which value goldpoint atentuater

[slr 5000]

hi all im doing volume control between my dbx260 and hypex poweramps it will need to control 2x 2way active speakers and be ballanced in and out , so i guess ill need an 8 gang goldpoint or dact im just not sure which value to use ?
the output impeadence of the dbx260 is 127 ohms and the input impeadence of the hypex 400hg amps is 100k .as goldpoint and dact are very expensive for a ballanced system like this i dont want to get the wrong one
is there a formula i could use to work it out ,or can anyone reccomend a value from previous experiance

 

[AndrewT]

Hi,
a balanced volume control is completely different from a single ended volume control.

You only need one adjustable (stepped) resistor between the poles.
Alternatively you need an H ladder but the series legs of the H MUST have very accurately matched pairs of resistors. I doubt anyone will select the adjustable series resistors accurately enough to preserve the Common Mode rejection of the balanced impedance connection, or charge an absolute fortune.

Try reading Walt Jung, ESP, Rane, Jensen and Doug Self.

 

[AndrewT]

http://www.diyaudio.com/forums/showthread.php?postid=1568657#post1568657

 

[slr 5000]

thanks mate ill have a read cheers

 

[slr 5000]

hi all .thanks for the link andrew dut i still need to know what value to get, my amps have 100k input impeadence so some say to use a 100k pot .others say to use a 50k or 10k id like to know which one as id prefer not to just guess 😕

 

[AndrewT]

A normal adjustable resistance will do the job. It does not need to be an attenuator.
But, the law on the resistance will be different from a conventional LOG law single ended attenuator.
As I said, balanced attenuation is different from single ended.