[SOLVED] Issue with a Polytone Mini brute that "crackles"

[Titimomotete]

Hi,

I just purchased a Polytone Mini Brute IV, diamond tolex era in a wonderful condition... An old dream.

But when it was delivered (yes, i ordered it from distance to a professionnal, i'm stupid), it seems something happened during transport : when I powered on the amp, it crackles ; see the vidéo :

Shared album - Tim Oté - Google Photos

Try to see if something wrong inside, I unplugged, check and plugged again RCA reverb connection but still crackle.
Any ideas?

I see reverb seems fragile; is it possible to just bypass it to ensure it is the reverb that is broken?
Here the reverb tank :


Thanks.

[Titimomotete]

Okay !

I answer to myself : it seems the problem is caused by a specific electrical wall plug !
I checked everything and test it on other wall plug and suddenly, no cracks ! Plugged where I usually plug my amps and cracks reappears... Maybe a false ground connection ?
Sensitive...

[starjasmine]

Perhaps digital noise being injected into the line by a device plugged into the same circuit in the house?

You could use something like this to test the grounding of the wall outlet:

Receptacle Tester Klein Tools

[Cunamara]

Well, you could by a tool to test it. Or just use an outlet that doesn't cause the crackling...

[Mick-7]

As starjasmine mentioned, you can buy a wall plug circuit tester for about $10 in any hardware store.

Have you tried flipping the Reverse power switch on the amp's top control panel?

[Titimomotete]

Yes, I try inverted mode but it changed nothing.

I use a powerline network extender : I try to deactivate it and, indeed, all cracks and noises disappear, except a little hum ; as soon as I powered on powerline extender, cracks appeared again.
So it is the powerline wiring extender that cause these cracks. I supposed the wall plug where is the powerline is on the same wire than the first plug where was the amp (not sure all this is good english...).

Thanks for the idea ! Was a good one.

I will try to find something to isolate the amp from electrical interferences.

[starjasmine]

I use a powerline network extender

Do you mean one of these?

TP-Link Powerline Ethernet Adapter Starter Kit

If the powerline adapter is injecting noise into the house wiring, you may be able to solve the problem by just moving the powerline adapter to a different wall plug.

If the amp is actually picking up RFI (radio-frequency interference) through the air instead of through its AC plug, that's going to be harder to solve.

You might just take the easy route of unplugging the powerline adapter when you want to use the Polytone.

Does the problem affect other amps?

According to this post on a hi-fi forum, you might try a powerline adapter that has a passthrough mains socket, or get rid of it for a different wifi solution, like a mesh network or a used Apple Airport Extreme.

[Herbie]

Hi Tim! I am glad You got the noise problem solved.

So congrats for the legendary amp!

The extra noises on Your video sound like they would make a noise music artist happier than thousand rabbits! But of course it makes the amp quite useless in other genres. I have had several Polytones and none of them sounded never like that.

[Titimomotete]

Do you mean one of these?

TP-Link Powerline Ethernet Adapter Starter Kit
Attachment 121074

Yes, this sort but Netgear ones.

Does the problem affect other amps?

No, I have a Fender Hot Rod and it is not affected at all.
Polytone seems it hates mobile phone too !

I asked some forum specialized in electric for a solution to filter powerline network frequencies.
I will keep you informed.