Channel Master Volume Problem

[SRusackas]

Hi everybody!
Problem: each channel master volume, when up at 10:00 or higher, develops a distortion that sounds something like a ring modulator effect. All three channels, in all modes. I have swapped out all the preamp tubes, and it's still there. The only way to get rid if it is keep the channel master at less than 9:00. It's not clipping as far as I can deduce, just has a very weird ring mod sound, especially noticeable on notes played on the G B and High E strings.
The amp is only 3 months old.
Thanks!!

 

[screamingdaisy]

Are you playing at extremely low volumes?

 

[SRusackas]

Yes, household levels during songwriting.

 

[bandit2013]

Are you using the reverb? Turn off the reverb and see if it that sound goes away. The connections to the reverb tank may be loose, or reversed. Black RCA plug attaches towards the front of the amp, the silver one is closer to the output transformer. On the tank for a head the black wire on the right, white to the left (as viewed from rear of amp). As for the Combo, connections should be the same on the amp terminals, not sure how it is connected in the bag (assuming they still bag them).

 

[screamingdaisy]

Yes, household levels during songwriting.

Each tube is made up of two separate triodes.

At very low volume levels the effects loop produces a filter effect due to signal bleeding from one triode to another inside the tube itself. It goes away once the volume is increased. On my amp is sounds more like a phasing effect than a ring mod... but it's been a long time since I last heard it so my memory is sketchy.

 

[farren]

I get this too, but that volume range is only a few dozen micrometers in output knob travel. I often play very quietly, but the area where the signal first begins to fill out is still very much in the "bedroom" range and not a lot louder than the narrow, unusably thin zone. I'd be surprised if anyone plays that quietly.

 

[SRusackas]

Thanks all for your help. Ill try this today and post what happens. Ill put the amp on a hotplate too and see what's what.

 

[SRusackas]

So I've been messing around with this for a few days now and here are my observations.
Output knob setting doesn't affect this sound I'm hearing, happens at all output volumes.
It happens with reverb on and off.
It happens with effects loop in or bypassed.
It's noticeable on all three channels ( just more on the clean channel)
It only occurs when the channel master is above 10:00 or so
It's only really apparent when the pickup switch is in the middle position on both my JP music mans (music men?) and Ibanez J-custom, meaning the twangy in between positions)

Again, I have swapped out all the Pre-amp tubes and it hasn't changed.

The sound is most like having a ring modulator pedal on, at about 50% mix.

 

[satch4u3]

Have you tried another cabinet? If so, I suggest you contact Mesa Boogie Support if you haven't already.

 

[SRusackas]

Haven't tried a different cab, but used my Peavey JSX on the same cab with no problems.

 

[mesa metal]

So I've been messing around with this for a few days now and here are my observations.
Output knob setting doesn't affect this sound I'm hearing, happens at all output volumes.
It happens with reverb on and off.
It happens with effects loop in or bypassed.
It's noticeable on all three channels ( just more on the clean channel)
It only occurs when the channel master is above 10:00 or so
It's only really apparent when the pickup switch is in the middle position on both my JP music mans (music men?) and Ibanez J-custom, meaning the twangy in between positions)

Again, I have swapped out all the Pre-amp tubes and it hasn't changed.

The sound is most like having a ring modulator pedal on, at about 50% mix.

i get that sound also....im wondering if it has to do with the pickup and string modulation.
it does happen at all volumes ,,,really annoying through the delay unit
i notice it more on channel 3

 

[jmontgomery]

What are the rest of the controls set at?

 

[mesa metal]

What are the rest of the controls set at?

channel 3 MKIV mode+pentode+bright.......the gain is at about 20clock,,master volume is 9 oclock
presence 1,,,treble 1,,,,mid 11:30,,,,,bass 12,,,,eq is set at the usual V curve but not extreme...
none of the controls are set too extremely either.......i didnt noticed this sound a couple of months ago
ive only had this amp since december....overall it sounds amazing.....i also notice if you raise the gain on channel 3
there is a substantial amount of hiss or white noise...but that all depends on the tubes....these are my settings for now
id like to hear what the other guy has his set at....

 

[SRusackas]

Here is an example of what I'm hearing. First part is with the Channel 1 Master Volume at 9:00, the second is with it at 11:00. Main Volume is at 10:00, and FX loop and reverb is off.
Gain is 10:00, all tone controls are between 10:00 and 1:00.
Clean mode, Bold on, 90Watt. (changing these settings does not affect the sound you're hearing.
https://soundcloud.com/sethrusackas/markv-clean-channel-problem
... And I'm sure its not fret buzz, i don't play with a low action, and the neck is set correctly with a bit of bow. This sound isn't really noticeable in the neck and bridge pickup positions, only the middle, and on the higher strings. Same between two different guitars.

 

[Karl Houseknecht]

That's clearly not normal, especially the second part. I think you need to take it to a shop.

 

[screamingdaisy]

That's clearly not normal, especially the second part. I think you need to take it to a shop.

+1.

Something is up there.

 

[SRusackas]

Tech support requested from Mesa/Boogie. When I hear back ill post what they say, in case anyone is curious. Figures I'd have a rare problem! :-(

 

[mesa metal]

yes please let us know...i listened to that clip about 10 times....
i thought you were describing something completely different till i heard the clip..

 

[SRusackas]

Spent the afternoon with Garey from Mesa Boogie, who by the way was amazingly helpful. We swapped out the V1 and V2 tubes, which are responsible for channel 1 and 2 since the problem seems to be common to both channels. Then he had me hold each power tube with a rag while playing to see if the problem stopped. Then we changed out V7, the phase inverter.
None of that helped.
So he referred me to an authorized Mesa Service shop here in San Diego, to get it looked at. Under warranty it'll be free for me. Woot!
Ill let you know what the problem was when I get it back.
Thanks guys for all your help.