Comments on: DIY – 12 to 2 – Passive Analog Summing Panel. http://www.rhythminmind.net/presetblog/2009/11/diy-12-to-2-passive-analog-summing-panel/ Audio processing tools - Information - & Captures. Wed, 28 Jul 2010 17:46:39 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Andrey Iluch http://www.rhythminmind.net/presetblog/2009/11/diy-12-to-2-passive-analog-summing-panel/comment-page-1/#comment-3544 Andrey Iluch Wed, 07 Jul 2010 02:56:33 +0000 http://www.rhythminmind.net/presetblog/?p=1004#comment-3544 Thank you for interesting information! Best Regards, Andrey Thank you for interesting information!

Best Regards,
Andrey

]]> By: rhythminmind http://www.rhythminmind.net/presetblog/2009/11/diy-12-to-2-passive-analog-summing-panel/comment-page-1/#comment-2989 rhythminmind Mon, 21 Dec 2009 23:40:27 +0000 http://www.rhythminmind.net/presetblog/?p=1004#comment-2989 I would use 10kohm input resistors. & 220ohm output resistors for that configuration. Read below for more info.. I would use 10kohm input resistors. & 220ohm output resistors for that configuration. Read below for more info..

]]> By: rhythminmind http://www.rhythminmind.net/presetblog/2009/11/diy-12-to-2-passive-analog-summing-panel/comment-page-1/#comment-2988 rhythminmind Mon, 21 Dec 2009 23:22:57 +0000 http://www.rhythminmind.net/presetblog/?p=1004#comment-2988 My design is based on the mixing network in NYD's drawing. http://www.twin-x.com/groupdiy/albums/userpics/balancedmixnetwork.pdf All you have to do is figure out how many channels you need. Pick a input impedance value. Modern balanced gear has an high input impedance usually around 20k. I picked 21.4kohm, only because I had "military grade" resistors on hand that happened to be 10.7k. Resistors between 5k-15k should work well for most applications. It's a balance between noise & crosstalk. The higher the resistor the better the crosstalk but with increased noise floor. 10k input resistors work well. Now for output impedance most mic pres want to see 150ohm signal. I recommend using a transformer based pre for the make up gain that accepts a wide range of impedance, like the hardy. You should pick your shunt resistors on the outputs to spit out around 150ohm. Mine is 200 something. But the hardy can easily handle anything from 60-600ohm The formula to figure out the output shunt resistor value for a 200ohm output with a input impedance of 20k = shunt ohm resistor = (20000/n)*200/((20000/n)-200) WHERE N = NUMBER OF INPUTS My design is based on the mixing network in NYD’s drawing.
http://www.twin-x.com/groupdiy/albums/userpics/balancedmixnetwork.pdf

All you have to do is figure out how many channels you need. Pick a input impedance value. Modern balanced gear has an high input impedance usually around 20k. I picked 21.4kohm, only because I had “military grade” resistors on hand that happened to be 10.7k.
Resistors between 5k-15k should work well for most applications. It’s a balance between noise & crosstalk. The higher the resistor the better the crosstalk but with increased noise floor. 10k input resistors work well.

Now for output impedance most mic pres want to see 150ohm signal.
I recommend using a transformer based pre for the make up gain that accepts a wide range of impedance, like the hardy.
You should pick your shunt resistors on the outputs to spit out around 150ohm. Mine is 200 something. But the hardy can easily handle anything from 60-600ohm

The formula to figure out the output shunt resistor value for a 200ohm output with a input impedance of 20k =

shunt ohm resistor = (20000/n)*200/((20000/n)-200)

WHERE N = NUMBER OF INPUTS

]]> By: Mark http://www.rhythminmind.net/presetblog/2009/11/diy-12-to-2-passive-analog-summing-panel/comment-page-1/#comment-2981 Mark Sat, 12 Dec 2009 22:57:25 +0000 http://www.rhythminmind.net/presetblog/?p=1004#comment-2981 Looks great - congrats! A question.... would the resistor values stay the same if you were to increase it to an 18x2 configuration? I've got a J. Hardy that I'd love to mate to a passive homebrew summer, too. Looks great – congrats! A question…. would the resistor values stay the same if you were to increase it to an 18×2 configuration? I’ve got a J. Hardy that I’d love to mate to a passive homebrew summer, too.

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