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

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#2,101
nige2000 said:
what r would u use ?

would think ps will have more influence than r tolerances
available
Click to expand...

The cheapest wirewound that I (we) can find! 😀 at least on most important sites...
More important than tolerances are noise figures per C°.

This has two sides: noise performance per se and T° raise of the unit.
As dear Simon has cleverly exposed, we have to think about other negative influences, like vibration and T° raise. In another thread I have also asked about this topic: oil? wax? epoxi?

I personally always use Dammar varnish with graphite powder on top of digital chips, but, hey, that's me :spin: ...some vibration damping they achieve...

Best wishes,
M
 
#2,103
Hi,
The sound of the Soekris DAC is really amazing.
Especially the totalCRaP_rev2.skr.zip filter sounds best with my electronic.
But my Aleph-X Amp needs balanced input for best sounding.
Both buffered outputs of the DAM are sounding bad compared to the native R2R Out.
Because of this I need a dual mono build of the DAM

When will it be possible to configure dual mono (one board for left channel and one board for right channel signal output) ?

Thanks!
Horst
 
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#2,117
Salomon said:
I think we will get it.
Look there:
#462
#828 3) Cascading for balanced use
Click to expand...

Yes, still waiting for the feature... was myself looking yesterday into DSP world to figure wether I could achieving such a feature without much drawback in the digital domain before hooking up to the DAM1021... then I saw price & complexity, and then I decided than it was more reasonable to wait again 😛

For pure discrete balancing stage: I had the idea that Nelson Pass universal gain stage with Supersymmetry©®™ 🙂D) could be a good candidate to balance & buffer signal in the analog domain while avoiding opamp. It could be used with 1.5x gain to provide standard output voltage. unfortunatly, best double jfets (2SK389BL & 2SJ109BL) for UGS are hard to find, pricy, and of course, there are many fakes around.
 
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#2,118
I compiled some data on the voltage levels related to the resolution bits.
dB table.png
From that it looks like there are "only" 21-22 bits above the noise level of the DAM at 20 kHz bandwidth (which nearly is identical to the thermal (Johnson Nyqvist) noise that we have from the 650 Ohms of the DAC ladder at that bandwidth ... which is not avoidable).

So what are the benefits of 28 bits of resolution? That's not a rhetorical question, I do not rule out that the 28 bits are good for something, I currently only don't see for what.
 
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#2,120
leehan said:
1. Try with Zterm version 1.2 first because Paul has already provided necessary steps in detail: ZTerm
2. Make sure ZTerm can detect "usbserial" port. This requires proper installation of the driver (follow the links in my post about driver installation).
3. Setup a profile for the DAC as stated by Paul.
4. Power off the DAC and connect serial port cable to mac
5. Power up DAC, ZTerm will connect to automatically
6. Send "+++" command, wait for 1 sec and a menu will appear
7. Upload the firmware as stated by Paul & Soren
8. Disconnect serial cable and power off DAC (full power cycle)
9. Connect serial cable and power on DAC
10. If you enter uManager again, it should show the new firmware version 0.90. Don't confuse it with hardware version which is 0.80.

I can also perform the same operation with Serial app as well (I didn't do a full power cycle initially and the firmware version didn't advance with my first attempt with ZTerm, then I tried with Serial, same thing happened but this time I reconnect both serial and power cable and it worked).

Cheers.
Click to expand...

Thanks leehan,

I did:
- install serials driver (I bought usbserial PL2303 as your)
- setup profile as Paul instructed
- connect adapter, power the DAC off and on as you instructed
- make dial

I guess everything is fine when I see the Mac already received some thing from DAC because when initiate I2S, or I play song: there are some "words" display on terminal. Same when I power on the DAC.
Problem is when I type "+++", there is no respond from DAC, even I wait for 5 min. I already tried with another Mac (Maverick) the result exactly the same.

Please have some advice, thanks a lot! 🙂

PS: I took a photo of how I connect usbserial adapter: I only use 3 wire:
- Black: GND
- White: RXD
- Green: TXD
- Red - not use: Vcc
And I already make cross wire as Paul and you instructed!
 

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