The Amp Garage

Lifted the ground on the treble control. MADE IT VERY VERY LOUD. Overall, not nearly as tonally interesting as with treble control active. Shoot, overall it was worse. Crummy. It made it hard to play, at any volume or combination of settings. Just wrong. Very gainy sound. About the time it started y...

Replaced the input R with a 68k because I had one. That made a very impressive difference. Almost Fender-like. Almost . Certainly not scooped, but getting right to it. Spinning knobs on amp or guitar now has a much greater effect than before. Beginning to overdrive the preamp. Smells like success. S...

The first thing I would try is paralleling a 33k across the 100k input grid resistor R1 to get more HF content through the first stage. Use Input 1 and put a 1/4" plug in the other input to lift the other 100k's ground so it doesn't divide the guitar signal. To get the full effect you can lift the ...

Sorry about the inline schematic. The PDF attachment is a lot better, but I couldn’t seem to upload it as an inline graphic, and the jpg conversion obviously did not go well. Local NFB via C2. So that’s what that is. Why would such a low-gain stage need NFB? Early on, I assumed the speaker was junk,...

Wow. This is good stuff, a great feast that has taken me awhile to digest, and I'm still at it. I want to explore some of what you've mentioned, but it will take me a little longer to gather and organize my thoughts. But right now, I want to thank each of you. I appreciate your response very much. Y...

What Makes the Epiphone Constellation a Bass Amp? More generally, what makes any bass amp a bass amp relative to a guitar amp, maybe besides having to pump more watts to get the same loudness? More specifically, when I plug my Strat into the EA-17, where do all the highs go? Fender and Marshall bass...

To be more precise, the cap that failed was on the output side of first gain stage, from plate to ground. Paul ran the amp without it and it worked just fine, but he did install a new one. I was confusing it with some other circuits I've been studying that toss a cap in between grid and plate. For t...

Holy mackerel, it's mid-August already. THE KALAMAZOO LIVES, in glorious silence at idle right up almost to 9/10. Briefly, Paul went through it, did a lot of the same things I did, verified that I hadn't really screwed anything up, cleaned up a bunch of connections and improved grounding, all of whi...

It's been awhile since I reported, but I have an excuse: I've been busy. Let's see. I did swap out r7. No change. I reflowed many but not all connections. No change. Oh, yeah, the little oscilloscope revealed a lot of RF in the circuits--double-digit megahertz on down--so added grid stoppers. That g...

Step bits yield surprisingly precise and clean holes. Where there is room to use one, the result is better than a tapered reamer, which is all I had for many years.. er, decades. Just an example of what I'm referring to: https://www.homedepot.com/p/General-Tools-1-8-in-to-1-2-in-3-175-mm-to-12-7-mm-...

A 47uF/630v Solen is about 2"x3" according to TubesAndMore specs. Solen sheet shows 10uF/630vdc to be 26x30 mm. So, bigger than the F&T's that I used in the Kalamazoo. A lot bigger but I might could have made room. There's plenty of room in the push-pull Epiphone Constellation, but that's a bass amp...

The Wonderful World of Oscilloscopy is a fearsome place. Pretty clear that I have a lot to learn here. Also pretty clear that a "real" o-scope would be easier to learn on than this little boxful of menus, but I've largely sussed the display and buttons. Less clear to me is what probing different spo...

If you watch it in a dark room you might be able to spot the arcing to confirm a bad OT, you would also likely be able to smell it. A bit more scientific, you can do this if you have a spare neon and a 9v battery. https://www.premierguitar.com/the-super-secret-transformer-tester If you don't have a...

...However, a megger (hi-pot ohmeter) is pretty inexpensive these days. About $100... Although I love an excuse to buy another tool--and I'm aware of more than a few occasions in the past where I could have used such an instrument--I'm also aware that I can get a suitable Hammond for far less than ...

The old OT: https://photos.smugmug.com/Projects/Kalamazoo-/i-GWtGqWS/0/MhxC65xvzbDVdF425cK6KCShS54HhRX9NJ6CKFQh3/X3/IMG_2942-X3.jpg https://photos.smugmug.com/Projects/Kalamazoo-/i-mxnBbLz/0/MQKpGF5Zp7pRMk3nSwwmxWFbBKS5WCPh2pJVT9ZDp/X3/IMG_2941-X3.jpg https://photos.smugmug.com/Projects/Kalamazoo-/i...