The Amp Garage

Have you ever seen the schematics of the matchless or the BadCat Hotcat? If you expect us to reference schematics, you should post schematics. I agree that your transformer choices are a bit strange, el34s could load down a power transformer that expects 6v6s so you might not get your expected volt...

It might be helpful to think in terms of what is sometimes referred to as "constellation grounding" where each stage has a local ground point which connects to the decoupling cap and whatever other stages are connected to that cap, then from the decoupling cap on to the main star ground. This limits...

Phil_S wrote: ↑Mon Apr 01, 2024 1:59 pm In general, when dealing with an unknown party, if it looks too good to be true, trust your instinct. Almost certainly, it really is too good to be true. Don't do it.

You mean there aren't hot local singles dying to meet me, just a click away?

I am mystified by those that are able to bundle amp wires like finely wrapped Christmas boxes. Still not sure which wires you can do that with and still maintain quietness in an amp. I think it's time to start reading up on this as is sourced by this thread. I've taken the opposite route where all ...

12vct transformers are very common, check mouser/digikey. I recently pulled a RadioShack 273-1352a from something if you need that RadioShack logo and want to make me an offer. It's 6.3-0-6.3 1.2A with 120v primary.

easy to bend it accidentally and make short circuit? so dangerous to use it I don't see why it would bend enough to break in normal handling/operation. It's usually a relatively thick ceramic substrate, so not much different than any other resistor. I don't think these have the same issues as tiny ...

I don't see why that particular resistor would be a problem, with a few caveats. Some thick film resistors require an external heat sync to survive their stated power rating. Always read the datasheet. Not all resistors have the same voltage rating. 350v isn't uncommon in sub 5w resistors, 500-750v ...

Two 40uf in series, plus the other two 40 in parallel = 40uf Plus the extra 100 in the can is 140. I doubt there is logic in this aside from weber having too many cheap caps they want to get rid of. I have heard of people using parallel caps from different brands as a hedge against long term failure...

bepone wrote: ↑Sat Mar 23, 2024 7:03 pm because every tube swapping (even 1 preamp tube) is the new situation

Yes.

I am talking average. If you don't plan to adjust for every tube swap, closer to center is more likely to be correct. Assuming there is a bell curve of average heater resistance.

More precise resistors would be closer to the average center over a lifetime of tube swapping, no? I agree that accuracy probably doesn't matter in the grand scheme, I usually use 5%, rarely a trim pot.

An ntc thermistor would probably do the trick, but it won't have the satisfying relay clicks and a cool box.

(1) And the heater center taps are sometimes not too accurate. A couple of resistors may well make a better center tap, with lower induced hum. Why do you think that the minimum hum is on the middle of very- too much precision- resistors ? Give us some technical reference and measurement. 8) Easier...

You are correct. You probably need to keep c12 and c13 in series for the voltage rating. Not sure what's up with the 40-8 pairs. Maybe a copyright trap, maybe that's just what the original builder had available? Edit: I didn't register c29 and c30 right after the series caps. That doesn't make much ...

Reeltarded wrote: ↑Thu Mar 21, 2024 5:50 pm I carve net shuttles like that from bamboo. You can make a very pliable tool from bamboo that is amazingly resilient to wear.

Thanks, might give that a try.

Beautiful! Thanks! Here's my scrap aluminum netting needle. Works great, just not for really tight spaces. Hemostats/tweezers seem to be faster when there isn't much space. Maybe a bendy plastic version would work better. External cable harness on a jig is definitely the way to go if you have the o...