yep thats the bipolar version I was talking about, i'm not sure i've seen it built yet, though I do know a few who planned to try. Yeah fet matching is a pain and idss alone wouldnt cut it, more with this design than many but I would probably still go for a vgs 3 point match, or single point at operating conditions. I got lazy though and bought some quads; with EOL parts it can get pricey and definitely more time consuming than I can justify at the moment. Patrick may have some quads left though if you did want to try.
its a pretty in depth article if you buy the mag, interesting section on getting the most out of the ADC for the measurements
yes thats the NTD1 thread, soundcard? no... thats a full blown Audio Precision system, cant remember if its a system 1 or 2. Since then hes also augmented it with an ESS ADC and his own preamp stage; it doesnt really get all that much better.
haha you fell for the 'joke' =) we all have our idiosyncrasies here, no harm in a little techno-xenophobia as long as its in good fun. Me I cant cop nos, just doesnt do it for me, but I understand the appeal in the time domain.
have fun with Patrick, should be interesting to watch his reply to using a switching supply =)
sounds like a fair comparison to me, it will also be influenced by the dac chip chosen. the gM and as a result, the inputZ of the circuit directly influences thd with the ESS dacs as, as a current source they arent all that stiff, it will vary with each chip I would imagine.
We (I supplied the gM matched fets for the group) also found a direct relationship between the supply voltage and the gM of the fets. this was expected, but not as profoundly as reality. i'm afraid I dont know a lot of about bipolars, having never done much serious building with them, I much prefer the distortion profile of fets
its a pretty in depth article if you buy the mag, interesting section on getting the most out of the ADC for the measurements
yes thats the NTD1 thread, soundcard? no... thats a full blown Audio Precision system, cant remember if its a system 1 or 2. Since then hes also augmented it with an ESS ADC and his own preamp stage; it doesnt really get all that much better.
haha you fell for the 'joke' =) we all have our idiosyncrasies here, no harm in a little techno-xenophobia as long as its in good fun. Me I cant cop nos, just doesnt do it for me, but I understand the appeal in the time domain.
have fun with Patrick, should be interesting to watch his reply to using a switching supply =)
sounds like a fair comparison to me, it will also be influenced by the dac chip chosen. the gM and as a result, the inputZ of the circuit directly influences thd with the ESS dacs as, as a current source they arent all that stiff, it will vary with each chip I would imagine.
We (I supplied the gM matched fets for the group) also found a direct relationship between the supply voltage and the gM of the fets. this was expected, but not as profoundly as reality. i'm afraid I dont know a lot of about bipolars, having never done much serious building with them, I much prefer the distortion profile of fets
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I don't understand the above. "nos" == NOS == New Old Stock ?
What is "cop" ? To buy, to steal, to grab ? If yes, what do you mean then by "I understand the appeal in the time domain" ?
Anyway, let's get back to OpAmps as chips in this thread. I meant the thread to collect opinions on various OpAmps used to buffer DACs.
I.e. the practical angel: suppose I buy a DAC board with OpAmp installed in a socket. What are good candidates to try. Not expensive ones.
By the way, has anyone compared LM833 to NE5332 as DAC buffer ?
I.e. the practical angel: suppose I buy a DAC board with OpAmp installed in a socket. What are good candidates to try. Not expensive ones.
By the way, has anyone compared LM833 to NE5332 as DAC buffer ?
read the Hawksford paper - op amps return at the end - everyone wants to make the discrete I/V
http://www.essex.ac.uk/csee/researc...Current steering transimpedance amplifier.pdf
I posted some of my thinking in http://www.diyaudio.com/forums/parts/205337-op-amp-requirements-i-v-converter.html#post2879091
http://www.essex.ac.uk/csee/researc...Current steering transimpedance amplifier.pdf
I posted some of my thinking in http://www.diyaudio.com/forums/parts/205337-op-amp-requirements-i-v-converter.html#post2879091
NOS = Non Over Sampling
'cop' as in 'handle' to say 'cannot cop' means I cannot handle/dont like it. cannot handle is more like there is something about it that annoys you or drives you crazy rather than just not liking it. so there is something about NOS dacs that doesnt sit right with me, i've never gotten along happily with them in my system, but I can understand why people like them.
I dont find a properly designed Sigma Delta dac with well realised signal path and filters is that compromised with regard to ringing, certainly not enough for me to worry about given ALL ADCs are SD, but the squarewave and/or time domain performance of NOS waveforms certainly LOOKS superior
ok: opamps for dac output: balanced? I like opa1632, opa827, lt1037, LT1028, AD797, and if you can use a current buffer as well, the opa1641 is a great low noise, reasonably low priced chip, but its a bit weak in the output stage. the pricing on lme49990 has just dropped quite a bit, as with its current buffer brother lme49600 and these 2 make a great combination.
then the CFB (current feedback) chips AD844, AD811, lme49713 (this is a great chip)
so there ya go =)
have fun!
I like both methods (discrete or IC based) and use both in 2 different builds at the moment. I use opa1632 in my portable dac and love it, keeps things really simple
'cop' as in 'handle' to say 'cannot cop' means I cannot handle/dont like it. cannot handle is more like there is something about it that annoys you or drives you crazy rather than just not liking it. so there is something about NOS dacs that doesnt sit right with me, i've never gotten along happily with them in my system, but I can understand why people like them.
I dont find a properly designed Sigma Delta dac with well realised signal path and filters is that compromised with regard to ringing, certainly not enough for me to worry about given ALL ADCs are SD, but the squarewave and/or time domain performance of NOS waveforms certainly LOOKS superior
ok: opamps for dac output: balanced? I like opa1632, opa827, lt1037, LT1028, AD797, and if you can use a current buffer as well, the opa1641 is a great low noise, reasonably low priced chip, but its a bit weak in the output stage. the pricing on lme49990 has just dropped quite a bit, as with its current buffer brother lme49600 and these 2 make a great combination.
then the CFB (current feedback) chips AD844, AD811, lme49713 (this is a great chip)
so there ya go =)
have fun!
I like both methods (discrete or IC based) and use both in 2 different builds at the moment. I use opa1632 in my portable dac and love it, keeps things really simple
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OPA1632 appears to be a great chip. But it's single, and the DAC I most likely will buy uses a dual OpAmp chip.
And, of course, the those new great chips are not DIP ...
If your system is fast enough, you can implement oversampling in SW.
I.e. you need a fast enough DAC and a fast enough channel feeding datastream into it.
My point is that having a non-oversampling DAC leaves the DIYer more degrees of freedom.
fair enough, yeah I already do as you mention, the PLL doesnt completely turn off when running the es901X dacs in NOS mode, but it effectively does nothing when the incoming clock is the same as MCLK. then use 64bit apodising OSF in puremusic on an i5 mac mini. i'm still not completely sure whether I prefer the OSF external or not, the 40bit OSF in the sabre is pretty decent
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