I'm in trouble with this sound

[dariez75]

Hi ampagarage community, this is my third dumble ods clone. It works and sounds fine but after 10 minutes from power on, the amp make the sound you can hear in this video. What happens? All solder points are ok.

[erwin_ve]

Hi ampagarage community, this is my third dumble ods clone. It works and sounds fine but after 10 minutes from power on, the amp make the sound you can hear in this video. What happens? All solder points are ok.

Hi Dariez,


1. Is it pre amp related or power amp? What happens when the volume knobs are dimed?

2.Maybe tube related? It's not uncommon that these things happen at tubes under high temperature.

3.You are sure it isnt outside of your amp; a kitchen device or something?

4. A cap charging/discharging?

5. A ground point at the pre amp cathodes losing a connection at temperature?

Erwin

[dariez75]

thanks erwin_we

1 I've swapped all preamp tubes and sound remains. If I put volume knob up the sound becomes loud but with the same ratio.
2 today I'll try to swap all power tubes
3 the amp make this sound in different places (my house, rehersal room, studio) but in rehersal room is more present and cyclic than in my house (antenna like fx?)
4 I need to test all filter caps but I don't know how.
5 this evening I'll try to resolder all cathod point

Cheers

[erwin_ve]

Maybe your cell phone?

[ChopSauce]

I googled "ticking amp" and 1st answer is "standby switch grounding defective" ...

... maybe you can continue the search from that?

Good luck, anyway...

[Guy77]

Can you get it to make this noise ( or other noise) by tapping on the back or bottom of the chassis while the amp is running?
Florescent lights and dimmers in a room can also contribute to noise.

I am guessing a grounding issue?

Cheers

G.

[martin manning]

Try bypassing the standby switch. Get it out of the circuit and jump the B+ over to the choke input.

Another possibility is a failing filter cap.

[dorrisant]

Start at V1 and pull preamp tubes one at a time. Tell us if/where the noise may stop.

[dariez75]

Pulling out V1 ticking has low volume, leaving v1 e pulling out v2 ticking is the same. Ticking goes definitely out when I pull the Phase inverter v3

[dariez75]

I googled "ticking amp" and 1st answer is "standby switch grounding defective" ...

... maybe you can continue the search from that?

Good luck, anyway...

Good idea

[dariez75]

Try bypassing the standby switch. Get it out of the circuit and jump the B+ over to the choke input.

Another possibility is a failing filter cap.

That’s the way I’ll try tomorrow. I hope is not a failing cap

[dariez75]

Hi guys, today I've bypassed standby switch and the amp sounds the same. Next step is search failed capacitor

[bal704]

You should be able to jumper a replacement in parallel without removing any caps yet. Not sure how one good cap and one bad cap in parallel will sound, but I would think you'd hear some kind of difference when you jumpered the defective one.

[67plexi]

Photos may help sounds like a arc high voltage to ground on your sound file
You may wish to turn on the amp and turn out the lights could also be a bad power tube socket
I had that happen with Belton octal defective from the factory arcing between the pins.

Good luck

[Mr. dB]

Could the ticking be an audio-frequency artifact or alias of some ultrasonic oscillation?