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akras  
#21 Posted : Thursday, September 13, 2018 3:56:57 AM(UTC)
akras

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I wouldn't leave the ground floating: this way you have no control of the input vs amplifier ground potential, and this can potentially lead to nasty things if/when that potential exceeds the limits...

I'm pretty sure people used Legato with UcD180, so I'll see what is there (Google is my friend)...

BTW, your inbox is full and doesn't accept any more messages.

Possum  
#22 Posted : Thursday, September 13, 2018 4:16:56 AM(UTC)
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If the amp has a 'proper' differential input then I cant see any reason why it wouldn't work. Getting rid of the caps made a noticeable improvement over the original Legato BTW. No such thing as a good series cap, just a necessary evil in some cases.

Feel free to connect Legato and amp grounds together if you like. I have never done it and never had a problem. I would advise, however, not to connect DAC and Legato grounds together (if you have a 100MHz+ capable scope on VD you will see why). Its also why I highly recommend to independently power AVCC on the DAC. Even my better half heard the difference immediately (and I'm not being condescending if she ever reads this Silenced )
akras  
#23 Posted : Thursday, September 13, 2018 5:31:11 AM(UTC)
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I completely agree on the caps.

There is no need to connect the grounds directly as long as the DAC and the balanced amplifier grounds are connected anywhere (say, mains ground). But letting one of them completely float is risky (common mode rejection of a differential input works only in a limited range of input voltages, input transformers being an exception).

Dealing with grounds for HF circuits is always a real fun, I can attest to that, too...
Possum  
#24 Posted : Thursday, September 13, 2018 6:08:15 AM(UTC)
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I would never ever connect a hifi circuit ground to AC ground under any circumstances - its like connecting the sewerage directly to your food supply.

Here in the land down under 'ground' is not really ground - its actually connected to neutral at the local substation. Perhaps you have a more pristine ground in your part of the world, but here it is merely a safety mechanism. Ground the casing only!!!!!
akras  
#25 Posted : Thursday, September 13, 2018 7:03:12 AM(UTC)
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It's all relative...

Cheers,

AK
Possum  
#26 Posted : Thursday, September 13, 2018 7:18:21 AM(UTC)
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Like kissin' cousins :-)

I cleared my mailbox if you'd like to PM me about anything. All the best with your project!

Poss
Brian Donegan  
#27 Posted : Friday, September 14, 2018 1:46:12 PM(UTC)
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So, we are working on this. Mostly the work is on the IV side and the best way to interface to it (it a lot of channels and complexity to make manageable).

It's been a hot summer, and we have been trying to enjoy some of it. We both have fairly high-pressure day jobs, so it's a question of (family) priorities. Boo hoo!

Anyway, kids are back to school and we are shifting our focus back to new stuff. You should see some updates soon.
akras  
#28 Posted : Friday, September 14, 2018 5:37:11 PM(UTC)
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Great to hear it, thanks!
akras  
#29 Posted : Saturday, September 22, 2018 7:03:53 PM(UTC)
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Those who are interested in this solution should respond to this:

https://www.diyaudio.com...d-eight-channel-dac.html
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