AD811
Hi Nick, Never liked the sound of the AD811. Looks great on paper. I also thought the LME49713HA would be a great I/V opamp. It wasn't. Looks pretty good on paper again. Super low distortion. Sounded Hi Fi. I could clearly hear some issues. Like low level distortion. The imaging was distorted although it was holographic on good material. Probably works great in a different application. I didn't try the ceramic version of the 811. I am having better luck with the Analog Devices improved EL2020 and it is available in DIP. Still think I may get better results with the AD844 triple stack on PCM1704. I need to build a new board I think to do it right.
Test tones?
Hi George, Maybe a test disc would have repeatable signals to try to capture the glitches and other HF nasties. I'd think you need to use the dac to see the issues. Woulds a spectrum analyzer be useful here?
Yes a test disc at 0dbf to make the dac give full output and work it's hardest, but you need 0dbf of silence to be able to view any noise without being swamped by the music. Then there's the glitches, they happen who knows when and need to be stored and frozen, and you need to see what the I/V stage is doing at that split second in time. (My head hurts). best off having no feedback and not tempting fate.
Cheers George
Cheers George
Glitches....
Hi George, Only way I can think of... It might be done with a spectrum analyzer and you'd have to figure out how to notch out the 0 dbm signal. That way you'd be looking at the dac's residual spectrum. As you say the glitches are more or less random and would be tough to get a handle on. You could be right on the "no feedback approach". Sadly just found out I need orthopedic surgery so that will slow down my progress on the 1704's triple stack. I think I should do a clean I/V stage for the PCM1704. That TDA1541 board is just to busy with current sources etc. Can't fit the AD844 nulling trimmers either. The 844 chip stack is straight forward, just need the 100 Ohm resistors fitted to the pin 6's. That is doable. I'd be able to check out the paralleled output stage that way.
AD844 stage is up and running
Hi George, Just finished the basic PCM1704 AD844 I/V stage. Just taking a first listen. For now single AD844's to test the board. One triple stack has the 100 Ohm resistors installed, the other when i get a chance. I also wired up the nulling pins to my adapters for just the bottom chip. I think you mentioned that is all that was needed? I am using a passive filter for now. I can say it sounds pretty smooth. I have enough room to add the AD825 buffer stage too. In a mad dash to get things done. Looking at open shoulder surgery in as few as 2 weeks. Ouch...
Attachments
Looks good wait till you hear the triple.
Yes the 1 x 20kohm dc trimmer goes only on one as I did it, don't know what would happen if you have on all three, it worked fine for me on one of the Ad844 nulling pins, stable dc offset +- 1mV.
As for the passive filter, it's the cap across the TZ resistor, I used 2.7kohm for the gain I wanted with 470pf across it which gave -3db at 125khz.
Cheers George
Yes the 1 x 20kohm dc trimmer goes only on one as I did it, don't know what would happen if you have on all three, it worked fine for me on one of the Ad844 nulling pins, stable dc offset +- 1mV.
As for the passive filter, it's the cap across the TZ resistor, I used 2.7kohm for the gain I wanted with 470pf across it which gave -3db at 125khz.
Cheers George
AD844 Triple stack
Hi George, Installed the triple stack just 2 hours ago. No problem getting much less then 1 mV offset. Sound is very clear. It seems with the PCM1704 this is very good. I'll need to do some more listening however I am impressed.
Hi George, Installed the triple stack just 2 hours ago. No problem getting much less then 1 mV offset. Sound is very clear. It seems with the PCM1704 this is very good. I'll need to do some more listening however I am impressed.
Me Too!
Have been following along with the developments over the course of this thread. Thus far I have made the IV conversion to stacked AD844s to replace the factory Denon dvd-5000 IV/buffer system. I was using the signal from the paralleled buffers to start with then only the output from pin 5 for some time. I also installed emitter follower supplies for each of the chip sets, one for the PCM's, AD844s and the nulling circuit. Each supply was loaded such that the plus and minus legs were loaded the same to match and reduce output impedance of the supplies. These were located over the chips. This seemed to improve the sonic balance and definition and the sound stage but I never got the wow factor that would of replaced my Meridian 596.
I went thru the process of installing the series resistor on the buffer outputs and connected them back to the Denon's outputs. Nice but still not what was being raved about throughout this thread.
I began to suspect my thru hole parts and layout(quite the mess) for the unanswered improvement. I then traced the signal path from the AD844 to the PCM1704s. The signal path to the AD844s was direct but the return was mind boggling on the factory board. I took the suggestion that it should be short and direct from abraxalito, I believe mentioned in this thread. Well, I installed a short jumper back from pin 3 of the AD844s to the analog ground of the PCM1704s. Holly DACMAN.........
Now I understand what the fuss is all about. Might want to make sure that the analog signal path between the chips is short and sweet. I am using the Meridian as a transport into the Denon as a dac at this point. This makes for a very nice improvement over using either the meridian or the Denon by themselves. I now understand the talk about dynamics. The snap of the snare drum or any percussion instrument is terrific. The biggest surprise for me was the amount of detail that came to the forefront. The accompanying instruments/singers are now a part of the picture not just in the background. The overall presentation is detailed and smooth.
Have been following along with the developments over the course of this thread. Thus far I have made the IV conversion to stacked AD844s to replace the factory Denon dvd-5000 IV/buffer system. I was using the signal from the paralleled buffers to start with then only the output from pin 5 for some time. I also installed emitter follower supplies for each of the chip sets, one for the PCM's, AD844s and the nulling circuit. Each supply was loaded such that the plus and minus legs were loaded the same to match and reduce output impedance of the supplies. These were located over the chips. This seemed to improve the sonic balance and definition and the sound stage but I never got the wow factor that would of replaced my Meridian 596.
I went thru the process of installing the series resistor on the buffer outputs and connected them back to the Denon's outputs. Nice but still not what was being raved about throughout this thread.
I began to suspect my thru hole parts and layout(quite the mess) for the unanswered improvement. I then traced the signal path from the AD844 to the PCM1704s. The signal path to the AD844s was direct but the return was mind boggling on the factory board. I took the suggestion that it should be short and direct from abraxalito, I believe mentioned in this thread. Well, I installed a short jumper back from pin 3 of the AD844s to the analog ground of the PCM1704s. Holly DACMAN.........
Now I understand what the fuss is all about. Might want to make sure that the analog signal path between the chips is short and sweet. I am using the Meridian as a transport into the Denon as a dac at this point. This makes for a very nice improvement over using either the meridian or the Denon by themselves. I now understand the talk about dynamics. The snap of the snare drum or any percussion instrument is terrific. The biggest surprise for me was the amount of detail that came to the forefront. The accompanying instruments/singers are now a part of the picture not just in the background. The overall presentation is detailed and smooth.
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AD844's...
Hi optimationman, Yes. The ground return is very important. You can tolerate a little distance just keep the impedance low. I am using Teflon insulated Silver wire. In my system the smoothness of the AD844 is very much heard. Yet during a dynamic peaks the impulse is superb and detailed. At this moment I rate my PCM1704 build as the best DAC I have here. My "Parallel 1541" DAC comes close however it doesn't have the depth or detail.
Philips CD303
At the moment, this cd player sitting on my desk, opened up. It was already ''tweaked'' by someone and I am wondering do you guys have any suggestions for TDA1540...I guess something similar to TDA1541 would work nice. I only have 8xAD844AN so no fancy buffers ... I will use AD's own buffer...
Cheers, Milan
At the moment, this cd player sitting on my desk, opened up. It was already ''tweaked'' by someone and I am wondering do you guys have any suggestions for TDA1540...I guess something similar to TDA1541 would work nice. I only have 8xAD844AN so no fancy buffers ... I will use AD's own buffer...
Cheers, Milan
Filter
Hi George, So the only filter you use is the 470 pF across the TZ resistor? I am using 2.5K Ohm resistors for TZ. I have been enjoying the PCM1704 DAC build. I should be up to some DIY in the next 2-3 weeks. So would like to give that capacitor filter a try. The surgery went OK. Just no strength yet in the left arm. Thanks, Dave
TDA1540
Hi Milan, I guess no one is going to chime in. If the TDA1540 is current out it should work fine with the AD844 stack. Not sure how much DC offset you have to worry about. The 1540 as I recall is a 14 bit D/A. Try a single AD844 and look at how much offset you have. You might be able to use Pedja's 2SK170 2 mA current source to null it out. Your a bit on your own here with the 1540. Hope some of this helps. Dave
Yep that's it, a 2.7kohm TZ resistor with 470pf across it which gives -3db at 125khz.
With this I only have a couple of mV of hf noise on the output of the 844's buffer at max digital volume. When cd's are in between tracks or no music playing you swear the system is switched off.
Cheers George
Pretty much describes what I'm hearing too from my 3x844 stacked Cary.
I compared mine with Georges this morning and they were pretty much identical. (Cary's that is)
I have a Marantz SM11 CDP which uses a cirrus logic CS4398 DAC followed by discrete current FB HDAM's, and after listening to the modded Cary it's very difficult to sit and enjoy music from it now, although it still gets used for SACD duties.
Btw, system consists of B&W 800Di speakers and state of Art amplification
Edit: when I have some time tomorrow I'll redo and post the fft distortion measurements. (2 stack vs 3 stack)
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Just had a look Arty for SM11 no cdp for this?
I think maybe it's a SA11 and there are S1 S2 and S3 versions which is yours.
But S1 and S2 look to have these for dacs
MARANTZ SA-11S1 2 x SM5866AS – DSP56364 – CXD2753R SACD HOP-1200R
MARANTZ SA-11S2 2 x SM5866AS SACDM-1 – HOP-1200W-B
Cheers George
Thanks George, my bad. It's the SA-11S1
The SM11 is the matching power amp, which I also have.
It must have been the previous model Marantz that used the Cirrus chip.
Also an interesting A/B we did on Arty's great system, was to play Native DVDA which some as you know is PCM 24bit 192. We played this through is DS based Wired for sound dac which can do 24/192 and it did sound very good.
But then we used the AD844 modded Cary PCM1704k based cdp unit as a dac, as it has digital input and output, and fed the DVDA 24/192 into it and it down sampled to 24/96 and it was better again than the Wired for Sound dac, showing just how good R2R Multibit is compared to DS.
Art's speakers btw are the B&W 800 Diamond, and he has made them even better than standard, getting rid of some phase problems they have from new, by xover mods, (I'll let him explain what he did)
Cheers George
But then we used the AD844 modded Cary PCM1704k based cdp unit as a dac, as it has digital input and output, and fed the DVDA 24/192 into it and it down sampled to 24/96 and it was better again
than the Wired for Sound dac, showing just how good R2R Multibit is compared to DS.Art's speakers btw are the B&W 800 Diamond, and he has made them even better than standard, getting rid of some phase problems they have from new, by xover mods, (I'll let him explain what he did)
Cheers George
Also an interesting A/B we did on Arty's great system, was to play Native DVDA which some as you know is PCM 24bit 192. We played this through is DS based Wired for sound dac which can do 24/192 and it did sound very good.
But then we used the AD844 modded Cary PCM1704k based cdp unit as a dac, as it has digital input and output, and fed the DVDA 24/192 into it and it down sampled to 24/96 and it was better again
Art's speakers btw are the B&W 800 Diamond, and he has made them even better than standard, getting rid of some phase problems they have from new, by xover mods, (I'll let him explain what he did)
Cheers George
Hopefully I'll be picking up the Auralic Vega dac this arvo too.
Yet another ESS9018 implementation.