Wolfson WM8740 DIR9001 PCM2706 DIY DAC

[dtses]

you mean swapping quartz to dedicated clock? (pls see att.)
according to the scheme that would affect only usb input.

btw, I didn't change all stock resistors and film caps, hope that it's not so grave as elkos and regulators.

 

[cobretti]

DIR9001 receiver has actually built in clock. Never mind. That cheapo crystal you circled is probably OK for USB input in this application. I use my DAC with SPDIF connection primarily, feeding it straight from Xonar sound card instead of using USB as I did before. I think it sounds better that way. I am just lacking 192kHz sampling, that DAC can not handle.

 

[apoopoo999]

Here's some pics from a Azur 640C. It has 2 8740 in dual differential mode. It uses 6 NE5532. There are some little black SMD on the voutrp, voutlp, voutrn and voutln. Anyone have any ideas what these are for?

An externally hosted image should be here but it was not working when we last tested it.

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An externally hosted image should be here but it was not working when we last tested it.

Uploaded with ImageShack.us

An externally hosted image should be here but it was not working when we last tested it.

Uploaded with ImageShack.us

 

[cobretti]

Probably I/V stage input resistors.

 

[Antonside]

Hi everyone has someone get the circuit diagram of the DAC from the supplier ?

 

[Chii]

Hi all Ive just started building one of these too, i plan to build 2 long turm

The kit I have is a 1.5 version which has a larger crystal package being used unfortunatly the caps and other parts on this kit are fakes so I am pretty much ordering everything in from scratch.

I have a question about the rectifiers two of mine are shatterd will Schottky SR5100, 5 A 100V be ok for this role?

With thanks

Andy

 

[dtses]

Hi everyone has someone get the circuit diagram of the DAC from the supplier ?

I've got it from the seller, see 1st page.

Chii

you can use it, but that would be like overkill for power supply. I replaced stock fakes with fast 1N5819. Moreover they are like almost free.

Btw, where did you get 1.5 version? Could you please attach any pics?

2 all

I'm thinking about replacing all resistors with Dale 1% 1/4w and 4 in parallel per channel on the opams' output. How do you think, would that be a noticeable improvement?

The second upgrade should be shunt regulated PS instead of 7812 & 7912 regulators for opams, though not sure if I have space left for that...

 

[Chii]

Hi DTSES

eBay - The UK's Online Marketplace is the auction I got the kit from.

[image]
[/image][image]http://img03.taobaocdn.com/imgextra/i3/88221699/T24oJLXitbXXXXXXXX_!!88221699.jpg
[/image]http://img03.taobaocdn.com/imgextra/i3/88221699/T24oJLXitbXXXXXXXX_!!88221699.jpg

Shows the new layout, the Board it self is nicely made however everything exsept the IC's and resistors are questionable.

Thanks for the tip on the 1N5819 I orderd 100 as you said nearly free!

Once I have all the replacement parts I will post images of my kit at the moment its a but of a mess because I am changing what I can out for better parts.

 

[Antonside]

Ive got 1.5 version too. I replaced the diodes and regulators to originals and i ordered ELNA Cerafine caps from ebay but i afraid that they are fake too

 

[Chii]

At this point i have dale 1% resistors on order to put in instead of the ones supplied, Cerafines for the 1uf, 220uf and larger voltage 47uf, Oscons for the 47uf 16v. Rifa's for the 3300uf and all of the film caps are now WIMAs. Ive also changed the op amps out for a spare set of BB627BP's i had on the shelf.

I am hoping that this produces something that will challenge my modded delta 290's and alpha 9's to show what there capable of. If not it will be relegated to the media center in the bedroom.

 

[cobretti]

Ive got 1.5 version too. I replaced the diodes and regulators to originals and i ordered ELNA Cerafine caps from ebay but i afraid that they are fake too

May I ask where those caps are coming from? If they come from east, they might be (will be) most likely fakes as well. Why don't you use good Nichicon caps? Just a thought.

 

[Antonside]

They coming from china. Now i use nichicon capacitors in my dac but they can be fakes although they looks genuine they come with the kit.
Maybe some one know a good seler on ebay who sale original parts ?

 

[tornislv]

Since ELNAs from eBay are mostly fake, I switched to Panasonic, Sanyo, Rubycon and Nichicon, available from Farnell, Mouser and ELFA. With such suppliers you can always start a dispute about the quality and I haven't encountered counterfeit goods from these suppliers.

 

[cobretti]

Mouser, Digi-Key, Newark won't sell you fakes. If you can't buy from suppliers like these and let them ship it to you, then, I think it's better to find reputable local dealer instead of buying parts on eBay. I would never buy anything from China again, I have bad experience... not even kitchen knives.

 

[dtses]

hi,

found very interesting article how to improve standard LM317 regulator circuit. I wonder would it give any improvement with DAC's 7812 & 7912 regs

 

[cobretti]

Well, it depends what the existing noise looks like. As a matter of curiosity, I just measured my output stage (L7912ACV from ST , can not read the positive one) and I got 35uV of noise on both positive and negative rails. You would have to try the specific circuit for yourself and compare it if gives you any audible benefit. 35uV is low enough number for me, hence I will not try to do any mods. If you want a tip on a low noise regulator, I measured SSR01 from Sjostrom and it produces about 2.3uV (add some percentage +- for error) of noise. I used cheap OPA134 opamp in SSR01. I think if you put genuine regulators, not those like mine I received in the kit, you shouldn't worry too much. But on the other hand, I would love to hear feedback from some experiments.

 

[TheGimp]

Is anyone using both oscillators (22.5792MHz, and 24.576MHz) and muxing them?

 

[gfiandy]

I haven't done it with this set up but I have designed multiple clock systems in the past. If you want to do this I recommend creating a kill circuit for the clock you are not using as the ineraction between the two sees to be enough to cause audible degradation. Presumably by introducing decision threshold jitter.

Regards,
Andrew

 

[miklos]

Mouser, Digi-Key, Newark won't sell you fakes. If you can't buy from suppliers like these and let them ship it to you, then, I think it's better to find reputable local dealer instead of buying parts on eBay. I would never buy anything from China again, I have bad experience... not even kitchen knives.

That's interesting, considering everything you own comes from China

 

[dtses]

cheers,

I wonder how many people ordered and built this DAC?

It has one feature that needs to be improved for sure. I guess everybody experienced it. When you turn the power switch off, cracking noise comes from the analog output to the amp and it's quite annoying and even terrible on high volume. As I've understood it happens due to direct opamp output and some filter or muting circuit should be added, am I right?