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Best method for I to V?


fierce_freak

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I think a volume-matched DBT between single ended m3 and balanced b22 would be interesting :)

I'd love to see that. I've gone back and forth so many times on whether I think the balanced b22 is any different from my 2-channel b22. As it is, today I think the balanced b22 is a little more clear on low-level stuff (cmrr?)

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Current steering seems to be regarded as the best. I don't know if this is because of the stuff Gilbert was talking about with overloading the input stage, if it's due to simply discrete offering better performance parameters (I haven't seen as much discussion about discrete op-amp versus current steering), or because of something else like better slew characteristics. I haven't yet tried colin's i/v though I will probably some time this summer.

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Excuse my ignorance, Filburt. My DIY knowledge isn't up to snuff. Is current steering the same as the current conveyer types?

Also, this is something I've been pondering for a couple days. How can the Sabre DAC operate as both voltage out and current out? I think I'm missing something...

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I'm not Filburt, but in answer to your question, I believe they are the same. And I'm not sure who Gilbert is that he is referencing.

Current steering basically work much as passive I/V does, with the exception of current mirror(s) actually providing the driving current for the I/V resistor, thereby not loading the DAC output and presenting a (hopefully) very low impedance to the DAC. At least that is my limited understanding of it.

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Excuse my ignorance, Filburt. My DIY knowledge isn't up to snuff. Is current steering the same as the current conveyer types?

I don't know if it is for sure, as I haven't looked a schematic for a "current conveyor", but it sounds like it probably is since Pars referenced Hawksford (who calls his own I/V "current steering").

Also, this is something I've been pondering for a couple days. How can the Sabre DAC operate as both voltage out and current out? I think I'm missing something...

It probably can just route the output of the modulator (or whatever is at the tail end) to either a switched capacitor filter internally (for voltage output) or straight out to external i/v.

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I'm not really sure. Looking at the manual online (at twisted-pear), it says:

'---------------

Output Characteristics:

The output of the buffalo can be used as a voltage source or a current source. Best DNR and THD will

be achieved using it as a current source.

The differential output of the buffalo is 0.924*1.65V (3.1746 Peak) + 1.65 DC bias and the series

output resistance is nominally 195 Ohms at each output.

'---------------

Doesn't say whether you have to provision pins/dip switches/programming to select which mode you are using... and from the schematic, it doesn't have different output pins that I can see.

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I thought something along those lines may be the case (though I didn't know all the terms used), but are the outputs auto-sensing of load, or is the DAC set to one or the other on power-up, to your knowledge?

I don't know what the operation is like. Might be controlled by a microcontroller, or otherwise just by pulling some pins high/low.

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  • 1 year later...
has anyone tried a zapfilter and buffalo1.2? does it work well?

i mtempted to buy a buffalo 1.2 on sale now at TPA

Getting the zapfilter configured optimally for a Buffalo might be problematic, because the Sabre DAC is apparently very finicky.

I would recommend you just grab an IVY module from TPA. For only $75, it is a good base to experiment from.

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ok thanks,

so maybe with the dac in the buffalo works well though...?

i was just looking for an upgrade to my zapfiltered zhaolu and thought it could be good for on ly 159$ as i already have a supply and case. now i m not sure it s really worth it to buy the buffalo+ivy+supply...

i ll probabbly then wait for AMB y3 or something like that

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you said: the sabre dac is finicky, so to set the zapfilter for the buffalo might be a problem. so it might be ok for the buffalo but not another dac boards. that s waht i meant. anyway i think we understand each other.

i heard people had problems with the buffalo and for others it worked well. so maybe there are certain things that need to be avoided or there is a kind of recipe that makes it works well every time.

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you said: the sabre dac is finicky, so to set the zapfilter for the buffalo might be a problem. so it might be ok for the buffalo but not another dac boards.

It doesn't matter what board it is on - the Sabre DAC chip at the core of the Buffalo board is finicky in terms of what it needs from an I/V stage. The zapfilter may or may not fit the bill.

so maybe there are certain things that need to be avoided or there is a kind of recipe that makes it works well every time.

Use a part specifically designed for it. Or design it yourself.

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No. I've given you plenty of hints, so I'll come right out and say it. Do your own reading. There is an 80+ page thread on DIY Audio for the Buffalo 24, and a 25+ page thread for Buffalo 32.

If you have a specific question in regards to a specific scenario, then come back. Asking vague questions with no background knowledge is useless.

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