DACs using dual differential balanced designs - have to be balanced XLR out?

spiritofmusic

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Jun 13, 2013
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I do get that Tao.
This is not a q of having to have the best.
It’s a q of not deliberately choosing the worst.
Not one respondent on this thread has said “no problem Marc, there really are only marginal differences going rca or xlr”.
If they had, I’d be less preoccupied w this matter.
 

the sound of Tao

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Jul 18, 2014
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Marc, when we are analysing every thing every small difference can seem important. I tend to like the sound of single ended as a preference and find xlr a complete downer... just joking, it’s all marginal unless you are putting the microscope on it in which case the differences instantly become more significant... but if you have great cables and a great single ended based system then I wouldn’t go any other way. Much in the same way that great horns don’t always a/b so well directly against much more linear and sonically correct systems some times. Still the music is where ever you ultimately find it.
 

Ken Newton

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Dec 11, 2012
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...Not one respondent on this thread has said “no problem Marc, there really are only marginal differences going rca or xlr”.
If they had, I’d be less preoccupied w this matter.

Probably, the first thing to make clear is that an wired signal interconnection can be balanced or unbalanced, but the active electronics driving that interconnection is more properly termed differential or single-ended. Differential drive is not necessarily synonymous with balanced interconnection, and single-ended drive is not synonymous with unbalanced interconnection. The active drive electronics and the wired interconnection are separate matters. For example, an single-ended driver circuit is rather easily adapted to fully benefit from the common-mode noise rejection offered by balanced interconnection.

Objectively, an correctly implemented balanced interconnection via XLRs is the superior to unbalanced via RCAs, primarily due to it's common-mode noise rejection capability. Subjectively it may, however, be another matter. Subjective differences (in the absence of common-mode noise) are likely due to the implementation of the internal circuits of the active differential electronics.

Setting aside the benefit of common-mode noise rejection offered by balanced interconnection - which is a huge advantage if your system's environment suffers such noise - differential driver circuits can offer other advantages over an single-ended driver, such as inherent even order distortion cancellation, +3dB higher SNR, faster slew-rate and reduced signal based modulation of the power supply rail(s) compared to an equivalent SE driver circuit design. However, the best differential driver circuits will also consume twice the number of parts, and therefore twice the cost, of an equivalent SE driver circuit. As such, many commercial differential driver circuits are compromised implementations in order to save parts related cost.
 
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asiufy

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I do get that Tao.
This is not a q of having to have the best.
It’s a q of not deliberately choosing the worst.
Not one respondent on this thread has said “no problem Marc, there really are only marginal differences going rca or xlr”.
If they had, I’d be less preoccupied w this matter.

And how do you account for what could be "marginal" for one, could be immense for you (and your system)? Or vice-versa...
 

spiritofmusic

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Jun 13, 2013
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Alex, I know I drive various guys here a little crazy with my prevarication etc.
As you say, there’s no real answer to my q, it’s all subjective/relative.
Just like my qs on SETs w Apogees, belt drive v non belt drive etc.
One could take the plunge.
Or sweat the variables and make the careful decision.
So yes, I could spend €15k on the Formula w upgrade and see how it goes.
Or see if there’s a dac that is ideally suited to single ended use (no luck here, yet).
Alex, I retain an interest in the Aqua La Voce.
You could do me a favour. Run it in various preamps that you sell, both RCA and XLR, and give me a frank appraisal of how both compare thru a handful of different preamps presenting different demands.
At least I’ll have some tangible opinions to make a decision on.
 

kernelbob

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Oct 23, 2011
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Hi all, I'm using the Lampizator Golden Gate balanced DAC which uses four non-chip ladder D/A converters to output the resulting four +/- phases of the two channels each to a PX4 output tube. From there, the signal goes to a Tortuga LDRxB balanced passive controller which uses light sensitive resitors to perform any attenuation. From there, I biamp my speakers, with one set of outputs going to a pair of Lampizator 211 True Balanced amps. The second set of outputs from the LDRxB goes to a second Tortuga controller, the LDR1B (one dedicated input), which is also balanced. I use that to adjust the signal level feeding a pair of Spectron Musician III Mk2 amps running in monoblock mode using XLR input.

The Lampizator amps are a great match for the system since it essentially has two 211 monoblock amps combined in each channel's amp with each 211 and its preceding tube stages handling only one phase of input. The outputs of the two 211's are combined in the output transformer. That's the first place in my system that the two phases of a channel are joined. These Lampi amps only accept XLR balanced input since they don't use a phase splitter at the input to derive the separate phases. The 211 tubes run in single ended mode, class A of course, with no local or global feedback used.

The Spectrons are stereo amps that were configured at the factory to either accept RCA input as stereo amps or one XLR input for each phase of a channel to be sent to one of the two stereo channels.

I've been very happy with the balanced signal path architecture. The amps I'm using process each phase of each channel in single ended mode. I'm not saying that all balanced systems are better that all single ended ones, far from it. I've heard good and not so good implementations of each.

Best,
Robert
 

Empirical Audio

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Steve, thanks for the offer, but £4k for yr transformers plus a set of XLRs is not an expense I can envisage when I’m already pushed on the budget for dac and streamer.
Maybe at a later date.
This late piece of info re 99.999% of dacs decidedly superior balanced out, my inability to go balanced (except at inflated cost via seperate add-on transformers/XLRs) due to single ended-only preamp, and discovering my cdp is actually optimal as I use it ie single ended, is all meaning I’m passing on any steamer/dac option other than a v basic one, with a cheaper dac that I can hope to find is not poor single ended, eg the Kitsune Edition Holo Springs, and even if not ideal, I won’t have splashed the cash in making a big mistake).

A pair of Final Drives is 2280 British Pounds, not $4K. Shipping is added of course, and exchange rate fee.

Steve N.
 

Empirical Audio

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Why not just have a local tech install XLR input jacks and balanced > se trafos in your preamp?

That will certainly work, but he SQ may be compromised. The quality of these transformers is critical. I get custom transformers made by hand in Japan. Grounding of the transformer and quality of wiring is important too. I use pure silver OCC wire from Japan, insulated with cotton.

BTW, I have one customer that purchased 3 sets of the Final Drive.

Steve N.
 
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Empirical Audio

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Oct 12, 2017
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Probably, the first thing to make clear is that an wired signal interconnection can be balanced or unbalanced, but the active electronics driving that interconnection is more properly termed differential or single-ended. Differential drive is not necessarily synonymous with balanced interconnection, and single-ended drive is not synonymous with unbalanced interconnection. The active drive electronics and the wired interconnection are separate matters. For example, an single-ended driver circuit is rather easily adapted to fully benefit from the common-mode noise rejection offered by balanced interconnection.

Objectively, an correctly implemented balanced interconnection via XLRs is the superior to unbalanced via RCAs, primarily due to it's common-mode noise rejection capability. Subjectively it may, however, be another matter. Subjective differences (in the absence of common-mode noise) are likely due to the implementation of the internal circuits of the active differential electronics.

Setting aside the benefit of common-mode noise rejection offered by balanced interconnection - which is a huge advantage if your system's environment suffers such noise - differential driver circuits can offer other advantages over an single-ended driver, such as inherent even order distortion cancellation, +3dB higher SNR, faster slew-rate and reduced signal based modulation of the power supply rail(s) compared to an equivalent SE driver circuit design. However, the best differential driver circuits will also consume twice the number of parts, and therefore twice the cost, of an equivalent SE driver circuit. As such, many commercial differential driver circuits are compromised implementations in order to save parts related cost.

Everything you say is true, I think, however this is not the main reason why most DAC's sound better from balanced outputs than SE.

It starts at the D/A chip, where there are two signals of equal amplitude (may be voltage or current) and invert phase from each other. The amplitude and therefore the S/N noise ratio of these two signals subtracted from each other will be twice of just one alone. If the SE output is created by subtracting these two signals, as in many DAC's, then this adds another amplification stage, resulting in more compression, noise and distortion. With an SE signal, the effects of ground-loops is immediate. Finally, there is the amplitude or "energy" of the 2 signals versus one signal. The more signal that is present early in the chain and the longer that is maintained, the lower the noise level. Why? because less amplification is needed in the intermediate stages. Higher gain = more noise and usually more distortion. Add these to the common-mode rejection benefits of balanced that you stated above and you have an audible difference, and usually it's obvious.

Steve N.
Empirical Audio
 

Empirical Audio

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Oct 12, 2017
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Hi all, I'm using the Lampizator Golden Gate balanced DAC which uses four non-chip ladder D/A converters to output the resulting four +/- phases of the two channels each to a PX4 output tube. From there, the signal goes to a Tortuga LDRxB balanced passive controller which uses light sensitive resitors to perform any attenuation. From there, I biamp my speakers, with one set of outputs going to a pair of Lampizator 211 True Balanced amps. The second set of outputs from the LDRxB goes to a second Tortuga controller, the LDR1B (one dedicated input), which is also balanced. I use that to adjust the signal level feeding a pair of Spectron Musician III Mk2 amps running in monoblock mode using XLR input.

The Lampizator amps are a great match for the system since it essentially has two 211 monoblock amps combined in each channel's amp with each 211 and its preceding tube stages handling only one phase of input. The outputs of the two 211's are combined in the output transformer. That's the first place in my system that the two phases of a channel are joined. These Lampi amps only accept XLR balanced input since they don't use a phase splitter at the input to derive the separate phases. The 211 tubes run in single ended mode, class A of course, with no local or global feedback used.

Best,
Robert

What I like about this is that the balanced signals are changed to SE at almost the last possible stage in the chain. Even better of course would be if it were the speaker itself doing the subtraction, with active signals driving + and -. This maintains more energy later in the chain, which requires less gain in the intermediate stages. Excellent job!

Steve N.
 

microstrip

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May 30, 2010
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(...) A pair of these plus extra set of XLR interconnects doubles the cost of the interesting more affordable dac I was considering buying.

A pair of top Lundhal transformers will cost you around 600 euros. The excellent Jensen's as used by several top high-end manufacturers will be less than half this price.
 

microstrip

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May 30, 2010
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(...) The Lampizator amps are a great match for the system since it essentially has two 211 monoblock amps combined in each channel's amp with each 211 and its preceding tube stages handling only one phase of input. The outputs of the two 211's are combined in the output transformer. That's the first place in my system that the two phases of a channel are joined. These Lampi amps only accept XLR balanced input since they don't use a phase splitter at the input to derive the separate phases. The 211 tubes run in single ended mode, class A of course, with no local or global feedback used.(...)

What is the exact topology of the output stage? Does it have a single or two output transformers? If it is just one it looks like a push pull without the inverter.

Audio Research used such topology since long in their amplifiers - the first one was the V70 in 1992. They even sold the BL1 - a balancing unit that allowed users to connect it to an SE output. Fortunately their new current designs accepts SE signals in the XLR input.
 

asiufy

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Alex, I know I drive various guys here a little crazy with my prevarication etc.
As you say, there’s no real answer to my q, it’s all subjective/relative.
Just like my qs on SETs w Apogees, belt drive v non belt drive etc.
One could take the plunge.
Or sweat the variables and make the careful decision.
So yes, I could spend €15k on the Formula w upgrade and see how it goes.
Or see if there’s a dac that is ideally suited to single ended use (no luck here, yet).
Alex, I retain an interest in the Aqua La Voce.
You could do me a favour. Run it in various preamps that you sell, both RCA and XLR, and give me a frank appraisal of how both compare thru a handful of different preamps presenting different demands.
At least I’ll have some tangible opinions to make a decision on.

That I can do, once I have an actual store :) We're almost done with the renovations, and next week we'll reopen. Given time, I can do what you're asking, easily.
Again, the MSB Analog DAC is best when used single-ended. There is representation in the UK, so you might give that a try. Keith has one, and he used to own a speaker like yours.
 

spiritofmusic

Well-Known Member
Jun 13, 2013
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Alex, much obliged.
All I’d request from you is that you pick maybe 3 preamps including a tubed one, and try La Voce on RCA and XLR on each.
Feel free to PM me if you don’t want to broadcast the results.
 

opus112

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Feb 24, 2016
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It starts at the D/A chip, where there are two signals of equal amplitude (may be voltage or current) and invert phase from each other. The amplitude and therefore the S/N noise ratio of these two signals subtracted from each other will be twice of just one alone. If the SE output is created by subtracting these two signals, as in many DAC's, then this adds another amplification stage, resulting in more compression, noise and distortion.

There is another way to 'subtract' without using a further amplification stage, that is use a transformer fed from the two anti-phase signals.
 

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