2 amps together buzzing? - Einstine - 23:28 16-11-05
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I am trying an old Fender Champ with a newer Blues Junior both fed from an Alesis Midiverb II,
left and right, and am experiencing 'buzzing'.
They only do it when plugged in together. Neither has a polarity switch. At least, that is what I call it.
Any tricks to stop this? And thanks in advance.
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Re: 2 amps together buzzing? - Clutch - 23:39 16-11-05
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"Einstine" <noway@nohow.net> wrote in message
news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com...
>I am trying an old Fender Champ with a newer Blues Junior both fed from an
>Alesis Midiverb II,
> left and right, and am experiencing 'buzzing'.
>
> They only do it when plugged in together. Neither has a polarity switch.
> At least, that is what I call it.
>
> Any tricks to stop this? And thanks in advance.
>
How are you delivering the signal to both amps? An impedence mismatch can
cause it, but more than likely it's a ground loop problem.
Now you're in the big time... do a google search on the term "ground loop
hum" or "ground loop" you'll find a bunch of info.
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Re: 2 amps together buzzing? - David Axt - 00:09 17-11-05
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"Clutch" <no@notachance.org> wrote in message
news:PK-dnYgCxdEflOHeRVn-iw@giganews.com...
>
> "Einstine" <noway@nohow.net> wrote in message
> news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com...
>>I am trying an old Fender Champ with a newer Blues Junior both fed from an
>>Alesis Midiverb II,
>> left and right, and am experiencing 'buzzing'.
>>
>> They only do it when plugged in together. Neither has a polarity switch.
>> At least, that is what I call it.
>>
>> Any tricks to stop this? And thanks in advance.
>>
>
> How are you delivering the signal to both amps? An impedence mismatch can
> cause it, but more than likely it's a ground loop problem.
>
> Now you're in the big time... do a google search on the term "ground loop
> hum" or "ground loop" you'll find a bunch of info.
>
Make sure everything is plugged into the same power strip.
-DA
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Re: 2 amps together buzzing? - David Gravereaux - 00:20 17-11-05
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Einstine wrote:
> I am trying an old Fender Champ with a newer Blues Junior both fed from an Alesis Midiverb II,
> left and right, and am experiencing 'buzzing'.
>
> They only do it when plugged in together. Neither has a polarity switch. At least, that is what I call it.
>
> Any tricks to stop this? And thanks in advance.
>
>
You have a ground loop. Does the midiverb have balanced TRS outputs?
If so, make two TRS to TS cable like so:
midiverb side Amp side
Tip ------------- Tip
Ring ------------ Shield
Shield ---------x
Shield from the TRS side is lifted (not connected) on the TS side. And
there ya go, balanced to unbalanced the way God intended.
Hmm.... The midiverb being a wallwart device might not have any ground
reference at all.. Ok, maybe you only one TRS to TS cable and use a
standard TS to TS for one of the amps.
Remember that a ground loop happens when there are multiple paths to
ground. But we do want one path!
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Re: 2 amps together buzzing? - Mike Schway - 00:22 17-11-05
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In article <11no3vq6usj7d76@corp.supernews.com>,
"David Axt" <daxtATpacifierDOTcom> wrote:
> "Clutch" <no@notachance.org> wrote in message
> news:PK-dnYgCxdEflOHeRVn-iw@giganews.com...
> >
> > "Einstine" <noway@nohow.net> wrote in message
> > news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com...
> >>I am trying an old Fender Champ with a newer Blues Junior both fed from an
> >>Alesis Midiverb II,
> >> left and right, and am experiencing 'buzzing'.
> >>
> >> They only do it when plugged in together. Neither has a polarity switch.
> >> At least, that is what I call it.
> >>
> >> Any tricks to stop this? And thanks in advance.
> >>
> >
> > How are you delivering the signal to both amps? An impedence mismatch can
> > cause it, but more than likely it's a ground loop problem.
> >
> > Now you're in the big time... do a google search on the term "ground loop
> > hum" or "ground loop" you'll find a bunch of info.
> >
>
> Make sure everything is plugged into the same power strip.
>
> -DA
>
Still won't help. You'll still have a ground loop at the inputs.
Solution is to use a signal isolation transformer on each input.
Something like the Ebtech Hum Eliminator. You don't want the signal
grounds of each amp to talk with each other.
This is the primary reason why modular PA equipment of any appreciable
quality uses balanced ("low-Z") lines between components; in a balanced
situation, the signal doesn't use ground as a conductor.
--Mike
--------------------------------------------------------------------
Mike Schway | [Picture your favorite quote here]
mschway@nas.com |
--------------------------------------------------------------------
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Re: 2 amps together buzzing? - Sacramento Dave - 08:58 17-11-05
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"Einstine" <noway@nohow.net> wrote in message
news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com...
> I am trying an old Fender Champ with a newer Blues Junior both fed from an
Alesis Midiverb II,
> left and right, and am experiencing 'buzzing'.
>
> They only do it when plugged in together. Neither has a polarity switch.
At least, that is what I call it.
>
> Any tricks to stop this? And thanks in advance.
>
> I had the same problem, Try plugging into an ungrounded extension chord.
I actually built a outlet box with no ground
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Re: 2 amps together buzzing? - Jim Anable - 09:41 17-11-05
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Einstine wrote:
> I am trying an old Fender Champ with a newer Blues Junior both fed from an Alesis Midiverb II,
> left and right, and am experiencing 'buzzing'.
GROUND LOOP.
>
> They only do it when plugged in together. Neither has a polarity switch. At least, that is what I call it.
>
> Any tricks to stop this? And thanks in advance.
Try plugging both amps into a single power strip. Use short cables.
If no go, Ebtech Hum Eliminator, or, if you are willing to take a slight
safety risk by relying on cable shield for ground, lift the ground on
one amp only (but I don't really advise that).
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Re: 2 amps together buzzing? - Jim Anable - 09:49 17-11-05
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Sacramento Dave wrote:
> "Einstine" <noway@nohow.net> wrote in message
> news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com...
>
>>I am trying an old Fender Champ with a newer Blues Junior both fed from an
>
> Alesis Midiverb II,
>
>>left and right, and am experiencing 'buzzing'.
>>
>>They only do it when plugged in together. Neither has a polarity switch.
>
> At least, that is what I call it.
>
>>Any tricks to stop this? And thanks in advance.
>>
>>I had the same problem, Try plugging into an ungrounded extension chord.
>
> I actually built a outlet box with no ground
No ground is not a good idea. If you lift ground on one amp, with most
setups, you ought to still have a ground to the other, but it will be
relying on the guitar shield (not the optimum situation, and a safety risk).
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Re: 2 amps together buzzing? - The Chris - 15:01 17-11-05
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"Einstine" <noway@nohow.net> wrote in
news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com:
> I am trying an old Fender Champ with a newer Blues Junior both fed
> from an Alesis Midiverb II, left and right, and am experiencing
> 'buzzing'.
>
> They only do it when plugged in together. Neither has a polarity
> switch. At least, that is what I call it.
>
> Any tricks to stop this? And thanks in advance.
>
>
Definitely a ground loop issue.
The quickest way is to put one of those grey ground-lift adapters on one of
your plugs - the thing that converts 3 prongs to 2.
It's not the *safest* way, but, It might help.
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Re: 2 amps together buzzing? - Jim Anable - 16:25 17-11-05
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The Chris wrote:
> "Einstine" <noway@nohow.net> wrote in
> news:AL2dnSnUQ-k-m-HeRVn-vA@comcast.com:
>
>
>>I am trying an old Fender Champ with a newer Blues Junior both fed
>>from an Alesis Midiverb II, left and right, and am experiencing
>>'buzzing'.
>>
>>They only do it when plugged in together. Neither has a polarity
>>switch. At least, that is what I call it.
>>
>>Any tricks to stop this? And thanks in advance.
>>
>>
>
>
> Definitely a ground loop issue.
>
> The quickest way is to put one of those grey ground-lift adapters on one of
> your plugs - the thing that converts 3 prongs to 2.
>
> It's not the *safest* way, but, It might help.
I've suggest this, mentioning the safety hazard. It occurs to me that
I'd be more confident in avoiding shock by doing this AND using an 1:1
AC line isolation transformer.
Here's a cheap possible fix:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3291246072&category=13718
But ask seller what the wattage rating is. Check the AC line wattage
rating of your amp (NOT the output rating), and don't exceed the rating
of the isolation transformer.
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