Ive been told (by the sound guy at my church) that my new amp picks up radio stations a lot (he says Behringers are notorious for this). Ive never noticed because i live on a lake with a big plateau right behind me where all the radiostations are (most). Its kinda hard to get a signal down here so i just get static (which i thought might be normal for this amp). Any ideas? I dont want to get a new amp. Can you sheild an amplifer or are they usually done like that? I intend on switching the tube to a higher quality one soon anyways so i can do it then. Theres no rush because im not gonna be playing in church for a few more weeks. Thanks guys.
By the way my amp is an AC112.
aka Izabella
Izabella
If you are not actually picking up radio stations, I wouldn't worry too much about it.
My old Marshall amp would pick up things on rare occasions. Once I heard the Police talking over the radio coming through the amp. I looked out the window and a Police car was driving by. So, this probably can happen with any amp on occasion.
That static could be from a number of reasons. A bad cord, single-coil pickup hum, even hum from electrical devices in your home. I think most people experience these sounds on occasion. See if you can identify the source of the static.
If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis
I dont get radio stations in my home, just static. BUT then once i go up on the plateau or over in bellevue (where my church is) i do pick them up (dont know how consistantly though).
aka Izabella
Radio signals get picked up due to the way the circuits are designed, there are modifications that can be made to a circuit to reduce this. Proper shielding helps avoid picking them up as well.
"And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down here on earth." - Eric Idle, The Galaxy Song.
Make sure that the 3rd prong is connected on your power cord (not power chord). In older buildings, sometimes they forget to connect the earth-ground. This is not guaranteed, but it often helps with this type of interference.
-Laz
The other thing to check is whether the amp still picks up radio signals if your guitar lead isn't connected - this is the major cause of radio disturbance due to long length of straight wire, which acts like an aerial
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You think this would work?
"Use coax cable in the signal path, at least in the early sections where noise counts the most. Tie one end of the shield to ground and terminate the other end with some shrink tube so it cannot touch anything. This way the coax shield acts as an antenna and conducts the RF to ground (as well as Faraday shielding hum out). If you tie both ends to ground you set up some capacitance (and the possibility of ground loops) you're better off without. The shield should be tied to the star ground point individually, and bypassed to the chassis locally with a good RF cap of about 0.001 to 0.01. "
aka Izabella
If your amp was picking up the morning or evening news then you've got a problem. That was used mostly for old all tube amps to cut down on the Rf from within the chassis, created by the transformers, bad wiring and high voltages.
If you have your guitar unplugged and the preamp volume/gain turned to say 10 and the master volume to say 10. What noise is the amp making? if its making a hissing sound thats normal, if it making a 60 or 120 hum it could be anything from bad tubes, bad power supply capacitors, heater wires not twisted properly, bad ground points, to name a few.
Have you heard what a marshall sounds like when their turned up setting idle. It's like an axillary power plant for a jet engine. if you listen real close you can hear marshalls saying lets rock, lets rock.
if it's picking up elevator music in between your chord changes then something needs to be done. unless your familiar with safety when working inside an amp, I will recommend you study up on it or take to a shop.
Joe
I always drain the caps when i open it up. I remove the ac wire too. No worries.
aka Izabella
I'm not sure what amp you have, being a newer one you'll probably find that it's grounded to some of the variable potentiometers. Have to tried different guitar chords? Different positions if you have a selector switch? You may want to try shielding the input jack from the chassis.
random thoughts
joe
