I/V + Output opinions needed for this circuit

[georgehifi]

Anyone have any experience with this for I/V and output stage substitution, will it work in my dac (attached) ? Is it any good?
I can't work out the inputs to the Borbely circuit for the dual dif output of my dac.

http://www.borbelyaudio.com/eb604417.asp

Cheers George

[audiosteve]

A friend of mine designed and built a DAC and he a used current feedback Op amp for the integrator. I won't pretend to understand all of the theory and technical reasons he rattled off as to why he believes this to be superior to conventional volage FB topologies (discrete or otherwise). But I repect this guy's opinion very much and the proof, as they say, is in the pudding. It is the best sounding DAC I have ever heard. Perhaps you can look into this yourself or someone smarter than me can comment on this.

[QSerraTico_Tico]

Current feedback opamps sound very bright as IV-converter. If you like that OK.

[audiosteve]

It doesn't sound bright to me. Very smooth and detailed. But then of course these old rock n' roll ears could be fried too.

[georgehifi]

Smooth powerful and detailed is what I'm after, but this can equate to bright and hard on some systems that may have a problem somewhere, then dark and rich (tubey) will gloss over that problem.

Anyway can anyone give me an answer to, if the output of my dac (+- Left and +- right) can be wired up to this Borbely board, no matter how many times I read the (General Design Information) I can't make sense of it, there is from what I can see a - input through R12, but no + input, they talk about the +input (R2 grounded) but I cannot see what their talking about, I do need sleep, maybe that's my problem.

audiosteve it sounds like you have one of these, did it come all built for 190euros or did you get a bag of parts and a board and have to solder it up yourself.?

Cheers George

[rfbrw]

Originally posted by georgehifi
Anyone have any experience with this for I/V and output stage substitution, will it work in my dac (attached) ? Is it any good?
I can't work out the inputs to the Borbely circuit for the dual dif output of my dac.

http://www.borbelyaudio.com/eb604417.asp

Cheers George

It will work and you will need 2 assuming dual channel cards.

[georgehifi]

rfbrw thanks but I was hoping that was not the answer, as to two of them is out of the question at 380euros, is there somthing else that's good pre-made like this that would suit my dac?

I've seen the LC Audio Zap filter MkII but that is dearer here in Australia, and I've heard too many problems with this, and do'nt feel confident in it. And looking at their instal options below it may not be suitable either.
http://www.soundlabsgroup.com.au/mm5...rmk2_setup.pdf

Cheers George

[rfbrw]

Nothing off the shelf. The mods that seem of interest, to me at least, need to built from a schematic at best and extrapolated from the information provided at worst.

[audiosteve]

Georgehifi,

The DAC my friend built does not use the Borbely board. It is an original design which uses a current feedback, as opposed to voltage feedback, integrator stage. Again, I am not an expert on this. When he explained the rationale for his topology to me it had something to do with the different behavior of current mode vs. voltage mode with respect to the pulse edges coming in to the integrator and non-linearites that can occur with voltage vs. current feedback. I don't know enough about it say anything more intelligent than that. But I do know that this guy really knows his stuff and I usually take his word on such things as gospel. And again, the DAC sounds phenomenal. I just offered these comments hoping that someone out there who knows more about such things could explain the issue more clearly than I.