone control settings will also affect the depth of the clipping within the frequency ranges they adjust.

As your mid control affects the depth of fizz, perhaps it's before the final clipping stage

 

[sirshackleton]

The big update you've all been sleeplessly waiting for: I reached out to 3rd Power about it and the owner/founder of 3rd Power wrote back within 15 minutes (!) and said, "Send it back to my attention...I'll go through it and make sure it's sounding it's best." Really, really pleased about that! So it's back with them for now.

Nothing you've described or recorded in that clip indicates a technical problem to me.
What makes you think this isn't just regular preamp clipping, exactly what the master volume is there to facilitate?

There may not be, but given my experience with these amps (this is the second one I've owned) it shouldn't be clipping at the volume settings I'm running.

These are designed to be very clean, high-headroom amps..."pedal platforms" if you will, though they really do stand on their own. The one I have some questions about is notably different than the combo version I've owned for....geez, like 7-8 years now (yikes!); tube versus solid state rectification, no master volume/HF damp on the combo, the head can use different power tubes, stuff like that but in terms of preamp design they are substantially similar from what I can tell. The combo doesn't start breaking up until you get around 2:00/3:00 o'clock, though it does "push" in a very nice way from 11:00 to 2:00. My gut says the head version should generally perform the same way, but.....

Either way, if there's is something wrong I'm sure the shop will sort it out.