Peavey 6505 Plus Channel Switch Popping

[rf7]

I've seen this in some of these amps where the first few times you switch between Rhythm and Lead channels, you get a massive pop out of the speaker. And then after about 5 channel switches, the pop no longer occurs. Any explanation for this?

Note that the amp is cold when this is happening.

I've looked on the scope, and the massive pop occurs after the Mute pulse has gone away.

When the amp is cold, even after the pops have stopped, if you turn the amp off and on again, you will get the popping back for the first 5 channel switches. Switching the Crunch channel in and out never causes popping.

Once the amp gets hot, turning the amp on and off does not cause this issue.

[Chuck H]

Short a schematic that's going to require acute experience to answer. Even WITH a schematic it wouldn't be easy because it's a complex amp (and schematic). But it sounds to me like a cap charge isn't fully stabilized for a while after the application of voltage or possibly even not until the channels are switched a few times. This may or may not be amendable. Peavey is pretty good about design anomalies. If it's a common problem they know about it. If it was amendable without tonal or safety detriment they probably would have done it already.

JM2C

[Jazz P Bass]

What are we talking about here?

Sw 6?

If so, I would look for Vdc on the switch, which would indicate a leaking coupling capacitor on V1 (C14).

6505+ 112.zip

[Enzo]

REmember 6505+ and 6505+ 112 are entirely different amps.

[Chuck H]

REmember 6505+ and 6505+ 112 are entirely different amps.

Good input if someone needed to source a schem!

Hey,?, aren't you retired How do you know this stuff when I can't even get the schems with a normal search?

[Enzo]

PV likes to recycle too many model names.

But we have been fighting the 5150 vs 5150-combo for years now. Guys will start talking about their 5150 when they really have the 5150 Combo. 6505+ is really the same amp as the 5150-II. The 6505+ 112 is the Combo, and like the earlier, it is not the same as the plain old 6505+ head. I was a PV service center for 30 years, so I am familiar, but more recently it is on my mind because we see that confusion over and over here.

Looking for schematics? the first stop I always make is nickb's site:
http://bmamps.com/Schematics/Peavey/..._Schematic.pdf


or maybe you just eat too many clams...

[g1]

Too many clams?
Like this?

[Enzo]

Holy shit...

[52 Bill]

I first heard that tape around the time that he died. It was on the radio, so it was heavily bleeped. Even with the bleeping, you could tell what he was saying.

[Justin Thomas]

I don't care how great you are, no reason to ever treat anybody like that... I hope he was either drunk or high, so at least there's an excuse to say "it wasn't me!" Just, wow...

Jus in

[Chuck H]

That occurred to me also. Then I thought "Maybe the band really did suck that bad that night." I thought that because I've been there. Funny thing is that it's usually the drummer whose most likely to be too drunk to perform by the SECOND SONG OF THE SECOND SET!!! I very much wanted to get my Buddy on that night.

[52 Bill]

I got to see Buddy and his band once, probably about the time these tapes were recorded. He had tremendous skills with an ego to match.

Unfortunately, Buddy Rich was notorious for his rants and tirades. But, I guess that his bark was worse than his bite, as he rarely fired the guys that he belittled so badly on the bus.

There have been lots of articles written about these tapes that will explain who recorded them and when they were recorded and why they were recorded. Surprisingly many of the musicians that were subjected to his rants said that they respected him for trying to motivate the band. They also said that he would respect them more if they actually stood up to him.

It was a different time and the world was a different place. Nowadays if somebody ran a band like that, there would be video all over the place and public lynchings.

[g1]

Apologies to rf7 for the hijack.
Can we get an exact model (head, combo?) so we can get the correct schematic posted?

[Rutherberg]

Hi,

Sorry for the old thread reviving, but I had the same problem than rj7 and found out the cause.

The problem is located in the feedback loop. There is a 22uF (C30) connecting the feedback signal to the PI. When the amp is powered on, the current flowing through the PI resistors generates a voltage across the 4.7k, and so DC voltage is applied to C30.
The problem is this capacitor is charging through the feedback loop, more specifically through the resonance pot and the OT. So if the resonance of the selected channel is 0, the charge will be almost instantaneous, but the more you raise the resonance knob, the more C30 will take time to charge.
So during the charge, there is decreasing "residual DC" in a portion of the feedback loop, and when the relay K1A is activated it makes the loud pop.
When the charge of C30 is over (0-30 seconds, depending on the position of the resonance knob), no more "DC" in the feedback loop and there is still a slight pop but considered as "normal".

The only easy workaround I see is remplacing C30 by a lower value, I simulated the circuit and 2,2uF should be ok without altering the sound, at least in an audible way. Or adding a resistor (220-330k) between C30 (negative pin) and the ground.
Or you can always wait 30 seconds before switching

If somebody knows another solution, please share :-)

PS : I'm referring to this schematic : http://www.thetubestore.com/lib/thet...-Schematic.pdf
It's the 5150 II, but as Enzo said, it is the same than 6505+ head.