The Amp Garage

Not sure if that was the OT or choke, though. Field coil often doubled as the choke. I'm guessing safety regulations are a part of why no one does this anymore. Cloth-covered wires without extra sheathing in the back of a cabinet probably didn't seem so crazy in the field coil days when you expect ...

I have changed countless "good" (but old) caps in amps where other techs in the area didn't. The difference was audibly surprising. Tighter low end, more headroom, less ripple on the B+ when the amp is tested with tones into a load. There is both a sonic and measurable reason to change them IMHO. T...

I think this was partly real partly in my head. After looking at the scope, I found some ringing on the lfo signal. I vaguely remember having some sort of noise problem with the lfo/inverter tube which went away after swapping tubes/moving wires. JJ ecc83s ring, just about everything else doesn't. P...

Since the 5 triode version with the lfo buffer should have a slightly deeper tremolo, I would assume it would also have more tremolo on lower settings if everything is working correctly.

really bizarre how the mixer tube could impact the trem speed in your revibe. I almost wonder if it's a speed of onset thing in terms of the phasing effect, i.e., an EQ difference that makes it seem faster? Yes, my money is on a perception thing opposed to reality. Was just jumpering in the resisto...

- I'm struggling to get my head around the operating point of the splitter/mixer stage from the Brown harmonic tremolo circuit. If I re-conceptualize that stage's shared 4.7k/2uF shared cathode as a split cathode arrangement, I think it'd have 9.4k cathode resistance with a 1uF bypass capacitor. Th...

It's also possible you got a pot with an odd taper. I've only messed with one original 6g7 and my revibe, so not a great sample size of harmonic trems, but both had noticeable tremolo on 1 or 2. Might be worth checking out Sluckey's revibe project if you are planning to build another. He has nicely ...

jer_vic wrote: ↑Fri May 24, 2024 7:22 pm The layout for the Weber Maggie kit...shows resistors across the switch.

Yep, it's generally a good practice to add them when you are switching caps in and out. I like the input jack drawing on webers layout much better, and the 220k bleeder resistor on the first filter cap is also a good idea.

Thanks. I think the voice/boost is that kind of thing. Here's the part of the circuit for that: Yep, my way only gives you one boosted setting but you get to keep the hi/lo input settings and get a footswitch option. If you add a pair of resistors across your switch it won't pop when you change set...

I don't think it should be subtle early in the rotation. Might be worth subbing in a new tube like johnnyreece suggested or double checking your wiring if it bugs you.

Thanks for the picture. I think it's one of these: https://www.piris.com/wp-content/upload ... sb-esb.pdf They're stated as both temperature and current protectors. I've not run into those before. Thanks for the link! I know how bimetallic strips work but didn't think of thermal protection. I guess...

Looks nice so far! Good on you for doing multiple test fits. For future builds, if you want to keep the two input jacks and have a hidden boost switch, here's a way to do it with an optional two button foot switch. https://ampgarage.com/forum/viewtopic.php?f=6&t=36383&p=454393&hilit=cloacal#p454393 ...

Any alcohol should do. Don't spill adult beverages on your shellac finish or you will have a bad time. I add a coat of paste wax for protection, lacquer then wax is even better.

xtian wrote: ↑Thu May 23, 2024 1:54 am The Fender Bassman RI (tweed 4x10) has a 3A fuse (accessible outside chassis) followed by a 4A fuse in series, inside the chassis. Strangely, the 4A fuse had gone open when the client brought it in.

Weird, do you know if the client replaced the 3A?

Weird. Was this factory wiring? Bimetal strips are weird in an amp. I wonder if it's a thermal cutout for the whole amp when the inside air is too hot, just in a glass tube package. Glass tube is stock to the Musicman. I have worked on several, all have it. I'm speculating about bimetallic strip, b...