The Amp Garage

A 50 watt 2 6L6, 5 12ax7 peavey 5150 can not have only 2 amps for filaments as all 7 tubes need 5.4 amps . Hey Steve, Peavey does a similar trick with the 40VAC winding that I've suggested, except way more complicated because they also use that winding to run relays, transistors, bias supply, and t...

Hi guys, I have a PT from a Peavey 5150 that I'd like to recycle into a new geetar amp. I've got 5 preamp tubes, and 2 6L6GCs in the power end. The transformer has 3 secondary windings with the following ratings: 6.2VAC @ 2.05A 40VAC CT @ 0.403A 361VAC @ 0.403A Given the limited available current on...

Sorry about the late follow-up. I got a job after graduating, so I had to move again and just started this week. When I replaced all of the problematic pots, the strange "fizz" sound all but disappeared. I can barely hear it anymore, and I'm certainly pleased with the hum level after replacing a LOT...

You're right! Here's a couple. Bear in mind, this was the first tube amp I've ever built, and there are a lot of things I'll do differently for tube amp #2 from what I've learned here. I put together the circuit with the help of books, forums, and articles, and designed the physical layout from scra...

Spent the day working on the amp, and I'm gonna ramble for a bit. Since I moved into a house with good wiring, MOST of the amplifier's hum disappeared without me doing anything to change the amp. The overdriven tone actually sounds nicer now that there's less 60Hz and 120Hz to create IM distortion. ...

Small poly caps normally bypass the filter caps, not the decoupling resistors. Either way I doubt this is necessary. You could do with increasing the resistance between stages a bit to help with filtering. Oops! :oops: I meant to say caps. I'll go make a note of that on the old post. I'll give the ...

Here's a thread I found on MEF that's been diagnosing a very similar sounding problem on Vox Night Train 15 amps. Sound clips included. http://music-electronics-forum.com/t27536-3/ More things on my list to try, as per this post : 1. Try putting a 500pF bleeder cap from grid wires to ground. 2. More...

I'll be keeping an eye on this thread, because it sounds very similar to the problem I'm having with a non-Trainwreck amp. I too would like to hear a sound clip. If you get it sorted, please come back to post what the cause of the problem was. Edit: Have you read these posts? http://music-electronic...

I found more problems with my EQ, particularly where the Rock/Jazz switch is concerned. A couple wrong connections, I believe. Interestingly, it still works well as an EQ the way that it is. Thursday afternoon I'm going to tear apart the EQ and put it back together CORRECTLY. Thank you Littlewyan fo...

I'm afraid not - I'm in the middle of moving houses and I had to pack up my tube amp last night. I won't be able to do any physical changes and testing until Thursday. In the mean time, I can still postulate and simulate! If I crank the first volume to overdrive V1b and cut the second volume so that...

One major difference I've just noticed between the ODS 3rd gen EQ and mine is that when the Rock/Jazz switch is in the Rock position, the bass capacitor is shorted across. I threw together a quick simulation with one gain stage, sweeping the bass control, and the cross-talk between the bass control ...

It all started here, but it's changed over time. http://ampgarage.com/forum/download/file.php?id=20293 There are differences between cap values and potentiometer values which followed some conversations with people on DIYAudio. That's likely where I went wrong. The amp doesn't sound bass heavy, espe...

Yes, I have an oscilloscope. The forum won't let me upload LTSpice file types, but I can change the file extension to .txt and upload them. You'll just have to change the extensions back to .asc and they'll open up again in LTSpice. Yes, you're right about the cap across the bass pot. I'll try swapp...

Thanks Littlewyan. What simulator do you use? I test things out in LTSpice, but if I have more than a couple tubes in a model it can't do transient simulations very quickly. I've attached my LTSpice schematic and a model of the EQ in a zip to help you out, if you're using LTSpice. Might be easier to...

Tubeswell - the OT is a Hammond 1750JA (4250 Ohm, 40W) and the PT is a Hammond 272HX (186VA, 600vct @ 230mA). JMFahey - when cranked up, the amp hums a little louder than I'd like it to. It's getting in at the reverb recovery, master volume, V1, and V2. I'm still working on sorting that out, but may...