I2S USB Input
I have used a USB convertor that outputs I2S straight to the DAC.
Also I have compared this to SPDIF using the complete DAC modified to Dario's BOM.
My current configuration is USB to I2S straight to the DAC.
Digital regulators as per the BOM.
Belleson 5v regulator for the analog side of the DAC
Auricap 3.9 uF capacitors straight from the DAC.
As soon as the I2S was connected (keep the connections as short as possible) the sound seemed to slow down, very relaxed.
I tried different brands of capacitor, but this is very critical and the best quality cap is important.
Bass is all present as the DAC is feeding into a high input impedence and the Cap is large enough to keep the low frequency rolloff below audiable frequency.
I know many would not agree with using a cap but I have tried differnt op amps, SRPP output stage, cheap output transformers, unbalancer and have found that simpler seems to work well
Good quality voltage regulation is also important (as it is with all audio)
Mark
I have used a USB convertor that outputs I2S straight to the DAC.
Also I have compared this to SPDIF using the complete DAC modified to Dario's BOM.
My current configuration is USB to I2S straight to the DAC.
Digital regulators as per the BOM.
Belleson 5v regulator for the analog side of the DAC
Auricap 3.9 uF capacitors straight from the DAC.
As soon as the I2S was connected (keep the connections as short as possible) the sound seemed to slow down, very relaxed.
I tried different brands of capacitor, but this is very critical and the best quality cap is important.
Bass is all present as the DAC is feeding into a high input impedence and the Cap is large enough to keep the low frequency rolloff below audiable frequency.
I know many would not agree with using a cap but I have tried differnt op amps, SRPP output stage, cheap output transformers, unbalancer and have found that simpler seems to work well
Good quality voltage regulation is also important (as it is with all audio)
Mark
Can't tell if you are saying this is an improvement or a reduction in quality ???
I2S
This is a massive improvement.
If you are using a pc as a source, then USB to I2S then straight to a DAC is far better that having 2 SPDIF conversions
This made more difference ( for the better ) than all of the mods to the output analog circuit
Mark
This is a massive improvement.
If you are using a pc as a source, then USB to I2S then straight to a DAC is far better that having 2 SPDIF conversions
This made more difference ( for the better ) than all of the mods to the output analog circuit
Mark
Which specific converter USB/I2S (eBay?) are you using? Any photos available?
How is it wired at the output? Just cap or cap + resistor? Where does it go to from there: preamp, volume pot, power amp?
Very interesting approach, Mark. Both on input and output. And regulators, of course.
Dario, could you post a straight top down picture of your current populated board? I've been browsing through several builders photos and see a few discrepancies. Since many are working from your upgrade BOM, it would be nice to establish a reference from you. I'm not sure if the picture at your Google docs page represents your latest PCB population.
Thanks.
Thanks.
Whatever output solution you choose, it should sum the differential outputs properly. A single DCB1 won't do that-
The pic in Google Docs (also attached to this post) represent exactly what is recommended on BOM.
The only tiny difference is that Cerafines around the AK4396 are NOS (red sleeve, they sound slightly fuller).
The actual DAC has two 47uF Black Gate PK instead of Cerafines on opamp decoupling.
Attachments
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You're right... I forgot it, sorry.
In fact the 3300uf 35V fits better but I've used that simply because I've had it at hand.
Well, anybody can do the whatever the h**l they want. But if they want to do it right then the Unbalancer is a solution.
no can do, Sir. still unavailable in the glassware store
until the point of desperation, i might as well go with point to point wiring to realize this unbalancer project
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no can do, Sir. still unavailable in the glassware store
until the point of desperation, i might as well go with point to point wiring to realize this unbalancer project
You can use the BCF (cathode follower) its easy enough for point to point.
this is the schematic for one channel
An externally hosted image should be here but it was not working when we last tested it.
Uploaded with ImageShack.us
some say the unbalancer should sound better than the BCF? i'm just trying to go with the crowd..
btw, i don't need to go point to point with BCF. its PCB is readily available in the store
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I2S
Check out this link
TE7022 24Bit 96Khz USB To Coaxial Converter I2S IIS + USB line | eBay
I powered this convertor from the 9V digital supply on the DAC board
Having started working with a kit, not an assembled unit, after the experiment was working .There was a lot of spare parts
Just remove the 4 resisters that pass the I2S bus to the DAC and link the I2S bus from the USB convertor
I used the resisters that were to fit in that location.(I don't really think the the resister are needed, links would do)
Keep the lenghts of the links short
Will post a picture as soon as I fined the camera
Mark
Hi
Check out this link
TE7022 24Bit 96Khz USB To Coaxial Converter I2S IIS + USB line | eBay
I powered this convertor from the 9V digital supply on the DAC board
Having started working with a kit, not an assembled unit, after the experiment was working .There was a lot of spare parts
Just remove the 4 resisters that pass the I2S bus to the DAC and link the I2S bus from the USB convertor
I used the resisters that were to fit in that location.(I don't really think the the resister are needed, links would do)
Keep the lenghts of the links short
Will post a picture as soon as I fined the camera
Mark
This may be going too far for this thread as not being specific to this DAC, but it does deal with the feed.
sterlingmck , I believe is stating or implying there is a double data conversion when using ASIO/SPDIF to feed this DAC from a computer. Also, a suggestion that one of these is eliminated by using the USB path.
Many Pro DAW (digital audio workstation) suppliers use the two/three pin s/pdif header direct from the motherboard for the specific purpose of avoiding the USB hardware/firmware.
If the goal is to pass unaltered (bit perfect) data, and there is proper I2S conversion embedded into this specific kit/design, why is adding a converter of any type not compromising the purity of the signal. I understand the need for volume control, but my preference is using LDR attenuation of the DAC output to again, eliminate as many chips,caps and resistors in the stream as possible.
There may well be much I'm not understanding about the I2S leg and am hoping for some clarification.
sterlingmck , I believe is stating or implying there is a double data conversion when using ASIO/SPDIF to feed this DAC from a computer. Also, a suggestion that one of these is eliminated by using the USB path.
Many Pro DAW (digital audio workstation) suppliers use the two/three pin s/pdif header direct from the motherboard for the specific purpose of avoiding the USB hardware/firmware.
If the goal is to pass unaltered (bit perfect) data, and there is proper I2S conversion embedded into this specific kit/design, why is adding a converter of any type not compromising the purity of the signal. I understand the need for volume control, but my preference is using LDR attenuation of the DAC output to again, eliminate as many chips,caps and resistors in the stream as possible.
There may well be much I'm not understanding about the I2S leg and am hoping for some clarification.
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