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MikeParry		#1 Posted : Saturday, July 28, 2007 2:13:37 PM(UTC)
Rank: Member Groups: Member Joined: 7/28/2007(UTC) Posts: 5 Location: Birmingham, UK		Hi Guys, Three questions for you: 1.I was wondering if the Opus can configured to give a single ended output without having to use the Ballsie. 2.What would be the advantages of using the Ballsie? 3.Is it possible to use a dicrete output stage like Jocko's for eg.? (http://www.diyaudio.com/forums/showthread.php?s=&threadid=6121&highlight=) Cheers Mike
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Brian Donegan		#2 Posted : Saturday, July 28, 2007 2:45:51 PM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 2,868 Location: Massachusetts, USA Thanks: 2 times Was thanked: 141 time(s) in 134 post(s)		1) Yes. You could use a transformer solution (not cheap), or just tap +Out and GND, but get 6dB less output. 2) You don;t get 6dB less output, and not as expensive as transformers (maybe even better, but you didn't hear that from me). 3) No. That's an I/V stage for a current-output DAC, which is not what the WM8740 is. I/V stage is for converting current output to voltage output.
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MikeParry		#3 Posted : Friday, August 3, 2007 7:48:57 AM(UTC)
Rank: Member Groups: Member Joined: 7/28/2007(UTC) Posts: 5 Location: Birmingham, UK		Thanks for the response Brian. So, in terms of sound quality, what is the best solution (assuming the -6dB is not a problem and I want SE)? Does the Ballsie add anything to the sound (in a positive or negative sense)? I've read the DAC datasheet/app notes but I'm still not sure what the Ballsie actually does apart from converting balanced to single end conversion and adding some gain. Cheers, M
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Brian Donegan		#4 Posted : Friday, August 3, 2007 7:56:53 AM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 2,868 Location: Massachusetts, USA Thanks: 2 times Was thanked: 141 time(s) in 134 post(s)		Well, it is a Balanced to Single-Ended converter, so that's all it's really designed to do ;) (along with optional LP filtering as in the Wolfson datasheet app). It does also act as an output buffer because of the op-amps, but that's secondary to it's purpose.
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neb001		#5 Posted : Monday, August 6, 2007 1:25:48 AM(UTC)
Rank: Advanced Member Groups: Member Joined: 7/30/2007(UTC) Posts: 31		Brian, Have you tried using the TXD in line driver mode as an output buffer? If so, have you noticed any difference in the sound? After reading about other folks contemplating putting a zapfilter in their opus dac's, I considered using the TXD to buffer the output
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Russ White		#6 Posted : Monday, August 6, 2007 5:08:42 AM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 3,979 Location: Nashville, TN Thanks: 25 times Was thanked: 89 time(s) in 83 post(s)		The TXD makes a great buffer, but the honest truth is that unless the DAC is driving an impedance of < 1K it is not at all necessary to use a buffer. I have used the Opus with and without a TXD after, and I cannot say I prefer one over the other, personally I would opt for the simplest approach. Cheers! Russ
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neb001		#7 Posted : Monday, August 6, 2007 7:13:30 AM(UTC)
Rank: Advanced Member Groups: Member Joined: 7/30/2007(UTC) Posts: 31		Thanks for the reassurance, I'll stick with the dac output, and then tack on the ballsie when that comes out. I'm looking forward to the Ballsie and all the other stuff you have lined up :)
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AudioBear		#8 Posted : Monday, August 13, 2007 7:59:47 AM(UTC)
Rank: Member Groups: Member Joined: 8/13/2007(UTC) Posts: 110 Location: UK Thanks: 8 times		Excuse my ignorance, but what about using a OPUS DAC single ended (+Out and GND) into a single ended TVC volume control/passive pre? Like the Stevens and Billington TX102? Accepting the loss in input put would this work? http://www.stevens-billington.co.uk/page102.htm I know they can be balanced but mine is signle ended.
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Russ White		#9 Posted : Monday, August 13, 2007 8:03:10 AM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 3,979 Location: Nashville, TN Thanks: 25 times Was thanked: 89 time(s) in 83 post(s)		As long as the input impedance of the TVC is > 1K then it should work just fine. :) Cheers! Russ
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OneyedK		#10 Posted : Monday, September 10, 2007 1:44:11 PM(UTC)
Rank: Member Groups: Member Joined: 9/9/2007(UTC) Posts: 11 Location: Muizen (Belgium)		Could we see the output of the WM8740 like the output of a bridged amplifier? Because in that case, it would be possible to connect a LL1531 Lundahl transformer in 1:1 configuration. Resistance between + and - would be 1kOhm and impedance would be equal to the next input stage. (one transformer per channel)
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