peavey heritage vtx help!

[juanpapino]

hi i need help to mod this amp .
clean chanel is not clean at all .. as more volume you add more distortion you get .. also got a lot a ground noise...this is the schematic.
http://www.schematicheaven.com/newam...ritage_vtx.pdf

i'm a nubi please try to be specific with location ...for mod ..
thanx so much ...my regards..
pablo..
can email me to pablo_juan@sbcglobal.net

[reubster]

Howdy, I have a Peavey MX VTX [basically the same amp without the phasor cct]
I've posted previously on this and Enzo gave some great advise....do a search.

If everything is ok the clean channel should sound very clean.
The amp clean should sound Fender Twin-ish and infact I run mine with a reduced 2 x 6l6 O/P and I prefer the sound to Fender and Boogies [bit more of an EL34style break up] but very clean nonetheless.

FWIW
I had a couple of problems with mine:

1. The speaker had been "compromised". It always sounded scratchy and distorted, but cleaned up a bit when the amp was goosed.
It turned out the air gap was full of gunk............after some very careful cleaning.......... all was good.
2. Also, I noticed, when the saturation control is > 80% there is some distorted spill BLEEDING through into the clean channel.
I've resigned myself to accept this as a design problem.
Back off the saturation back and see if the problem goes away.

Some of my other problems included:
1. leaky/Almost shorted filter cap in the preamp power supply, so one of the rails was held very low...obviously, both channels were affected but the clean was more obvious.
2. Blown Transistors and diodes in the O/P bias stage : measure the volts points via the schematic to work out what is not ok.
Again, the clean channel showed up this problem moreso.

So I'd suggest to check these things.

My biggest gripe is that the shared "Post" volume control balance is too loud for the dirty channel compared with the clean channel.

Overall [and I'm a tone snob with a quiver of vintage valve amps] and I'm pretty surprised by how good this amp actually sounds: The clean channel is great and the distortion channel is pretty much on par with standard commercial pedals [eg boss DS-1].

Down the track, I intend to change the PS to a lower impedance design, upgrade the opamps and also generally any caps in the signal path.
I figure if I remove some of the clipping diodes [so the Vfwd is halved] I will be able to reduce the voulume of the dirty channel.

Good luck and keep us posted.

[gNEUS]

Problem with Peavey Classic VTX 212

Hi guys, I have Peavey Classic VTX 212 and although it is a nice amp I'm having some issues with it. Reading what you've done on your amp was wondering what would you suggest about my problem.

Few things to know.
I almost never pass 1 on the volume knob. Almost every time after I've been playing for over 30 minutes the amp will start to act on me. It will go down in volume then up again maybe few times. 5 minutes later it'll do the same thing. Some times, the sound will go to dull bassy sound or to sound with more highs accompanied sometimes with volume variation and sometimes without volume variations.

I though that must be from the tubes that seemed were 10+ years old, so since yesterday I have brand new matching pair ruby reds 6L6.

Unfortunately the same problem appeared back yesterday while I was testing the amp after about 20-30min. The sound went down and up few times, aggravating me a lot.

The sound quality I got with the old pair tubes did not differ at all from the new pair tubes. At least I cannot hear anything different.

Any ideas and suggestion will be greatly appreciated.

[reubster]

gnues

I did experience something similar, but first let me say that just changing the tubes will not resolve anything if the problem is elsewhere.

In my amp, I had problems in the stage that drove the output tubes.
There are bias/voltage points indicated on the schematic, that will enable you [or a qualified tech] to quickly determine if there is a problem there.
If you did not hear some degree of improvement with the new tubes, I would suggest you have a look at this driver and bias stage.

Given you description, it is possible your problem relates to a heat related failure:
eg a solder joint/component/track is failing after a certain time/heat.....if you switch the amp off for an hour and switch it back on, does the problem return immediately or does it take 20-30minutes?

In my case [probably different to yours], the sound would cut in and out, often I would "apparently" lose power and sometimes the bass would cut out. Often the sound was scratchy.
This could occur anytime [did not need a warm up time], but often the problem would stabilise if I cranked the amp for a few minutes.

After fixing all the electrical problems, biasing and adding newly matched tubes .... it still persisted.

It turned out to be a speaker issue.There was heaps of gunk in the airgap and the coil was catching. Once cleaned out voilla: problem solved.

[gNEUS]

Thank you for the suggestions. I have no clue about how to work on it or check on its schematics.

I have never turned it on hour later to check if it'll do it again but i'll try that tomorrow probably.

It is a great amp and I will hate for it to go. I'll consider your advices when I get somebody to look at it. I have schematic regarding Peavey Classic series, but not exact match for my Classic VTX 212. Any idea where can I search for one?

[Robert M. Martinelli]

I advise you to contact Peavey, I've dealt with them in the past, they're friendly, kind and cooperative. Send' em an e-mail, if you ask them politely they'll most likely provide the schematic you need.

Hope this helps
best regards
Bob

[gNEUS]

will do, Thank you Bob

Now I just want to update y'all. Yesterday I powered it on and after 15 minutes the same problem arose again. I turned it off and on for 10sec and that seemed to help but the issue continued to come back and I experienced sound variations and volume up-and-downs.

Later on, my friend and I jammed for 2 hours having 2 guitars plugged in and I couldn't notice any problems with the sound. Although I noticed that if 2 instruments are plugged in, the overall volume drops, but I guess this is normal.