I'm getting a lot of hum and buzzing on both speakers making quiet passages in music less than quiet. I have checked any possible power cord interference without any effect. The hum begins when the Adcom is turned on and only diminished after the pre-amp is started. Still, it is too loud to be exceptable. Any suggestions?
Well folks I solved my problem and the amp has never sounded better. It had always hummed and now it close to stone quiet. The secret was it really never a problem with the amp. The problem was the result of either the pre-amp, interconnect cables, or the combinations of them. The solution came when I added a "drain wire" or ground to the cable I was using. There must have been a ground loop or some in-balance that required a wire to be connected to the earth (-) side at the source on the interconnect and then left unconnected at the other or receiving end of the interconnect. Anyway, no more hum, and the solution took some spare wire and solder.
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Yes it almost certain to be the big Electrolytic Capacitors in the power supply. What you are hearing is the 50/60hz mains hum they are supposed to take out. Don't know the amp in question, but this is common problem with all amps. You can't miss these. But be care full they can hold a charge! There might be just one big one or more. At the least 2,000UF. Replace all.
prob just a cheap w/less receiver. I guessing it's FM. Doubt it will make a lot of diff but have you tried using a extension lead so the receiver is not near your amp? Also if you are using a mono mike and putting it into a stereo rca try only using one input if you can switch to a mono output. I'm not a axpert but i've fiddled a lot and you will have to try and try again. Is there any other sources of FM frequency around?
You should have reported the faults back to the repair people! It does however sound like an earth link is missing or detached. It's possible that somebody has not soldered something right, or during transit a dry joint developed.
Buzz through speakers usually means it is picking up humm from a power source. Check your mixer and amp input (gain) levels. If one is turned up really high you will get buzz. If that doesn't work check where it is plugged in. Is it sharing power with another electronic piece of equipment? You can also buy a power conditioner (I believe it is called). It will put out "clean" power (power without Hz humm). They can be expensive though. Less exspensive mixers will put out humm. Lower that gain as low as possible and raise the amp gain. Or vice verse
I had the same problem on my VTX65. I noticed it would oscillate with different effects so I removed the effects module. Problem solved. Now it's dead quiet. I use a Digitech RP500 so removing the effects module was a non issue.
Normally, power transformers don't hum loudly unless there is a problem in power supply circuit. If all seems normally operational, the problem may be simply anchor screws that hold transformer to frame may be loose. Try tightening them
Disconnect any input cables from the amp. Turn down the volume controls and disconnect the speakers. Power back on. If you still blow fuses with nothing hooked up, have the amp fixed.
If the fuse holds, shut down and connect the speakers, leaving the volume controls down. Power up and see if your fuse holds. If you have hum, an output transistor is most likely shorted. If you have no noise, SLOWLY turn up the volume controls and listen for the hum. If all is quiet, turn down the volume controls and connect your input cables and turn the volume back up. Noise? check your cables!
The buzzing is possibly the electrical mains hum at 50hz, all amps have a hum/buzzing... if you have to tap the jack lead between the guitar and amp it could simply be a connection problem, the cable may be old and internally damages, maybe loose wiring on the other side of one of the input jacks