Re: amplifier hum

"George Gleason" <tbmoas58@xxxxxxxxxxxx> wrote in
news:8zxtf.329$ZA2.162@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx:

>
> "Tom Reese" <tomreese@xxxxxxxxxxx> wrote in message
> news:k_KdnRXF7uy2PivenZ2dnUVZ_s-dnZ2d@xxxxxxxxxxxxxx
>> I could use some advice on how to get rid of what is apparently RFI
> induced
>> amplifier hum. The facts of the case:
>>
>> two amplifiers 1. Marshall practice amp and 2. Fender Hot Rod Deluxe
>> both exhibit the same hum
>>
>> the hum only appears when a cable is plugged into the input jack on
>> an
> amp.
>> The hum is there whether a guitar is plugged into the other end of
>> the
> cable
>> or not. It changes a bit when a guitar is plugged in but I assume
>> that's because I've changed the characteristics of the antenna.
>>
>> I've plugged the practice amp into several different circuits in the
>> house and the hum is there in every circuit.
>>
>> three different cables (Monster, Fender, cheapo) all produce hum (the
> cheapo
>> is by far the worst).
>>
>> there is a cell phone tower right next door.
>>
>> the hum gets worse when I hold the cable in the air and aim it (sort
>> of
> like
>> aiming a rabbit ears on a tv).
>>
>> Is there a supershielded cable I can try to fix the problem?
>>
>> Is there something else I can do?
>>
>> thanks for any help anyone can offer.
>>
>> Tom Reese
>>
>>
> these are suggestions
> as hum busting can be quite a wild hair
> try cutting the sheild on the cable at the end you plug into the amp
> take the amp in for repair/and or sheilding
> try ferrite choke around your cable
> look into a transformer based humbuster like the EB-TECH
> I doubt the cell tower is related to this issue
> I would GUESS it is not RFI but rather EMI interference
> what ever you do
> do not lift the saftey ground
> george

George is right. It sounds like a 60Hz, EMI problem and he's covered
all the bases. Don't forget dimmer switches and flourescent or
transformer based lighting. Baseboard electric heat?

Another source of hum is internal to the amp. I've seen the power
transformer couple to the reverb tank in several amps. If the amps have
reverb, try unplugging the cables that go to the tank and see if the hum
goes away.

Of course it could just be your magnetic personality causing the
problem. Have you tried wrapping yourself in tinfoil and grabbing a
cold water pipe? :-)

Good to see you here again. How's that CATH Martin?

Steve Hawkins
.

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