Hi Guys,
There is a new 9038q2m card on the market:
KHADAS Module DAC USB DIY ES9038Q2M - XMOS U208 - SPDIF - PCM 32bit / 768kHz DSD256 - Audiophonics
What do you think of it?
And by the way, the Allo katana is coming on July 15.
New FIFO buffer for RPI/SBCs
There is a new 9038q2m card on the market:
KHADAS Module DAC USB DIY ES9038Q2M - XMOS U208 - SPDIF - PCM 32bit / 768kHz DSD256 - Audiophonics
What do you think of it?
And by the way, the Allo katana is coming on July 15.
New FIFO buffer for RPI/SBCs
Probably anticipate not as good as one of the boards in this thread when fully modded, which in turn is not as good as a Benchmark DAC-3. Don't think it probably lives up to the moniker 'audiophile.' Phase noise appears cut for the same reason some of the other info is displayed in lo-res images or otherwise obfuscated. It probably would not be something I would like or use if somebody gave it to me. Then again, don't know about the market it is positioned to occupy or how much it sells for. It might be good given such considerations. All the above my personal opinion only. Have not listened to one of the units, so opinion could be subject to change but not likely by much.
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Every electronic component is a distortion generator, but none is 'just' a distortion generator. It is one of the aspects of components that engineers have to learn how to deal with. There is nothing dismissive or reductive about it, IMHO.
Hard to say given how little we know about this one. It was hard to say about su5 before listening and looking close up. Obviously, this one has much less circuitry in it. DAC-3 has a lot, and for good reasons (see pic below).
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Is there a review and measurement of the SU5 board somewhere?
I am more thinking about the ES9028PRO because of Mikett's experience. The the SU5 box is half that price.
Don't know about outside reviews. I have one of course and talked about it some starting around back here: http://www.diyaudio.com/forums/digital-line-level/314935-es9038q2m-board-158.html#post5473201
I would sum it up as 'not recommended.' But, it is not quite that simple. Output stage, power supplies and clock would all need work. Fitting better power supplies in the original case would be pretty challenging. There is a sound quality issue with the very poor, pretty unbelievable way they laid out the ground plane scheme that could be complicated to fix, hard to say. It looks like there is a limit to the maximum sample rate it could work at because everything goes through the CPLD chip.
If a lot of work, limited sample rate, and likely a new case are all okay with you then I guess it could probably be modded into something pretty good that offers Bluetooth.
I would sum it up as 'not recommended.' But, it is not quite that simple. Output stage, power supplies and clock would all need work. Fitting better power supplies in the original case would be pretty challenging. There is a sound quality issue with the very poor, pretty unbelievable way they laid out the ground plane scheme that could be complicated to fix, hard to say. It looks like there is a limit to the maximum sample rate it could work at because everything goes through the CPLD chip.
If a lot of work, limited sample rate, and likely a new case are all okay with you then I guess it could probably be modded into something pretty good that offers Bluetooth.
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The 9028pro DAC that I have put together is proving to be a very very good DAC. Moving from 9038Q2M to a 9028Pro board
What the distortion it produces, I don't know but it is low enough to allow me to pick out the faults in the 4392 SRC. It is also highly revealing.
Please keep in mind that when it comes to resolution, the other part of the system must be able to also pass it through to be heard. This is important and is often a missed point when people compare components and say "no difference". So when upgrading, you must be aware of that possibility. Remember that Markw4 is doing a lot of testing with a "tweaked" Headphone Amplifier which is essentially a microscope into the sound of a system. Extremely resolving. Markw4's endpoint is an excellent DAC, it is reachable within the guidelines of how to get it there.
So when you make a decision make it knowing that there is a fork in the road. One branch requires more work and circuit manipulation and raw fabrication. The other path requires purchase of Ebay inexpensive boards and assembling all the pieces. It is more costly but is easily doable by the intermediate builder...perhaps maybe just a weekend project or maybe two weekends at most.
First thing if you go the 9028PRo route is to remove the LT317/337 on the board. These are not good enough on that board they must be replaced. This is my recommendation the differences are greater than op amp changeouts. It is not the tonality but the dynamic presentation. The LT1963s are OK to stay in there for a while. So if you are contemplating going that route, order a SuperRegulator power supply board first, assemble it and get it working first. After that modding the 9028PRO is very simple.
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These are inexpensive simple reliable regulators that have been around for a long time. Prior to 317/337s the LT340/LM78xx series too their place and are even simpler to implement. They are OK for general use and general consumer equipment. Better power supplies have been around since the 80s. The LT317/337 "sound" can be heard to experienced ears with reduced dynamics and lost low level details.
They are OK for entry level systems considering their low cost, reliability and simplicity but there are better ones around but a lot more complicated and much costlier. Some use 317/337 to precondition the supply prior to final regulation. There's a place for them but not at the highest level.
They are OK for entry level systems considering their low cost, reliability and simplicity but there are better ones around but a lot more complicated and much costlier. Some use 317/337 to precondition the supply prior to final regulation. There's a place for them but not at the highest level.
Ian, this is why I suggested that you could use the LM317/337 supply as pre-regulation later, if you plan now to make it so you could adjust the output up to +-18v or so.
Also, if you have not already done so, you might want to take a look at what Mikett is doing in the other thread. He seems to feel he has found an easier way to get good results than what I did here. i only use the word 'seems' because we have not directly compared each others approaches. But, I would expect them to come out close to the same if perhaps not exactly the same. Either way, you could probably end up with a DAC you will be happy with. Only problem with switching paths at this point is you have already ordered the board used in this thread. If money is a big issue and you want to stick with this one that is of course fine. If you are looking for an easier path and can afford to spend a bit more then Mikett's version might be lot easier to get finished up.
EDIT: I should probably add that there is no one 'best' regulator. It always depends on various factors. Some regulators use a whole lot of feedback to regulate very precisely up to pretty high frequencies. That means they are more likely to interact in unwanted ways with loads and with wiring. Also, the very clean and precise outputs they can produce can get dirtied and contaminated with noise the further away circuitry gets from the regulator. So, local regulation still may be needed, ground planes are needed (power planes are good too), and proper bypass practices cannot be ignored.
However, if you want to read about some that amazing good, you could download data sheets for LT3042 and LT3045. The data sheets have references that point to application notes and other documents. So, you can become your own expert if you are willing to read and study.
In addition, I don't think I mentioned to you that we sometimes use adhesive-backed copper foil to fabricate ground planes and low impedance connections. It can be purchased at places like Amazon or on ebay. I used that to make a ground plane for my modified headphone amp, as one example.
Also, if you have not already done so, you might want to take a look at what Mikett is doing in the other thread. He seems to feel he has found an easier way to get good results than what I did here. i only use the word 'seems' because we have not directly compared each others approaches. But, I would expect them to come out close to the same if perhaps not exactly the same. Either way, you could probably end up with a DAC you will be happy with. Only problem with switching paths at this point is you have already ordered the board used in this thread. If money is a big issue and you want to stick with this one that is of course fine. If you are looking for an easier path and can afford to spend a bit more then Mikett's version might be lot easier to get finished up.
EDIT: I should probably add that there is no one 'best' regulator. It always depends on various factors. Some regulators use a whole lot of feedback to regulate very precisely up to pretty high frequencies. That means they are more likely to interact in unwanted ways with loads and with wiring. Also, the very clean and precise outputs they can produce can get dirtied and contaminated with noise the further away circuitry gets from the regulator. So, local regulation still may be needed, ground planes are needed (power planes are good too), and proper bypass practices cannot be ignored.
However, if you want to read about some that amazing good, you could download data sheets for LT3042 and LT3045. The data sheets have references that point to application notes and other documents. So, you can become your own expert if you are willing to read and study.
In addition, I don't think I mentioned to you that we sometimes use adhesive-backed copper foil to fabricate ground planes and low impedance connections. It can be purchased at places like Amazon or on ebay. I used that to make a ground plane for my modified headphone amp, as one example.
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For a good weekend reading try Walt Jung's site. He is a legend when it comes to SS high performance audio. Go through the articles in 1995 forward...
References & Regulators | Walt's Blog 2014
Quick rundown from Tangentsoft.
Op-Amp Based Linear Regulators
Then there is the world of the SHUNT regulator as well.
In all these circuits the practical implementation is very important. The aspect of proper grounding should not be neglected.
References & Regulators | Walt's Blog 2014
Quick rundown from Tangentsoft.
Op-Amp Based Linear Regulators
Then there is the world of the SHUNT regulator as well.
In all these circuits the practical implementation is very important. The aspect of proper grounding should not be neglected.
ALBUM PLAYER
For those using USB, an alternative free player to foobar2000 on windows with VST (!!) support and up-sampling dsp, ASIO, DSD, very stable on XMOS ASIO, with a very special oldscool interface...
ALBUM PLAYER
Audio player Album Player 2.110
I was wandering though, if those software up sampling methods could be as useful as the hardware used by Markw4's mod.
For those using USB, an alternative free player to foobar2000 on windows with VST (!!) support and up-sampling dsp, ASIO, DSD, very stable on XMOS ASIO, with a very special oldscool interface...
ALBUM PLAYER
Audio player Album Player 2.110
I was wandering though, if those software up sampling methods could be as useful as the hardware used by Markw4's mod.
Another AK4137 SRC board
Hey Mark, have you seen this one: AK4137 flagship high end DAC SRC audio 384K 32Bit DSD256 DSD IIS conversion-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
Hey Mark, have you seen this one: AK4137 flagship high end DAC SRC audio 384K 32Bit DSD256 DSD IIS conversion-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
Don't be afraid of feedback. It has a bad name in audio circles for some reason, and it is one of the few tools you have to make a low output impedance regulator, especially over a wide frequency range. The inherent output impedance of the regulator output stage can have its impedance lowered by using a high standing current, either by directly running the pass device(s) at a higher standing current or drawing excess current through the regulator output. But, after a certain point, further improvement in this way becomes impractical. The second way is to wrap the output stage inside of a wideband amplifier and apply lots of feedback. As long as the output stage has sufficient bandwidth to make the loop stable (which is helped along by using high standing currents), there is no downside to this, aside from the cost and complexity.
To avoid unexpected problems, you can drive the regulator output foil right at the load with a fast square wave through a 50Ω resistor, and look for any ringing or other unexpected instability. Any voltage you see at the load will be from residual PSU impedance, and if there's ringing, then the regulator feedback loop might not be stable. If you make sure the regulator installed in the board with the load is stable, then using as much feedback as possible is always better - no need for uncertainty or being blindly cautious.
Agreed! Using large foil geometries is the final step that is required to make low impedance regulators, especially if you need some distance from the regulator to the load. The impedance (AC and DC) of a 4" x 4" square of copper is the same as a 0.4" x 0.4" square of copper, about 500µΩ for 1 oz. copper foil, so all foil used to connect the regulator to the load should be as wide as possible to get as close as possible to that minimum impedance value. The ultimate conclusion is to make the PSU 'traces' an entire plane of copper in the PCB, or to use foil instead of wire if you're not in a multi-layer PCB.
At the minimum, I feel that 4 layer PCBs are useful for low impedance regulators and analog circuitry. I typically use the inner layers for + and - power, and only a little bit of routing, in order to not cut the foil up too much. The outer layers can have components an routing, along with ground pours, again, spaced sufficiently to make the ground pour shapes as geometrically 'stout' as possible.
Agreed. I briefly described that procedure before. It's just that we have some people interested in learning more about DACs who appear to be new to some of this stuff and it doesn't really work to overwhelm with too much information too fast.
Understood - sorry for not reading back into the thread sufficiently. Yes, it sounds like a simple procedure, but even getting a scope probe accurately grounded to a PCB ground plane isn't all that simple, and if you don't, you can get some awful looking waveforms. Lots of things can go wrong when you work with fast mixed-signal circuits, as you well know!
All the best,