el cheapo DAC

[PinkFloyd]

Right Leo.... what would you do with it? I bow to your superior knowledge here mate....... I have plenty of 100nF film caps (it would appear the "other" DAC utilises 100nF Wima types.... I also have all the resistors you mention and L7808 (and a cornucopia of exotic caps ranging from russian PIO to the revolting B-gates)

It would appear my DAC is pretty much the same as the other one (the red board) apart from the components...... the 10uF caps are unknowns and the 100uF "fine gold" I fitted myself.....

Anyways Leo....... over to you sir.

[leo]

Ok, it looks like the dac voltage is from that Lm317 adjustable reg

Anyway, you don't need the 8v reg, simply adjust the onboard LM317 to output 8v (220R adjust to output ,1k2 adjust to ground should give you near enough 8v

Change the 1k resistor that goes to pin7 of the TDA1543 to 1k5, change the 1k resistor to pin6 of TDA1543 to 2k7, change 1k resistor to pin8 of TDA1543 to 2k7

This should at least increase the output

[leo]

Infact those parts look quite nasty tbh, I'd definitely try removing the pair of 2n2 polyester caps or at least change them to polypropylene or polystyrene

God knows about those yellow axial coupling caps, I'd ditch them and use something else, 4.7uf up to 10uf should be fine.

See if adjusting those resistors + increasing voltage helps first

You may also need to adjust the dropper resistor for the led, I'd personally remove that resistor altogether, led's are noisy , having the led after the reg on the dac supply is a stupid idea

[Deleted]

You may also need to adjust the dropper resistor for the led, I'd personally remove that resistor altogether, led's are noisy , having the led after the reg on the dac supply is a stupid idea

Hey Leo !
You better rip those 4 out of your SC HA, and the 2 out of your Class A ! All that pesky noise going diectly into unbypassed transistor bases must be completely stuffing up the S/N ?
Alex

[leo]

used as an indicator their noisy as in dropper resistor to led to ground, yes I have checked normally the reason why half decent designers stick them before the regulator

[leo]

BTW, have a go at using an led on the dac supply pin and tell me you can't hear a difference

[Deleted]

Leo
I suspect that many people use crappy carbon dropping resistors, because "they are only LEDs " You could probably even hear the difference with an ordinary diode and dropping resistor at that location too. Doesn't say much for the DACs supply bypassing does it ?
Don't forget that a LED is a DIODE ,and will happily demodulate digital crap given the right conditions.
Alex.

[PinkFloyd]

Jan 17, 2009 2:19:08 GMT leo said:

Ok, it looks like the dac voltage is from that Lm317 adjustable reg

Anyway, you don't need the 8v reg, simply adjust the onboard LM317 to output 8v (220R adjust to output ,1k2 adjust to ground should give you near enough 8v

Change the 1k resistor that goes to pin7 of the TDA1543 to 1k5, change the 1k resistor to pin6 of TDA1543 to 2k7, change 1k resistor to pin8 of TDA1543 to 2k7

This should at least increase the output

Cheers Leo, much appreciated, I will swap those resistors and get back to you with a progress report. Agreed, the capacitors seem pretty spurious and could be improved on..... I'm sure I've got something suitable kicking about in my armoury

[robertkd]

Ok this seemed interesting so went for the BB 1793 module, at least it's got buffered O/P even if the PSU needs a re-think ;D

cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=290289492742#ebayphotohosting


any other gotchas ??

[Deleted]

Or to be more precise, AU$102.21

Jan 18, 2009 11:59:34 GMT robertkd said:

Ok this seemed interesting so went for the BB 1793 module, at least it's got buffered O/P even if the PSU needs a re-think ;D

cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=290289492742#ebayphotohosting


any other gotchas ??

And I suppose that it cost you AU$102.21
Perhaps you bid on it ?

[robertkd]

OK can we be very clear here WTF?

[robertkd]

maybe I can be a LITTLE CLEARER, it's a buy now price

What the hell is the matter with you Alex?

[Deleted]

Robert
I just happened to have paid that amount for one this afternoon..
BTW, the "Or to be more precise, AU$102.21" at the top of my post was an error that I missed when editing.
Alex

[robertkd]

Ok maybe I misunderstood,


yes it's about $100.00 AU but seems way better value then the Philips TDA1543 DAC version

well waiting for this one

[leo]

Glad others are taking a pop at these cheap dacs, its normally me faffing about with the things got to admit though guys both are cheap, imagine buying something like these a few years ago?

Both should sound decent once fettled, they will sound quite different in signature though
I look forward to seeing how you chaps get on with them, that cheap CS4397 based dac I got a while ago sounded shite as standard but after some work it didn't sound bad at all

One thing you have to watch with some of the Chinese dacs is mistakes, the CS4397 one couldn't do 96k as stock, a few alterations sorted that out, also they made a pigs ear of the output stage filter resistor values, the designer seemed to forget this chip is differential , the output looked really bad on the scope, a few resistor alterations made it bang on measurement and sound wise

[PinkFloyd]

Change the 1k resistor that goes to pin7 of the TDA1543 to 1k5, change the 1k resistor to pin6 of TDA1543 to 2k7, change 1k resistor to pin8 of TDA1543 to 2k7

This should at least increase the output

Not on this occasion Leo!! I changed the resistors (as above) and all I got was a faint kinda hashy sound.... erm Changed all three back to 1K's. Will await further instructions on this, you've obviously missed something mate.........

In the meantime...... it's WIMA city baby!! Yup, WIMA all the way in this puppy (apart from the two blue EVOX polyprops) I've also changed the 1N4007 to UF4007 (ultrafast baby!), the 1000uF to 2200uF and fitted and ELNA cerafine 100uF.... oh, I also fitted a handful of those "noVer" for audio 10uf caps.....

Any difference? Most certainly old chap..... more movement, better placement, less congealed, greater clarity, more 3 dimensional (or psuedo 2D), "airy" and fast as fck' in the bass..... actually VERY nice sounding now, the only grumble being the lowish output but a crank of the volco soon deals with that.

Better than the onboard CD17 Dac? NO! Better than the onboard CD52 Dac? different..... less bloomy and more fleet of foot, certainly not as rich but definitely more analytical.

PS: a few of the resistors are soldered on the underside of the board.

She's had about 2 hours on her, I will report back once WIMA city has warmed up a bit......

NOW:

BEFORE:

[PinkFloyd]

By the way...... I got rid of the dubious EPCOS "yellow" coupling caps and have fitted 2 x 3u3 WIMA's in parallel per channel (6.6uF)..... I have room to fit another 3u3 per channel which will total 9.9uF of pure polypropylene WIMA juicyness per channel..... it can only be good news for the consumer

[Deleted]

Jan 18, 2009 15:39:34 GMT mrarroyo said:

Jan 18, 2009 12:28:28 GMT robertkd said:

...

What the hell is the matter with you Alex?

Did you forget to take your "happy pill" when you woke up?

Miguel
I tried too be too cryptic/smart with the answer. I thought that quoting the converted selling price would be a big hint.
And yes, I am a little forgetful and sharp at the moment due to severe leg and back pain from RA. ((Rheumathoid Arthritis)
I'm leaving cupboard doors open and other stupid things at the moment,including missing editing mistakes.

Alex

[PinkFloyd]

Heh... this is bastard good actually ;D Listening to the Beatles "love" album and the fab four are singing away right in front of me (or so it seems) on the track "because"..... what a difference a few capacitors make eh? From shite to right in a jiffy.... fire up your rod, blitz in some caps and, BLAMMO!!, musical satisfaction on a plate.

Obviously a lot to be done yet with this DAC but trained ears have definitely homed in on the improvements the tried and tested cap flavours have brought about.....

Off to try it with both the piglet (X-10D) and the X-10v3 in circuit..... BTW, power supply is linear regulated 9V (self built) so she is being fed the BEST I can feed her.

Peripheral shunting, much like musical chairs, is the best you can do with a DAC..... it's all about getting the recipe right and OH SO EASY to over egg the pudding...... 4 ounces of WIMA, a teaspoon of EVOX, a desert spoon of NoVer, a sprinkling of Panasonic NHG, a pinch of Cerafine and years of experience with cap rolling will do for now

[leo]

Very strange, this is set same as that one I knocked up on vero, only difference is I used a fixed 8v regulator instead of the adjustable LM317 in yours, our S/pdif receivers are different but it shouldn't have any effect at all on the dacs output setting

Did you get 8v on pin5 of the TDA1543 to ground? The voltage here has to be set to 8v because your increasing the dacs output, these new I/V and VREF values give an output of 4v before the coupling caps (half of the supply voltage)
Only other thing is if the voltage was much higher than 8v on the chips pin5 the dac may have shut down

There should be about 2.2volts across the 1k5
There should be about 4volts across each of those 2k7's

The other led on there I presume is a S/pdif lock indicator, did this do what it normally does (goes on or off) when powered up to show its locked onto your cdp

Theres nothing much else to check, I presume the external DC supply feeding the dac has enough headroom for the increased onboard 8v ? as long as 2k7 goes from pin8 to ground, a 1k5 from pin7 to ground and 2k7 from pin6 to ground theres nothing to stop it working

[leo]

Hold on mate, your external supply is 9v? isn't this going to be too low for the onboard reg that gets adjusted to output 8v for the dac chip? theres going to be more drop over the input DC diode too

[rickcr42]

Is it just me or does it not seem a bit strange just how many "products" sold to hobbyists need pages and pages of work just to get them to operate as you would expect them to (with the evidence just about any DIY audio forum) and no one not only don't seem to mind but many times will actually recommend the same kit to others (with the 'this is what you need to do first" addendum of course !)

There was a time when if something was not functionl right out of the box and by functional I mean USABLE IN THE GD SYSTEM or if a kit and unless a flawed build again functional IN SYSTEM they word would be to stay away rather than how it is now and the fact that modern consumers not only allow but expect flawed products needing some work to get them to perform at a high level is a sad statement in itself from where I sit.

If I design a scratch build I expect a TS stage but if a kit or an alredy constructed PRODUCT I PAYED FOR I for one would be ripping pissed if it was not EXACTLY as advertised and that means a working unit with a level of performance at LEAST above newbie hobbyist design and build

[Deleted]

Jan 18, 2009 21:27:21 GMT rickcr42 said:

Is it just me or does it not seem a bit strange just how many "products" sold to hobbyists need pages and pages of work just to get them to operate as you would expect them to (with the evidence just about any DIY audio forum) and no one not only don't seem to mond but many times will actually recommend the same kit to others (with the 'this is what you need to do first" addendum of course !)

There was a time when if something was not functionl right out of the box and by functional I mean USABLE IN THE GD SYSTEM or if a kit and unless a flawed build again functional IN SYSTEM they word would be to stay away rather than how it is now and the fact that modern consumers not only allow but expect flawed products needing some work to get them to perform at a high level is a sad statement in itself from where I sit.

If I design a scratch build I expect a TS stage but if a kit or an alredy constructed PRODUCT I PAYED FOR I for one would be ripping pissed if it was not EXACTLY as advertised and that means a working unit with a level of performance at LEAST above newbie hobbyist design and build

;D

[leo]

Mine built on Matrix board works and sounds quite nice too

Rick, you know your dac chips mate, can you see any reason why increasing the output isn't working for Mike? am I missing something?

[leo]

My thought is they sell these kits cheap on purpose so us plebs do the R&D work for free, post results and they can swipe the work