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Old 9th July 2006, 06:46 PM   #1
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Default Building a Dddac questions?

I was planning on getting the USB DAC with 12 stacked dac chips. I have a Odyssey Stratos amp with 47k input impedance. I was wondering the best way to output from the DDdac to the amp. I would prefer just using a pot instead of a buffer but will that work. Also a question does anyone have a design for a good power supply for these units or should I just run it off of a battery. Will the power supply effect sound quality? Thanks.
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Old 10th July 2006, 12:12 PM   #2
ssmith is offline ssmith  France
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Default Re: Building a Dddac questions?

Quote:
Originally posted by excetara2
I was planning on getting the USB DAC with 12 stacked dac chips.
I just ordered one -- a 24 chip version assembled by Deode (not confident in my soldering skills!)

Quote:
Originally posted by excetara2
I have a Odyssey Stratos amp with 47k input impedance. I was wondering the best way to output from the DDdac to the amp. I would prefer just using a pot instead of a buffer but will that work.
Not sure myself. Doede told me that the output impedance for the 24-DAC version is 90 Ohm. Output Vrms is 1.6v. In my setup, I've also ordered a
Tubalizer buffer stage to put immediately after the DAC's output, but will experiment.
Suggest you mail Doede directly. He's very quick in answering (a noob myself, I asked lots of stupid questions, to which he replied fully and concluded "no stupid questions, only stupid answers I always say".
Sorry can't help you much on this.

Quote:
Originally posted by excetara2
Also a question does anyone have a design for a good power supply for these units or should I just run it off of a battery. Will the power supply effect sound quality? Thanks.
I've decided to put the Dac in one box and the power supply in another. In another box I'll put a battery and charge set-up. That way I can switch between both (in case of power cuts). For the mains power supply, I'm going for a 12v out switching power supply, and will experiment with caps on its output.

Do check out this site for pictures of implementation and interesting comments on power supply.
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Old 10th July 2006, 11:50 PM   #3
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Why did you decide on the 24 over the 12? I will ask him about the second question. Are you going to use a battery or build one of the power supplys on the site. I think I am going to build that linear power supply to power it. It sounds like a linear and battery power supply sound the same to him. I will probably also try a battery. Now have to decide on one DAC chip or two. Also the best way to output it to the amp. Thanks a lot.
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Old 11th July 2006, 12:19 AM   #4
phn is offline phn  Sweden
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I'm not butting in here to tell you what to do. But the highly regarded and higher priced 47 Labs Progression DAC has only one TDA1543 IC.

Doede Douma explains the use of multi-ICs on his website.
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Old 11th July 2006, 01:07 AM   #5
protos is offline protos  Greece
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Quote:
Originally posted by phn
I'm not butting in here to tell you what to do. But the highly regarded and higher priced 47 Labs Progression DAC has only one TDA1543 IC.

Doede Douma explains the use of multi-ICs on his website.
What is your point phn?
If you have heard multi-ic vs one chip versions you should just offer your impression, otherwise your statement is a bit confusing.

In my system with aleph x amps the original dddac mk1 works reasonably well with a passive pot but dynamics are definitely down so in this context not recommended.
Now driving my 300b set amp with it's high impedance 50k input pot is ok.Ditto for the myref rev.c chip amp but this has a pretty high impedance and good voltage gain stage .So it is difficult to say.Normally a high impedance low capacitance amp input stage should be no problem for the dddac.
As to the power supply the best ps is to my ears Andy Weekes version of the supereg ps (search the forum for this), next is batteries and then the rest.The ps can make quite a big difference to the final sound quality.
To my ears the dddac is even preferable to my Perpetual Technologies P1a-P3a-ps combo (modified with opa 627 + freds+ black gates) which had reviewers drooling a few years ago.
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Old 11th July 2006, 01:44 AM   #6
phn is offline phn  Sweden
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I thought my point was pretty obvious. That is, you can evidently get good result with just one chip. On the other hand, multiple chips do produce higher resolution. DIYers tend to go with the latter. My point is that there is an alternative to stacking chips, some reportedly go as far as 64! In the end, only the original poster can decide what he likes.

Of course, I could have mentioned that most mass-market CDs have less than 14 bits. 12 chips are enough for that. But, again, what is enough is not for me to decide.
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Old 11th July 2006, 01:53 AM   #7
protos is offline protos  Greece
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Well,ok.
I don't think anybody doubts that there one chip nos dacs that may sound very good.However it is always helpful to members not to state something mundane and obvious but to offer some personal insight or private experience on the matter of e.g. one chip vs multi-chip dacs.As the thread starter is referring to a specific dac it would be helpful if you had some concrete opinions on its sound and function vs other similar units.
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Old 11th July 2006, 02:50 AM   #8
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Protos what version do you have? Do you have the 24 or 12? I think I am just going to go with 12 for now. See how I like it. I will look up that power supply. I may just go with batteries.
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Old 11th July 2006, 06:54 AM   #9
ssmith is offline ssmith  France
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To be honest, I decided to go with the 24 chip version because my budget would stretch that far. In terms of price/performance, my guess is that the 12 and 24 options are probably the best. I would have been happy with the 12, but my budget could stretch to the 24. There you go, not very scientific I'm afraid. I only ordered the usb for input.

For the PS, I'm planning on using a three-box solution: one box for the DAC, one for a switching supply, and one for a battery/charger.
Like this I will be able to easily compare battery with the SMPS. Also, India has alot of power cuts, so I can use battery when needed but have the convenience of an SMPS too.

The Andy Weekes version of the supereg ps (I immediatel searched the forum) looks too complicated for me....
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Old 11th July 2006, 01:43 PM   #10
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Yeah, I think I am just getting the twelve USB version. Thanks for the advice. I am going to go with the super regulator. Know all I have to figure out is whether I can use a pot with my amp or I need a buffer stage/pre-amp. Thanks.

-Jeff
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