Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Bash on September 11, 2025, 02:07:11 pm

Title: Tremolo causes clicking sound (Supro DualTone build)
Post by: Bash on September 11, 2025, 02:07:11 pm

Some time ago I build a Supro DualTone amp (decribed https://el34world.com/Forum/index.php?topic=26708.0 (https://el34world.com/Forum/index.php?topic=26708.0)).

Since last week the tremolo causes a rhythmic clicking sound. When using the tremolo depth knob, the clicking becomes softer (tremolo depth low) or louder (tremolo depth high).
Any idea what might cause this?

It is not the tube, nor the LED (cause I replaced them both). I checked and measured all solders in the tremolo circuit and everything seems OK.
If anyone could give me hint on where to start looking, so I don't have to replace all the parts of the tremolo circuit, it would really help me.

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: tubeswell on September 11, 2025, 04:44:34 pm

Schematic?

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: Bash on September 12, 2025, 02:39:49 am

Ah... sorry. I thought I had it in my original thread.

I used Steve Lucky's schematic.

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: Bash on September 12, 2025, 02:59:48 am

And this is the schematic for just the tremolo.

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: tubeswell on September 12, 2025, 03:01:54 am

If its clicking, it could be in the signal path (more so than in the LFO circuit).


Seeing as how the LFO wiggles the cathode of the input tube, and seeing as how it only started a week ago, it could be the input tube has gone off. Try a fresh tube there.

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: Bash on September 12, 2025, 03:24:10 am

Thanks. I will give it a try this evening.

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: SEL49 on September 12, 2025, 08:45:22 am

Quote from: Bash on September 11, 2025, 02:07:11 pm

It is not the tube, nor the LED (cause I replaced them both).

Replace the LED with a 1K resistor like the original circuit. The LED causes the LFO output to increase dramatically and is probably just overdriving the cathode of V1.

Title: Re: Tremolo causes clicking sound (Supro DualTone build)
Post by: Bash on September 12, 2025, 12:20:54 pm

Just replaced V1, which solved the problem.

Thank you everyone.