Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz - Page 111 - diyAudio
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Old 28th January 2015, 11:40 AM   #1101
Dimdim is online now Dimdim  Greece
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This is strange. Soekris wrote that when the pot is out of the circuit, the volume control defaults to 0db, thus it shouldn't be clipping.
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Old 28th January 2015, 11:46 AM   #1102
soekris is offline soekris  Denmark
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Or more likely your soundcard clips as the balanced output gives out 4V RMS balanced, 2V RMS unbalanced at 0db gain....
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Old 28th January 2015, 11:49 AM   #1103
TNT is offline TNT  Sweden
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Quote:
Originally Posted by vanwykca View Post
Just some data points with this DAC. My measurements are with Juli@ sound card. First image is a measurement of ESS9018 DAC just to show measurement limits of the ADC. Second image is Soren's DAC direct out (bypassing the balanced/buffer opamps).

https://www.dropbox.com/s/cnu86nonn1...a4700.jpg?dl=0

https://www.dropbox.com/s/5t12jyh7ob...4.4db.jpg?dl=0
3rd overtone looks like > 100% dist.

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Old 28th January 2015, 12:05 PM   #1104
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Quote:
Originally Posted by TNT View Post
3rd overtone looks like > 100% dist.

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That's just the cursor on the third harmonic. The DAC sounds great balanced to nCore400/PMC OB1, but I could hear clipping into my second system (Electrocompaniet EC4.8/PassF5/PMC Fact8. That was with the volume fully up though:-(. I started measuring the DAC and when I realised that full volume is +15db, it made sense, and all was well with it turned down.

I did the same measurements with EMU0404usb but the soft limiting circuit kicked in with the volume set quite low, so I gave up.

My posts were actually just to show how good the direct measurements are.
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Old 28th January 2015, 12:34 PM   #1105
soekris is offline soekris  Denmark
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Here is a schematic to show how to connect the SPDIF inputs. Please note that the FPGA LVDS Receiver need to be biased around 1.25V, convenient there is 1.2V available from the FPGA Core voltage at J2.
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File Type: pdf SPDIF_Receiver.pdf (5.7 KB, 461 views)
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Old 28th January 2015, 12:37 PM   #1106
SGK is offline SGK
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Vanwykca, please use Insert Image so that your Dropbox images display in the thread rather than requiring new browser windows.
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Old 28th January 2015, 12:37 PM   #1107
soekris is offline soekris  Denmark
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Quote:
Originally Posted by vanwykca View Post
I did the same measurements with EMU0404usb but the soft limiting circuit kicked in with the volume set quite low, so I gave up.
If you use a XLR cable into the EMU-0404 then you're using its MIC input, you need to use the Jack input for line levels. Still, I use a -6 db pad otherwise the line input still overload....
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Old 28th January 2015, 01:16 PM   #1108
soekris is offline soekris  Denmark
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Here is a schematic to show how to connect the SPDIF inputs. Please note that the FPGA LVDS Receiver need to be biased around 1.25V, convenient there is 1.2V available from the FPGA Core voltage at J2.
(First drawing had incorrect pin numbers on the toslink receiver)
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File Type: pdf SPDIF_Receiver.pdf (5.7 KB, 1044 views)
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Old 28th January 2015, 03:50 PM   #1109
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Input impedance is 330 Oh.

Should we don´t use a standard transformer 1: 1 or 1.21: 1?

Is this the best option?
2:1 transformer for SPDIF (75:330)
1,73:1 transformer AES / EBU (110:330).

Last edited by oneoclock; 28th January 2015 at 03:55 PM.
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Old 28th January 2015, 03:57 PM   #1110
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Default Initial listening impressions of the DAM1021-01.

Initial listening impressions of the DAM1021-01.

Disclaimer - I have only been listening to this dac for about an hour, at the most, and not very intensively. No A/B reference testing yet.
My test setup - Squeezebox Touch USB out->Amanero I2S->DAM1021-01 onboard xlr out->Questyle CMA800R solid state headphone amp->Audeze LCD-3 (non Fazor vers.) I consider my LCD-3 rather laid back, which I like. And I’m also normally a tube fan. So now you’re warned.

No distortion whatsoever on low level solo piano music (sustained notes) like my old unipolar r2r dac had.
Very detailed, as in micro details - quite unsuspected from this type of dac.
Sound is quite harsh to my ears - dac probably needs to settle and get some more hours to burn in. Only about 24 hours at the time of listening.
Very up front sound signature, forward, in-your-face picture. Not very relaxed. (Which I quite frankly hate).
Wiiiide sound stage. Not much going on center. Very left/right orientation w. some music, at times it sounds almost as something is a little bit out of fase. Sound coming almost from behind rather than in front.
Focus on upper mid and treble. Less bass and oomph. Which is why I at first didn’t bother to try it with my electrostatic Sennheiser HE60 & Stax hybrid amp, as these stats are focused on the mid- & upper region.
A short click is heard when changing between tracks w. different sample rate and the FIFO takes a while to settle thus cutting off the beginning of the track. Sometimes the FIFO makes the music fade in lasting 1 second or so.
Apart from this the timbre of the instruments sounds right w. some air/spacing between instruments. Seperation could be much better though, like r2r dacs normally present.

Okay, so just by chance I swapped in my Senn stats and the Stax amp that has a tube output stage. (balanced input).
Accidentally I played a rock music track by Beck from Guero album (a music genre that not normally suits the Senns IMO). Lo and behold. All of the above impressions didn’t apply anymore!
Frequency spectre was much more linear w. a bass punch I’ve seldom heard from this setup. Lovely airy separation between instruments, more holographic like the r2r’s I’m used to. More laid back presentation. Quite relaxed.
In short, the whole system was playing MUSIC. Effortlessly.

Is this a synergy thing? Shifting from dynamic headphones(speakers) and solid state to stats and tubes.

Still, it’s VERY early days but this dac definitely has got potential.

Is there a default filter selected? Default oversampling & upsampling?

Last edited by SebastianL; 28th January 2015 at 04:05 PM.
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