Recent Posts

21

Tube Amp Building - Tweaks - Repairs / 5E3 Build Smoke Comes out of Resistor

« Last post by apeontheweb on January 23, 2026, 12:47:28 pm »

I built a chinese Ebay 5E3. I plugged it in and it sounded great. I smelled smoke and shut it down. The smoke came from a 4.7K voltage dropping resistor in between the first and second filter capacitors. On some schematics, it's noted as a 5K resistor. To help orient you on the schematic, it is tied to a 22K resistor I was wondering if anyone could help me troubleshoot my problem. Edit: I realized when I the resistor started getting hot that I was playing with the amp in the orientation so that the open side was laying down. There was no ventilation. Could that maybe have caused the resistor to overheat?

22

Tube Amp Building - Tweaks - Repairs / Re: 5E3 build troubleshooting

« Last post by dsones on January 23, 2026, 12:31:17 pm »

Power tube bypass cap connected to pin 8 of power tube.

23

Tube Amp Building - Tweaks - Repairs / Re: Ampeg B15, there's still sound when the standby is on

« Last post by pbman1953 on January 23, 2026, 10:29:54 am »

True, it's the design and it's really not a "problem". I just don't like it, because if the cable's is touched there's noise, compared to  a more traditional standby like Fender and others which is a total disconnect.

24

Tube Amp Building - Tweaks - Repairs / Re: 5E3 build troubleshooting

« Last post by dogburn on January 23, 2026, 10:15:12 am »

You can resize your photos to make the file size smaller (how you do it depends on whether you are using Mac, PC, phone or whatever). What do you mean by first 25uf cap? Where exactly is it and what is it attached to?

25

Other Topics / Re: Anybody watching Gold?

« Last post by EL34 on January 23, 2026, 10:14:46 am »

Silver just hit $100

26

AmpTools/Tech Tips / Re: Substitution box rotary switch question: Shorting vs non-shorting

« Last post by Merlin on January 23, 2026, 09:42:58 am »

Non shorting should be fine. You just have to remember when using the boxes that "this circuit will go open for a moment when I turn the switch". But that's a pretty normal expectation when operating any switch.

27

Tube Amp Building - Tweaks - Repairs / Re: Adding FX loop

« Last post by Merlin on January 23, 2026, 07:56:25 am »

The cathode follower is irrelevant. It's a cheap n dirty way to do it. Output impedance is high and you have no recovery gain, so some pedals won't be able to drive the power stage to full output. It has major shortcomings but it's better than no FX loop at all, I guess.

28

Tube Amp Building - Tweaks - Repairs / Re: Ampeg B15, there's still sound when the standby is on

« Last post by ac427v on January 23, 2026, 07:47:08 am »

Looks like this standby switch works by cutting the high voltage center tap connection to ground. I've never seen this and do not understand how this relates to your problem. Maybe another member has better insight???

29

Other Topics / Re: Anybody watching Gold?

« Last post by shooter on January 23, 2026, 07:29:59 am »

just read Wyoming bought 10Million in gold

30

Tube Amp Building - Tweaks - Repairs / Re: Testing Bad Filter Cap with a scope for 120HZ hum

« Last post by shooter on January 23, 2026, 07:26:37 am »

adjust the Fq per div so that the sinewave is "stretched" out till you start to see something coherent