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Running Legato balanced directly to amp?
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mjock3  
#1 Posted : Saturday, April 7, 2012 8:50:15 PM(UTC)
mjock3

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Am I able to run the balanced outputs of the Legato directly into a balanced inputs of a amplifier? If so are there any precautions in doing so? I have never used balanced before so I am quite ignorant in these matters. Do I need to make any compensations to enable it to work?

Also could I still use the SE for a subwoofer using the volume control?

Thanks very much for making this setup. You have given me sound that I otherwise would not be able to afford.

Mark
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LeonvB  
#2 Posted : Sunday, April 8, 2012 6:24:47 AM(UTC)
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No, not any amplifier. If the amp has coupling caps you could link to it directly. If it doesn't you could end up feeding DC to your speaker units, which can cause smoke.
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mjock3  
#3 Posted : Sunday, April 8, 2012 12:39:26 PM(UTC)
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Is there DC coming out of the balanced outputs?

And would I be able to run the SE as well as the balanced at the same time?

Thanks
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Russ White  
#4 Posted : Sunday, April 8, 2012 2:04:55 PM(UTC)
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The Legato can be trimmed to have no differential DC (measured between the balanced outputs) - but unless you add coupling caps it will have common mode DC (measured from either output to GND).

If you are unsure if a balanced amp can handle common mode DC (many can, some can't) then you should add the coupling cap to be safe. The size of the cap will depend on the input impedance of the amplifier.

Edited by user Monday, April 9, 2012 8:05:22 PM(UTC)  | Reason: Not specified
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mjock3  
#5 Posted : Monday, April 9, 2012 1:05:21 PM(UTC)
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Russ,

Would I be losing anything in the way of sound by doing the coupling caps? Or would I be just as well off converting SE to balanced?

Thank you
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Erlend Sæterdal  
#6 Posted : Monday, April 9, 2012 2:52:51 PM(UTC)
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LeonvB wrote:
No, not any amplifier. If the amp has coupling caps you could link to it directly. If it doesn't you could end up feeding DC to your speaker units, which can cause smoke.


8 v dc on the cables is a bad idee.

Electrolytic capacitors sound very good when there is some voltage on them , much better than Metallized polypropylene if you ask me.
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Russ White  
#7 Posted : Monday, April 9, 2012 8:06:38 PM(UTC)
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I wouldn't FRET over the coupling caps. There should have negligible impact on the final result.
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mjock3  
#8 Posted : Tuesday, April 10, 2012 7:22:26 AM(UTC)
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Thanks Russ. :d/
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mjock3  
#9 Posted : Thursday, April 12, 2012 5:36:17 PM(UTC)
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Is it possible to run a subwoofer on SE outputs while running the amp via balanced?

Thanks
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Russ White  
#10 Posted : Friday, April 13, 2012 6:35:15 AM(UTC)
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Absolutely.
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Erlend Sæterdal  
#11 Posted : Saturday, June 2, 2012 9:44:28 PM(UTC)
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I wonder why the discret Legato 3.1 sounds much better with minus ( 3 ) connected to ground ! Anybody else with that exsperience ?
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Russ White  
#12 Posted : Sunday, June 3, 2012 8:14:16 PM(UTC)
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NO - that's exactly opposite of my experience.

It could have to do with your amp.
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Russ White  
#13 Posted : Sunday, June 3, 2012 8:19:15 PM(UTC)
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Also you would never want to try that if you don't have output caps on the legato. You are basically just using one half the signal, which would not be good for many reasons.
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mjock3  
#14 Posted : Wednesday, June 13, 2012 1:26:35 AM(UTC)
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I am finally getting around to giving it a try. I just want to verify, the coupling caps go on pin 2 & 3. Is that right?

Thanks,

Mark
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Brian Donegan  
#15 Posted : Wednesday, June 13, 2012 3:03:38 AM(UTC)
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Yes.

Pin 1: Ground
Pin 2: +
Pin 3: -

What amp are you using? With many amplifiers (truly differential inputs), you can simply omit the Ground pin connection and no coupling caps are needed. A quick look at the schematic of the amp will tell the story...
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mjock3  
#16 Posted : Wednesday, June 13, 2012 5:58:38 AM(UTC)
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Ncore 400
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Erlend Sæterdal  
#17 Posted : Wednesday, June 13, 2012 11:17:49 PM(UTC)
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Originally Posted by: Russ White Go to Quoted Post
NO - that's exactly opposite of my experience.

It could have to do with your amp.


No it had something to do with the output on the Legato. At the minus output I had 22 uf. cap than 3,3 ohm Carbon Composite.
At the plus output I had 3,3 ohm and than 22 uf.

I changed that so the resistor was first for both. Also the new Trident V3 is just fantastic. Such a huge difference. Now I am running balanced sounds great.
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mjock3  
#18 Posted : Thursday, June 14, 2012 9:18:33 PM(UTC)
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Originally Posted by: Brian Donegan Go to Quoted Post
Yes.

Pin 1: Ground
Pin 2: +
Pin 3: -

What amp are you using? With many amplifiers (truly differential inputs), you can simply omit the Ground pin connection and no coupling caps are needed. A quick look at the schematic of the amp will tell the story...



Thanks Brian, I guess that is what I will do. I just want to make sure I understand, just don't wire the ground pin coming out of the Buffalo DAC right?
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mjock3  
#19 Posted : Thursday, June 28, 2012 8:24:13 PM(UTC)
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If I float the ground on the Legato to the amps without sub hooked up everything sounds fine. Once I hook the sub into SE I get a ground hum out of the sub. I had no ground hum when running everthing SE. Any suggestions on how to eliminate the ground hum?

Thanks
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Brian Donegan  
#20 Posted : Monday, July 2, 2012 3:44:29 PM(UTC)
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Off the top of my head, I cannot think of why this would cause a ground loop. If you disconnect the balanced connections to the amps, does the hum go away?
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