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Soekris discrete R2R DAC?


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2nd DAM1021 build close to being complete, waiting for a 1-foot USB cable.

This one is with the DAM1021-12 board, the one the uses .01% and .02% resistors which can be visually identified by the blue resistors in the R-2R ladder. 

The TPA Cronus/Hermes re-clocking and isolator is probably an overkill here given the DAM1021 already provides both functions on the board. The power supply for the DAM1021 is based on TPS7A3301 set for 9.3VDC rails. Based on my experience I would not skimp on the PS for the DAM1021. The extra power supply is needed for the Cronus/Hermes. 

 

DAM1021-12.JPG

DAM1021-12 - 1.JPG

DAM1021-12 - 2.JPG

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The last part finally came in so here is the finished build.

I did run into a weird problem using the Cronus/Hermes/Amanero with this DAM1021 - the combo plays music through Audirvana fine but had serious dropout issues when playing YouTube and Amazon videos. I was able to find a few Amanero CPLD/CPU firmware combinations that seems to have addressed the issue. I started a thread over at DIYAUDIO on this topic. Right now I am using CPLD firmware "slave_for_1080" and CPU firmware "CPU_1099c".

Even though the DAM1021 has its own isolator and re-clocker I feel subjectively adding the Cronus/Hermes is an improvement over using Amanero alone.

  

DAM1021-12 - front.JPG

DAM1021-12 - rear.JPG

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^ Starting to get interested in these myself. I know you were getting some of the buffers for something Michael, but had you thought about using a ubal board for the balanced on the DAM1021 instead of the opamps Soekeris is using?

Also, did you have any luck finding a Mac serial cable (USB->serial)? I thought it was for dealing with the DAM1021?

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Ordered a USB - serial cable but have not received it after several weeks so have not tried configuring the filter files etc. using a Mac yet.

Also have not tried the diamond buffer nor the unbal-bal with the DAM1021 yet. I built this DAC for my son to use at school with the single-ended Dynalo so really not intend to max it out. Although I will likely be exerimenting with it.

I personally did not find the OP based balanced output as bad as some have made it out to be on the web. 

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would love to test this vs a TPA Buffalo III or pro.  I listened to the yggdrasil at canjam and it didn't wow me but can't vouch for source material and the headphones were Audeze LCD-3 I think then switched to some Mr speakers model.  I think the amp was the ragnarok

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  • 8 months later...
  • 2 years later...
  • 6 months later...
On 7/19/2021 at 8:40 PM, starcat said:

Anyone managed to build the fully balanced dam1941 version? How is the sound and filters available? 

Just finished today with the raw version, case and final cables are left for later.

Soekris PSU and buffer boards. The designed Amgis transformer was not on stock, so I had to replace it with a 2x6V Toroid. 'm using OPA1602 now, but will switch to OPA1612 when they arrive. Have not yet finished the controll board, although I'm not sure I will.

The sound is very similar to the dac2541, definitely better than the RME ADI2FS or other similar quality DS based DACs. More spacious and detailed. I think it even bests the Qutest, although it was a while I listened to it the last time. Can only recommend!

Soekris dam1941.jpg

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  • 2 weeks later...
On 2/6/2022 at 11:59 PM, JGergo said:

Just finished today with the raw version, case and final cables are left for later.

Soekris PSU and buffer boards. The designed Amgis transformer was not on stock, so I had to replace it with a 2x6V Toroid. 'm using OPA1602 now, but will switch to OPA1612 when they arrive. Have not yet finished the controll board, although I'm not sure I will.

The sound is very similar to the dac2541, definitely better than the RME ADI2FS or other similar quality DS based DACs. More spacious and detailed. I think it even bests the Qutest, although it was a while I listened to it the last time. Can only recommend!

Soekris dam1941.jpg

Looks very nice! 

The GRLV might make a better power supply, maybe something to upgrade later to.

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11 hours ago, audiostar said:

Looks very nice! 

The GRLV might make a better power supply, maybe something to upgrade later to.

 

Thank you!

As the boards were only 30EUR and only few parts needed, I thought that it should be able to run ASAP and will upgrade/change elements later.

I'm working on both the KGLV and a Walton-Didden Supperregulator to be able to compare them. :)

Edited by JGergo
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  • 1 month later...
9 hours ago, Pars said:

Oh, the SINAD crowd... I'll pass. Let me guess, Topping won?

 

Not really, the Soekris does pretty well. I'm guessing that having more HD than other models, but without noticeable inharmonic distortion would help to make its sound more "natural" whatever that means.

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It seems if I recall correctly that when he reviewed one of Kevin's estat amps (KGSS, Carbon, I forget) that he didn't set the AP analyzer up correctly, and bristled when Kevin called him out on it.

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It was one of the Stax amps and he measured it as if it were a dynamic unit.  When puzzled by the sheer stupidity of his findings he said he couldn't believe people thought this sounded good.  Two things there that spring to mind, not listening at all and the sheer lack of technical know how needed to pull something like this off. 

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amir using his AP measured the koss amp directly which promptly went into power supply overload at about 100 volts into the 100k input impedance of the AP. then he measured one of the stax tube amps and came up with equally useless graphs. refusing to build an input attenuator he continues to believe in his measurements.

if he had tried to measure a kgsshv-carbon without an input attenuator he would have blown the AP to crap, as the kgsshv-carbon is more than happy to put 900 volts peak to peak stator to ground into a 100k load.

amir is as i have said before is just another idiot with an AP. and continues to find a way to represent an amplifier as 1 single number. which purrin has correctly labeled as amirNAD.

simmconn on the other hand did correctly build a 10x attenuator and has been measuring and posting graphs. and knows what he is doing.

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Thank you, Dr. Gilmore. Given the background of amir (mid-high level on the corp ladder at M$), I wouldn't expect him to be as hands-on as the lab monkeys who spend most of their days with an AP. In an earlier post on that site I saw him struggling with setting up the AP to measure the deviation from RIAA of a phono pre-amp. Apparently he's never done that before and just like many of us, don't want to read the manual. Everyone has his/her limitations and comfort zones that takes some courage and effort to step out of.

To give this guy some credit, he is able to measure the conventional gears in a consistent way, disclose the data and offer some objective comparisons/analysis, at no cost to everyone who is interested. That alone is worth some praise. Besides, some data is better than no data.

When it comes to discrete R2R DAC, what intrigues me is that most designs use generic logic chips to drive the resistors. No matter how well the resistors are matched, the driver chips are not. No manufactures would specify or production-test the matching of a 10 cent bus driver, bit-to-bit or part-to-part. Parts coming from the same batch could be from the same wafer and perform somewhat close to each other, but there is no guarantee. The end result is therefore pretty much on a 'best of luck' basis.

Edited by simmconn
Die->wafer
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i've been saying that the switches in a r2r dac were a real problem for many years now. especially the ttl versions.

the teac ud-701n is the cheapest ($4k) of the esoteric dacs that use custom and hand matched switches. I expect that better switches will be the new big deal in the next couple of years.

 

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