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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

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#3,709
Hi @all,

a little clean up. 😀 No more 3V3 for the isolator chips (now only that one on the DAC).

An externally hosted image should be here but it was not working when we last tested it.


Bürklin has cheap U.FL cables (https://www.buerklin.com/default.asp?search=72+F+2161&event=ShowSE()&l=d&ch=73872&suggestion=). 2,70 Euro each (300mm).

Short statement: I think with U.FL cables i hear more controlled bass and a harder / clearer locatability or sharpness of the instruments. Please that are only impressions from my hearing at my working bench. On one is really impressive for this (the snap of the fingers from her): Ulla Meinecke => Die Tänzerin

Try it. 😎
 
#3,711
DAM 1021-12, 0.012% rev2 version ordered and payed! 🙂 I've ordered DIYINHK XMOS DSD Module and Salas Reflektor D to power XMOS and 3.3V ISO on DAM. DAM will be powered via dedicated toroidal transformer. I'll use RAW output direct into GM-70 full dht monoblocks.

Can't wait to try it.
 
#3,712
normundss said:
The problem with isolators is that nobody specifies high frequency noise leakage for them. Isolators are intended for galvanic separation, they are not EMI filters. Furthermore, some types of isolators introduce their own noise, which may or may not have a noticeable effect in this application. For example, the Si86xx isolators used in DAM1021 use modulated RF carrier. The datasheet does not specify how much of the carrier signal may be present on the outputs, nor the carrier frequency.

In this respect, I think there may actually be some benefit to using multiple isolators, as long as they attenuate more EMI than they introduce. It may also be beneficial to add lowpass filters on the dirty side of the isolators. Come to think of it, I may actually add some data line EMI filters to the upcoming input board GB. Need to look into it.
The reclocker should be able to handle the additional jitter introduced by limiting I2S signal bandwidth, but it will not do much for jitter caused by EMI.

Common mode noise coming from the isolators may be another problem. Since the isolators are single ended devices, the common mode noise gets coupled directly into the ground plane and pollutes it.

Jitter introduced by the FPGA is probably the limiting factor for DAM1021, but the other jitter sources are still additive and may make a noticeable difference.
Click to expand...

Thx for pointing that out. There must be an explanation why USB filters such as the AQ Jitterbug and USB Regens cause quite a dramatic difference (dramatic in audiophile terms). And even these devices, even if chained are not the final word.

If you look up all the USB-interfaces you'll see pretty basic XMOS implementations all over the place. They all seem to follow a pretty basic implementation proposal of XMOS.
Nobody is really addressing the subject.. They all let the junk in.
 
#3,716
Took the plunge. Did the vref mod. First 16x caps mod from hifiduino.
Tested the dam. Works ok.

Then the other 0r, 0.1r mod.
And also the 27k4r poweron/poweroff mod.

Measured resitance after with a dmm. Seems ok.

Power on and no sound. Can connect to umanager with no problems. The dam got signal and lock but unfortunately no sound.
Late here now. Will do some more testing in a day or two..
 

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#3,719
bambadoo said:
Took the plunge. Did the vref mod. First 16x caps mod from hifiduino.
Tested the dam. Works ok.

Then the other 0r, 0.1r mod.
And also the 27k4r poweron/poweroff mod.

Measured resitance after with a dmm. Seems ok.

Power on and no sound. Can connect to umanager with no problems. The dam got signal and lock but unfortunately no sound.
Late here now. Will do some more testing in a day or two..
Click to expand...

Check the vref voltages for starters, its the first thing I did upon poweron after performing my 16 cap mod.
 
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