Keep it! Its very good. I had one for many years. I gave it to a friend who finds it very nice in his system feeding a Goldmund pre that drives a Threshold gripping his Apogees.
It gets much better if you use a power cable with an RF filter. DPA sold those too for a purpose. I strongly recommend Audioquest NRG-2. Also an Audioquest 50 euro digital coax will help it a lot if you havent got something special already.
Mine was heavily upgraded also but it was a difficult task (DPA was the first SMD dac ever). I think that mr. DPA, Robert Watts (if I recall his name correctly) designs the highly regarded Chord digital gear now.
It gets much better if you use a power cable with an RF filter. DPA sold those too for a purpose. I strongly recommend Audioquest NRG-2. Also an Audioquest 50 euro digital coax will help it a lot if you havent got something special already.
Mine was heavily upgraded also but it was a difficult task (DPA was the first SMD dac ever). I think that mr. DPA, Robert Watts (if I recall his name correctly) designs the highly regarded Chord digital gear now.
I was ready to do it, but then I put it in a system vs an Audia Flight CDP, there it wasn't skinny and was far better. Then I saw a thread of how about its engineer had thorough answers about his component choices. Got it to a postproduction studio then. It was spot on again. After 15 days on power it gave much more flesh and balance. I put some vintage driver stage tubes in my 6L6GC amp. Much better. Then I took on my speakers, leveled down by 1dB a midhigh plateau that was great with Hi-End sources. Tell you something. The Benchmark was spot on all time. High End sources were contrived. I moved the digital in jumper to coax only, this gave some little more sweetness bypassing the front switch. So I left it to its own devices since I had many speaker projects on the line. I am convinced that it takes much time and care to genuinly improve on a DAC 1 without unbalancing it. I postponed tinkering it for the future when I will have much time and a very clear head.
Here are some pics of a DAC1 modded by empiricalaudio.com:
http://photo.head-fi.org/showphoto.php?photo=4983&size=big
I like the idea of improving power delivery to opamps, but I do not agree with how this was implemented above. As an example, the Nichicon 1000uf/25V after the 18V regulators, can be replaced with smaller black gates Nx 1000uf/25V, which can fit vertically. It would be interesting to discuss the pros and cons for the two groups of three caps used for "improving power delivery" to the opamps.
As an alternative, Chris Johnson from partsconnexion.com does not alter the schematics but suggests performance part replacement only: OPA627, black gates, and CREE SiC 4A 600V (zero recovery time rectifiers).
Today am am replacing the two opamps from the headphone amps with OPA627 and I will post the results.
Marin
http://photo.head-fi.org/showphoto.php?photo=4983&size=big
I like the idea of improving power delivery to opamps, but I do not agree with how this was implemented above. As an example, the Nichicon 1000uf/25V after the 18V regulators, can be replaced with smaller black gates Nx 1000uf/25V, which can fit vertically. It would be interesting to discuss the pros and cons for the two groups of three caps used for "improving power delivery" to the opamps.
As an alternative, Chris Johnson from partsconnexion.com does not alter the schematics but suggests performance part replacement only: OPA627, black gates, and CREE SiC 4A 600V (zero recovery time rectifiers).
Today am am replacing the two opamps from the headphone amps with OPA627 and I will post the results.
Marin
After replacing 2 opamps (in the headphone of DAC1) with 4 OPA627, three people noticed an improvement by using a pair of AKG K701 headphones. I would say the sound is more "liquid" with a better transient response (and not "thin" at all). I did not expect such a significant change since several opamps between the DAC and the headphone amp have not been replaced (yet).
As soon as I will receive the other parts (black gates and CREE CSD06060A), I will do the full replacement of 11 opamps, caps and rectifiers.
As soon as I will receive the other parts (black gates and CREE CSD06060A), I will do the full replacement of 11 opamps, caps and rectifiers.
Attached is a pic of the OPA627 mounted on browndog adapters in the headphone amp section of DAC1.
In the meantime I also found an article by autoengr in which he explains the principles that he uses for power delivery: http://www.positive-feedback.com/Issue15/modsnugent.htm
It would be interesting to discuss some of his (re)design choices, for example:
- why he chose the big 1000uf/50V immediately after the 18V regulators (instead of 330uf)? Maybe to recharge the smaller 100uf blackgate that he added? Any disadvantages?
- if his choices for opamp decoupling (3 caps) apply also to OPA627 (which seems to have a better on-chip power delivery)? I was thinking that a blackgate NX Hi-Q 0.1uf/50v is good enough (this is the approach used by audiocominternational.com) and, if only necessary, maybe add a 1nf poly for HF.
In the meantime I also found an article by autoengr in which he explains the principles that he uses for power delivery: http://www.positive-feedback.com/Issue15/modsnugent.htm
It would be interesting to discuss some of his (re)design choices, for example:
- why he chose the big 1000uf/50V immediately after the 18V regulators (instead of 330uf)? Maybe to recharge the smaller 100uf blackgate that he added? Any disadvantages?
- if his choices for opamp decoupling (3 caps) apply also to OPA627 (which seems to have a better on-chip power delivery)? I was thinking that a blackgate NX Hi-Q 0.1uf/50v is good enough (this is the approach used by audiocominternational.com) and, if only necessary, maybe add a 1nf poly for HF.
Attachments
I found answers to many of my questions in the following thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54009&perpage=10&pagenumber=1
Among others, Ray (6h5c) presents a list top opamps and a clever way to replace the .1uf ceramic decoupling caps with a pair consisting of a blackgate (47uf/25V PK fits nicely in DAC1) and a 0.1uf PPS (audioengr uses a bulky blue polypropylene). Additionally, audioengr uses a 5000pf polystyrene. I looked for a smaller alternative and the best one that I found is: http://www.alltronics.com/cgi-bin/item/04P005/12/0.0056uF-100V-Polystyrene-Pkg-of-12.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54009&perpage=10&pagenumber=1
Among others, Ray (6h5c) presents a list top opamps and a clever way to replace the .1uf ceramic decoupling caps with a pair consisting of a blackgate (47uf/25V PK fits nicely in DAC1) and a 0.1uf PPS (audioengr uses a bulky blue polypropylene). Additionally, audioengr uses a 5000pf polystyrene. I looked for a smaller alternative and the best one that I found is: http://www.alltronics.com/cgi-bin/item/04P005/12/0.0056uF-100V-Polystyrene-Pkg-of-12.
Dear,
We are an (commercial) modification company in the Netherlands, and this is how we modify the Benchmark DAC-1 included the (Guido) Tentlabs XO2 clock.
For questions and/or remarks any time. I'm more then willing and open to answer.
Here you can see an picture:
Our website is www.soundevolution.nl but all in dutch I'am sorry.
A couple of comments I can make already.
-Download the datasheet of the AD1853 D/A converter. The layout fromt he first 4 opamps after the D/A converter is identical to the datsheet in the DAC1.
If you don't use de DAC1 balancerd and as an preamp, take the output signal direct from the first half of the second dual opamp. The to way many opamps in de DAC1 degrade the resolution and performance, and that is so sad...
-Remove al the smd caps (triple bypassed) in the outputstage, and replace by a single blackgate 47uF nx hiq. Currently we designing a DC servo to deal with the last 200mV DC offset.
-Replace the XO clock with an Tentlanbs XO-2
-Increasse the capacitance pre the ruglators.
-Replace the 7805 that feeds the upsampler chip
-Replace the smd filter condensators in the feedbackloop of the opamps for wima MKP's
I strongly advice to replace the NE5532 I-V conversion opamps with two AD797's in a browndog adapter. Sound the best to my ears as I-V converter in this dac. Better then the current feedback AD811 etc.
Replace the second dual opamp with OPA627 withh browndog adapter (only the first half of the dual opamp) the second half leave it open and connect the input to the output on the browndog chip.
and so on and so on.
for specific questions any time.
Best regards,
Bas
We are an (commercial) modification company in the Netherlands, and this is how we modify the Benchmark DAC-1 included the (Guido) Tentlabs XO2 clock.
For questions and/or remarks any time. I'm more then willing and open to answer.
Here you can see an picture:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Our website is www.soundevolution.nl but all in dutch I'am sorry.
A couple of comments I can make already.
-Download the datasheet of the AD1853 D/A converter. The layout fromt he first 4 opamps after the D/A converter is identical to the datsheet in the DAC1.
If you don't use de DAC1 balancerd and as an preamp, take the output signal direct from the first half of the second dual opamp. The to way many opamps in de DAC1 degrade the resolution and performance, and that is so sad...
-Remove al the smd caps (triple bypassed) in the outputstage, and replace by a single blackgate 47uF nx hiq. Currently we designing a DC servo to deal with the last 200mV DC offset.
-Replace the XO clock with an Tentlanbs XO-2
-Increasse the capacitance pre the ruglators.
-Replace the 7805 that feeds the upsampler chip
-Replace the smd filter condensators in the feedbackloop of the opamps for wima MKP's
I strongly advice to replace the NE5532 I-V conversion opamps with two AD797's in a browndog adapter. Sound the best to my ears as I-V converter in this dac. Better then the current feedback AD811 etc.
Replace the second dual opamp with OPA627 withh browndog adapter (only the first half of the dual opamp) the second half leave it open and connect the input to the output on the browndog chip.
and so on and so on.
for specific questions any time.
Best regards,
Bas
salas said:
Dear Salas,
Wel I think it is not correct to mention prices here. My intension to write is not for commercial purposes but to share and to learn.
I can give a link to the PDF file of our re-design program. We have different options and prices. Even when it is in dutch the prices are clear. http://www.soundevolution.nl/mm/DAC1redesign.pdf
Offcourse for DIY-ers this is never be a good value for money. But for music lovers and audiophiles it is a great value for money.
DIY-ers don't bring theyr stuff to modifcation company's anyway
That's why I'm open to tell about the mods here. No secrets no guru stuff and no BeeBee ****! Best regards,
Bas
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