New HQ DIY DAC

[jeffc]

Chris,

Hang on your Cricket PCB spares, you might need one to try the CVXO. I'm quite proud of my p-to-p ones anyway and they seem to work fine. Before I reassemble everything in the case though, I might swap out the 4.7uf BG NP caps for tantalums, which are probably more appropriate anyway and I can then use the BGs elsewhere.

cheers.. jeffc

[Deleted]

Right you are Jeff.

Your case sounds like it's going to be the biz, I look forward to seeing that

I'm still umming and arrring over whether to go for "as compact as possible" in a case of my own making (a la SCHA) or buy in something like a 2u rack chassis as I'll probably go that route for the A Class....


I have to add that the DAC in it's latest guise is sounding superb, I think my Meridian's DAC will finally have to abdicate!

[Deleted]

I have to add that the DAC in it's latest guise is sounding superb, I think my Meridian's DAC will finally have to abdicate!

Hi Chris
It's good to see that it is now performing so well.
It's a far cry from the performance of the original basic design,
isn't it ?
Once again, it shows that power supply is everything, irrespective of whether it's with amplifiers or dacs, digital or analogue.
One day even the original sceptics will realise that power supply is every bit as important for digital too.
To further illustrate that, one day you may wish to try a Paul Hynes 3.3V regulator for the Input PCB.
In my own build it wasn't an earth shattering difference, but it was clearly a further worthwhile improvement.
If only, they weren't so damn expensive! A lower power DIY reg with performance almost as good, that was also a similar size to the PH regs would be nice, wouldn't it ? Especially if it was compatible with a 78XX type pin-out. (The PH 3.3V reg that I am using, isn't.)
A challenge worthy of someone like Frans perhaps ?
Alex

[jeffc]

Hi Chris,

My modified SC-DAC has been compared to a Meridian G07 too and even with different digital cables having quite an influence on SQ, 4 pairs of ears all thought the SC-DAC to be more transparent, liquid, musical, involving and ultimately enjoyable. More vibrant and alive as you've already discovered. I'm not sure how my DAC casing will go, but whatever, I'm going to try and make it as solid and resistant to vibrations as I can.

Alex, you know I've been looking at the Belleson regs for digital supplies as they come as drop in replacements for either LMXXX or 78XX IC regulators, but bugger they are as bloody expensive if not more so than PH's regs. They have good specs though and I'm very tempted, someone stop me please .

www.belleson.com/techdetails.php

cheers.. jeffc

[Deleted]

I've been looking at the Belleson regs for digital supplies as they come as drop in replacements for either LMXXX or 78XX IC regulators, but bugger they are as bloody expensive if not more so than PH's regs. They have good specs though and I'm very tempted, someone stop me please .http://www.belleson.com/techdetails.php

Hi Jeff
Hang fire a little, and see if you can find any comparison tests about them from the more tech type forums .
I think David2vk was interested in those ?
Alex

[Deleted]

4 pairs of ears all thought the SC-DAC to be more transparent, liquid, musical, involving and ultimately enjoyable.

Jeff,

I reckon that's it in a nutshell (I was comparing to 506.24)

3.3V regulator... A challenge worthy of someone like Frans perhaps ?

x2!

Subtle Alex, I like your style ;D

[jeffc]

Hi Chris,

I’ve had my SC-DAC in its new home since last weekend but have been too slack to unhook it to take it outside into better light to get a photo of it finished, will try and get to this tomorrow, and too busy listening to it as it sounds even better now its cased up.

Boards mounted to 5 mm think aluminium with 3M 2552 tape damping under the PCBs. Case bottom and top damped with Flash Tack bituminized aluminium sheets (stuff my son had left over from is plumbing days), plus blue masking tape at edges to cushion the top/bottom from the side panels, just to go OTT, and to go even more OTT wool felt pads placed between the case bottom plate and the 5 mm plate holding the boards. Flash Tack pieces also added to all 4 side panels, but I’ll need pics of it completed to show these.

Aim of all this: make it as solid and resilient to vibrations as possible.

A few pics, will explain more tomorrow, and Alex no questions about those tall capacitors on that dual +ve JLH. And those with eagle eyes will note the use of 3 incarnations of JLH PCBs

Case top and bottom panels

Case bottom panel showing positioning of the wool felt pads

Case bottom plate with mezzanine plate containing the PCBs fixed by 8 x 10 mm stand-offs


cheers.. jeffc

[Deleted]

and too busy listening to it as it sounds even better now its cased up.

Must be a Placebo, or "expectation bias" thing ! ;D

[jeffc]

Must be a Placebo, or "expectation bias" thing !

Maybe....... but I genuinely think it is sounding better, at least it was until this morning after I stuck some small pieces of 3M tape to the tops of the I/V OPA134 opamps on a whim. As you know, I also made a few parts changes and additions whilst everything was in pieces and these might have helped improve SQ .

And in any case, placebo or not, I don't give a shite, after all the piddling about to get the DAC in a case finally, I'm just glad to have something that looks like a piece of audio gear rather than a rats nest of wire and PCBs stuffed with electronics parts.

cheers.. jeffc

[Deleted]

Hi Jeff
Rest easy. It was only a sly dig at the dynamic Duo
Alex
Goodnight from Sydney Au. !

[lark]

Jun 18, 2011 10:56:57 GMT @sandyk said:

Must be a Placebo, or "expectation bias" thing ! ;D

[Deleted]

Sept 16, 2010 8:50:36 GMT @gregerskine said:

Hi all,

I have decided to join in !! I picked up an Altronics kit today.

Don't tell Alex, he might think I was impressed with his when I heard it a couple of weeks ago.

regards

Well, in record time, I finished a project. ;D

A couple of weeks ago I finished building this SC DAC, stock standard to start with. I have been running it in using my Squeezebox Duet.

Results: It works fine, but my initial impressions is it is only on par with the internal Squeezebox DAC.

Alex, has Dave finished his? I would like to get together to compare the standard SC DAC with the modded SC DACs before I start doing the mods. I have an additional PSU and numerous JLH ripple eaters ready to go, and one of Will's AK Cricket PCBs.

regards

[Deleted]

has Dave finished his? I would like to get together to compare the standard SC DAC with the modded SC DACs before I start doing the mods. I have an additional PSU and numerous JLH ripple eaters ready to go, and one of Will's AK Cricket PCBs.

Hi Greg
I have sent a copy of your post to david2vk
Hopefully, he will reply to your post.
Alex

[Deleted]

Jul 15, 2011 7:39:40 GMT @sandyk said:

Hi Greg
I have sent a copy of your post to david2vk
Hopefully, he will reply to your post.
Alex

Thanks Alex,

It would be interesting to hear Dave's 2 SC DACs, your modified one and my stock standard one in one listening session. Are there any others in the Sydney area?

regards

[Deleted]

Jul 16, 2011 2:25:10 GMT @gregerskine said:

Jul 15, 2011 7:39:40 GMT @sandyk said:

Hi Greg
I have sent a copy of your post to david2vk
Hopefully, he will reply to your post.
Alex

Thanks Alex,

It would be interesting to hear Dave's 2 SC DACs, your modified one and my stock standard one in one listening session. Are there any others in the Sydney area?

regards

Greg
Alfred has one, and Allan has one recently completed.
Don't forget that you heard mine at the most recent listening session.
The original SC design wouldn't have even come close to what we heard that day.Originally, mine was very mediocre and a little on the dull side, and not really better than either of my DVD players.The only recent change to mine has been fitting a Paul Hynes 3.3V regulator (thanks Syd !) in place of the half Cricket supplying the Input PCB. (DIR9001 etc.)
Alex

[Deleted]

Hi Alex,

The brand new JLH ripple eater installed on the 15-0-15 supply. OMFG, I am having trouble comprehending the vast improvement. It must be the power of suggestion or some other voodoo going on here.

Anyway, more testing required to prove I am not just imagining things.

Regards

[leo]

Regulation and psu's will have a large influence on SQ if this dac is anything like the ES9018 based ones.
Of course with some dacs you'll just be polishing a turd but some can be really transformed, luckily it seems the SC one has potential

[Deleted]

Regulation and psu's will have a large influence on SQ if this dac is anything like the ES9018 based ones.

Leo
Yes. You are correct.
I have now relocated the Xtal oscillator PCB to enable the installation of a second toroidal transformer.
The 2 PSU and 3 JLH PCBs, were already configured so that the Input PCB and the DAC PCB had power feeds from separate regulated PSU PCBs, although the secondary windings of the existing transformer supplied both PSUs in parallel.The use of 2 separate transformers has meant that the 0 volts/earth of both the Input and DAC PCB are no longer joined at the centre tap of the transformer. Initial results last night were slightly disappointing in that the centre image seemed a little more diffused and perhaps a slight increase in very low level noise/haze.
Today, remembering the lessons learned with the Class A HA,
I removed the new transformer, and installed an identical type to that which was already used.This enabled me to "phase" the wiring of both transformers the same way. i.e. blue and brown primary wires the same way around, and the secondary wire colours the same way around, The initial trial transformer had 2 orange primary wires.
The improvement was then VERY obvious with improved and more solid imaging, along with what appears to be a marked improvement in S/N ratio. i.e. no noticeable "haze" this time.
There is absolutely no doubt in my mind that today was the best that I have heard from this DAC. Even DTV stereo sounded great, with a very good surround sensation.The downmix of "Queen- Another one bites the dust" in 24/96 sounded fabulous when played from the Oppo 981HD. A real surround type sensation from just 2 stereo speakers.
Alex

[Spirit]

Jun 18, 2011 12:15:08 GMT jeffc said:

And in any case, placebo or not, I don't give a shite, after all the piddling about to get the DAC in a case finally, I'm just glad to have something that looks like a piece of audio gear rather than a rats nest of wire and PCBs stuffed with electronics parts.

cheers.. jeffc

You beat me to it mate!

Still waiting on TPA to release their USB transport, and then I'll grab an arduino...
and hope I can fit it all in the one case...

[Deleted]

Aug 8, 2011 10:17:28 GMT Spirit said:

Jun 18, 2011 12:15:08 GMT jeffc said:

And in any case, placebo or not, I don't give a shite, after all the piddling about to get the DAC in a case finally, I'm just glad to have something that looks like a piece of audio gear rather than a rats nest of wire and PCBs stuffed with electronics parts.

cheers.. jeffc

You beat me to it mate!

Still waiting on TPA to release their USB transport, and then I'll grab an arduino...
and hope I can fit it all in the one case...

Phil
Wait till Jeff finds out it sounds even better using 2 transformers and can't fit another one in !
Alex

[Deleted]

Wait till Jeff finds out it sounds even better using 2 transformers and can't fit another one in !

BUGGER!

It definitely won't fit the case I have mine half shoe-horned into now!

Grrrrrrrrrrrrrrrrrrrrrrrrrrrr

Jeff,

Did you finish that casing up job, the pics above looked very PRO!

Chris

[jeffc]

Hi Phil/Chris,

Yep, all cased up as neatly as I could muster and I'll try and get time over the weekend for a couple pics. This might also prompt me to fit a second transformer to separate the PSUs for the receiver and DAC PCBs as Alex has done with good results.

I can pinch the 30VA from my SC-HA but I've also discovered some Nuvotem 15VA toroidals at RScomponents which they seem to have a fire sale on ATM so I might get a couple of these as they’re the same as I used in my AK Class A HA and close to dead quite. These ones

australia.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2237787

And Alex, by chosing a large case I could probably fit half a doz transformers and a Class D amplifier.

cheers.. jeffc

[Deleted]

And Alex, by chosing a large case I could probably fit half a doz transformers and a Class D amplifier.

Class D amplifier?
Go wash your mouth out with hot soapy water .
They haven't yet got digital audio replay right yet after all these years, and you expect Class D audio to be good ?

[jeffc]

And by popular demand here are some pics of my SC-DAC cased up. My collection of that terrific sounding 'Dun Mei Audio' gear is expanding, with 1 small and 1 large case still to fill with something I could have quite a collection .

Front Panel (LED on/off hole still to populate)

Rear Panel (Extra holes drilled for optical input and extra RCAs in a handy position just in case I decide to add a Twisted Pair Audio Legato 3 capless-balanced I/V output stage in addition the SC-DAC I/V stage)

Top view (keeping quite, less said the better )


cheers.. jeffc

[Deleted]

Hi Jeff
Looking good !
You need some new decals for the front panels though.
Perhaps you could change the name to "Dun by Mei" ?
Alex