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Vingborg  
#1 Posted : Friday, July 4, 2014 9:43:45 AM(UTC)
Vingborg

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Denmark
Location: KBH - Denmark

Hello Everyone Angel

I have a Buffalo and a Legato which I have just got up and running but.. My pre amp will not deal with the 9,47 volt on the XLR output between + / ground and - / ground..

The volume is scratchy and when I turn up the volume, the power amp turns off!

I need some coupling caps but is there someone at this nice forum who can tell me which value for these caps??

And maybe the output impedance for the Legato?

The input impedance on my pre is 47k.
I don't how to calculate the value on these coupling cap..

I look forward for reply's Angel

Best from Vingborg
avr300  
#2 Posted : Friday, July 4, 2014 12:54:35 PM(UTC)
avr300

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First try disconnecting the GND between the DAC and the pre.

In other words, only connect hot (+) and cold (-)
SCompRacer  
#3 Posted : Friday, July 4, 2014 6:44:57 PM(UTC)
SCompRacer

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This may be system specific, but when I disconnected the XLR ground (just - and + XLR connected) I would get loud pops when changing source with the pre amp so I would have to turn the volume down before changing source. With coupling caps and ground connected, no pops when changing sources. I had one balanced preamp that didn't work with XLR ground disconnected.

VCap has a coupling cap calculator. I've used Sonicaps and Dynamicaps in the couple of DAC's I built. For what its worth, my pre input impedance is 48500 and I'm using 2uf coupling caps.

http://www.v-cap.com/cou...capacitor-calculator.php

Edited by user Friday, July 4, 2014 6:51:58 PM(UTC)  | Reason: Not specified

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