Additional info on balanced version
After further perusal, I find that they use both the 9001 (as spdif input) and 8805 Perhaps some of our more astute digital minds can tell me why. I have never seen a circuit with two input chips before. It could just be twp variations of the same design, but from the schematic, that does not appear to be the case.
After further perusal, I find that they use both the 9001 (as spdif input) and 8805 Perhaps some of our more astute digital minds can tell me why. I have never seen a circuit with two input chips before. It could just be twp variations of the same design, but from the schematic, that does not appear to be the case.
I just received OPA627BP from DIYElectronics (Burr Brown OPA627BP precision high speed difet op amp - eBay (item 260683270742 end time Feb-22-11 12:35:34 PST)). They sell them for US$16.95. They look original. Installed them and will report on first impressions in a few days. So far so good.
Received dac today. DOA! Checked fuse, ok. Took off the top and found that the main power plug was not connected (they are now using plugs rather than hard wiring for the power connections. Plugged it back in. Power came up. I am too tired to reassemble so I will test tomorrow. Thank DHL for the loose plug. BTW it only has the 9001, but a place for the Wolfson chip. I have no idea what is going on.
glad to hear it works after all. I am curious to hear what the difference in sound is between the old one (unbalanced) and the new one (balanced). i ordered new rectifiers from digikey and also nichicon pw for power supply, will replace them next weekend and report on the result. Already replaced all caps in filter stage with Sanyo SEPC 16V 470uF and output stage with a combination of Nichicon KZ Muse and Panasonic FM. Also replaced RCA connectors with silver Audio Note. The sound now is very different, that is much better. I'll report on changes after the rectifier diode and power caps change.
Anyone using a computer with this DAC? If so, then let me know some details (OS, interface, player and any kernel drivers if applicable). I'd really like to use a Linux laptop with it but am not sure if its supported. Just completed converting 300+ audio cds to flac. So will start to shop for a USB DAC soon.
According to the seller's specs, the USB input goes to a PCM2902, which should work fine with linux (no guarantees though...). The dac is not ideal for USB use as the PCM2902 will only support up to 48kHz sample rates, and over time more and more audio will be in higher sample rate formats. Most USB dacs that run with Macs and Windows without additional drivers should be well supported by linux these days. I have three which all work perfectly.
For a similar price, Audio-gd offers a dac/headphone amp with multiple WM8741 dacs, USB input supporting 96kHz audio (TE7022 chip) and some other goodies. It's less 'tweaker friendly' as it has discrete output sections, but looks like great value. Can't wait for mine to arrive
. It was a close call between this dac and the Audio-gd NFB-12.
Too bad I'll probably never get to A/B the two dacs side by side.
For a similar price, Audio-gd offers a dac/headphone amp with multiple WM8741 dacs, USB input supporting 96kHz audio (TE7022 chip) and some other goodies. It's less 'tweaker friendly' as it has discrete output sections, but looks like great value. Can't wait for mine to arrive
. It was a close call between this dac and the Audio-gd NFB-12. Too bad I'll probably never get to A/B the two dacs side by side
.DAC schematic
Does anyone have the schematics of this DAC? In my unit, AD797 causes noticeable distortions at high frequences. Perhaps I hear the distortion because my Thiel speakers are very revealing and clearly show flaws in the system. I am trying to modify the buffer in relation to "distortion cancellation" and also to "controlled compensation", both as per Walt Jung's 2002 paper. I need the schematics to do that properly. Any advice and/or schematic would be greatly appreciated.
Does anyone have the schematics of this DAC? In my unit, AD797 causes noticeable distortions at high frequences. Perhaps I hear the distortion because my Thiel speakers are very revealing and clearly show flaws in the system. I am trying to modify the buffer in relation to "distortion cancellation" and also to "controlled compensation", both as per Walt Jung's 2002 paper. I need the schematics to do that properly. Any advice and/or schematic would be greatly appreciated.
Yes it is a Buy it yourself Dac,
I bought it off ebay, It is a assembled dac consisting of 4, yes 4 wolfson wm4870.
I just wanna upgrade the sound of my cd players, I did'nt expect it would sound this good.
The stock Opamps are opa134, And I dont think it is that bad, But I just ordered six ad797 to replace them , To see what the differences are.
But in stock form , This dac sounds very good, very detailed,very transparent, very musical and very involving, Only needs a very very tiny bit of refinement or smoothness.
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Hi:
Your also could replace WM8740 to WM8741 too and not change OP only.
Because between WM8740 to WM8741 is IC to IC even pin to pin and no need change circuit.
BTW WM8741 have beter codec IP than WM8740.
That's why Linn streamin choice WM8741 already.
WM8741 have better sound filed of the deep carved.
There are also have WM8742 on market too. still pin to pin and IC to IC.
For your reference WM8741 > WM8742 > WM8740 ........(base sound color.. because codec IP is different).
ASter
Mr211's blog
http://tw.myblog.yahoo.com/jw!9frLFy6fAkV0gBy_oZT_geG5fC24WQ--
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Hi:
WM874,,WM8742 is SOP-28 pin package.
I chnaged 3 time for ESD broken codec experience and I replaced by hand soldering.
Receiver I pick CS8416.
H/W setup CS8416 and WM8741 working.
Not support DSD (WM8741,wm8742 only)play and let PC feed SPDIF signal.
Your also could take a look ....
Forums ....Toy1 My first time Audio DIY ... D/A.
ASter
Mr211's Blog
Mr211's Blog - Yahoo!?????--
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maybe output is too hot for your preamp or amp? so many dac chips in parallel could easily produce too high voltage for some hardware. the distortion cancellation pin on the 797 is for getting rid of the last drop of distortion for instrumentation amps, if it is high enough you can audibly hear the distortion, then I do not think using this pin will help you; I feel your problem is elsewhere
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Several people including QUSP have suggested that this opamp may be unstable in this circuit. That may be the case. For what it is worth I have the schematic and would be glad to send it to you. email me at jd803walnut@yahoo.com Regards John Dozier
I am also thinking it could be elsewhere. What made me think distortions are due to AD797 is that when I placed LME49710 in the filter stage and kept OPA627 in the output stage, there were no distortions at all. As I write, I am listening to it and it sounds good, bass is somewhat stronger than I'd want it, but no distortions whatsoever.
I ordered some 15pF capacitors and some 10R resistors from digikey and I'll try to cancel distortions that way. I have no idea where else would the problem be, so I'll give it a try.
AD specs and also Jung's paper suggest that distortion cancellation should not be done by connecting the resistor and capacitor (in parallel) from leg 6 to leg 8: would you know if they do not connect to leg 8, where than? The end of the buffer?
Thanks John for the offer, I just got the schematic from Hui.
I ordered some 15pF capacitors and some 10R resistors from digikey and I'll try to cancel distortions that way. I have no idea where else would the problem be, so I'll give it a try.
AD specs and also Jung's paper suggest that distortion cancellation should not be done by connecting the resistor and capacitor (in parallel) from leg 6 to leg 8: would you know if they do not connect to leg 8, where than? The end of the buffer?
Thanks John for the offer, I just got the schematic from Hui.
yeah I didnt want to mention that again, because every time I do someone comes and tells me/argues it 'sounds good' so must be OK, I do believe it is the case and bandwidth limiting is needed. 797 is stable at low gains with the right circuit to support this, but without it things can easily go pear shaped
@ m3brooklyn
the distortion cancellation pin will not fix your audible distortion, that isnt what they mean. 120db 'distortion' (number plucked from the air) is not audible, your problem is elsewhere, output too hot or input impedance of the next stage too low (would have to be ridiculously low) or marginal joint perhaps; or something else, but not the distortion of this already excellent chip
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