Consider building an Easy DAC

[lykkedk]

Hello.

For long, I have in mind, building a DAC, and now I think it's time.

The main reason, I would build it, is that I want to connect my Envy24HT Revolution 7.1 Sound Card, with S/PDIF out (Coaxial) to it for improving sound.
I would like to tell, that I own a SONY X55ES Cd-player too (Don't know if I can use a DAC with it) ?

I am completly new into DAC's, so I would like some guideline's.

Doe's some know an easy starter-DAC ?, a cheap one maybe ?, or a good website ?

Any help appreceated.

Jesper (lykkedk)

[lykkedk]

I find this layout, simpel enough, for me to make, but I am in little doubt if I read the schematic correct. Please look it throug, and write a comment.

I have put in purple line's. Are they correct ?

where is the G1 / G2 attached ??? , I can't see.

Peter Daniel's original schematic was found here
http://www.diyaudio.com/forums/attac...amp=1122133987

Thanx in advance...

[Brent Welke]

The NOS (Non Over Sampled) TDA1543 DACs are easy to build, easy because they have a low part count. Buy a kit and make it a fun experience.

Peter's DAC and my DAC (built on Peter's design) have had countless hours of tweaking to bring out the best sound.

If you use all the recommended parts then you have something wonderful. If you use your own choices of parts you loose years of experience. The recommended parts are a starting point, tweak from there is my recommendation.

SPDIF is a hard interface to get right. Using different cable, connectors and phase of the moon (not really, but you get my point) all seem to have an effect on sound quality. Since you are using a computer I recommend a USB DAC. The USB interface has none of these problems. I can tell you from experience it is very good.

You were wondering where the two grounds are connected. They are connected at the ground pin of the TDA1543 chip.

Before I added the USB interface to Peter's DAC I was using a Envy24 sound card with SPDIF out into one of Peter's early/prototype DACs.

Please post more questions if you have any.

[john65b]

I too have been considering a DAC for a separate project - a controller on a computer CD-rom using the Digital SPDIF out.

Got the CD-Rom controller working and have connected the CD-Rom Digital out to a basic DAC (a Yamaha Preamp) and works fine. Locks to the SPDIF with no problems. I have also played with teh analog outs of the CD-Rom, but am more interested in using the Digital outs...

I just want a nice DAC kit to couple to a Stepped attenuator in a separate enclosure for use on one of my many amps (UCD180, Gainclone, Tripath TA2020) and am torn between the Scott Nixon Basic DAC and the DIYParadise DAC kits (Monica II)....I beleive both are TDA1545 chipset...

Anyone have a opinion? They both should do fine for us DAC newbies who do not wish to spend a fortune on a DAC.

[Brent Welke]

My experience is that the passive I/V stage of the typical TDA1543 needs a buffer. For example the output of the I/V into a 50K pot and then off to a gainclone sounds lifeless. If a lower value pot like 25K or 10K is used the problem is even worse.

Many who are trying to go low cost will take this approach (I was one).

A buffer is required to get the best sound. Not all buffers work or sound good. A simple solution here is a unity gain opamp buffer. Being unity gain makes it easy to try it with and without the buffer to judge the difference it makes. OPA627 is my recommendation. It sounds great and is DIY friendly in this configuration.

I found that I could add a 50K pot between the DAC and OPA627 buffer with little or no negative affect in sound quality. The end result is that the buffer output can be directly(DC) connected to a poweramp or two. The output impedance becomes around 20R instead of the R value of the pot. This also helps with noise on interconnects as you can use 100R input to ground resistors at the amps.

See my schematic here (file to big to post)
http://resources.myaudiosystem.com/P...ith_OPA627.pdf

[lykkedk]

OK... Sound's great to me !

Your'e design, look's clean and neat to me that's really something i like

Just got some quistion's :

1. If I use your'e design, I have to use a USB soundcard right ?

2. I could just leave-out the pre-amp section, and plug it directly into my BoSoZ right ?

3. Maybe you have a parts list or PCB layout ?

4. If not I assume the Voltage-Regulator's must be something aka LM7805 ?

5. Any 'special' part's ?

[Brent Welke]

lykkedk: 1. If I use your design, I have to use a USB soundcard right ?

I think your question "Is this DAC USB input only?" This DAC has no SPDIF input, USB input only. See audiosector.com for a SPDIF version. The DAC is the soundcard. The computer must have a USB version 1.1 port or better (2.0) to work with the DAC.

2. I could just leave-out the pre-amp section, and plug it directly into my BoSoZ right ?

Yes. If you have a preamp already you would want to try it. In this case you would only build the DAC half of the board. The board has score lines you can snap the board in half. I have a feeling the OPA627 buffer will be even better then your BoSoZ. I think we would both like to know the answer to that question

3. Maybe you have a parts list or PCB layout ?

Yes. http://www.diyaudiosystem.com/Products/DAC/USB1543/bom/

4. If not I assume the Voltage-Regulator's must be something aka LM7805 ?

For the full DAC with Buffer there are 7 voltage regulators. 3 on the DAC side of the board. The TDA1543 runs at 8volts, the USB chip and clock run at 3.3 volts and the opamps (buffer) run at +/- 18 volts.

5. Any 'special' part's ?

Yes and no. Yes in that you should use them all as specified to get the best sound. The parts are all available on the Internet. The suppliers are Digikey, Mouser, Partsconnexion, Jaycarr, Hammond (if you use the big transformers). It sounds the best with a pair of 130VA transformers - believe it or not!

[lykkedk]

Thank you very much, for nice and clear answers!

I think I am misunderstanding things with USB and S/PDIF (sound-cards), I bellive that my soundcard :

http://www.m-audio.com/products/en_u...n71-focus.html

are not capable of delivering through USB
Therefore, I would like a S/PDIF input.

[andrew_whitham]

Have a look on Ebay. At the moment there's a seller in the US doing a kit form of either a USB or a SPDIF DAC could be a good starting point. Dont know how good they are but they 'look' pretty reasonable from the spec. Item number #9711525188

They arent NONOS like Brent's though (nice work there BTW )
I do have to wonder if it comes with the Nichicon caps & OPA627's though, or if the pictures are of a tweaked version.

BTW I think youre correct about your soundcard, looks like Coax digital output to me. But it wouldnt matter if you used a USB DAC

Hope thats useful

Andy

[lykkedk]

--> BTW I think youre correct about your soundcard, looks like Coax digital output to me. But it wouldnt matter if you used a USB DAC <--

? I don't understand

sorry