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Old 31st August 2008, 01:51 PM   #1
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Default DA24QS DAC build

Hi all

I'm opening this thread to document my attempt to build a DA24QS DAC. I'm starting with the DA24QS PCB and then I'll source parts from US sources.

I've chosen this project because Ewe has actually has PCB's available, I like the CS4398, and everything most is through hole. I have a hard time with SMT, I don't care what folks say.

I'd appreciate it if folks limit their commentary to constructive criticism directly relative to the build process. I know there are better DACs out there, but this one seems interesting to me.

First task is sourcing the parts on the BOM from suppliers in the US. One of the tougher parts is the Toshiba TORX147PL. Digi-key has them on order for October 2008. I've ordered two along with the LM4562, even though I may not use either. Most everything can be had from cheaper. I'll post my preliminary BOM once I get that settled.

I do intend to use fancy resistors and caps on the output's signal path, but I haven't settled on anything yet. I'm hoping to use Nichicon KZ's for the electrolytics which I can source from Handmade Electronics but they may be too chunky for the job. The opamps may be swapped out for something else.

Stay tuned
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Old 29th September 2008, 05:27 PM   #2
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Digi-key has the Toshiba TORX147PL(F,T) in stock! I got two. Get 'em while you can.

I also got a EPM3064ALC44-10N just in case the pre-programmed one I got has problems. I suspect sensitive parts are getting fried by my local postal service, but I have no proof aside from a collection of dead opamps and tripath chips that didn't survive shipping.

Finally I picked up a LM4562NA opamp from digi-key even though I'll likely use a pair of OPA602's instead.

Digi-key part numbers:
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Old 29th September 2008, 05:44 PM   #3
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Here's a list of parts to get from Mouser. I still need to add appropriate ceramic capacitors, but I need to see what I've got about in my stash first. My selection of resistors is a bit helter-skelter, but I figure as long as the values are correct, I could care less about the manufacturer. I may have some that I can use from my own stash too. I've highlighted in red parts that I need to verify as being suitable.

Crystals CMOS Clock Osc 4Pad +/-50ppm 0/70C,Tri-State 25MHz

SIP Conformal Coated Resistor Networks 5pins 47Kohms Bussed

SIP Conformal Coated Resistor Networks 9pins 220ohms Bussed

Metal Film Resistors 1/2Watt 100ohms 1% SFR25H Series

1/4W, 1/2W and 1W Precision Metal Film Resistors 1/4 W 10 Ohm

1/2W 1% Metal Film Resistors 180ohms 1% 50PPM

Metal Film Resistors 1/2Watt 1Kohms 1% SFR25H Series

1/4WATT Metal Film Resistors 1/4watt 1.3Kohms 1% Rated to

1/4WATT Metal Film Resistors 1/4watt 1.5Kohms 1% Rated to

1/2W 1% Metal Film Resistors 1.54Kohms 1% 50PPM

1/4WATT Metal Film Resistors 1/4watt 2Kohms 1% Rated to 1/2watt

1/4Watt Metal Film Resistors 1/4W 300 ohm 1%

1/4Watt Metal Film Resistors 1/4W 33 ohm 1%

1/4Watt Metal Film Resistors 1/4W 3K ohm 1%

1/4W 1% Metal Film Resistors 430ohms 1% 50PPM

1/4Watt Metal Film Resistors 4.7K 1% 100PPM

1/4Watt Metal Film Resistors 1/4W 510 ohm 1%

1/4Watt Metal Film Resistors 620ohm 1% 100PPM

1/4W 1% Metal Film Resistors 75ohms 1% 50PPM

1/4W 1% Metal Film Resistors 82ohms 1% 50PPM

Diodes- Schottky 1A 20V

Standard LEDs Green Tint Diffused

tandard LEDs Red Tinted Diffused

Standard LEDs Yellow Tint Diffused

Regulators - Non-Isolated Switching DC/DC Bipolar Regulated V


Voltage References Adj Shunt

Regulators - Standard 5V, 100mA Fixed Pos Voltage Regulator

Transformers CHOKES

Small Signal Transistors TO-92 NPN GP AMP

Small Signal Transistors TO-92 PNP GP AMP

Converters - Digital to Analog (DAC) Stereo Multi-Bit DAC
192kHz, 120dB w/VC

Audio Interface 192kHz Digital Audio Receiver
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Old 29th September 2008, 06:12 PM   #4
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I didn't add any electrolytic capacitors yet. I have some Nichicon Muse ES 10uF 50v's that I'll like to use. They're a tight fit, but they do fit in some places. I need to double check that. The leads on the Nichicon Muse KZ's are too chunky so they're a no-go. That and I've got all sorts of little Panasonics about and I'm not above transplanting good parts from dead electronics.

Capacitors 4.1, 4.2, 5.1, and 5.2 likely will have the most effect on sound and this is where I was hoping to use the KZ's. A film capacitor would be ideal, but finding something 100uF that is a reasonable size may be tricky.

I also need to part out a 8-dip socket so I can roll op-amps.

I could get real fancy and replace the op-amp stage with a tube stage instead! Heaven knows I've got the parts, but that could complicate things more than I'm ready for.
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Old 19th October 2008, 11:27 PM   #5
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Hi White Lab Rat !!!

How is your project going ? I just received a Beis AD24QS Circuit Board which I will be working on. My quest is to use the best parts possible to keep the sound as pure as possible when it converts the digital to signal.

I would like to convert the signal to 192 kHz through the Toslink if possible.

Let me know how it goes.

Thanks much !

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Old 20th October 2008, 02:37 AM   #6
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I'm taking it real slow. Probably the most important thing is getting the Toshiba TORX147PL which can be hard to source. Digi-key had them last time I checked. That and you'll have to program the EPM3064ALC44-10N.

It would seem that the only place you'll get any improvement is on the output stage. I don't think you'll get great results replacing every bit with fancy parts. The output stage will likely yield decent results. The opamp will likely make the biggest difference.

You could get real wild and modify the output to a transformer coupled output.

I don't see myself making any progress anytime soon. I hope to buy most of the parts by January.
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Old 20th October 2008, 02:05 PM   #7
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I am in the same boat as you are. I want to source all the parts. I am in the middle of a speaker upgrade (upgrading caps). Will be updating those slowly.

I cant imagine getting fancy with small components such as resistors and diodes. They are so small that I cannot imagine they would make a difference going with something fancy. I may try it with the caps - may go with Black Gates on the electrolytics. I would love to know if there is a substitute electrolytic cap equivalent for audio quality since I heard BG is now out of production.

If you have any suggestions on improvements, I would love to hear them.

Thanks much !

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Old 20th October 2008, 02:46 PM   #8
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It would appear that C4.1, C4.2, C5.1, and C5.2 and IC 3.3a and 3.3b will most effect sound. I think that those caps are part of a filter to cut off frequencies above 97khz according to the schematic. There may be opportunity to tweak that.

I was hoping to use Nichicon KZ's at those positions but the leads won't fit in the holes. I tried. So be careful. I don't see why you couldn't use non-poloarized caps here. Avoid the balance output stage if possible.

If I can get away with using a smaller value cap in place of the 100uf then a film cap becomes more possible. Black Gates may be good, but even a cheap film cap may be even better. A 100uf film cap isn't reasonable though so I may change the value.
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Old 23rd January 2009, 12:52 AM   #9
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I've finally begun to stuff the board. So far so good. After I got the SMD bits on I put in the resistors for the output section. I used PRP's where I could find the right values, an then cheap metal films otherwise.

I'm perhaps getting a bit carried away with the snakeoil, but I picked up a pair of Blackgate F's and then I realized I needed four. Too pricey to buy just another two, so I ordered a whole set of Elna Certifine caps, and a set of Similic II's. I'll use them all, but I'm not sure where yet. I also got a bunch of Nichicon ES's for other places on the board.

The RCA plugs will likely be off-board, along with the input selector. I just couldn't find the right parts from a single source.
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File Type: jpg dac_start.jpg (76.8 KB, 669 views)
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Old 23rd January 2009, 02:36 AM   #10
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Looks good so far. I may use PRP resistors, or maybe even Mills, but the Mills are bigger, are in 5 and 12 watt versions, and cost 5 ot 10 times the cost of PRPs. Maybe I will stick with PRPs as they are reliable resistors.

I purchased the board months ago, but have yet to start on that project. I am trying to complete other projects before starting wiht this one, which I need to start soon.

Think about using copper core RCA Connectors. I have used Vampire Wire CM2F/CB with fabulous results !

Good luck whitelab rat !!!
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