Experience with this DIY DAC ?

[be.audiophil]

Dear Fanz,

many thanks for your inspiration ...

... i´ve bought that DAC just for some experiments with an MUVID Internetradio and Streaming Client.

Yesterday i´ve been going the transformer way with a couple of Tamura ST-302358 600:600 Ohm transformes i´ve found in my stock.

Simply Wonderfull ... the sound became tremendously better. More room with more deepth and a great tonality ... the harshness of the original Board ist gone ...

Besides the Tamura tranies i´m using Allen Bradley resistors and Mullard mustard caps.

Thanx again.

 

[minniedog]

Hello,
I'm new to this so please be kind!

My kit arrived today and I fitted it in a old case, set all the switches and jumpers, turned on and all the LEDs lit up BUT got absolute silence.......

Can anyone see anything obvious from the pic?
The case is earthed but should the board be grounded from one of the corner "screw holes"?

Many thanks!

 

[McCrackers]

Is your power trafo is hooked up properly?
Are your inputs/outputs properly soldered to the board. The legs on these things are really cheap and can easily break when moved.
Have you tried it without the upsampling board? i.e. with four jumpers in place and switches set to non-upsampling mode. I had a defective US board on mine.
I can't see what else could be wrong.

 

[McCrackers]

One more thing - Are your selection jumpers set to the proper input(optical, coax)?

 

[minniedog]

Thanks for your advice it's much appreciated,

Checked the legs and soldering and they look fine. All switches double checked and fine. I'll try without the upsampling board tonight and give it another try.

Should the "ground" on the corners of the board be connected to the case?
The board is currently on plastic legs and isolated.

Thanks again

 

[McCrackers]

...
The board is currently on plastic legs and isolated...

That's OK

 

[Netdewt]

Also, what is the physical size of the board? What size chassis would it fit in?

 

[be.audiophil]

... the Tamuras i´ve used ...

 

[lbj]

Also, what is the physical size of the board? What size chassis would it fit in?

The board is about 7 x 5-1/4 x 1-3/4 inches. I don't know about a case, I'm personally going to screw it and the transformers onto a piece of wood.

Here are the pics of the power transformer connection off of the cd:

 

[Bill Fuss]

I used a 12x12x3 case from Parmetal. Not fancy but not bad.

 

[Franz Gysi]

Dear be.audiophil (Rolf?)

fine that you like it also!

Now, I recommend to connect a fine buffer circuit to the tamuras. For example a B1 with symmetrical PSU.

You will find better mids and bass, simply more body to the sound.

Greetings to Munich
Franz

 

[be.audiophil]

Dear Franz,

yes it´s me ... Rolf ...

Thanks for your recommendation concerning the buffer stage.

Currently I´m using a variation of the octal phono stage Thomas presented last year at the german RuH-Forum to accompany the so called "Forenamp". You know ... the amp Thomas an I presented and did the work with the kit for that.

You may have seen these reports over there and the thread how about i implemented the circuit into old cases from the german manufacturer Braun.

We implemented a full 6SN7 line stage in order to get a full working preamplifier with integrated phono. The output stage is transformer coupled, volume control is done with an TVC after the output stage.

The Line In goes directly via one cap to the getter of the tube.

In this case i think there is no need for an extra line buffer.

 

[pchw]

The big dac is up and playing, but it doesn't sound right.
There is some kind of crackling. My best description is that it is similar to the sound through a dirty pot or a speaker with broken surround/cone. There is no different whether I use the upsampling board or not. The dac is unmodified because I wanted to make sure the dac is fully function first.

I didn't see any that looked like cold joints. Any suggestion on what to look for?

Thanks,

 

[rhinomite]

Hi Michael,
If you are going to try the opamp output circuit you will need a power trafo similar to the one offered by the seller with 12-0-12 and 8-9v windings. If you do away with the opamp circuit all you need is a single 7-12VAC trafo. The load is less than 250ma on the digital side so you don't need anything big.

Many thanks for the advice Bill..I'm going to go with the upsampling board.

After digging around to try and understand the practical application of transformers and how to read their specs, I'm still having trouble working out what transformer is right for what job based on published specs. I'd appreciate if anyone can point out any good articles/background on transformers (mainly interpreting the specs)

For example for an R-core transformer for my DAC power supply, how do I decipher all these specs from http://diyclub.biz/catalog/product_i...products_id=55.. apparently R26-34 is the model to use?

R26-08 primary 115 X2 :0-32(0.67A)X2; 0-9-12(0.6A)
R26-09 primary 115 X2 :0-220(50mA)X2; 6.3(1A) X2
R26-10 primary 115 X2 :0-18(0.65A)X2; 0-9(1A)X2
R26-11 primary 115 X2 :0-12(0.78A)X2; 0-15(0.78A)X2
R26-14 primary 115 X2 :0-18(1A)X4
R26-16 primary 115 X2 :0-28X2; 0-35X2; 12-0-12
R26-22 primary 115 X2 :0-18(1.75A)X2
R26-24 primary 115 X2 :18-0-18; 0-9
R26-27 primary 115 X2 :0-35(0.27A)X2 0-42(0.27A)X2 12-0-12(0.27A)
R26-28 primary 115 X2 :0-12(1.2A)X2; 0-9(1.2A)X2
R26-29 primary 115 X2 :0-9 X3(1.11A); 9-0-9(1.1A)
R26-34 primary 115 X2 :0-9X2; 0-15X2
R26-42 primary 115 X2 :0-50-55(0.45A)X2
R26-51 primary 115 X2 :0-24X2; 0-9X2
R26-75 primary 115 X2 :0-20(0.5A); 0-4(0.5A).0-1(12A).0-9(1.5A)
R26-79 primary 115 X2 3.15-2.5-0-2.5-3.15)X2(3A); 0-12.6(1A); 0-5(2A)
R26-90 primary 115 X2 :0-165V(0.1A); 0-9V X2(1A)
R26-93 primary 115 X2 :0-9 X3 (1.5A)
R26-99 primary 115 X2 :18-0-18(0.2A); 0-9.5(0.7A); 0-10.5(2.5A)

? Sorry I feel like I'm slightly OT, but I'm itching to get to work on this DAC and the trannies are holding me up now...

 

[xTr3Me]

wow really a lot of people seem to have problems with the newer versions of the dac. im still waiting for mine since almost 10 days (since shipping from hongkong started).

i hope it arrives soon and in a good condition.. dont feel like wanting to send it back. shouldnt the seller check the dacs before shipping them? it would be nice if they would work when they finally arrive...

 

[be.audiophil]

wow really a lot of people seem to have problems with the newer versions of the dac.

... i got the version DAC3_V9 too ... and I´ve got no problems at all ...

... this pcb kit was fully functional ...

And this is what i´ve read due to the last 170 pages too ... nobody having really trouble with that pcb ;-)

 

[McCrackers]

@ rhinomite
I would have thought R26-28 would be the best choice. That's what I use. Or you could get a PWRC10V2A-1 and a PWRC12.6V1.5A-1 from Edcor. When you include the shipping costs there's not a big difference in price.

 

[lbj]

My kit arrived today and I fitted it in a old case, set all the switches and jumpers, turned on and all the LEDs lit up BUT got absolute silence.......

Hmm. I just fired up my board for the first time. Same story as minniedog, all the leds light, but no sound. V9 board. Tried optical and usb inputs, tried with and without the upsampling board. Could be a bad batch of boards?

 

[be.audiophil]

OK ... i´ve had some confusion with this input selector bridges ... play a little bit arround with this and you will get it working in seconds ... i´m using only one bridge over the pins ...

 

[minniedog]

Hmm. I just fired up my board for the first time. Same story as minniedog, all the leds light, but no sound. V9 board. Tried optical and usb inputs, tried with and without the upsampling board. Could be a bad batch of boards?

Done all that too and still silence. I'm giving it one last check over tonight and if I get no joy then the board goes back.

I get a 23V AC reading on the 15V input. Is that to be expected or does this imply something problematic?