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Old 21st October 2006, 12:20 AM   #1
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Unhappy Preamp hum problem somehow related to inputs

Hi all,

I recent bought a preassembled Twisted Pear Kookaburra preamp from a friend and have just finished putting it in an enclosure.

It sounds fantastic and puts my current consumer hi-fi integrated amplifier to shame, even with the problem I've encountered.

I have to say I have very little knowledge of electronics, but you have to start somewhere, right?

Anyway, the problem is, at high volume a rather loud hum appears to be generated and can be heard from the speakers.

I found if I wave my fingers near the input RCA or cable it affects the sound of the hum significantly. And, if I place my finger over the end of the RCA, the hum stops.

Does anyone know what the problem is, and if so, how can I solve it?

Thanks in advance.

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Old 21st October 2006, 12:36 AM   #2
v-bro is offline v-bro  Netherlands
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Seems like there's a ground problem, how does it sound with the input unplugged?
Max. cone displacement can be several foot on any speaker!Too bad it can be done only once......
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Old 21st October 2006, 01:07 AM   #3
Leolabs is offline Leolabs  Malaysia
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Maybe bad contact regarding ground wire.
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Old 21st October 2006, 02:15 AM   #4
Minion is offline Minion  Canada
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Yes, It sounds like the Ground (Maybe the ground on the RCA inputs/Outputs) as loose or not connected....

Try tieing the ground wire from the RCA to Ground....
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Old 21st October 2006, 07:06 AM   #5
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Thanks for the replies. Quite right - it seems one of the inputs was not gounded properly.

It seems so simple now :-)

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