Loud buzz in AM radio when my amp is on.

[navdave]

Guess I never done this before because I've never heard it...
Put my tube amp I built in 2007 located in my bedroom on standby, had the radio in the restroom on
listening to the morning news on an AM channel. Then I hear loud BUZZ coming from the
radio in the restroom? I'm pretty sure the plugs are on the same circuit, my house is old
and this part of the house does not have the earth ground wired to these particular plugs.
Funny thing is if I plug in my Fender Prosonic amp I get no BUZZ through the same radio?
Should I start looking at my main b+ filter supply or try swapping the primary ac wires?
My power supply is lifted from a Soldano.

[jjasilli]

Usually the complaint is about hum in the amp!!    1.  Does the radio noise go away when the amp is full ON?   2.  Maybe get a long extn chord and plug the radio into some distant wall outlet, not on the same line as the amp.  See if the noise in the radio goes away.  3.  Move the amp around in the bedroom.

Report back the results.

[Dave]

Am receivers are much more susceptible to EMI than FM receivers. This is because the demodulators are looking for variations in the amplitude of the signal. Well, anything and everything creates EMI and some of it will inevitably be in the frequency range of the radio station you are listening to. Any of that EMI whose ampiltudes are greater than the amplitude of the signal you are listening to are going to become audible.

FM doesn't have this problem (at least not for the same reason) because its demodulator is looking for slight variations in frequency, and amplitude is not of much concern.

The nerves in your sphincter create EMI, so your amp certainly does (much more than your sphincter). If the EMI created by your amp has elements in the frequency range you are tuned to, you are likely to hear it.

I would say, listen to FM or turn your radio off.

Dave

[navdave]

On or standby noise is the same. Gonna try moving it around when I get off werk tonight.

Usually the complaint is about hum in the amp!!    1.  Does the radio noise go away when the amp is full ON?   2.  Maybe get a long extn chord and plug the radio into some distant wall outlet, not on the same line as the amp.  See if the noise in the radio goes away.  3.  Move the amp around in the bedroom.

Report back the results.

[Ritchie200]

The nerves in your sphincter create EMI,

Dave

AHAH!!!  It has nothing to do with your amp!  It is the AM radio placement in the BATHROOM that is causing the problem......

Sorry,
Jim

[billcreller]

Could be worse, like my Hawaiian buddy's amps pick up local radio stations.  We tried the little iron rings on the cords etc and other things, but I believe he's stuck with the problem. We tried shielding the pre-amp on his recording rig too, with no results.   We can see the antennas of the stations from his fifth-floor apartment and they are not very far away.  We could move his stuff to the beach and work from there, I told him    But maybe then we would get  "surf modulation"

[Willabe]

We could move his stuff to the beach and work from there, I told him    But maybe then we would get  "surf modulation"

                               


            Brad           

[navdave]

What an analogy huh sphincter's and am radio who would of ever thunk?
Funny thing is one amp will cause the radio to buzz loud the other one wont.
Well got home tonight tried it and it still did it but a lot less at night.
Used an extension cord to plug in the radio from another outlet in the kitchen,
but left the radio in place in the restroom no BUZZ.
Moved the radio around a little in the restroom plugged into
the restroom outlet no BUZZ LOL oh well......

The nerves in your sphincter create EMI,

Dave

AHAH!!!  It has nothing to do with your amp!  It is the AM radio placement in the BATHROOM that is causing the problem......

Sorry,
Jim

[jjasilli]

Orientation of the radios's antenna could also be a factor.  Anyway, the problem is solved?

[octal]

You don't have any "snubbing" caps across your rectifier diodes. Semiconductor diodes switch "on" abruptly and generate hash / RFI. You'll sometimes see caps between .01 to .1 uf across rectifier diodes for this very reason.

Nathan

[navdave]

Guess I can give that a try if it comes back.

You don't have any "snubbing" caps across your rectifier diodes. Semiconductor diodes switch "on" abruptly and generate hash / RFI. You'll sometimes see caps between .01 to .1 uf across rectifier diodes for this very reason.

Nathan