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fernfrost  
#1 Posted : Thursday, November 5, 2015 7:15:29 PM(UTC)
fernfrost

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Have been test running my legato on the SE outputs. Connected the balanced output and no sound on either channel. SE outputs still work fine.

It is connected to two monoblocks with balanced signal input. In order to use the SE outputs i paired negative and gnd.

The monoblocks have wake-on-signal and when using the balanced outputs they do turn on. But no sound.

Measurements on the balanced outputs: 9.33V on both negative and positive on both channels.

Suggestions?

Is there a simple way of checking if the balanced outputs are producing sound and if the problem lies in the wiring to the amps? Sacrificing a pair of headphones?

All help appreciated
fernfrost  
#2 Posted : Friday, November 6, 2015 4:49:01 PM(UTC)
fernfrost

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The solution appears to be to add coupling capacitors to the balanced outputs.
http://twistedpearaudio.com/forum/yaf_postst2867_Legato-3-1-and-Ncore-issue--coupling-caps-or-other-solutions.aspx

Got the sound working using a pair of 4,7 uF but with buzzing noise that is probably grounding issue.
SCompRacer  
#3 Posted : Sunday, November 22, 2015 8:55:23 PM(UTC)
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Is that 9.3v ac across the pos and neg balanced? IIRC the Legato only outputs a max of 1.6v ac when configured with supplied resistor values.

Have you tried disconnecting the ground on the balanced outputs? I recently disconnected the grounds on my balanced outs so I could remove the coupling caps. Russ and Brian have suggested that as an option here and at diyaudio IIRC. Previously I was using 2.0uf couplers.

I had one balanced pre amp that would not work without the balanced ground connected. I also notice you can get a noise spike when changing sources with no balanced ground, so I mute first.

In regards to size of coupling caps, the least cap value you can run is better. V Cap has a corner frequency calculator and explanation page so you don't have to do the math. You need to know the input impedance of what you are connecting to.

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

Edited by user Sunday, November 22, 2015 8:57:48 PM(UTC)  | Reason: Not specified

Brian Donegan  
#4 Posted : Monday, November 23, 2015 1:58:46 PM(UTC)
Brian Donegan

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Quote:
In order to use the SE outputs i paired negative and gnd.


This is on the balanced input of the amps, not the balanced output of the Legato, correct?
fernfrost  
#5 Posted : Monday, November 23, 2015 2:28:54 PM(UTC)
fernfrost

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Originally Posted by: Brian Donegan Go to Quoted Post
Quote:
In order to use the SE outputs i paired negative and gnd.


This is on the balanced input of the amps, not the balanced output of the Legato, correct?


Correct
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