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#1 |
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diyAudio Member
Join Date: Oct 2011
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Could anyone comment on how the PCM1794 sounds in relation to the PS1's AKM4309AVM??
I am asking because I am looking to build an affordable DAC unit-- the PCM1794 has been recommended. However, it requires a relatively complex output stage to fullfill it's potential. The Playstation 1's DAC however, just requires a couple of resistors.. and i've heard it and I like the sound. This DAC is out of production, however. So, would the PCM1794, with proper I/V output stage sound significantly better?? (can anyone reccomend an I/V stage??), or is there a good (in-production) alternative which has a simple output stage like the AKM4309, whilst remaining affordable and sounding as good or better? |
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#2 |
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diyAudio Member
Join Date: Jan 2008
Location: Virginia
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Is this a real question?? Of course is better. And yes, it needs quality OpAmps to achieve the maximum from I/V conversion, if you look for "direct output" you need some voltage output DAC's - like the PCM1793 or PCM1781 (this one has really simple output).
AKM4309 is a nice simple DAC, but it's just a modest performance, delta-sigma DAC. Regardless what fans say - THD @ -84dB, S/N A weight @ -90dB are nothing to be excited for - especially in a delta-sigma DAC. I even listen one (they are cheap here in CashConverter stores) but was nothing special. Last edited by SoNic_real_one; 22nd January 2012 at 06:31 PM. |
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#3 |
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diyAudio Member
Join Date: Apr 2003
Location: Eastern Pennsylvania
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The PCM1794A does not require an op-amp I/V circuit to obtain excellent sound. In fact, there are several high-end digital audio component vendors who sell very highly regarded non-opamp I/V units based on T.I.'s PCM179x series of DAC chips. Among them are; Audio Research which utilizes a passive resistor I/V, Neko which utilizes a Jensen transformer I/V, and Yamamoto which utilizes a zero-feedback grounded base PNP transistor I/V.
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Ken Last edited by Ken Newton; 22nd January 2012 at 11:21 PM. |
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#4 |
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diyAudio Member
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 62
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Note to mention Ayre's QB-9 which (from eyeballing a PCB pic) has passive resistor I/V followed by discrete transistor amplification.
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When a measure becomes a target, it ceases to be a good measure. C.A.E. Goodhart |
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#5 |
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diyAudio Member
Join Date: Jan 2008
Location: Virginia
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Yet, again, none of those is listed in the TI datasheet. Those "solutions" are nothing more than gimmics ment to find a niche suitable for their marketing and pushing high prices.
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#6 | |
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diyAudio Moderator
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Quote:
An interesting aside is that the THS4130/4131 were originally developed as DSL line amplifiers, when TI noticed people using these for audio and for driving ADCs they rewrote their datasheets and application notes to reflect this note. Just because it is not mentioned in an app note does not automatically invalidate a given design approach.
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"Extraordinary claims require extraordinary evidence." - Carl Sagan |
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#7 |
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diyAudio Member
Join Date: Oct 2011
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Sonic: I haven't heard the PCM1794, and i haven't read any direct comparisons, so I can only know how they compare by asking. I assume you listened to the correct version (100x or 5xxx)? I thought it sounded very good (as do lots of people, apparently), but i have not had a 'proper' DAC so i'm sure there is room for improvement still.
Anyone else have an opinion on how they compare?? Everything i've read on the I/V stage has suggested that avoiding OP amps (ie discrete I/V stage) is the way to go. This is my starting point... can anyone suggest a better alternative?? I'm looking for unbalanced. Is there anything worth considering that is similarly priced that allows for much simpler output stage implementation? ..or are there other chips i should consider? or any cheaper ones worth considering? |
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#8 |
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diyAudio Member
Join Date: Mar 2008
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Hmm, PS1 and PCM1794 seem to be designed with different goals in mind. Stereophile has measurements of the PS1, if measurements are of any importance to you.
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#9 | |
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diyAudio Member
Join Date: Dec 2003
Location: Sydney
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Quote:
Properly implemented OP I/V stage in a low-noise environment will sound consistently (not dependant on the rest of the audio system) excellent AND neutral …. so… to a priori disregard OP’s is a mistake. .. many are actually not ready for such solution –> it can sound too realistic; almost frightening in a good system….. so transformer / resistor solution might be preferable choice. Anyway – with 8mA of current swing, you can rest assured that you picked the best contender for passive I/V, so have fun! Boky |
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#10 |
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diyAudio Member
Join Date: Oct 2011
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So, i think you are suggesting i use the transformer? If so.. i have no idea what transformer i would want.. [e: .. and it seems they can get very expensive so as stated.. i want to avoid that. Is the transformer solution still the best given a requirement for affordability?]
And why this over the op-amps, since you seem to rate them highly?? You think this would be better than the type of circuit i posted?.. Am currently getting very bogged down and confused reading many posts regarding 1794 output / i/v stages.. Last edited by sfasf; 23rd January 2012 at 01:39 PM. |
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