The Amp Garage

Understood Drew and Max, thanks for the replies! After posting this, I unscrewed the jewel and immediately noticed that the bulb was loose in the socket. Took it out and then saw that its contact surface was sort of lop-sided - which I thought would make it prone to poor seating. So I cleaned the co...

So I’m playing my 2nd gen ODS clone today and I hit an E flat at the 11th fret of the high E string and the note rings, then fizzes. At the same time - I notice the pilot light (regular socket type, not an LED) dimming. It’s like that note on that string is vibrating something and causing this behav...

Hey, didn’t even think of that Martin. Conditioned through the years to reverse the “power-up” process without a second thought. Sometimes the simplest answer isn’t obvious; but for me the obvious is usually the least simple, lol. Sounds like a fortune cookie :roll: Thanks for the advice Martin! I’l...

Small little detail I’m looking for advice on: When I switch stand-by to “stand-by” during power down, I sometimes get a “pop” through the speaker. Is this something that can be solved with a capacitor on the switch or is it indicative of a different problem I should be chasing? I’ve searched and se...

Thanks Martin! I figured a little over 2 was ok - as long as it was at least 2? Truthfully, the whole FET “sausage” still eludes me as far as understanding the second and third order effects of this part of the circuit. I do know that it definitely helps my single coils sound better through the amp ...

Still sounds great today (IMHO). Tried a Celestion G12K-85 with it. It’s a pretty full range and neutral speaker for a Celestion and I figured it might work well with this circuit. Turns out it definitely gives the OD channel more “bark” for lack of a better word; but the clean isn’t quite as full a...

Thanks Dan! As usual, I couldn’t have done it without you guys
Sounds like an exaggeration; but I learn a hundred new things every time I build one of these. This time was definitely educational.

My collection of random tubes is anything but matched, lol. I just try to get my power tubes closely matched and wing it with the rest. As for the choke thing - I hear you Martin. I’m always a bit skeptical of these types of things but I definitely heard a difference with this circuit. Over time I’l...

I had a feeling it was in my interpretation of the three references combined with the variables you mentioned - that’s why I kept reviewing and looking for possible misinterpretations. I remembered that I was confused by those connections initially, so I figured it warranted some digging before tear...

Hot dog! That’s it! Everything is working as it should now and sounds pretty good! Amp is dead quiet, no oscillations even with OD and PAB cranked. Definite Marshall character and really full (vs scoopy) cleans. Going through a NOS 1989 EVM12S that I got a deal on from an on-line stereo/hi fi store....

On the power amp master volume - is the identified V1b coupler connection at NC2, or should it go directly to the .02 coupler on the board? [/quote] On the layout, the lead from the Clean Master says "V1b .02 coupler," which to me would mean on the board. [/quote] Thanks for the info Martin! That’s...

Just OD; and with everything maxed out and PAB on. How would I drive the power amp with 102? Preamp out from 102 plugged into power amp in on BM? Would I use regular cables or speaker cables? Any risk involved that I need to pay attention to? On the power amp master volume - is the identified V1b co...

Thanks Dan, that certainly helped! Now the OD switches in and out as it should, as does the PAB. Confirmed all tone controls/switches function as they should as well. Still weak with weird behavior though: Pre-amp volume goes off in the middle of its rotation (call it “5”) with weak volume from 1-4 ...

Ok, hopefully I can get this thought out in some sensible fashion. After comparing the layout, schematic, board plans, and re-reading my questions about the changes - I think I might see where I went wrong. Bear with me because I still struggle with how these things flow from a theory POV - so I may...

Thanks Dan, I appreciate the offer and will put some up here soon. Right now I’m going through each run between components and verifying they are going where they’re supposed to. Once I have that figured - I’ll take a couple of pics and re-start the signal tracing. Dumb question, but just to make su...