New HQ DIY DAC

[Deleted]

Robert
I must have been adding the link while you were posting.It's at the bottom of my previous reply.
Alex

[Deleted]

Altronics has given 20th November for the release of their SC DAC kit.
It will retail for AU$299 and include a prepunched and labelled 1U rack case, as well as all power supply components.
There is more than ample room in the 1U rack case to slot in a JLH,which will further improve HF separation, as well as overall performance.
The Output PCB has DIP8 gold insert sockets which will make opamp substitution a snack.
The Jaycar kit is AU$139, but you need to factor in the cost of a case (or make your own) as well as all PSU components including the KC5418 PSU board which is not part of the short form kit.
Alex

P.S. Silicon Chip magazine will in December, publish a Balanced Output board with XLR connectors.

[Deleted]

Miguel
You would not be able to buy the Altronics kit with a U.S. transformer.
The Altronics kit would use standard I.E.C. sockets though, and all the rest would be compatible. Shipping may be fairly expensive due to the weight of the 1U rack case in particular, as well as the included transformer.
Alex
P.S.
I still haven't decided which version to build. Using the short form Jaycar kit, would mean sourcing suitable metalwork and other PSU components, and LOTS of metalworking ! It wouldn't look professional either. On the other side of the coin, I may be able to get a Jaycar kit via a friend for just under AU$100 via their wholesale arm.

[Will]

The DAC is up on the UK site:
www.jaycarelectronics.co.uk/productView.asp?ID=KC5487&keywords=KC5487&form=KEYWORD

£40.50!!! Thats a bloody good price for a kit DAC, and well worth the money, especially as they do the SMD soldering for those who are a bit wobbly on that side.

Step away from the keyboard, Will, step away...

[Deleted]

Dec 8, 2009 11:37:24 GMT Will said:

The DAC is up on the UK site:
www.jaycarelectronics.co.uk/productView.asp?ID=KC5487&keywords=KC5487&form=KEYWORD

£40.50!!! Thats a bloody good price for a kit DAC, and well worth the money, especially as they do the SMD soldering for those who are a bit wobbly on that side.

Step away from the keyboard, Will, step away...

Will
The photo only shows the input PCB. There are also the front panel PCB and the DAC PCB. You also need a dual reg supply PCB as per the SC HA.
I have a kit waiting ready to start, but a friend has his working with polyprops for the main time constant caps in the analogue stage, which made a big soundstage improvement over supplied capacitors,and a JLH for the main +-15V rails, which also feed a reg for the DAC.Also a marked improvement. A polyprop in the DIR filter area works well too. The icing on the cake is LME49710s in the analogue stage after the other mods have been done. I think he also has a JLH for the Digital 5V area too, but with 2 x 4,700uF 10V low ESR per voltage rail.
Alex

[Will]

Had a read through the blurb, and the kit does include the i/o, dac and switch pcb's, but no PSU pcb, as you say. I was wrong about the SMD though, you have to solder yourself. So I think we can expect discussions about 'flood and suck' to crop up.

[Deleted]

Dec 8, 2009 12:50:06 GMT Will said:

Had a read through the blurb, and the kit does include the i/o, dac and switch pcb's, but no PSU pcb, as you say. I was wrong about the SMD though, you have to solder yourself. So I think we can expect discussions about 'flood and suck' to crop up.

Will
That seems strange about 2 different versions being supplied by Jaycar.
It could be wise to double check. Mine came with the SM devices already fitted in Australia!,not overseas as many would have thought.
Seems a bit weird, as all the kits come from Australia.
Alex

----- Original Message -----
From: Alex Kethel
To: [e-mail]
Sent: Wednesday, December 09, 2009 7:36 AM
Subject: KC5487 Silicon Chip DAC kit - Attention Joerg Edler


Hi Joerg
A forum member from the U.K. has given the attached link, which indicates, that unlike the kits supplied in Australia by Jaycar,
the U.K. version requires the SMD devices (DIR9001 ,DSD1796) to be fitted by the constructor.
Is this correct ? It does not seem logical to have 2 different versions of the same kit, and would even reduce the basic appeal of the kit to many people.
My own kit did of course have the SMD devices already fitted.
Kind Regards
Alex. Kethel

www.jaycarelectronics.co.uk/productView.asp?ID=KC5487&keywords=KC5487&form=KEYWORD

[Will]

Looking at the description on the two Jaycar sites, the description is the same, stating that the kit has two SMD chips that require soldering. This is for the short form kit, KC5487.

[Deleted]

Dec 8, 2009 20:43:15 GMT Will said:

Looking at the description on the two Jaycar sites, the description is the same, stating that the kit has two SMD chips that require soldering. This is for the short form kit, KC5487.

Will
It seems likely that the web sites have not been updated.
Let's see what their production manager has to say. I expect that U.K. kits will be identical to the kit that I got through Electus (Jaycar wholesale)
Alex

[Deleted]

Some preliminary photos to start with.
You can click again on the Image Shack photos for a full size photo if required.
The original design was published in Silicon Chip magazine late last year. Both SMD devices were already mounted on the PCBs , as they will be on all short form kits from Jaycar.
The top photo is of the Output PCB. The generic capacitors around the opamps for filtering, have been replaced by polypropylene types.
The 2 x 2n2 capacitors at he output, after the 100 ohm output resistors were replaced by 100pF polypropylene capacitors for improved definition, as well as an improved sound stage.
The last 2 opamps, which are for the output, have been replaced by LME49710. This results in a more balanced sound, otherwise you can get a typical "house" sound from using all the same types of I.C.s .
The other 4 I.C.s are the generic OPA134 as supplied with the kit.
I elected to use better quality output RCA sockets, as I hate sockets protruding through holes in the metalwork, and it is so hard to make look perfect, as well as mounting the rear end of the PCB is a P*I*T*A if mounted as intended.
The 2nd photo is of the Input PCB which carries 2 Toslink sockets, and a RCA SPDIF IN socket.The 100nf capacitor at the input of the SPDIF has been replaced by a smaller value polypropylene type, which was the largest value that I had of that type. Normal generic capicitors are not normally recommended for that application because of their high dielectric absorption, which means they really are not suitable for much more than about 8 bits. The generic 4n7 at pin 22 of the DIR9001 was also replaced by a polypropylene type for markedly better sound quality.
The 3rd photo also shows a non current limited JLH, which uses 2 x 4,700uF low ESR capacitors per supply rail, for a simulated capacitance of
1 FARAD . (!)The Jaycar PSU PCB has the usual PW5 resistor in the 5V rail removed, and a 7812 voltage regulator fitted for further improved regulation of the 5V rail. It was surprisingly easy to fit, just by drilling 2 more holes for the Earth and output terminals. A short wire link was used to connect the centre terminal of the voltage regulator to earth.
The last photo shows the front of the unit, however the 2 larger LEDs are ever so slightly above the internal Blue LEDs of the 3 pushbutton switches due to the PCB itself. The hole is for the Infra Red I.C. which is mounted behind it.
If anybody is interested, I will go into minor construction niggles at a later time.
Although it is still very early days, the sound quality is very good, but not quite yet up to the standard of my MF X-DAC V3.
Alex

[Will]

Nice looking build there, Alex.
Did you get the full kit to save on case work?

I ordered this DAC up over the Holidays (same time as a SCHA for my Dad's birthday) so it should be arriving February time, if previous experience is anything to go by.

Lots to try with this beast!

[Deleted]

Did you get the full kit to save on case work?

Will
I wish !
I absolutely hate cutting out holes for IEC mains sockets etc. in aluminium. Making close enough to square holes for Toslink sockets, and respectable looking round ones for front panel push buttons etc. was a real challenge. As for drilling holes in the steel bottom plate for mounting the PCBs, that was something else again ! Bloody half blunt drill bits that wandered with a mind of their own were a real PITA !
If I ever make another one it will be from a complete Altronics kit with prepunched and labelled metalwork.
Let me know before you even insert a single component into ANY PCB, and I will help you avoid some of the trials I went through. (mostly of my own doing!) Ask about the LEDs in the Switch Panel ! Due to the PCB itself , the 5mm green and yellow front panel LEDs are ever so slightly higher than the tiny blue LEDs in the 3 push button switches.
The leads of the push buttons blue LEDs are very thin too, and don't touch the sides of the PCB holes. IF you are very careful to avoid burning the push button switches when soldering,only half of the blue LED leads end up having solder flowing around them !!!

Alex

[Will]

Alex,
In that case, it makes the case work more impressive. I'm the same, case work is the least exciting part for me.
I need to have a good look at this kit, as I want to use it as a dedicated dac in the same case as my SCHA, so will set it up with spdif only input, and bypass the pushbuttons. Initially, I'll build it up on some board, to get it working, and then have a play

Oh, and shouldn't the last sentence of your 'build' post read:

"Although it is still very early days, the sound quality is very good, but not quite yet up to the standard of my MF X-DAC V3, yet"

[Deleted]

Will
The 1796 isn't as quite as good a DAC as the 1792. However, I still have the option of a better clock as distinct from the simple Xtal type.
It will also be possible to use another half a JLH, purely for the 5V supply to the Input PCB, which should also further improve clock stability as well via the 3.3V regulator. A very handy feature of the JLH PCBs from you and Jon is the ability to split the PCB into 2 separate PCBs with whatever polarity supply you wish.
Alex
P.S. At the moment I am using a 33nF polypropylene at the SPDIF input
instead of the original generic 100nF capacitor, as that was the largest value I had. As the frequency is around 2.8MHZ it shouldn't matter too much.
I have ordered a few 68nF polypropylene caps from RS, and will replace that one. I will also replace the other generic 68nf associated with pin 22 of the DIR9001. I'm not sure if it will make much difference with 680 ohms in series with it though. Note that this resistor should be 680 ohms as per data sheet, not 6.8K as on the schematic, and supplied.

[Deleted]

Jan 2, 2010 10:32:14 GMT Will said:

I'm the same, case work is the least exciting part for me.

Awgh guys, speaking as an electronics follow-the-leader-er (grammer? nah, not me mate!) I love the casework bit, It's my only chance to call the creation MINE

[PinkFloyd]

Jan 1, 2010 11:31:20 GMT @sandyk said:

I absolutely hate cutting out holes for IEC mains sockets etc. in aluminium. Making close enough to square holes for Toslink sockets, and respectable looking round ones for front panel push buttons etc. was a real challenge. As for drilling holes in the steel bottom plate for mounting the PCBs, that was something else again ! Bloody half blunt drill bits that wandered with a mind of their own were a real PITA !

[/quote]

Good quality drill bits are the key here Alex, not those £2 for a set of 20 types but the £8 each types ;D Drill speed is another thing, as is punching etc. etc. etc.... I won't waffle on but have a read of this: www.diyfaq.org.uk/powertools/drillfaq.htm

[Deleted]

Jan 2, 2010 23:09:13 GMT PinkFloyd said:

Jan 1, 2010 11:31:20 GMT @sandyk said:

I absolutely hate cutting out holes for IEC mains sockets etc. in aluminium. Making close enough to square holes for Toslink sockets, and respectable looking round ones for front panel push buttons etc. was a real challenge. As for drilling holes in the steel bottom plate for mounting the PCBs, that was something else again ! Bloody half blunt drill bits that wandered with a mind of their own were a real PITA !

Good quality drill bits are the key here Alex, not those £2 for a set of 20 types but the £8 each types ;D Drill speed is another thing, as is punching etc. etc. etc.... I won't waffle on but have a read of this: www.diyfaq.org.uk/powertools/drillfaq.htm

[/quote]

Mike
I know most of that, but I don't have a workshop area in these rented premises. I rarely do metalwork because I hate it, and this shows in my preparation ! (or lack of !) If I hadn't been able to save $50 on the kit, then I would have bought the complete Altronics kit, complete with punched metalwork and screen printing.
Alex

[Deleted]

Other SC DAC mods.

See also :

www.diyaudio.com/forums/digital-line-level/151738-silicon-chip-dac-kit-4.html

[jeffc]

Guys I’ve just built the SC-DAC kit and now its had 50 h of run in, time for an update on how its going.

The project got the go due to encouragement from Alex and generous offers of help with upgrade parts, and as a mate has a Denon 3910 multiplayer that uses the same BB DSD1796 DAC chip. This was always a reasonable digital source in standard form, not quite up to my slightly modded NAD C542 CDP in musicality, but nice and solid. However, recent modifications to his Denon in the way of a Terra Firma Lite clock and new I/V output stage have transformed it into THE BEST, MOST ANALOGUE sounding digital source I have ever heard, period, quite spectacular really, but these ~$1500AUS upgrades are a story in themselves, and for later.

So as the SC-DAC kit uses the same DAC chip and has the good DIR9001 receiver, and seems well thought through and tested technically, and cheap enough, I though why not get it going and think to possible clock upgrades if it deserves them.

The build was quite straight forward except for the selector PCB that I still don’t have working. Plus I’ve soldered opamps in which was a stupid idea, say no more , I like to make my life difficult, and should be sent to see the headmaster for a good spanking. Oohs, that should be headmistress.

Parts upgrades are mostly as per Alexs posts.

PP filter caps for the opamps and on the DIR9001 receiver.
JLH-PSRR (nice AK/JC/WW board with 4700uf caps supplied by Alex) on the +/-15V supply to the DAC/output stage PCB
SF14 fast diodes (thanks Alex) used in the Jaycar PSU

Differences at this point
Extra JLH-PSRR fitted on the 5V supply to the receiver PCB
470uf Elna Silmic used before the 3.3V regulator on the receiver PCB
100uf Oscons on the Vdd and Vcc supplies of the DIR9001
22nf MKP1837 PP cap on the digital input as that was the highest value I had at hand
100uf Suntan CD286 low esr caps used at the DAC board input fed from the JLH-PSRR
LME49710-NAs used for I/V conversion
LME49710-HAs used in the differential amplification stage
All opamp +/-V supplies bypassed locally with 0.1uf BG NX-HiQs rather than the generic polyester caps
2.2nf low-pass output filter caps omitted

A happy snap (albeit a crappy one, low light 1/15s no flash, will give you an idea) – casing up still to do.



How is it sounding with 50 h of continuous on time. GREAT is all I can say, bags of detail, fast and dynamic. Only listening done so far has been with it playing direct into a good quality 10K ladder attenuator to a Charlize T-amp feeding my “toner cartridge box” cardboard panel speakers and piezo tweeter cone panels.

Will get more into SQ once hooked up to more conventional speakers but that and further mods will have to wait for a couple of weeks until I get home from a trip. Based on technical measurements of THD etc as well as Alex's listening impressions, it seems that the OPA134s supplied with the kit do a much better job with I/V conversion in this application so the LME49710-NAs will exit and there are a couple of caps that will be changed on the receiver board which I’m sure Alex will report on before I get a chance.

In summary, cheap, fun and exceptionally good sounding kit DAC to build. Plus you privileged folk in the UK get the Jaycar kit for a proverbial song at £40, incredible bang for buck even with a few more £ spent on PS parts and parts for mods.

cheers.. jeffc

[Will]

However, recent modifications to his Denon in the way of a Terra Firma Lite clock and new I/V output stage have transformed it into THE BEST, MOST ANALOGUE sounding digital source I have ever heard, period, quite spectacular really, but these ~$1500AUS upgrades are a story in themselves, and for later.

Is that for when you have reverse engineered it for us?

Nice write up Jeff, do you have any more plans for the dac?

Also, I was wondering what sort of dc offset you guys who have built it are getting on the output. I know it will differ from the standard opa134's to the lme49710NA and again to the lme49710HA (if the experiences from the SCHA are to go with. Just wondering, as there a lot of people out there with no input caps on their amps.

[Deleted]

Also, I was wondering what sort of dc offset you guys who have built it are getting on the output.

Will
From memory , around 1mV. Definitely <2mV
That is with 4 x OPA134, and 2 x LME49710.
Alex

[Deleted]

Jeff,

Does the Jaycar kits' switching board come complete with the switches that petrude through the front panel as in Alexs build?

PS did you get your switch board to behave?

Chris

I'm reckoning on buying the Jaycar kit, their PSU board, transformer (which one?), other panel hardware and make my own case. Apart from mods would that be the whole shooting match?

[Will]

Jan 7, 2010 10:01:38 GMT @sandyk said:

Also, I was wondering what sort of dc offset you guys who have built it are getting on the output.

Will
From memory , around 1mV. Definitely <2mV
That is with 4 x OPA134, and 2 x LME49710.
Alex

Cheers, Alex.

I'll leave the caps out of my SCHA then.

[bpgoa]

Hi Guy's....


First off I'm a noob.. so I'm going to ask some stupid questions...

I've built a few projects in the past (including a full CNC controller) but have never ventured into the world of Audio /HI Fi. I bumped into this kit while looking for a logic probe kit on the Jaycar site (please no laughs) and really fancied having a go, so it's on order!!!

My plan is to use this DAC, driven by a Squeezebox 3 (classic!) then out into a Krell pre/ power amp and B&W Nautilus speakers. I'd love to get the best from the kit from the start so... After reading this thread and a similar thread on DIY Audio I have a few questions which must be only to obvious to everyone else. I'll ask them and if anyone can put me on the path I'd be grateful.

On DIY Audio, alfredrofe suggested these parts as upgrades.

Parts used
Op Amp LM 49710
4.7 nf Polypropylene Capacitor RS 401-4766
68 nf Polypropylene Capacitor RS 401-4918
2.7nf Polypropylene Capacitor RS 401-4867
8.2nf Polypropylene Capacitor RS 401-4794
2.7nf Polypropylene Capacitor RS 401-4722
2.2nf Polypropylene Capacitor RS 401-4716 - later removed
100uf Oscon Farnell 121-7611
47uf Lo ESR Jaycar RE6332
Bead Ferrite WES FB12
Oscillator HyQ QXO8CBA 24m576
“Flea” Pink Fish Media
“Ripple Eater” Rock Grotto Forum


Question 1 - Where do I get the PCB for the "Ripple Eater" and is this the same as the JLH that Alex mentions in every post ( jokio). Everyone on the DIY forums seems to have them falling out of their pockets but after 4 hrs of searching I still don't know where to get a kit / pcb/schematics

Question 2 - It was great to get the RS item numbers however these are not available in the UK (they are AUS RS codes!). Can someone suggest alternatives which I can buy in the UK. (and also for the electrolytic caps). I spent 3 hrs today looking at Capacitor specs only to come to the conclusion that they were all great. I suspect listening tests would not bare that out so I would be grateful of your experience, even if it's a starting point and some alternative suggestions. And if anyone knows of a supplier where i don't have to buy a bag of 100 ... Gggrrrreat...

Question 3 - This may be a little contentious but if I don't ask then I'll remain ignorant and I don't like that idea. ? He suggested changing the simple xtal clock for a better cmos clock module. My understanding from the articles is that this clock is not being used to drive the data transfer to the DAC and is only used as a comparative signal against the spdif signal. So the question is ... should I upgrade this and why does it make a difference? (go easy on me guy's as I was shocked the first time someone told me to upgrade my cables, and now they cost as muck as my CD unit)

Question 4 - I would like to have the power supplies and the DAC in two separate boxes... Are there any special considerations for this. I have mighty ambitions of adding a tube Analogue stage at some time (got to aim high) and it seems accepted practise to separate the supply circuits.

Question 5 - I'd like to stack the input board and the DAC/Analogue board inside a half width case. Is there any further screening I should do? Also to make the casework easier and the connections to the interconnects better I was planning on fitting chassis based RCA sockets using silver plated units and silver wire connections (and later on, XLR's if they publish the circuit changes). Should I not fit the sockets to the board and solder straight into the holes(there's a picture somewhere where the board still has the sockets on it)? Also, should I twist the wires from the board to the sockets

Question 6 - should I fit a filtered IEC socket to the PSU?

Question 7 - is the resistor on pin 22 of the 9001 chip 980k?

Question 8 - How much money is it worth spending on this design?

I'm so sorry to be just taking from the forum (and asking all these questions) rather than being able to add to it.. but I have to start somewhere.


Thanks


Adrian

(Hertford-UK)

[Deleted]

Jan 7, 2010 16:21:05 GMT @cjarchez said:

Jeff,

Does the Jaycar kits' switching board come complete with the switches that petrude through the front panel as in Alexs build?

PS did you get your switch board to behave?

Chris

I'm reckoning on buying the Jaycar kit, their PSU board, transformer (which one?), other panel hardware and make my own case. Apart from mods would that be the whole shooting match?

Chris
I will have to speak for Jeff, as as he was due to be at the airport at 5AM.
Yes, the pushbutton switches with integral blue LEDs come with the kit. No, Jeff has not had time to find the fault in the switching PCB. There is very little to go wrong there, other than dry joints on the THIN Blue LED leads, and IDP cable problems which can be verified using a DMM.
The problem with the whole 3 blue LEDs, was in my case due to solder not flowing properly around the thin blue LEDs leads at the same location each time, due to those thin leads being much smaller than the diameter of the drilled holes. I doubt that there would have been a problem if the leads of the LEDs had been the usual thickness. A reluctance to burn the shit out of the plastic switches with the small soldering iron used, was the cause in my case. Perhaps the LED leads' PCB holes could be tinned beforehand to help with the solder flow later ?
The other parts also needed are an IEC socket and panel mounting fuse holder with M205 500mA fuse.Due to weight,the transformer would be best obtained locally ,or from the U.K. It is a 230V Primary 15-0-15VAC 20 OR 30VA Toroidal transformer.
Alex