Wiring Attenuator for dual channel Balanced

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.

you can´t 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.
I´ve 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)

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.

Yes that is true, and that is the nice thing about this balanced attenuator. It only switches one restistor between hot and cold (after the two series restistors) so it is always balanced perfectly.


I´m not sure we are talking about the same thing.

I´ll try to say it more precisely:

The attenuation by changing only one resistor (between hot and cold) won´t change the balance (between hot and cold) of this channel. It will stay as it is.

If the balance between hot and cold needs to be better than 0,01% I don´t know. This would mean using only precision resistors to set the gain and attenuation. Most preapms using 4-way pots and 1% resistors (at best) will never get near this value.

Hi all... Thank you for all ur precious advices . The attenuator now works fabulously. I used a 50k pot instead of 10k as recommended. I would also like to find out with this configuration can I use a 100k pot ? Also for both the 5K resistors is there any power rating or requirement? (I.e 1/4 watts or something with bigger values? Thank you once again you had been a fabulous people.!!!