Peavey Windsor problem

[Decimator]

I just got my new Windsor studio. When I first powered it up and played it made only this farting noise. When I strummed the guitar louder the sound totally disappeared. I tested to run my Ada Mp-1 to the effects return - works good, so the power amp section is ok. Then I opened the amp and did some re-soldering (almost all the solder joints did look very crappy ).

Now I can play at moderate preamp gain levels, but when I crank the gain near to the max and and strum the strings a bit harder the sound starts farting and fades out. If I don't play anything for a few seconds the sound fades back. So the amp did got better, but the problem is still there. Does anyone have clue what could be the problem here. I have tried the amp with JJ, EH and Engl preamp tubes.

Here's a sample
http://koti.mbnet.fi/torkkis/windsor-problem.mp3 Recorded through effects send. (sounds a bit like the outro of bleak by Opeth )

 

[Notuern]

That sounds like a bad tube, weird that its still there after switching though.. maybe biasing error?

 

[Trevoire520]

Probably shouldnt have took it apart and messed with it man. If my amp was making sounds like that I'd take it straight back to the store to be replaced.

 

[Wolfeman]

If you are positive it's not the preamp tubes themselves, next I would check the tension on all the preamp tube sockets..... Could be loose causing intermittent shorts while playing.

FYI when you pull tubes, don't rock them out, pull straight up. Rocking usually causes the sockets to lose tension.


But what you are explaining sounds like faulty tubes just to let you know......

 

[Decimator]

Thanks for the tips Notuern and Wolfeman!

I ordered that amp from France so it would take weeks to get it repaired, so I'm not too interested to ship it back. I used to work at TV repair so I'm not new to electronics. The tubes are that I'm not familiar with, but you got to start somewhere .

I am not sure of anything but I did test with 4 pairs of preamp tubes (2 pairs of JJ, 1 pair of Engl and now in place pair of EH:s) I will check the tube sockets when I get home from work.

Had to take the tube holders away, the EH tubes would not fit in to the socket with them . Also the sping reverb tank was not attached properly .A bit crappy I would say . The amp was cheap, so I'm not too bothered about this. The clean sounds I got from the amp were nice!

 

[Decimator]

I cleaned and checked the tube sockets, but it did not help. I checked the Windsor head schematics (couldn't find them for studio) and find out the part numbering was very similar at least fot the preamp part.

Preamp schematic http://koti.mbnet.fi/torkkis/Windsor.jpg

On my Windsor there wasn't resistor R13 at all (connected between V1 grid 2 and ground). I soldered a 1M resistor in place and the amp got a lot better. No fading out anymore! When playing on full preamp gain the amp still seems to choke a bit. Any suggestions what to do next?

 

[Wolfeman]

R13 in that schematic isn't necessary, and really shouldn't do anything (if my math is correct). That's why VR1 is there. It's not only a gain control, but acts as a grid leak resistor to keep the second stage grid at DC ground potential.

BTW I think I have seen an actual Windsor schematic before, and this one looks a bit different....

Anywho, that input stage is very close to a Fender Champ.

 

[Decimator]

Hmm, strange. I didn't change or touch anything else when I soldered the resistor in place. I have tested now with the other preamp tubes and it seems to work with those too. Except of course for that little problem on higher gain.

 

[Wolfeman]

PS, if you want some sweet gain out of it, try swapping a 390k in place of the 100k on the v1 plate resistor.... You might like it...

 

[Decimator]

PS, if you want some sweet gain out of it, try swapping a 390k in place of the 100k on the v1 plate resistor.... You might like it...

Thanks, I just might try it out.

 

[Wolfeman]

Or better yet, change all of the plate resistors to 220k....

 

[DaWolf]

Maybe a problem with the input ? The clip sounds like empty batteries on a wireless or pickup.

 

[Wolfeman]

Maybe a problem with the input ? The clip sounds like empty batteries on a wireless or pickup.

I was thinking that too, but it only happens when he increases the gain higher on the amp, so its got to be something in that area...

 

[Decimator]

Yep, that's right. No batteries on my guitars. After I put the 1M grid leak resistor, the choking happens only on full gain.

 

[Rico]

Hya guys...I too have a Peavey Windsor and a problem too....when I Turn the amp ON and it`s in Stand by, I hear some noise, like little pops...The thing is, that it was worse a while ago.When I wanted to turn off the amp,I put it in stand by and the guitar sounds just came around in periods...Any help?
Thanks!