Tube Amp Archive

Hi. Just put up my Soldano Slo Clone from C3amps and had som minor crackling in it. Thought maybe a tube problem, so I started changing tubes. Unfortunatley I accidently put in a 5881 tube where the steering pin was faulty, so I had it in the wrong way, resultang in a smoke situasion in the 470r res...

Thanks Guy. I'll check it out.

Hi. Any tips on where to find layout of a stereo power amp? Say 20-30watt?

Yes. I tried smaller values up till the 2200R, and the noise slowley went away.

I ave this Marshall type 18 w amplifier I built years ago that I thought I'd use for some stuff. Problem is/was that i is very noisy. So I tried to change the cathode resistor from 130R to 2200R and the amp was suddenley almost dead silent. Is this a good to do or is there somewher else I should loo...

pdf64 wrote: ↑Thu Oct 26, 2023 8:02 pm Or just use a regular transformer and add external series resistance to taste.
Copper losses should be pretty straight line linear, so a resistor should provide a very close result.

How would I do that, resistors in series?

Is there a very audible change in the pot ride or is it rather subtle?

GAStan wrote: ↑Tue Apr 16, 2024 4:30 pm Do you have slide or toggle switches installed?

I have slide ones.

I changed the switch, the only difference is that the bass pot is giving some kind of reaction when turned, and the treble might have a relativelive weak reaction. Could it be a change to 500k pot will change anything?

Maybe a failed R/J switch that is not closing in Rock setting, resulting in PAB? Measure resistance across switch pins. The DPDT switch measure 0.5 ohms in all positions. A measured a new one, same result? All the switches seem to work, ecept the Treble/Bass/Mid- section in when in Rock-setting.

The controls work in the jazz-settings, but non responsive in rock-settings?

Hi. I was hoping to not asking you guys for advice, but the Eq section in my Dumble 50w build is not active. I was wondering if this might be a quick fix, or I have to go through all the paths again? (I have, but I can't see any obvious reason for this.)

ViperDoc wrote: ↑Thu Apr 11, 2024 7:30 pm An amp that's "burnt three Weber PTs" likely has a problem that needs sorting. Good recommendation to use fuses or proper bulb limiter to protect and diagnose the circuit.

Thank you for that, but I have tried both of those things.

The blue wire is the bias tap. Check to be sure you get resistance readings from the blue to each red and also the white to confirm. Thank you Sluckey. I counted the leads coming out of the 022814 on the 50w'er and it also hahave 7 leads, so I hoped it would be like that. The company wasn't very in...

I am wondering if the Ov on this drawing is the 53v tap? I have never seen this before, so I thought I'd check it first. The colour codes doesn't match the transformer.


Primary:
230VAC, 50 HZ
Secondaries:
a) 420VDC @240mA FWCT, 330-0-330 VAC, 240mA with 53V bias tap
b) 6.3V, 3.15A