Hi Mark, I'm still interested in this thread, so far i have 2 x lt1763 underneath for XO and VCCA, i have one more to make up for DVCC.
As for AVCC, i have all the parts and have laid them out but not soldered up yet, I'll most likely put the 10K divider resistors with the O/P stage. What is the reason for not using tantalum for the 3 x 10uf caps? i see the poly tants have low ESR.
No pics as yet, i'm the worlds worst photographer.
Thanks for keeping the thread going, Much appreciated.
Andy
As for AVCC, i have all the parts and have laid them out but not soldered up yet, I'll most likely put the 10K divider resistors with the O/P stage. What is the reason for not using tantalum for the 3 x 10uf caps? i see the poly tants have low ESR.
No pics as yet, i'm the worlds worst photographer.
Thanks for keeping the thread going, Much appreciated.
Andy
Hi Mike,
One thing I am thinking of doing is to see if I can get OPA1612 to sound more to my liking. I want to try adding some more big filter caps on the dac board for +-15v and make sure the PS regulators are okay with it. Just to make sure there is plenty of local current reserve. Don't know if it will make any difference, just an experiment.
Then I would like to try OPA1612 for the three output stage opamps. If distortion looks lower as I expect, I might try adding a little H3 to see how I like it.
Thing is, there are some differences between my 1st and 2nd modded dacs I don't understand. The 1st had a little H2 and H3. The 2nd has almost no H2, but much more H3 and other odds than the 1st dac. No idea why since the opamps are the same in both cases. The AVCC opamp is currently a dual AD797 with a glued-on heat sink. Temp is okay that way. Don't think that would account for different distortion profile.
What is different is the output stage filtering and how that loads the opamps. Could have something to do with it, don't know. However, on the 2nd dac with H3 compensation at -150, it sounds quite good with LME49720. Good is good, so no worries. I would just like to understand more than I do right now.
The other funny thing had to do with clock substitutions on AK4137. No idea why it sounded more jittery. Unfortunately, I don't have a way to measure AK4137 jitter and or clock module jitter directly. There is a j-test in Arta, but it looks at the dac analog output so its clock, ASRC, DPLL bandwidth, etc., may cause confuse trying to understand the clock module itself.
Another thing I noticed that I don't understand is that I could get DSD DPLL bandwidth quite a bit lower and still stable with the 1st dac as compared to the 2nd one. Could be the Crystek clocks behave a little differently, but don't have the equipment to measure them directly.
There are all kinds of things that could be investigated with time, money, and personal energy. Lot of work developing a really good understanding of some of this stuff.
Well, if we had an active of diy'ers in this thread we could make a lot of headway figuring out some of the little puzzles. It is necessary to figure out how to best allocate all available resources, which is to say, whatever Mark will do next. Probably just wait on some of these things and wait to see if anyone else ever mods one of these dacs. Kind of crazy I have been working on this for several months, at times getting almost 2,000 views per day for the thread. Yet, not one person has fully modded one dac. Maybe nobody ever will, not ever. Strange. Thing is they sound really good will all the mods and tweaks.
Pretty soon I am expecting Katana 1.2 for review. They say they will ship it next week. Probably take a week in transit, so maybe a couple of weeks. Then I am waiting to see if they have any advice on power supplies.
Both Katana and the my 2nd dac will be compared with DAC-3 and with each other. Since both the Q2M dacs have been improved since last time, no telling which one will sound better, or maybe they will come out about the same. Only way to find out is to watch this thread
.
In other news, you may have noticed I am planning to do some work with ES9028PRO. Want to see how much different it is from Q2M given a couple of differences that can be exploited. If it works, I'll tell you how to maybe make yours sound better. It will be interesting, and will hopefully give me some ideas about what I need to do with Spartan 6.
One thing I am thinking of doing is to see if I can get OPA1612 to sound more to my liking. I want to try adding some more big filter caps on the dac board for +-15v and make sure the PS regulators are okay with it. Just to make sure there is plenty of local current reserve. Don't know if it will make any difference, just an experiment.
Then I would like to try OPA1612 for the three output stage opamps. If distortion looks lower as I expect, I might try adding a little H3 to see how I like it.
Thing is, there are some differences between my 1st and 2nd modded dacs I don't understand. The 1st had a little H2 and H3. The 2nd has almost no H2, but much more H3 and other odds than the 1st dac. No idea why since the opamps are the same in both cases. The AVCC opamp is currently a dual AD797 with a glued-on heat sink. Temp is okay that way. Don't think that would account for different distortion profile.
What is different is the output stage filtering and how that loads the opamps. Could have something to do with it, don't know. However, on the 2nd dac with H3 compensation at -150, it sounds quite good with LME49720. Good is good, so no worries. I would just like to understand more than I do right now.
The other funny thing had to do with clock substitutions on AK4137. No idea why it sounded more jittery. Unfortunately, I don't have a way to measure AK4137 jitter and or clock module jitter directly. There is a j-test in Arta, but it looks at the dac analog output so its clock, ASRC, DPLL bandwidth, etc., may cause confuse trying to understand the clock module itself.
Another thing I noticed that I don't understand is that I could get DSD DPLL bandwidth quite a bit lower and still stable with the 1st dac as compared to the 2nd one. Could be the Crystek clocks behave a little differently, but don't have the equipment to measure them directly.
There are all kinds of things that could be investigated with time, money, and personal energy. Lot of work developing a really good understanding of some of this stuff.
Well, if we had an active of diy'ers in this thread we could make a lot of headway figuring out some of the little puzzles. It is necessary to figure out how to best allocate all available resources, which is to say, whatever Mark will do next. Probably just wait on some of these things and wait to see if anyone else ever mods one of these dacs. Kind of crazy I have been working on this for several months, at times getting almost 2,000 views per day for the thread. Yet, not one person has fully modded one dac. Maybe nobody ever will, not ever. Strange. Thing is they sound really good will all the mods and tweaks.
Pretty soon I am expecting Katana 1.2 for review. They say they will ship it next week. Probably take a week in transit, so maybe a couple of weeks. Then I am waiting to see if they have any advice on power supplies.
Both Katana and the my 2nd dac will be compared with DAC-3 and with each other. Since both the Q2M dacs have been improved since last time, no telling which one will sound better, or maybe they will come out about the same. Only way to find out is to watch this thread
. In other news, you may have noticed I am planning to do some work with ES9028PRO. Want to see how much different it is from Q2M given a couple of differences that can be exploited. If it works, I'll tell you how to maybe make yours sound better. It will be interesting, and will hopefully give me some ideas about what I need to do with Spartan 6.
Hi Andy,
Welcome back to the thread, and good to hear from you!
The reason for not using tantalum is they are leaky and noisy. Aluminum electrolytic are too, but to a lesser extent. Tantalum is not good when real low noise is desired.
Rather than putting the Vref dividers on the output stage, I would still recommend putting them on the AVCC board. That helps keep AVCC clean and the opamps stable, IMHO. What you could do down at the output stage board is put a 10k in series with Vref, and then put a 10uf electrolytic to ground. It will make a 2nd filter, but without the 2nd resistor that would be needed for a voltage divider. That would probably be best for AVCC and maybe best for the output stage if concerned about noise getting into Vref.
Just to be fully clear, the caps I am using for Vref are aluminum polymer, not tantalum anything. They leak more than plain aluminum electrolytics which would probably be fine too. They we just convenient and small, so I decided to try them on the 1st modded dac. They seem to work okay, so I didn't do any more tests to compare. Maybe someone else would like to try that, but no need to try tantalum, IMHO.
Curious as to why you say you are a bad photographer? I took other people's advice and got a flexible arm to hold my cell phone that I can clamp onto the bench or other things. Also, got a bluetooth button so I can trigger the cell phone camera to take a picture without having to touch it and possibly wiggle it. Keeps the pics from getting blurred that way. The last thing is lighting. I look around the house and the back yard for places to try the lighting. Sometimes have to tip the dac up on an angle so the light hits it evenly without glare. These are the things I am using now: Amazon.com: Cell Phone Clip on Stand Holder - with Grip Flexible Long Arm Gooseneck Bracket Mount Clamp for iPhone X/8/7/6/6s Plus Samsung S8/S7, used for bed, desktop, Black: Cell Phones & Accessories
Amazon.com: CamKix Bluetooth Camera Shutter Remote Control for Smartphones – Create Amazing Photos and Selfies (Bluetooth Remote, White): Cell Phones & Accessories
I import the pictures into my computer and crop them and sometimes adjust gamma correction in the freeware Irfanview program. Just basic functionality and easy to use, that's what I need there.
Now you know everything I do about taking pictures. Hope you find it helpful. Also hope we get to see some pictures eventually. Don't worry if your work doesn't look perfect, mine doesn't either.
Best,
Mark
Mark, it is getting obvious to me that what one achieves in one's creation will now necessarily be repllicated. Everything little thing makes a difference....and we know that. BUT how big a difference. This is where we need to sit back and take a look at ourselves.
As time progresses and listening critically for months on end, you begin to get picky. Things that you never really took notice of , you might now. Same for others.
Once I get mine to the point I saw, YES. I am closing the door on it. Why? another mod might make it better or worse but wait. How would I know? not sure. It would be different...but better maybe, maybe not.
I once could hear wire directionality many many years ago, Yeah, sounds crazy and I was so skeptical of the fools about it, until I could make it out 6-8 times out of 10. Now? I don't think so. Haven't tested recently because it's too small to really notice, once you tune out for a day or so you won't perceive it. But sit in a room for hours on end and perk up your ears and you can hear it. Which direction is better? I could not say then and could not determine which was better but different they were indeed. Same for op amps I say. If it sounds better in your system, then it is better. Why? Taste.
After this I am considering a CBT line array for 2019. I've been following DB Keele since the 70s when he started telling the world about Thiele Small parameters in AES papers. Now it looks like his final work is CBT and technically it is something I understand and appreciate. I want one. Everything he describes about the weaknesses about conventional speakers is true and I have known that for years, but finally his CBT is truly an elegant solution to the issues. Nice work. Don Keele's CBT (Constant Beamwidth Transducer) Page
As time progresses and listening critically for months on end, you begin to get picky. Things that you never really took notice of , you might now. Same for others.
Once I get mine to the point I saw, YES. I am closing the door on it. Why? another mod might make it better or worse but wait. How would I know? not sure. It would be different...but better maybe, maybe not.
I once could hear wire directionality many many years ago, Yeah, sounds crazy and I was so skeptical of the fools about it, until I could make it out 6-8 times out of 10. Now? I don't think so. Haven't tested recently because it's too small to really notice, once you tune out for a day or so you won't perceive it. But sit in a room for hours on end and perk up your ears and you can hear it. Which direction is better? I could not say then and could not determine which was better but different they were indeed. Same for op amps I say. If it sounds better in your system, then it is better. Why? Taste.
After this I am considering a CBT line array for 2019. I've been following DB Keele since the 70s when he started telling the world about Thiele Small parameters in AES papers. Now it looks like his final work is CBT and technically it is something I understand and appreciate. I want one. Everything he describes about the weaknesses about conventional speakers is true and I have known that for years, but finally his CBT is truly an elegant solution to the issues. Nice work. Don Keele's CBT (Constant Beamwidth Transducer) Page
Paul,some pics from mine that i promised some time ago
still waiting for the crystek clock, but replaced the power for the oscillator with a separate regulator. Also changed the 7805 to lm1086.hopefully will finish up the avcc board this week.
View attachment 701131
View attachment 701132
What are those 2 separate regulator PSU boards you are using in your first pic? Are those home-grown, or available on eBay? link? Maybe buried in the thread somewhere!
I'm getting ready to tackle this project and want to have everything I need. I may not make the board level mods, but do want to improve the PSUs at a minimum. I'm currently waiting on the XMOS module.Thx.
Mike,
Regarding when it is good enough and time to stop, my situation may be different than yours. I always have DAC-3 here to remind me what is really on a CD and just how good a well produced one can sound. That keeps me attuned to a certain level of quality whereby I can't be satisfied that a much inferior sound is satisfactory. I have to get as close as I can with what I have to work with. The 2nd modded dac sounds very good. Something to be very happy with for long time. Even something to use professionally until something like a DAC-3 can be acquired. Something to enjoy DVD and Blueray concert recordings with, among other things.
I guess maybe I need to get some diyaudio members in the local area over to my house to listen and compare. Then they could post their impressions in the forum. For something one can cobble together for very low cost it is quite something. Probably better to make sure it is as good as I can get it first though, as you only get one chance to make a first impression.
Regarding when it is good enough and time to stop, my situation may be different than yours. I always have DAC-3 here to remind me what is really on a CD and just how good a well produced one can sound. That keeps me attuned to a certain level of quality whereby I can't be satisfied that a much inferior sound is satisfactory. I have to get as close as I can with what I have to work with. The 2nd modded dac sounds very good. Something to be very happy with for long time. Even something to use professionally until something like a DAC-3 can be acquired. Something to enjoy DVD and Blueray concert recordings with, among other things.
I guess maybe I need to get some diyaudio members in the local area over to my house to listen and compare. Then they could post their impressions in the forum. For something one can cobble together for very low cost it is quite something. Probably better to make sure it is as good as I can get it first though, as you only get one chance to make a first impression.
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OPA1611AID with extended flow 200MA current Class A output single op amp | eBay
Mark, get yourself a couple of these for the difference amps and let me know what you think.
Right now, on the PCM1794 DAC it is magic. Leap and bounds superior to the AD797 in that position. How can I describe it. Never gets congested. Articulate without being bright. Separation of different sounds are excellent and the low end digs DEEP. Surprising, I had these sittting there and always thought nothing of this gimmicky thing until I installed them. If anyone liked what the OPA1612/11 did these improve on that by quite a bit. Music is full of life, bass is solid, midrange is open, highs are there and never harsh. Drums are spot on. Maybe I lucked out.
I'm studying now if I should try four of these in the transimpedance stages. I'll decide after I install them into the 9028pro dac.
Mark, get yourself a couple of these for the difference amps and let me know what you think.
Right now, on the PCM1794 DAC it is magic. Leap and bounds superior to the AD797 in that position. How can I describe it. Never gets congested. Articulate without being bright. Separation of different sounds are excellent and the low end digs DEEP. Surprising, I had these sittting there and always thought nothing of this gimmicky thing until I installed them. If anyone liked what the OPA1612/11 did these improve on that by quite a bit. Music is full of life, bass is solid, midrange is open, highs are there and never harsh. Drums are spot on. Maybe I lucked out.
I'm studying now if I should try four of these in the transimpedance stages. I'll decide after I install them into the 9028pro dac.
Mike,
That looks like an OPA1611 with a two transistor output buffer. Can't tell from the picture if it is really Class B or Class AB. Very unlikely really Class A. Cross over distortion probably gives some 3rd and other odd harmonic distortion that adds little sense of more clarity and detail. Nevertheless I will check out a couple as they might be useful for AVCC.
As far as the effect you hear from them, I can probably beat that if using a Sabre dac by using an unbuffered OPA1611 and a little harmonic distortion compensation to dial H3 right in where it sounds best, if not at minimum distortion.
You really are missing things by not going forward with more mods, but so long as you are happy with the sound that's the most important thing.
That looks like an OPA1611 with a two transistor output buffer. Can't tell from the picture if it is really Class B or Class AB. Very unlikely really Class A. Cross over distortion probably gives some 3rd and other odd harmonic distortion that adds little sense of more clarity and detail. Nevertheless I will check out a couple as they might be useful for AVCC.
As far as the effect you hear from them, I can probably beat that if using a Sabre dac by using an unbuffered OPA1611 and a little harmonic distortion compensation to dial H3 right in where it sounds best, if not at minimum distortion.
You really are missing things by not going forward with more mods, but so long as you are happy with the sound that's the most important thing.
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Paul,
What are those 2 separate regulator PSU boards you are using in your first pic? Are those home-grown, or available on eBay? link? Maybe buried in the thread somewhere!
Thx.
@redjr,
Don't know if Paul is going to respond or not. If he doesn't, I might be able to help you out with some power supply info. Depends on what quality of regulation you want and how much you want to spend. What are you using now, or are you not using the dac?
Well I did put it on the 9028PRO DAC. That op amp assembly actually needs to stabilise a bit before it starts sounding correct. It probably really is Class A biased as I can see a LED that lights up underneath when it is powered. Most likely that is used for biasing.
This sucker is staying in the DAC. I also went and ordered four more...just to see. Oops only now I realize I did not check that the width exceeds what can fit on a DIP adapter.
It's not the distortion as much as unloading the output stage even though it is well within the current specs unbuffered. The sense of ease in loud passages is uncanny.
Okay, but for output stage opamp swapping you can do largely the same stuff with your ES9028 in software, and you can get it exactly as you prefer it. You can dial in exactly how much 2nd and 3rd harmonics you want. You don't need opamp swapping to play around with that. Use the opamps that give the lowest distortion to begin with, then add as much adjustment as you like. Higher order harmonics than 2nd and 3rd don't sound good anyway, so the dac registers allow tweaking exactly what you want exactly however much you want. In fact, you could create presets for different kinds of music, and switch them at the touch of a button, or even with a remote control if you want.
In fact, we were just playing around with that here on my 2nd modded dac. If one doesn't mind a little more overall distortion, adjusting H2 and H3 to taste can actually produce very musical sounds coming out of the speakers. Helps to keep the numbers reasonably low. Minimum distortion right now is with H2 = 0 and H3 = -157. For a very musical tonal balance we ended up with H2 = 100 and H3 = -125. Some of preference coming in at those values may be dependent on the speaker characteristics, and the fact that the AHB2 power amp is extremely low distortion so no preexisting coloration from it.
However, despite the fun and games at this point, I still want to do some more investigation to see if I can get odd order distortion lower to begin with, before using any harmonic compensation. If so, then less playing around with harmonic tweaking is likely to sound as good. It is sort of a pleasant bandaid to cover up the excess odd order I have now. That being said, I'm sure it would be a feature some people would love to have to tune in sound they like.
In fact, we were just playing around with that here on my 2nd modded dac. If one doesn't mind a little more overall distortion, adjusting H2 and H3 to taste can actually produce very musical sounds coming out of the speakers. Helps to keep the numbers reasonably low. Minimum distortion right now is with H2 = 0 and H3 = -157. For a very musical tonal balance we ended up with H2 = 100 and H3 = -125. Some of preference coming in at those values may be dependent on the speaker characteristics, and the fact that the AHB2 power amp is extremely low distortion so no preexisting coloration from it.
However, despite the fun and games at this point, I still want to do some more investigation to see if I can get odd order distortion lower to begin with, before using any harmonic compensation. If so, then less playing around with harmonic tweaking is likely to sound as good. It is sort of a pleasant bandaid to cover up the excess odd order I have now. That being said, I'm sure it would be a feature some people would love to have to tune in sound they like.
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They might be hiding a couple of resistors and diodes under the board - but I
doubt it. I've seen this completely unbiased OP BJT's arrangement on the back
of an opamp in some old pro audio gear and couldn't believe it.
Hi Mark,
I've been lurking around still reading this thread.
No, I'm not using the DAC now, but finally getting around to collecting what I need. I've seen this one on DIYINHK. Would a couple of these provide adequate +- 15VDC, and 5VDC respectively for the ESS and the SRC boards. I'd prefer kit, or ready-made form.
I really need to go back through the thread where I'm sure you made some recommendations, but it seems with every new post you've done something else to the project - some with positive improvements and others not so much. It's hard to keep up!
I will say, I'm usually not one to mod a board to the point where we try to wringe out all possible sound influencing improvements. I believe there's a point of diminishing returns. Other hobbyists do and I'm okay with that. If I can get to 95% of nirvana I'll be happy.
So, I would first like to start with the basic DAC, add the SRC with XMOS USB board, and power it with well-tuned dual linear PSUs with the proper regulators you recommend.
Rick
Hi Rick,
The Diyink power supply you linked to looks to be a kit you would have to build. It is a dual power supply, so it could be configured to do both + and - 15v. You would need a second one if you wanted to make 5v too. They are $59 for each kit, then you would need power transformers for each supply, maybe around $30 each? All of a sudden your $39 dac would be a $220 dac without even a chassis to mount things on.
However, if going for a really good dac then power supplies are a serious issue and good ones are a must. If one knows at the outset that low cost is the first and foremost issue, then there are much cheaper options, but with less regulation. Not necessarily a bad thing though if wanting to start incrementally.
If you don't want an AK4137, and you don't want to do a lot of work then you would only need one +-15v dual power supply. The XMOS boards are powered by USB by default.
For lowest cost, you could get a LM317/LM337 dual power supply from ebay or aliexpress. A low cost dual secondary torroid power transformer might be possible for not too much. That would be enough to get you started. Such power supplies tend to be short on filter capacitance and may use unsnubbed slow recovery rectifiers, but if not doing a lot of mods you might not notice such things. Later if you wanted to start upgrading you could use the LM317/LM337 as a preregulator for a better power supply. If you might want to do that later, just make sure you get a power supply board that has adjustment pots and buy a transformer that will let you run the power supply up to maybe +-18v or so. Enough to act as a preregulator for secondary +-15v regulators.
Only other thing is I might warn you that only adding a dual power supply and XMOS board will leave the dac board you have sounding pretty awful. Nowhere near 95%, not even 50% to my ears. Maybe 20%? Hard to say exactly and depends on lot on how one would measure. If a fully modded dac is probably around $1,000 sound quality class, and you are comparing it to a $39 board with $10 power supply board, $20 transformer, and $35 xmos board, maybe not even 10%. On the other hand if you are comparing static THD @1kHz expressed in dB, it might be closer to 60%. Something like that, but it wouldn't sound like 60% to me or some other people, yet it might to other people. Just shows people vary a lot in how they listen.
Another thing to consider before investing more in what you have now, you might be better off to wait a bit and consider buying an Allo Katana dac. You would still need to buy power supplies and an RPi, but most of the work is done for you and the sound quality will probably be very good, maybe very close to what you could do with a fully moded ES9028Q2M board. Don't know exactly about that yet though. Should have a Katana 1.2 here for review in a couple of weeks or so, and intend to get to listening comparisons as soon as I can. I expect it will be a very good dac for the money in any case.
The Diyink power supply you linked to looks to be a kit you would have to build. It is a dual power supply, so it could be configured to do both + and - 15v. You would need a second one if you wanted to make 5v too. They are $59 for each kit, then you would need power transformers for each supply, maybe around $30 each? All of a sudden your $39 dac would be a $220 dac without even a chassis to mount things on.
However, if going for a really good dac then power supplies are a serious issue and good ones are a must. If one knows at the outset that low cost is the first and foremost issue, then there are much cheaper options, but with less regulation. Not necessarily a bad thing though if wanting to start incrementally.
If you don't want an AK4137, and you don't want to do a lot of work then you would only need one +-15v dual power supply. The XMOS boards are powered by USB by default.
For lowest cost, you could get a LM317/LM337 dual power supply from ebay or aliexpress. A low cost dual secondary torroid power transformer might be possible for not too much. That would be enough to get you started. Such power supplies tend to be short on filter capacitance and may use unsnubbed slow recovery rectifiers, but if not doing a lot of mods you might not notice such things. Later if you wanted to start upgrading you could use the LM317/LM337 as a preregulator for a better power supply. If you might want to do that later, just make sure you get a power supply board that has adjustment pots and buy a transformer that will let you run the power supply up to maybe +-18v or so. Enough to act as a preregulator for secondary +-15v regulators.
Only other thing is I might warn you that only adding a dual power supply and XMOS board will leave the dac board you have sounding pretty awful. Nowhere near 95%, not even 50% to my ears. Maybe 20%? Hard to say exactly and depends on lot on how one would measure. If a fully modded dac is probably around $1,000 sound quality class, and you are comparing it to a $39 board with $10 power supply board, $20 transformer, and $35 xmos board, maybe not even 10%. On the other hand if you are comparing static THD @1kHz expressed in dB, it might be closer to 60%. Something like that, but it wouldn't sound like 60% to me or some other people, yet it might to other people. Just shows people vary a lot in how they listen.
Another thing to consider before investing more in what you have now, you might be better off to wait a bit and consider buying an Allo Katana dac. You would still need to buy power supplies and an RPi, but most of the work is done for you and the sound quality will probably be very good, maybe very close to what you could do with a fully moded ES9028Q2M board. Don't know exactly about that yet though. Should have a Katana 1.2 here for review in a couple of weeks or so, and intend to get to listening comparisons as soon as I can. I expect it will be a very good dac for the money in any case.
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I really need to go back through the thread where I'm sure you made some recommendations, but it seems with every new post you've done something else to the project - some with positive improvements and others not so much. It's hard to keep up!
Rick,
On the question of latest recommendations, the latest schematics by MrSlim and the latest BOM I think are good, except for maybe the differential output option on the output stage. I suggested a different way to do that if people want the option, but I don't use it myself. The earlier schematics by bih are also very close to the same as MrSlims in terms of the actual circuits depicted, mostly in MrSlim's the style was changed and some parts values clarified. (Thanks to both bih and MrSlim for their contributions to the documentation !!!)
There may be some newer hints and tips, such as a new write up on clock swapping, but the schematics show the AVCC and output stage boards correctly (aside from balanced). There is other discussion about local regulators for clock and VCCA that is in more recent posts. External power supplies have been left up to each individual modder, as most people are familiar with doing those. AK4137 boards come in two varieties, so the idea is to pick one or other based on features and cost.
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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 $$ into this project! Sure, I could have gone out and bought a Benchmark DAC3, but what fun would that have been.
At the moment, I have a couple different DACs I'm playing with; (1) TerraBerry DAC HAT (AK4490), and a Topping D50 external DAC with dual ES9038Q2M Sabre chips. Both using linear 5VDC PSUs.
I can say unequivocally, the Terraberry HAT (which does include an AK4137 reclocking chip, complete with DSD support sounds amazing. The richness, full body sound, separation of channels and incredible dynamics is beyond stunning. I can sit in my listening position and be blown away. One such CD my son has in DSD format is Michael Jackon's Thriller. It sounds amazing. I no longer am listening to my speakers, but the music.
So, for me those two DAC are my reference point. Not DAC3 quality, but certainly more than enough for me - at the moment. I will be interested in hearing how this next project will fair.
Rick
Based on your recommendation to me earlier in the thread, I purchased (eBay) the AK4137 reclocking board with optical and coaxial inputs. I already have a custom toroidal xformer with dual 18V and dual 9V secondaries that I could use. My question about the 0.56uV PSUs from DIYINHK is, are they 'good enough' as a starting point to yield better sound through better regulator? Kits are not a problem for me, as I've been using a solder pencil since the 60s, and upgraded to a Hakko years ago when I got serious about building more DIY audio projects. I'm a long-time, legacy Heathkit builder.
My plans for this project are to incorporate a RaspPi or equivalent so that I can use it as a roon client. That of course too, will need a separate linear PSU. So, realizing what could potential go into my choice of enclosure, I also purchased this case from my favorite supplier 'along' in China.
As I'm not too constrained budget wise, I am already several hundred $$ 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
Hi Rick,
Other people have been using power supplies similar to the diyinhk one you linked to. They will probably work fine. Looks like they may use jumpers to set the voltage.
EDIT: Just a note to be careful. You might not want to use an 18v transformer with the diyinhk supply boards since they use LT3045 regulators, which have an maximum input voltage rating of 20v. Ripple or peak rectification from an 18v transformer might exceed the 20v limit.
Also, if you want to keep mods minimal at least at first, you might try one very simple one which is to solder some more electrolytic caps on the bottom of the board under the 47uf AVCC caps which are in the board now. A very good designer named Victor used three each 1800uf caps for each of the two AVCC supplies. He soldered the extra caps onto the bottoms of the pins of the existing 47uf caps. It should help quite a bit, although it is far from a really good and proper AVCC supply.
The caps in question are located in the positions outlined in orange in the pic attached below.
EDIT 2: Another trick you could do would be to reduce harmonic distortion quite a bit using an RPi. An RPi can be used to control I2C bus with some simple commands. If you have the optional display unit for your dac board, it is easy to stop the MCU and use I2C bus to go in and turn on harmonic distortion compensation and set it to reduce some of the distortion that comes from using the original, built-in, single opamp output stage. I could give you some more info if you want to give it a try at some point.
Other people have been using power supplies similar to the diyinhk one you linked to. They will probably work fine. Looks like they may use jumpers to set the voltage.
EDIT: Just a note to be careful. You might not want to use an 18v transformer with the diyinhk supply boards since they use LT3045 regulators, which have an maximum input voltage rating of 20v. Ripple or peak rectification from an 18v transformer might exceed the 20v limit.
Also, if you want to keep mods minimal at least at first, you might try one very simple one which is to solder some more electrolytic caps on the bottom of the board under the 47uf AVCC caps which are in the board now. A very good designer named Victor used three each 1800uf caps for each of the two AVCC supplies. He soldered the extra caps onto the bottoms of the pins of the existing 47uf caps. It should help quite a bit, although it is far from a really good and proper AVCC supply.
The caps in question are located in the positions outlined in orange in the pic attached below.
EDIT 2: Another trick you could do would be to reduce harmonic distortion quite a bit using an RPi. An RPi can be used to control I2C bus with some simple commands. If you have the optional display unit for your dac board, it is easy to stop the MCU and use I2C bus to go in and turn on harmonic distortion compensation and set it to reduce some of the distortion that comes from using the original, built-in, single opamp output stage. I could give you some more info if you want to give it a try at some point.
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Thanks for the tips. Yeah, 18VAC will yield 25.6 after rectification and filter caps, so will need to go with 12VAC secondaries to get +-15VDC after regulators. That custom xformer came with another, older DAC I bought secondhand that did not work out.
I'm sure I'll reach out more as the build progresses.
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!
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!