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-   -   Wiring Attenuator for dual channel Balanced (http://www.diyaudio.com/forums/pass-labs/214522-wiring-attenuator-dual-channel-balanced.html)

wengtech 15th June 2012 04:19 AM

Wiring Attenuator for dual channel Balanced
 
hi everyone,
i need to add a passive volume pots for my aleph 30 in balanced way.
i am planning to use 10k 24step ladder attenuator pots like this one :

http://i50.tinypic.com/15acd5.jpg

my question is:
how to wire this attenuator for dual channel balanced
using only one attenuator like in the picture.

thanks.
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Zen Mod 15th June 2012 06:46 AM

consider each phase (+ one , - another one ) as separate channel

edit : of course , that means that you need two of those for stereo , meaning - one per balanced channel

wengtech 15th June 2012 07:03 AM

zen mod,
do you mean i should use 2 attenuator for 2 channel balanced amp?
attenuator like in the picture only support (+in -in gnd, +out -out gnd) one channel.
so, to wire 2 channel i need 2 attenuator (+inR -inR gnd, +inL -inL gnd, +outR -outR gnd, +outL -outL gnd) is that true?

my friend said there should be a wiring technique which using only one attenuator
for 2ch amp, but i don't know yet how to do that.

secanbj 15th June 2012 02:17 PM

I did like this with an alps pot. i think you should be able to do the same with yours, but i might be wrong

picture only shows one channel

http://www.bergsatra.com/xlr-volume.png

Frank Berry 15th June 2012 02:35 PM

That method will work. I've used a similar circuit in the past.

wengtech 15th June 2012 03:58 PM

secanbj:
that is interesting, but can you explain which one IN and OUT?
and how about the result in sound, compared with using 2 pots.

secanbj 17th June 2012 02:55 PM

The side with the resistors is the "in". Regarding sound with one vs two pots i have no idea as i have only used this configuration

Holger1975 9th December 2012 09:24 PM

Donīt get the wiring
 
Hello Community,

tried to wire it like on the scrabble, but i donīt get it. Could somebody describe where to put which wire on the shown switch from photo ?

Thanks in advance!

wuffwaff 11th December 2012 10:56 AM

Hi,

you canīt use a normal 10klog pot for this. The resistor values for a "balanced" pot are completely different. I use one on the output of my X-BOSOZ.
Iīve got an excel sheet where you can calculate the resistor values depending on the two series resistors (here 5k). I can try to find it.

To wire it you have to put the switch after the two resistors. With this you change the resistance between the two output resistors. If the resistance is zero the output is shorted and more or less silent. Without a connection the output is only attenuated by the output resistors.

Depending on the volume set the output impedance of the control will change quite a lot (from almost zero to 5k diff. in this example)

William

AndrewT 11th December 2012 12:26 PM

With a balanced interconnection, the impedance on both the hot and cold are identical. If they are not identical then the interconnection is not balanced.

The attenuator must insert identical resistances into both the hot and the cold poles of the signal connection.


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