For those who have hum with theyr gainclone (loud or not)

Bricolo · 11th July 2003, 09:45 AM

Hi all,

I noticed a strange thing with my gainclone.
Both channels have a slight hum, use the same PS (with a velleman 18V 225VA toriod, dual bridge, and 2000µF per rail)

Whith no input, I can hear the hum.
The strange thing (tell me if you have noticed the same thing) is that when I manually move (push on) one channel's woofer, the other side's hum is "modulated" by the 1st channel's woofer motion.

Is this normal?

thanks
Alex

UrSv · 11th July 2003, 11:18 AM

A GC should be dead quiet so no that is not normal.

Bricolo · 11th July 2003, 11:37 AM

My gainclone has no case, so this can explain the hum (I'm working on the case since yesterday. I started assembling all the aluminium plates)

But I know I'm not the only one with hum, so my question was dedicated to the other people with hum

lieven · 11th July 2003, 12:13 PM

floating ground..... check ground connections between supply area and chip.

Maybe wrong placed resistor on ground connection...
Check zobel

my 2 cents.

Bricolo · 11th July 2003, 02:43 PM

I do'nt want to talk about my hum problem, it'll be certainly fixed when I'll put the amp in it's metal case

I wanted to know if the other people that have hum ( even if it's very low) have the same thing as I have, when they manually move a woofer

Paulr · 16th July 2003, 09:11 AM

Hi Bricolo,

By moving your woofer you are inadvertantly causing a voltage to flow backwards towards the amp/ground. A speaker is a magnet & a coil of wire, move the coil back & forth over the magnet & you cause electron flow just like in the science experiments in school.

This is where I come unstuck: does the backward voltage go via the earth & change the relative voltage on the (-) pole on the other speaker? or does it affect the chip itself to cause the modulation?

Heres hoping I've helped more than I've opened new lines of questions.

Cheers

Paul

rocktboy · 16th July 2003, 07:57 PM

i tried pushing my woofers on one channel and the other channel isn't affected by it.

my hum/hiss actually become less as i turn up the volume

either way the hum/hiss can be heard only when you stick your ears right next to the cones. i can't hear a thing from my listening position.

11th July 2003, 09:45 AM	#1
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	For those who have hum with theyr gainclone (loud or not) Hi all, I noticed a strange thing with my gainclone. Both channels have a slight hum, use the same PS (with a velleman 18V 225VA toriod, dual bridge, and 2000µF per rail) Whith no input, I can hear the hum. The strange thing (tell me if you have noticed the same thing) is that when I manually move (push on) one channel's woofer, the other side's hum is "modulated" by the 1st channel's woofer motion. Is this normal? thanks Alex

11th July 2003, 11:18 AM	#2
UrSv diyAudio Member Join Date: Jan 2002 Location: Sweden	A GC should be dead quiet so no that is not normal. __________________ UrSv Those who say it can't be done should not stop those who are doing it.

16th July 2003, 09:11 AM	#6
Paulr diyAudio Member Join Date: Nov 2002 Location: S.Yorks, UK	The joys of electromagnetics Hi Bricolo, By moving your woofer you are inadvertantly causing a voltage to flow backwards towards the amp/ground. A speaker is a magnet & a coil of wire, move the coil back & forth over the magnet & you cause electron flow just like in the science experiments in school. This is where I come unstuck: does the backward voltage go via the earth & change the relative voltage on the (-) pole on the other speaker? or does it affect the chip itself to cause the modulation? Heres hoping I've helped more than I've opened new lines of questions. Cheers Paul

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11th July 2003, 11:37 AM	#3
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	My gainclone has no case, so this can explain the hum (I'm working on the case since yesterday. I started assembling all the aluminium plates) But I know I'm not the only one with hum, so my question was dedicated to the other people with hum

11th July 2003, 12:13 PM	#4
lieven diyAudio Member Join Date: Aug 2002 Location: Belgium	floating ground..... check ground connections between supply area and chip. Maybe wrong placed resistor on ground connection... Check zobel my 2 cents.

11th July 2003, 02:43 PM	#5
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	I do'nt want to talk about my hum problem, it'll be certainly fixed when I'll put the amp in it's metal case I wanted to know if the other people that have hum ( even if it's very low) have the same thing as I have, when they manually move a woofer

16th July 2003, 07:57 PM	#7
rocktboy diyAudio Member Join Date: Jun 2003 Location: not where i want to be	i tried pushing my woofers on one channel and the other channel isn't affected by it. my hum/hiss actually become less as i turn up the volume either way the hum/hiss can be heard only when you stick your ears right next to the cones. i can't hear a thing from my listening position.

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