Polytone MiniBrute IV radio interference

[epistrophy.]

I just moved my MiniBrute cross country to a new home and plugged it in for the first time and am picking up radio stations even without an instrument cable plugged in. I know it got jostled a bit during the move as some of the screws on the underside had wiggled loose, but I tightened them back up, popped off the back, and didn't see any broken or disconnected connections. The amp otherwise still functions as it should and sounds good. Not sure if the issue is bad grounding in my new apartment (very old building) or if maybe a solder joint needs to be touched up somewhere. Does anyone have ideas on fixing or troubleshooting this one? Unfortunately I don't have another amp to try out, but no issues with my HX Stomp or hifi setup. I know this isn't a tech forum but there's a lot of Polytone knowledge here so hopefully someone can help!

[wintermoon]

Could very well be a grounding issue.
Also try another outlet or even another guitar cable.

[bako]

Years ago Patty Hearst was kidnapped by a group that called itself the Symbionese Liberation Army. I first learned about this from a radio news broadcast that came in on my Polytone Bass Amp while playing a jazz session with friends. Pretty strange.

[Mick-7]

Years ago Patty Hearst was kidnapped by a group that called itself the Symbionese Liberation Army. I first learned about this from a radio news broadcast that came in on my Polytone Bass Amp while playing a jazz session with friends. Pretty strange.

How groovy, the revolution will not be televised but you may hear about it on your amplifier!

[skiboyny]

Reversing polarity help at all? You might be close to a transmitter and if that's the case going to be tough to fix. You could try a isolation transformer.

[Alter]

The amp may be fine and still getting radio signal if the current has a ground problem. I recently got radio stations on a brand new (and very expensive) Two Rock with a vovox cable, because my Tele needed pot cleaning and was shorting..

[vintagelove]

I just moved my MiniBrute cross country to a new home and plugged it in for the first time and am picking up radio stations even without an instrument cable plugged in. I know it got jostled a bit during the move as some of the screws on the underside had wiggled loose, but I tightened them back up, popped off the back, and didn't see any broken or disconnected connections. The amp otherwise still functions as it should and sounds good. Not sure if the issue is bad grounding in my new apartment (very old building) or if maybe a solder joint needs to be touched up somewhere. Does anyone have ideas on fixing or troubleshooting this one? Unfortunately I don't have another amp to try out, but no issues with my HX Stomp or hifi setup. I know this isn't a tech forum but there's a lot of Polytone knowledge here so hopefully someone can help!

check to see if it’s coming through the reverb (return circuit).

[epistrophy.]

Well I've now taken it to every outlet in the apartment and the only one that is kind of ok (still some interference but tolerable) is the bathroom outlet. Save the jokes--I know Coltrane practiced 24/7 but i don't think I can make this work. The polarity switch doesn't make a difference, and though I'm finding that the reverb amplifies the radio signal a bit, unplugging only helps a little--the radio still overpowers the guitar signal. So frustrating!

[epistrophy.]

I unplugged the preamp and it went silent, so I guess the problem is the pre and not the power (maybe some of you already figured as much). Although I got better results with the outlet in my bathroom, could it be that there's a bad solder joint on the preamp that is picking up the noise? This thing went 3000 miles on the floor of a U-Haul with no padding, so I would not be surprised if a sketchy joint finally went bad.

[213Cobra]

Try a Henriksen Blu 6 or Bud 6, with 30 days return privilege if you don't like it. Or, heck, for much less even a DV Mark Little Jazz. Life is too short to wrestle with a radio receiver Polytone. Play guitar and stop futzing. There are better ways to spend your time than wrangling an old Polytone. -Phil

[epistrophy.]

Not looking for amp suggestions, thanks.

[Doctor Jeff]

Years ago Patty Hearst was kidnapped by a group that called itself the Symbionese Liberation Army. I first learned about this from a radio news broadcast that came in on my Polytone Bass Amp while playing a jazz session with friends. Pretty strange.

Were you jamming on I Heard It Through the Grapevine at the time? I heard it through the Polytone?

[Doctor Jeff]

I had an Alvarez amp that I couldn't use due to electrical interference. I picked up NPR just like Nina Totenberg was in the same room...

We have old tube and post wiring in our current house. (Newer house is getting an electrical upgrade this week, and should be AOK.)

I assume it was poor grounding and ground loops, but I didn't have the energy to sort it out. I sold it ASAP.

[vintagelove]

I unplugged the preamp and it went silent, so I guess the problem is the pre and not the power (maybe some of you already figured as much). Although I got better results with the outlet in my bathroom, could it be that there's a bad solder joint on the preamp that is picking up the noise? This thing went 3000 miles on the floor of a U-Haul with no padding, so I would not be surprised if a sketchy joint finally went bad.

Is the radio present with the volume on zero (and reverb on zero)?

[epistrophy.]

Is the radio present with the volume on zero (and reverb on zero)?

Yes to both -- none of the controls have any effect on the radio signal