Next dac project

[Gordon Macfarlane]

Hi guys ,

My next project is to build a higher res dac(than the TDA1541A).

My intention is to combine one of these : http://hifimediy.com/index.php?route=product/product&path=62&product_id=60

with one of these http://glass-ware.stores.yahoo.net/bcpcbusgu.html

[Grimmie]

Terrific work Oz, will you be boxing it all up nice and neat or going for the bare bones and lethal look. I'd love to have a listen once ready.

G

[Addicted to music]

Hi Oz,

I had a simular version but it was a Gigaworks PCM 1798 it came with a PSU and it was a little over $100AUD deliverd from HK in 4 days of placing the order. It was my 1st dac and I kid you not this thing was the best value $100 I have ever spent on this hobby. It made a world of difference and it only had AD826 opamps in the I/V. At that time I really havent heard any dacs but it beat the Rotel 956 and other transport I had. I dont think anything will come close in beating this for value, still have it BTW but it doesnt get much use!

[Gordon Macfarlane]

Hi P , I have one of the Gigawork 'Big Dac' CS4398 boards that I am using in my pc system . The signals go directly from the dac chips analogue output pins to the inputs of a 6N3 based buffer stage , This works quite well but the above dac board sounds better.

I had problems with my original sample of the above dac and am waiting for a replacement.

I reckon the new dac with Mr Broksies balanced to single eneded tube convertor should improve things a notch or two.

Ged , I have found that laying the circuits out on thin chopping boards (Coles 2 for $10) makes for easier and more robust assembly and tweaking but once I have a sound that I like then everything goes into a case to prevent the cats from electrocuting themselves

[Gordon Macfarlane]

Another TDA1541A dac variation finished:

[Addicted to music]

Great work Oz,

I admire the idea that you gutted a Yamaha amp, great job , my Gigaworks PCM 1798 and PSU was individually wrapped in bubble wrap and placed in cardboard box, my brother was that impressed with it he was going to supply a cabinet but never got around to it.

Oz, if you dont mind me asking cause I need to get it right, did you say that the little CS 4398 pcb in youre original post sounded better than the Gigaworks version?

You sent that one back to get a replacement?

Because you are taking the signal direct from the output via MKP caps and there are no filters do subsonics from the dac effect SQ???

[Gordon Macfarlane]

Hi P , correct the wee Hifimediy dac board sounded better than the modified Gigawork board.

The problem I had with the wee dac was that it had a lot of distortion in the hf , kind of a whislting sound that seemed to beat in time with the music.

I had removed the Mundorf MKP CAPS FROM THE DAC BOARD as the valve buffer had caps on the input , so no point in doubling up.

Hifimediy have reworked my board , adding resistors where the CS8412 upsampler was. I don't use the hardware upsampler preffering to do that within Jriver.

Hifmediy , discovered that disabling the upsampler on their board could cause distortion if the cs8412 was not replaced by resistors.

The MKP CAPS are there to block 2.5v dc of the dac chip but in theory are not needed if the next stage is capacitor coupled and in my system sound quality was better.

As I understand it the worry with direct out dacs , ie those lacking a low pass filter is in the hf rahter than at low frequencies , without a lp filter the digital noise can destroy hf units . or so I have heard.

[Addicted to music]

Many thnxs for the feedback Ozcall,

I just looked at the other thread you had going to. Youre not missing much in regards to Sabre 9018, I reckon its way overrated, I wanted to go for the Twisted Pair direction but backed off when I failed in numerous attempts to secure a order due to slow 3G internet and the cost can blow out over the $1000AUD mark and still the thing may not work. I went the EE mini max plus and still have it. And yes its very skeletal in SQ.

Am I getting it right that you have a working DIY linestage integrated volume control, if so I am wondering what thats like because as you havent notice I hate mechanical pots which is why I went the NAD M51. I wanted to build this project but at $600+ it was a bit rich.

Im a bit strap for cash ATM due to my DAD being paralysed from the neck down, ones thats sorted Im going to get this hifimediy CS 4398 as I am curious of its sound signiture, and the DIY linestage volume control.

You are on the right path as you do not need 2 sets of caps in series, I did this removal on my pre and power amp combo.

Edited August 10, 2012 by pchan

[Gordon Macfarlane]

Another TDA1541A dac variation finished:

Powered up the dac in my test system this morning. Bugger , hum on both channels and signal only on the rhc at very low volume. Tried to do a bit of investigation but couldn't work oput what is causing the problem.

Anyway I had a brand new Universal valve stage to hand , so after a few hours the rebuild is complete and the dac is now producing sound. Will give it a few days run in on the test system and then do some comparisons with the other Tda 1541a dac, both dacs now have the same output stage.

[Gordon Macfarlane]

HI P , I do have a working DIY line stage and volume control.

Using the Volume control in passive buffered mode gave excellent , detailed , harmonically rich but very neutral sound.Only real negative was a certain lack of drive to the sound.

Now while the Linstage works very well in my dacs adding the linestage to the volume control was not sucessful , resulting in a rather bland sound which was not a patch on my Supratek active valve pre.

So my plan is to add the volume control system to my Supratek , relacing the S-teks Alps blue pot and mechanical input selector switch.

I would still recommend the Passive buffered version of the volume control as it is a great starting point and you can add a decent active stage from the likes of J Broksie : http://glass-ware.stores.yahoo.net/listheam.html

for not too many $$$ later on .

Cheers,

G

[Nada]

awesome DIY experimenting again Oz

I look forward to reading about the Supratek volume mod outcome

thanks

[Gordon Macfarlane]

Thanks for the comments once again Nada.

Here are a couple of pics of the revised 2nd TDA1541A dac :

Cheers,

G

[Gordon Macfarlane]

Re : the Supratek , I have made some very simple mods already : better psu caps , film oil Obligatto replacing the Electrolytics on the HT side , ELNA SLIMIC 2 electrolytics on the heater supplies. In the head unit I have replaced the Auricaps with Ampohm Cu film in oil. The sound now has a lot more body , better timbral resolution with no loss of musicality . Overall I would say the sound is also more neutral or accurate

Changing the volume and input switching control looks to be realtively easy and revesible if the results are not as desired.

[Gordon Macfarlane]

Well dac 2 (tda1541a,just above) is up and running in the main system , being fed by the music server and blow me down if it doesn't sound just great. Using a jan Sylvania 6922 and Obligatto 2.2uf tinfoil caps on the output.

The sound seems to suit the Gales really well being big and for lack of a better word majestic. This is not a shock and awe type of sound , it's detailed but not in an overly explicit way. Bass depth and texture seem better than dac1.

On an other note Mick M saw my post regarding the Supratek pre and sent me an email with a few more tips for future upgrades , big thanks to Mick.

As far as pc based sources go I have to admit that I am very pleasantly surprised at the level of sound quality available without coming remotely close to breaking the bank. Bare in mind that I have only recently come to feel that cd is capable of decent results compared to a good (expensive) vinyl set-up.

I don't feel the need to place the 3 source types in any form of hierarchy , they all have their plusses and minuses.