Pop, fizz, stink, and a new hum on a homegrown tweed tremolux. Looking for ideas.

[Dave H]

850 Vac at some cap in the filter..? That is not good! Check your filter in detail.

It's probably the meter. If it's half wave rectified, average sensing callibrated RMS for a sinewave and it doesn't have a DC isolating cap then it will read about 850 when measuring 370Vdc + ripple on the Vac setting. I'd try measring it again with a 10n 450V cap in series with the meter +ve probe.

[wcrankshaw]

Due to the lack of absolute destruction, I'm guessing it's the meter. Otherwise, those numbers seem appropriate right?

[Dave H]

Due to the lack of absolute destruction, I'm guessing it's the meter. Otherwise, those numbers seem appropriate right?

The DC reradings look OK. The AC ripple should read correctly if you use the 10n cap in series.

[überfuzz]

If you look at this amps schematics, what B+ do you see? I believe a Tremolux is somewhere in the realms of 400+. Check if yours is low or not.

[wcrankshaw]

If you look at this amps schematics, what B+ do you see? I believe a Tremolux is somewhere in the realms of 400+. Check is yours is low or not.

Pretty sure it's right on the money with respect to the original schematic.

Edit: actually I'm not really sure what the plate voltage is supposed to be, but based on everything I've read 370-380 seems to be the target. It doesn't appear to be marked on the schematics.

[überfuzz]

380:ish seems ok, in the lower end of the spectrum if you have a 6L6 power-stage. But not as important as the ripple in the filter. You really should fix that before you do anything else.

[wcrankshaw]

380:ish seems ok, in the lower end of the spectrum if you have a 6L6 power-stage. But not as important as the ripple in the filter. You really should fix that before you do anything else.

It's a 6V6 driven amp. Like I said, I don't know for sure, but I'm guessing 370 is about right if you think it should be around 400 for a 6L6. I think Dave's assessment is probably correct in his explanation of the ripple voltage. I'm using a standard (inexpensive) meter from Lowe's.

[überfuzz]

I'm using a standard (inexpensive) meter from Lowe's.

The 800+ Vac you see might be wonky measurements, but you have a busted filter. Otherwise you'd see virtually no ripple there what so ever.

[Dave H]

The 800+ Vac you see might be wonky measurements, but you have a busted filter. Otherwise you'd see virtually no ripple there what so ever.

I'm not sure about the busted filter. OP needs to measure the ripple again with the series cap. My cheap meter would measure 370V of pure DC (no ripple) as 821V on its AC range without the cap.

[überfuzz]

I'm not sure about the busted filter. OP needs to measure the ripple again with the series cap. My cheap meter would measure 370V of pure DC (no ripple) as 821V on its AC range without the cap.

Mhm, interesting... I never seen that behaviour in a multimeter if the B+ ripple has been acceptable.

[Chuck H]

If you don't already know that you can do this without killing yourself, or worse yet damaging the amp further, take it to a tech.

I don't know if this was a slight misstatement when looking at it in context, but I'd been waiting for a new sig

[wcrankshaw]

Today I replaced the damaged capacitor, and seem to have gotten things back to baseline. Hum with a telecaster is virtually gone when I stand perpendicular to the amp, and is otherwise right in line with what I would expect I guess. (speaking of ground hum with telecasters that only goes away when you touch the strings...)

There is something else I noticed, which may be incidental and not matter at all. I'm using JJ 6V6 tubes. Since I started poking around the other day, I realized that the filaments on the different tubes are glowing in different ways. The red/orange glow on one is very bright at the base end, but not so much at the top. The opposite is true for the other tube. This does not change when the tube position is switched. Anomaly or something real?

[The Dude]

Different tubes have different filament "glows". Nothing to worry about.