It looks like the same Chinese company that makes the ES9038Q2M DAC boards is now also making their own SRC board.
It is cheaper from Ali Express than ebay, or so it appears:
sandy AK4137 DAC SRC Audio 384K 32Bit DSD256 DSD IIS Conversion-in Headphone Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
HiFi AK4137 DAC SRC Audio Decoding Board PCM 384K 32Bit DSD256 IIS Conversion 142372810754 | eBay
Besides the fancy user interface and higher cost, the SRC chip on this one might be a little better than the SRC4392 board, although the latter is probably more than good enough.
It is cheaper from Ali Express than ebay, or so it appears:
sandy AK4137 DAC SRC Audio 384K 32Bit DSD256 DSD IIS Conversion-in Headphone Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
HiFi AK4137 DAC SRC Audio Decoding Board PCM 384K 32Bit DSD256 IIS Conversion 142372810754 | eBay
Besides the fancy user interface and higher cost, the SRC chip on this one might be a little better than the SRC4392 board, although the latter is probably more than good enough.
Looks a little cheaper on Taobao, though of course the delivery's not included here. 368RMB translates to just over $58 at today's rate.
AK4137 ????DAC SRC?? 384K 32Bit DSD256 DSD IIS ??-???
AK4137 ????DAC SRC?? 384K 32Bit DSD256 DSD IIS ??-???
The problem is in your wall-wart, or USB.
In the case of USB, maximum current is 500mA (900mA in USB3) so the power will cycle. In the case of wall-wart your guess is as good as any, but the SSW will draw a lot more than this on startup. You can see this effect with a current limited linear power supply.
The feedthrough of switching transients exists, but not sufficient to be audible. These screenshots using an old and noisy wall wart will illustrate. First "Peak", Second "Average", Third "Ringing". Note the period.
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Jack, nope. You are barking up the wrong tree. The DAC has LME49720's in it for one thing. They have known RF sensitivity. See attachment below. Also, in the case based on some experimentation over at Richard Marsh's house using his test equipment the DAC chip itself has something funny going on that looks rather similar, although more work needs to be done.
What I have been using is a portable shortwave radio with adjustable RF sensitivity and an external antenna jack. Using an external antenna I can trace RF hash radiating up the wires from the switcher in the wall wart through the SS and up to the DAC. That's no good for my purposes because it is audible though some unknown mechanism that presumably involves rectification. Don't now if any bias level shifting as a result.
To be clear, I didn't start by looking for RF, I started by hearing some kind of distortion and trying various substitution experiments pointing at a power problem associated with switching sources before hitting on using the radio as an RF detector. What it detects correlates quite well with distortion I can hear, although the distortion may be at a very low level. Perhaps inaudible to some fraction of the population, haven't tried to measure that. Signals causing the problem could be down in the high nanovolt region, that I don't know.
Anyway, some of these devices with high sensitivities can produce very low level audible artifacts. My point has always been that how would one know if one had a very sensitive device to tiny amounts of RF? So far, a number of people have pointed at SS as a gold standard power source that can always be relied upon no matter what. I haven't found that to be the case.
Some of the DAC guys use LifePo4 batteries as their gold standard and I am coming around to the view that may be a better choice than SS. I will do some experiments soon to find out. Do you have any opinion on that?
What I have been using is a portable shortwave radio with adjustable RF sensitivity and an external antenna jack. Using an external antenna I can trace RF hash radiating up the wires from the switcher in the wall wart through the SS and up to the DAC. That's no good for my purposes because it is audible though some unknown mechanism that presumably involves rectification. Don't now if any bias level shifting as a result.
To be clear, I didn't start by looking for RF, I started by hearing some kind of distortion and trying various substitution experiments pointing at a power problem associated with switching sources before hitting on using the radio as an RF detector. What it detects correlates quite well with distortion I can hear, although the distortion may be at a very low level. Perhaps inaudible to some fraction of the population, haven't tried to measure that. Signals causing the problem could be down in the high nanovolt region, that I don't know.
Anyway, some of these devices with high sensitivities can produce very low level audible artifacts. My point has always been that how would one know if one had a very sensitive device to tiny amounts of RF? So far, a number of people have pointed at SS as a gold standard power source that can always be relied upon no matter what. I haven't found that to be the case.
Some of the DAC guys use LifePo4 batteries as their gold standard and I am coming around to the view that may be a better choice than SS. I will do some experiments soon to find out. Do you have any opinion on that?
Attachments
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Regarding concerns about possible current limits of USB power sources, the USB hub is rated for charging, and SS did produce constant +-15v measured with a DVM. Whether there were any hiccups not detected by the DVM remains a possibility.
Wall warts tested were rated up to 2A. Noise was lowest with a 500ma rated wall wart, as it happened, but still present.
Wall warts tested were rated up to 2A. Noise was lowest with a 500ma rated wall wart, as it happened, but still present.
I would say the closest thing some people might have any experience with would be undithered 16-bit audio. Not exactly that, though. For those who may have heard it, sometimes the term grainy is used by some people. Grainy doesn't make much sense however until you hear it and then it's like, oh, that's what they mean by grainy. Otherwise, not really any words to describe it.
Maybe another way to describe it would be to say it sounds like low level high order harmonic distortion. Depends if you know what that sounds like. Or, what it sounds like when you don't have it.
It is low level though, it could be worse than a lack of dithering, or more subtle. Depends. But it's there and some people can hear it. If one listens to a very clean DAC for a long time and suddenly one day it's there you would probably notice and not like it.
I would say that if you let that distortion be there in your particular DAC, it is unlikely it would measure as well as mine did. Look at the attention to detail and component selection recommended by ESS. They aren't making that stuff up. Attention to all the little details is necessary to make a really good DAC. Power quality is one of them.
Maybe another way to describe it would be to say it sounds like low level high order harmonic distortion. Depends if you know what that sounds like. Or, what it sounds like when you don't have it.
It is low level though, it could be worse than a lack of dithering, or more subtle. Depends. But it's there and some people can hear it. If one listens to a very clean DAC for a long time and suddenly one day it's there you would probably notice and not like it.
I would say that if you let that distortion be there in your particular DAC, it is unlikely it would measure as well as mine did. Look at the attention to detail and component selection recommended by ESS. They aren't making that stuff up. Attention to all the little details is necessary to make a really good DAC. Power quality is one of them.
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Well I have known about power quality, digital or analogue. Some evenings the sound is just not there. Then it comes back. Thin, grainy, not smooth and then at other times it is ok.
That is when I sometimes tell myself open the wallet and be done with it. Don't know if it is psychological or real. Trouble is up in Canada a DAC3 is around 3k with taxes. I would not want to know that it was all psychological and $3k did not fix it.
Like today, Changed my motherboard and boom. It sounds different. Then I tested Coax and Optical very different sound. This is counter to what I had tried years ago. This digital stuff appears to be very finicky and possibly more so than analogue where a sound signature stuck with a particular setup.
That is when I sometimes tell myself open the wallet and be done with it. Don't know if it is psychological or real. Trouble is up in Canada a DAC3 is around 3k with taxes. I would not want to know that it was all psychological and $3k did not fix it.
Like today, Changed my motherboard and boom. It sounds different. Then I tested Coax and Optical very different sound. This is counter to what I had tried years ago. This digital stuff appears to be very finicky and possibly more so than analogue where a sound signature stuck with a particular setup.
Thin and grainy sure sounds like a distortion problem. Power lines can have EMI/RFI problems that come and go. They do tend to get virtually completely filtered out in distribution transformers, so any source would likely be fairly local.
However, 'sounding different' can mean many different things. With a new motherboard and with Windows I would be inclined to check the sound device settings. Windows, and most modern OS's will perform real-time resampling of the sound stream as needed automatically and without warning, at least for the selected 'default' sound device.
In Windows if you go to the control panel, open the Sound settings, and see what devices are listed. If you click on one to select it then you can click on the properties button on the lower right to open its settings. Under the Advanced tab there you can select the default sample rate and bit-depth. If it is set to 16/44, then every sound you play will be sample rate converted to that, and not with good quality. If it is set to 16/48 and you play a CD it will sound worse than if was set to 16/44, since in the latter case no SRC would be needed.
However, 'sounding different' can mean many different things. With a new motherboard and with Windows I would be inclined to check the sound device settings. Windows, and most modern OS's will perform real-time resampling of the sound stream as needed automatically and without warning, at least for the selected 'default' sound device.
In Windows if you go to the control panel, open the Sound settings, and see what devices are listed. If you click on one to select it then you can click on the properties button on the lower right to open its settings. Under the Advanced tab there you can select the default sample rate and bit-depth. If it is set to 16/44, then every sound you play will be sample rate converted to that, and not with good quality. If it is set to 16/48 and you play a CD it will sound worse than if was set to 16/44, since in the latter case no SRC would be needed.
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jiackinnj, At the present moment the DAC board has more filter capacitance on it than may be compatible with SS. I suppose I could clip a couple of them loose and run it that way in order to make a recording.
I do have something else in mind though. I am working on getting my notch filter working so I can look at the low level harmonic spectrum. That might be preferable to an audio clip. It is a higher priority for me to get that working so I would prefer to continue in that direction for now. After that clipping out caps to do some testing could be interesting.
I am curious as to what would make you think of two frequencies beating, and how that might related to what sounds like high order harmonic distortion. There were no visible aberrations on the power rails or at opamp outputs using an 100MHz scope. Anything fixed frequency would have had to have been less than 10mV using 10x probes (or closer to less than 1mV at lower frequencies where 1x probes can still work, tried it both ways).
Also, I didn't mention before but I tried a couple of off-the-shelf +-15v switching supplies and got essentially the same effect as with SS and wall warts. Between switchers and various wall warts, the effect is only a matter of degree, there is no difference in basic character, at least in terms of audibility.
Tried putting one of the switchers in a metal box with RF feed-throughs to bring the power out, but the tightly sealed box didn't attenuate radiated EMI/RFI enough to do much good. In addition, capacitance between the box and one of the switching supplies caused its noise emissions to increase considerably. Found that holding my finger near a spot on the top of the power supply had the same effect. Very strange. Abandoned all switchers for the time being.
Also, as an aside what we saw with the DAC over at Richard's house curiously consisted of spurs spaced at right around 100Hz intervals. Unfortunately, I didn't think to ask at the time if there was a DECT phone system in use.
I do have something else in mind though. I am working on getting my notch filter working so I can look at the low level harmonic spectrum. That might be preferable to an audio clip. It is a higher priority for me to get that working so I would prefer to continue in that direction for now. After that clipping out caps to do some testing could be interesting.
I am curious as to what would make you think of two frequencies beating, and how that might related to what sounds like high order harmonic distortion. There were no visible aberrations on the power rails or at opamp outputs using an 100MHz scope. Anything fixed frequency would have had to have been less than 10mV using 10x probes (or closer to less than 1mV at lower frequencies where 1x probes can still work, tried it both ways).
Also, I didn't mention before but I tried a couple of off-the-shelf +-15v switching supplies and got essentially the same effect as with SS and wall warts. Between switchers and various wall warts, the effect is only a matter of degree, there is no difference in basic character, at least in terms of audibility.
Tried putting one of the switchers in a metal box with RF feed-throughs to bring the power out, but the tightly sealed box didn't attenuate radiated EMI/RFI enough to do much good. In addition, capacitance between the box and one of the switching supplies caused its noise emissions to increase considerably. Found that holding my finger near a spot on the top of the power supply had the same effect. Very strange. Abandoned all switchers for the time being.
Also, as an aside what we saw with the DAC over at Richard's house curiously consisted of spurs spaced at right around 100Hz intervals. Unfortunately, I didn't think to ask at the time if there was a DECT phone system in use.
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thanks Mark! the thing measures pretty close to Pre Box S2 now. nevertheless, they sound is rather different, what also reflects in the spectrum.
what was somehow surprising that discrete regs are doing better than LT3045. unlikely noise wise, but maybe they can handle better such a tricky load as Sabre32 chip. i wonder whether someone has measured what is going on with LT3045 regulated AVCC when playing something like 384/32 or high rate DSD?
unfortunately, I do not have an appropriate oscilloscope at the moment.
Don't know myself. Maybe somebody else reading knows and can tell us?
Also, I wonder why you say "unlikely noise wise." Chinese LT3045 modules can have noise at very low frequencies up as high as as -70dB, depending on the value of Cset (according to the noise spectrum posted in some of the online ads). Can you tell us the value of Cset for your LT3045s?
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the LT3045 module I have is not exactly Chinese ... LT3045 . the author of these reg boards is also on this forum, I believe.
the components claimed are:
BOM (Bill of Materials)
LT3045 : IC, Low Noise Power Solution, Linear Technology – United States
T495C226K025ATE300 x 1: Cap Tant Solid 22uF 25V C CASE 10%,Kemet – Japan
CRCW0603xxxxFKEA x1: Res Thick Film 0603 1% 0.1W(1/10W) ±100p, Vishay – USA
GRM31CR71E106KA12L x2 : Cap Ceramic 10uF 25V X7R 10% SMD 1206, Murata – Japan
GRM31MR71E475KA01L x1 : Cap Ceramic 4.7uF 25V X7R 10% SMD 1206, Murata – Japan
the components claimed are:
BOM (Bill of Materials)
LT3045 : IC, Low Noise Power Solution, Linear Technology – United States
T495C226K025ATE300 x 1: Cap Tant Solid 22uF 25V C CASE 10%,Kemet – Japan
CRCW0603xxxxFKEA x1: Res Thick Film 0603 1% 0.1W(1/10W) ±100p, Vishay – USA
GRM31CR71E106KA12L x2 : Cap Ceramic 10uF 25V X7R 10% SMD 1206, Murata – Japan
GRM31MR71E475KA01L x1 : Cap Ceramic 4.7uF 25V X7R 10% SMD 1206, Murata – Japan
22uf is the maximum recommended value for Cset. Below are a couple of pics from the LT3045 data sheet. They show the pin labeled "Set" has a capacitor and resistor. The cap is Cset. Presumably the Cset for your module is the 22uf tantalum, but maybe you could check to confirm if that is correct?
