Hi Paul,
You are very welcome. I am happy to be of any assistance in people's efforts to improve the sound quality of their systems, especially Q2M dacs.
Only other really big piece of advice I would offer is that an ES9038Q2M dac can be staggeringly better than what you have so far. If only you were located out here in Northern California, I would offer to show you in person.
Speaking of that, if we have other thread participants out near where I am, we could talk about getting together sometime in-person for a listening session. That may be the only way for people to find out what they could potentially do with their dac projects.
You are very welcome. I am happy to be of any assistance in people's efforts to improve the sound quality of their systems, especially Q2M dacs.
Only other really big piece of advice I would offer is that an ES9038Q2M dac can be staggeringly better than what you have so far. If only you were located out here in Northern California, I would offer to show you in person.
Speaking of that, if we have other thread participants out near where I am, we could talk about getting together sometime in-person for a listening session. That may be the only way for people to find out what they could potentially do with their dac projects.
Good information. Thanks for the links. I'm not sure in what direction my mods will take or how extensive I feel I will need to go. It seems like everyone active here, implements Marks suggestions at some level. Having said that, at some point mods must be viewed in the realm of diminishing returns, and that the changes can become subjective nuances, that are otherwise masked by other links in the audio chain. Is it possible we hear something different, or 'better' because we want to?Hi Redjr
below are the links from ebay for the boards
https://www.ebay.com/itm/LT3042-Low...ro-XMOS-DAC-/173021810599?hash=item2848e74fa7
https://www.ebay.com/itm/Dual-DC-12...one-Pre-AMP-/182139118107?hash=item2a6856621b
I used the above, but they are fairy cheap solutions. If you will use something more expensive the results might be better.
Regarding the dac, I have added some regulators based on lt3045 to the avcc supply.Along with the changing of the clock for me those were the upgrades with the most audible results. I have finished the dac for now, and im putting it in a nice case now.When ill finish ill post some pics.Maybe ill add an output stage in the future. For now i want to start an amp project for the winter.
For last few months i was listening only to this dac, but now that im putting it in a case i plugged in my old dac and the sound is so much better that even my wife noticed immediately.
For me all the upgrades were worth it, the cost was probably around 300-350eu, but the sound is much better then my current dac TEAC 501, which had a cost of around 1k.
Thank you Mark for all the advice , without your work this would not have been possible!
Please report, on how your DAC sounds relative to what you had before. I for one would be curious - even if subjective - which is all it can ever be without some kind of measurements as a reference point. I would so much like to have for a day, the Benchmark DAC-3, simply to compare with what I enjoy today, with my system, my amp in my room on my speakers.
Yes. Steps must be taken to counter that effect. In practice, that means using some level of blind testing fairly frequently.
redjr, looks like you are in CT. If you ever get out to Northern California we could arrange to show you what a modded Q2M dac can sound like, and how it compares to DAC-3. They can sound a lot better than you probably could imagine, and much better than any live sound you ever heard. That's because records are mostly made to sound better than real. Maybe slightly analogous to an OLED tv picure, or a expertly Photoshoped hi-res print of a color nature scene, except with records the incredible color is created in the studio and a low-distortion reproduction system just plays it back as it was made to be heard.
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Mikett,
If you want to use a service like roon, for streaming hi-def content throughout your house, a Raspberry Pi and Katana DAC HAT make the perfect end-point for quality output. I have a highly networked home and all my music is on a central NAS box, and all my files have been ripped to FLAC. Most rooms are hard-wired with giga-bit LAN and seamless wireless across all three floors. I have an end-point in several rooms for playback. I don't have a Katana HAT - yet, but have used other Allo PiHATs and other DAC HATs as well.
Hi Mark,
I'll take you up on that if I'm ever out there! I spent a lot of time in the SF Bay area in the late 80s as a consultant, but haven't been back in a couple decades. I take it you're north of SF? Area?
Mark,
Based on your recommendation to me earlier in the thread, I purchased (eBay) the AK4137 reclocking board with optical and coaxial inputs. I already have a custom toroidal xformer with dual 18V and dual 9V secondaries that I could use. My question about the 0.56uV PSUs from DIYINHK is, are they 'good enough' as a starting point to yield better sound through better regulator? Kits are not a problem for me, as I've been using a solder pencil since the 60s, and upgraded to a Hakko years ago when I got serious about building more DIY audio projects. I'm a long-time, legacy Heathkit builder.
My plans for this project are to incorporate a RaspPi or equivalent so that I can use it as a roon client. That of course too, will need a separate linear PSU. So, realizing what could potential go into my choice of enclosure, I also purchased this case from my favorite supplier 'along' in China.
As I'm not too constrained budget wise, I am already several hundred $$ into this project! Sure, I could have gone out and bought a Benchmark DAC3, but what fun would that have been.
At the moment, I have a couple different DACs I'm playing with; (1) TerraBerry DAC HAT (AK4490), and a Topping D50 external DAC with dual ES9038Q2M Sabre chips. Both using linear 5VDC PSUs.
I can say unequivocally, the Terraberry HAT (which does include an AK4137 reclocking chip, complete with DSD support sounds amazing. The richness, full body sound, separation of channels and incredible dynamics is beyond stunning. I can sit in my listening position and be blown away. One such CD my son has in DSD format is Michael Jackon's Thriller. It sounds amazing. I no longer am listening to my speakers, but the music.
So, for me those two DAC are my reference point. Not DAC3 quality, but certainly more than enough for me - at the moment. I will be interested in hearing how this next project will fair.
Rick
Rick,
Are you converting everything to DSD in 4137 or playing in whatever the
source format is?
Thanks,
T
hi, there,
pls share your info about q2m i2c thd compensation, i'm working on a driver to get the q2m configuration.
thanks
@eslei,
I sent you a private message. Some information is not public, so we would have to talk a little bit in private first. Not sure what kind of driver you mean, would it be for RPi? If for Arduino, I already have some code I might be able to share for that. Easier to do if someone has executed an NDA. A little more complicated if not, but still doable.
However, I can say right now that occip reported setting H3 to: 0xF800 ( = value in 16-bit signed int register) for the original output stage with one opamp. That was back here: https://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-211.html#post5502201 Think there was an earlier post about his other board coming in with H3 at the same value.
Back here occip said he did an AVCC mod: https://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-208.html#post5499095 Not sure if that was a board that got the HD setting above. Some more here: https://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-208.html#post5498749
Maybe occip can clarify for us a little what mods he did, which of them helped the most, and what he thinks about the sound quality at the end of the modding.
I sent you a private message. Some information is not public, so we would have to talk a little bit in private first. Not sure what kind of driver you mean, would it be for RPi? If for Arduino, I already have some code I might be able to share for that. Easier to do if someone has executed an NDA. A little more complicated if not, but still doable.
However, I can say right now that occip reported setting H3 to: 0xF800 ( = value in 16-bit signed int register) for the original output stage with one opamp. That was back here: https://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-211.html#post5502201 Think there was an earlier post about his other board coming in with H3 at the same value.
Back here occip said he did an AVCC mod: https://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-208.html#post5499095 Not sure if that was a board that got the HD setting above. Some more here: https://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-208.html#post5498749
Maybe occip can clarify for us a little what mods he did, which of them helped the most, and what he thinks about the sound quality at the end of the modding.
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Did an interesting experiment recently. Don't have measurements yet though, its on my list to do pretty soon. One issue I have been trying to look into is why the 2nd modded dac has much more H3 than the 1st modded dac. On the face of it, there didn't seem an obvious reason. Used the same AK4137, same external power supplies, etc. All looked to be the same.
Since the 2nd modded dac has sockets for the AVCC opamp and the output stage opamps, I looked around and found an OPA1612 on an SMD to DIP adapter. So I tried swapping it in for one of the output stage opamps. Tried for I/V and for differential summing. In both cases, it didn't sound bright at all like LME49720, but it didn't sound right either. It sounded like the dynamics were compressed quite a bit. So, why did the two different types of opamps sound so different from one another, and neither sounded quite right?
Decided to try an experiment with the +-15 power rails. Thought the might be the most salient commonality that potentially could affect the opamps differently. I gathered up all the big film caps I have, and soldered them together in two groups. There is nominally about 110uf of total capacitance in each group of film caps. Connected one group between +15 and ground, and the other group similarly connected to the negative rail. This is in addition to several thousands of uf of electrolytic filter caps per rail, and pairs of tantaum and ceramic caps at each opamp power pin. Pictures attached below.
As I said above, I haven't measured anything yet, and haven't even finished subjective experiments, but there is a change for the better in sound quality with the LME49720 opamps. Haven't tested with OPA1612 yet. The excessive brightness is less now, maybe by about half, and it sounds smoother (less distorted, I think). I expect when I do measure I will likely find I don't need -150 counts of H3 compensation to null H3 to a minimum, meaning odd harmonic distortion is probably reduced.
Obviously, I have some more work to do on this, but thought it might be of interest to thread participants without having to wait longer for the final conclusions.
EDIT: Forgot to mention, for this experiment I replaced the LME49720 opamps with LME49860 opamps. That is because the latter opamps are on SMD adapters which are easier to swap in and out without bending pins. However, the types of opamps in this case are exactly the same except for maximum voltage ratings. They sound the same.
Since the 2nd modded dac has sockets for the AVCC opamp and the output stage opamps, I looked around and found an OPA1612 on an SMD to DIP adapter. So I tried swapping it in for one of the output stage opamps. Tried for I/V and for differential summing. In both cases, it didn't sound bright at all like LME49720, but it didn't sound right either. It sounded like the dynamics were compressed quite a bit. So, why did the two different types of opamps sound so different from one another, and neither sounded quite right?
Decided to try an experiment with the +-15 power rails. Thought the might be the most salient commonality that potentially could affect the opamps differently. I gathered up all the big film caps I have, and soldered them together in two groups. There is nominally about 110uf of total capacitance in each group of film caps. Connected one group between +15 and ground, and the other group similarly connected to the negative rail. This is in addition to several thousands of uf of electrolytic filter caps per rail, and pairs of tantaum and ceramic caps at each opamp power pin. Pictures attached below.
As I said above, I haven't measured anything yet, and haven't even finished subjective experiments, but there is a change for the better in sound quality with the LME49720 opamps. Haven't tested with OPA1612 yet. The excessive brightness is less now, maybe by about half, and it sounds smoother (less distorted, I think). I expect when I do measure I will likely find I don't need -150 counts of H3 compensation to null H3 to a minimum, meaning odd harmonic distortion is probably reduced.
Obviously, I have some more work to do on this, but thought it might be of interest to thread participants without having to wait longer for the final conclusions.
EDIT: Forgot to mention, for this experiment I replaced the LME49720 opamps with LME49860 opamps. That is because the latter opamps are on SMD adapters which are easier to swap in and out without bending pins. However, the types of opamps in this case are exactly the same except for maximum voltage ratings. They sound the same.
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Hi
My first board was a green board
First Mod : LT3045 after +12V switched supply : Bad high harmonic (- 90db H3) + noise
Second Mod: add 1800uf on avcc pins: less harmonics + same noise + more bass
Third Mod: added lme49720 for avcc supply : less harmonics + less noise
Fourth Mod: linear supply +12v with lm317 + big capacitors: same harmonics + lower noise on low frequency ( 50Hz , 100hz ...)
Fifth Mod: H3 register set to F800 : less harmonics on H3 ( -96db)
Sixth Mod : OPA swap for Muses 8920D for audio path ( stock voltage mod)
lower harmonic ( only on 1 channel ...) + good feeling on hearing
For my ears , the first mod is to have a linear supply with a lot of capacitors ( at least 10000uf) then add 1800Uf on avcc pins. you will have a very cost effective solution, other mods will cost much more without substantial gain.
Tweaking H3 is good for benchmark but not really hearable, if your volume level is less than -5 dbfs.
But with 99$ you could have higher sound quality
I discovered the Tone board feeded by usb cable
( on board xmos + low jitter oscillators ) and with a very low harmonics and noise for 99$ . I was very skeptical at first but after measurement I found that the guys at Khadas have engineered a exceptionnal piece of hardware !Take a look at audio science review. For me this board has the best price/sound quality ratio and the XMOS software is tweakable ( I'm running my own firmware on it now Please note that the H3 reg is near 0 on the tone board ( current mode buffer is used);
I will be very happy to see RMAA measurement in order to compare to few values I posted on this thread before.
It would be good to measure the improvement of all the mods showed on this thread, less talks more numbers
an Asus xonar sound card is a good start to measure with RMAA Occip
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Regarding numbers, I don't have Asus xonar, and the only test I can do at the moment is HD @1kHz. That is absolutely insufficient to characterize a dac, as anyone can see looking at the set of measurements performed on dacs at Stereophile. Even at that, Stereophile doesn't measure everything that some people can hear, at least according to Scott Wurcer's friend, Martin Mallinson, VP of engineering at ESS. (Who is also the guy with all the patents.)
So, like I have said before, if anyone has all the test equipment, is in the local area here, and would like to measure my dacs, then sure, please do. Be very interesting to see. So far, I haven't gotten any volunteers.
EDIT: Doesn't surprise me that tweaking H3 with a voltage mode output stage doesn't help sound quality much, if any. Just demonstrates that numbers are not the whole story, particularly static HD tests for a dac.
So, like I have said before, if anyone has all the test equipment, is in the local area here, and would like to measure my dacs, then sure, please do. Be very interesting to see. So far, I haven't gotten any volunteers.
EDIT: Doesn't surprise me that tweaking H3 with a voltage mode output stage doesn't help sound quality much, if any. Just demonstrates that numbers are not the whole story, particularly static HD tests for a dac.
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Tried a couple of things today. Put three OPA1612 opamps in the output stage. The differences between the way they sound relative to the sound of LME49720 (or LME49860) are much reduced with the film caps still connected up to the power rails (~110uf per rail). In theory, these particular different opamp types (OPA1612 vs LME49720) shouldn't sound any different from one another in an output stage like this. That tells me the +-15v power probably still isn't good enough, or as good as I require it to be. Of course, there could be some other issue making them sound different such as how they are loaded by the output stage passive components, but I'm not done checking to see of there are any more power related issues before considering other possibilities.
Thinking some more about power issues, maybe I should have gone with LDOs for the final 15v regulators rather than lower performance linear regulators and lots of filter caps. Thing is if I were to use LDOs for +-15v, I would need to put them on the output stage board (close to the loads) and remove excess other caps that would degrade LDO performance. It would still be appropriate to take steps to keep LDOs as low noise at low frequencies as reasonably possible.
Unfortunately, we are not using multi-layer PCBs with power planes. The distributed capacitance and low series impedance in that case would probably ideal for the most high performance output stage.
Maybe at some point I will try an LDO approach. I can turn up the voltage on my external +-15 supply to give LDOs a little regulation headroom. That's the thing about working this way performing experiments instead of using a room full of test equipment. Sometimes it would be really nice to have the test equipment. Can't justify the cost though for as infrequently as it would be used. Instead I have to do the manual labor to try different things. Of course, if we had a few more people at the stage of modding where I am at then we could better divide and conquer some of these issues. In the meantime think I will try a little more good quality filtering and see what happens with that.
More or less around the same time I was trying opamps, I was also experimenting with DPLL bandwidth. With gold flashed connectors on the I2S lines, that helps a lot to get one confounder considerably attenuated. At one point found that strategically placing a finger on the SMD filter caps at each side of the dac chip allowed me to get DPLL bandwidth much lower without audible evidence of instability. However, as I have seen before, when I came back a little later and tried putting my fingers in the same places I had much less luck with it. My takeaway is that I decided to clean up the digital power going into the dac chip, so it will get its own dedicated regulator and maybe some upgraded caps for the 1.8v internal regulator. I know that issue came up for discussion before, but I don't think we had a clear idea of what we expected messing with it to fix. I'm still not sure I can fix anything by working on that area, but at least I know that I am trying to help stabilize minimal DPLL bandwidth settings. If I can affect it for some improvement then great, I will know why a fix is needed there. If no change in symptoms, I still won't know if there is any reason to do work on those power supply areas. Either way, it's okay. I do it all for you guys, as I don't need a better dac myself. But, I do see a need for people to have good dacs which unfortunately remain expensive and hard to make, so here we are trying to remedy that problem a little as best we can. Also, maybe we can contribute a little to knowledge of what affects what with these Sabre dac design choices. Always good to have a better understanding of that type of thing.
Thinking some more about power issues, maybe I should have gone with LDOs for the final 15v regulators rather than lower performance linear regulators and lots of filter caps. Thing is if I were to use LDOs for +-15v, I would need to put them on the output stage board (close to the loads) and remove excess other caps that would degrade LDO performance. It would still be appropriate to take steps to keep LDOs as low noise at low frequencies as reasonably possible.
Unfortunately, we are not using multi-layer PCBs with power planes. The distributed capacitance and low series impedance in that case would probably ideal for the most high performance output stage.
Maybe at some point I will try an LDO approach. I can turn up the voltage on my external +-15 supply to give LDOs a little regulation headroom. That's the thing about working this way performing experiments instead of using a room full of test equipment. Sometimes it would be really nice to have the test equipment. Can't justify the cost though for as infrequently as it would be used. Instead I have to do the manual labor to try different things. Of course, if we had a few more people at the stage of modding where I am at then we could better divide and conquer some of these issues. In the meantime think I will try a little more good quality filtering and see what happens with that.
More or less around the same time I was trying opamps, I was also experimenting with DPLL bandwidth. With gold flashed connectors on the I2S lines, that helps a lot to get one confounder considerably attenuated. At one point found that strategically placing a finger on the SMD filter caps at each side of the dac chip allowed me to get DPLL bandwidth much lower without audible evidence of instability. However, as I have seen before, when I came back a little later and tried putting my fingers in the same places I had much less luck with it. My takeaway is that I decided to clean up the digital power going into the dac chip, so it will get its own dedicated regulator and maybe some upgraded caps for the 1.8v internal regulator. I know that issue came up for discussion before, but I don't think we had a clear idea of what we expected messing with it to fix. I'm still not sure I can fix anything by working on that area, but at least I know that I am trying to help stabilize minimal DPLL bandwidth settings. If I can affect it for some improvement then great, I will know why a fix is needed there. If no change in symptoms, I still won't know if there is any reason to do work on those power supply areas. Either way, it's okay. I do it all for you guys, as I don't need a better dac myself. But, I do see a need for people to have good dacs which unfortunately remain expensive and hard to make, so here we are trying to remedy that problem a little as best we can. Also, maybe we can contribute a little to knowledge of what affects what with these Sabre dac design choices. Always good to have a better understanding of that type of thing.
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T - Are you referring to the TerraBerry DAC? If so, at the moment I've got it set to up-convert incoming signals to DSD. I have roon set to 'DSD over PCM' (DoP) for playback strategy. I've just started on the other ES9038Q2M project (this thread topic) that will include an AK4137 reclocker board too.
Rick
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Well I finally got my Super Regulator built up and I am using the PCM1794 as a test vehicle before installing it on the 9028PRO.
Why did I wait so long to do this. WOW! I cannot believe the difference it makes. Now as a repeat preface on the 1794 DAC, the +- 15V feeds both the IV as well as an LDO to supply the DAC with 5V for AVCC. What appears to have happened is that this superfast with outrageous low impedance power supply really helps the LDO. So could I separate the Super Reg from the AVCC? No. But man, the way it breathes power into this simple board and the depth and image is way beyond what I had expected. There is simply NO comparison in this case to using a 317/337 or even a Sulzer power supply driven by 5534s. I was using an AD817 on the Super Reg, then I switched to the LME49710s thinking that they're both approximately the same bandwidth but so about the same/ Not so the LME49710 indeed sound a lot more focused and the depth increased. The biggest difference is skin tight drums. Guitar strumming is no longer a blur. That the Super Reg will have a place in the 9028 Pro.....yes definitely. Next, I have to acquire a low voltage OP amp to use in a super reg as well to drive the 9028PRO AVCC. I finally found it. Jan Didden suggested an AD8031 that he uses 80Mhz. Nice. I have a spare super reg to generate the 3.3V and I am thinking of placing the LT6655 right in there for the reference voltage. Remember the super reg, uses the regulated voltage to power itself and the reference. Kind of illogical but it works and is very high performance.
The other thing I am also noticing is that certain op amps are more sensitive to the power supply to which it is attached. The AD797 needs a good power supply like the Super Reg. With that, I have no reservations about its performance now. With the 317/337 and the Sulzer you sensed something was lacking in imaging and energy. That is no longer the case.
So in my view a lot of things could make the sound of the DAC change and some of them have no "real explanation" currently though of course it exists but we don't know why. Any ideas why all DACs from different brands sound different? It becomes pretty obvious....and frightening that different production batches can easily sound different.
Kind of fearful that this 1794 the way it is now actually might sound better than my 9028pro at this stage. Oh well..we'll see when I start putting on the regs and clocks etc.
I did suggested to use Jung-Didden superregs approx a half year ago here. You can hear a massive improvement when powering the output stage at +-15 V. Also, Salas regulators (BiB, SSLV1.3, Reflector) are very good to power the clock and the digital patrs. Salas regs are far better than any of 1763 LDO based stuff what you are using now.
https://linearaudio.nl/superregs
Check the bottom of the page: Updated for version 2.3
https://linearaudio.nl/superregs
Check the bottom of the page: Updated for version 2.3
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Thing is, I notice that DAC-3 gets by fine without using superregs. There are no heat sinks, no SCR, nor other stuff needed to make a superreg. Instead there is a SMPS, and looks like some LDOs. One of these days I should probably look at the insides of it close up and make note all the branding codes on the SMD parts. Might be able to figure out a little more of what they decided to use. Of course, I still think a multi-layer board with power planes is probably best. In addition of course to whatever regulators are used. Selection of good filter caps is important too, but I don't see film caps used in DAC-3.
Anyway, I know there has to be more than one way to get sufficient performance, and I am probably pretty close right now. I am going to make a few small changes then check opamp differences in the circuit again. I don't want there to be any difference, or at least keep to a very small minimum. And, it should sound just as good with either type of opamp, even if very slightly different.
Thing is....what if the Super Reg can and does improve over the DAC3 when used in a hobbyist DAC ? Is it possible that this point is within reach.........?
I can assure you that 20+ years ago when this reg was used on preamps...that was the case..it was better than anything commercially available.
The other thing that I noted is that a Super Reg in front of the LDO LT1761-5 appears to help immensely....well not appears but DOES. In the DAC3 they are possibly using a very high performance SMPS.....and if that is used in front of the LDO then voila. We know that a high performance SMPS is good. But Benchmark might have done a great job at that.....hence the IV also benefits as well. Well I am sure they've done that. The influence of the PS cannot be doubted and its interaction with various op amps is at this point...pick and choose based on eventual sound.
If we can take real close look at the items that Benchmark is using on the board and we remove the IV circuits we can pretty much figure out what is left for the AVCC supply. They claim it is buffered......that might provide another hint. I tried but the provided pics was not high res enough. I was not able to make out the marking on the devices.
I can assure you that 20+ years ago when this reg was used on preamps...that was the case..it was better than anything commercially available.
The other thing that I noted is that a Super Reg in front of the LDO LT1761-5 appears to help immensely....well not appears but DOES. In the DAC3 they are possibly using a very high performance SMPS.....and if that is used in front of the LDO then voila. We know that a high performance SMPS is good. But Benchmark might have done a great job at that.....hence the IV also benefits as well. Well I am sure they've done that. The influence of the PS cannot be doubted and its interaction with various op amps is at this point...pick and choose based on eventual sound.
If we can take real close look at the items that Benchmark is using on the board and we remove the IV circuits we can pretty much figure out what is left for the AVCC supply. They claim it is buffered......that might provide another hint. I tried but the provided pics was not high res enough. I was not able to make out the marking on the devices.
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Also note that Jan Didden also explicitly states that high performance caps are not necessary for the Super Reg and does not have ANY film caps on board as well. Just a bunch of generic caps, a fast op amp and a good pass transistors and that is it really. The performance is all in the topology. Most of the information on this reg is no longer accessible on the web since Walt Jung closed his site. But it is over 25 years old and still eminently relevant. That says something about the work and thought that went into the design which took a master years to nail down back then.
Here is where it gets crazy. I'm now thinking of putting together two of these for AVCC and taking the feedback sense lines return directly from the DAC pins to regulate AVCC. That way I can easily add a dual supply to my 9028pro DAC. That will take another 6 months to complete.
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