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Hegel H80 Balanced vs Unbalanced Inputs

Hi,

I am looking at some options for getting an outboard DAC for the H80. I think the amp is great but the DAC, using an older TI/Burr-Brown 1754 chip and old school USB input, could use some improvement.

Some of the DACS I am looking at have balanced outputs but I am wondering if this matters much. Seems that some amps show a difference when using balanced inputs, and some don’t.

Does anyone has experience with the balanced inputs (XLR) on the H80 (or Hegel Amps in general) and in comparison with the unbalanced (RCA)?
Thanks!
nquery
auxinput
2,920 posts
 

Based on pics, I would say the Hegel H80 is not balanced internally. That being said, I am going to assume that the balanced inputs would be a benefit because the XLR would (typically) drive both the positive and negative lines on the input circuit (possible an opamp). The input circuit would convert the signal to "single ended" internally inside the Hegel.

That being said, it would really only be truly beneficial if the DAC you chose had real balanced (differential) output circuits. There are DACs that do have an XLR output, but the negative polarity pin is not really generating any signal -- usually it is just shunted to ground, possibly through a resistor.

nquery OP
103 posts
 
Thanks for the response. 

I was unsure about the internals of the H80 though their product page does state "The H80 features 5 digital inputs with 24 bit technology, 1 true balanced analog input and 2 unbalanced analog inputs". Does "true balanced" mean that it is balanced internally? Hard to really tell and I can't dig anything else up from the internet other than 1 poster on this site that said that the soundstage really opened up with balanced connections - but the gain is also know to be higher and so hard to say if it was not just louder.

Good point on the DAC outputs - I know that the Schiit Gungir *is* a real balanced design, but one of the other DAC's I am looking at, Gustard X20, might not be. Again, it has twice the gain on the balanced outputs so looks can be deceiving.
auxinput
2,920 posts
 

We can only assume stuff on the Hegel balanced input. It’s entirely possible that it is using all pins on the XLR. This means that it will use both the positive and negative polarity signals on the XLR, as shown in this op amp example:

https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Op-Amp_Differential_Amplifier.svg/300px-Op-Amp_Differential_Amplifier.svg.png

However, I highly doubt that the signal is balanced after this. The op amp will convert the balanced (+/-) signal to a single-ended "unbalanced" signal internally. The amplifier part of the Hegel is not going to be fully balanced/differential. It’s difficult to see, but it appears that there are 4 transistors mounted to the amp heatsink. This means it’s only single-ended. The amp will use 2 transistors per channel (one transistor for positive side of waveforms and a second transistor for the negative parts of the waveforms.  There aren't that many amps that are truly balanced internally. They are usually monoblocks, but ATI and Theta have models that use balanced amp cards.

http://2.bp.blogspot.com/-d9V_PoFrbx4/UzHRUZXW_RI/AAAAAAAAXLw/wzgZdKol-Ok/s1600/HegelH80-07.jpg

That being said, I have always had superior results using balanced connections, even though the source/preamp device is not truly balanced.

nquery OP
103 posts
 
Thanks for the insight. So while they state they are 'true balanced' inputs that only goes as far as the inputs. So I am assuming I would gain *something* by using a truly balanced source. Question is how much and weighing that against other factors.

I am down to two DAC's - Schiit Gungnir Multibit "Gumby" (balanced design) or an Audio-GD DAC-19 10th anniversary (R2R single ended). From what I have read some people feel that Gumby in Balanced out is about equal to the DAC-19 but falls behind when used SE. DAC-19 is $400 cheaper and while very very well built, it isn't as easily upgradeable like the Gumby, nor US based. Decisions, decisions .... 
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