A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

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Bones13

Bones13

Member
Joined 2006
Paid Member
I received Salas Shunt boards today. I'll need about a week to figure them out, and order caps an transistors. I need to figure out if case mounting will be enough heat disappation or if I'll need to mount heat sinks with external fins. External cooling might make my project a 2 box device, with PSU and DAC connected with the 12 and 5 volt cables.
 
M

Mark Verhoeven

Member
Joined 2009
Bones13 said:
I received Salas Shunt boards today. I'll need about a week to figure them out, and order caps an transistors. I need to figure out if case mounting will be enough heat disappation or if I'll need to mount heat sinks with external fins. External cooling might make my project a 2 box device, with PSU and DAC connected with the 12 and 5 volt cables.
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Hello Bones,

Did you already listen to your DDDAC in any form or still building and modding? I am REALLY curious how it compares to the AN DAC kit 4.1! (which I own also)

Thanks,

Mark.
 
R

rovinggecko

Member
Joined 2014
dddac said:
no pot... a TVC (Transformer Volume Control). In this case 12 secundairy windings. Specially at normal listening levels, this results in very low output impedance, driving the next stage with extreme ease. Result is very detailed Sound
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Building out 4 deck board with cinemags which will go directly onto my active speakers (a pair of Linkwitz Pluto's).
Saw your TVC remark but could not find more details. Anything sharable?

I'm basically looking for some sort of ' master volume', so I can do some finetuning of the volume in the digital source (i.e. CAPS / SBT) in the high end of the range to the SQ stays uneffected.

Thoughts?
 
Supersurfer

Supersurfer

Member
Joined 2013
G600 said:
Can someone compare those setups sonically :
- capacitor output
- direct output
- cinemag
(- sowter)
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Direct: best, you cannot get more detail, openness and dynamics
Sowter: little less openness and detail compaired to direct
Capacitor: slightly bloating bass, less open than sowter ( jensen copper foil in oil)

Different caps and trannies will yield some differences in sound balance but the above is the global ball park they are in.

Mind you: I am using a single ended tube amp with input transformers. I have used coupling capacitors and interstage transformers in numerous tube amp designs and found the same sound differences as on this dac. In a tube amp a transformer is almost always better.

You know the first(tube) amplifiers were designed with all coupling transformers, later on they found that a capacitor is a much cheaper way to couple stages............
 
Bones13

Bones13

Member
Joined 2006
Paid Member
Mark Verhoeven said:
Hello Bones,

Did you already listen to your DDDAC in any form or still building and modding? I am REALLY curious how it compares to the AN DAC kit 4.1! (which I own also)

Thanks,

Mark.
Click to expand...

My DDDAC is still pretty much theoretical at this point. All the parts Doede sent are still in the bags in the box. Looking at power supplies, cases and such currently. Probably a few months from being complete. I tend to cogitate on a project much longer than I build on it.

Sorry for my tardiness. The DAC 4.1SE is no slouch, so I don't feel any pressure to hurry it along.
 
M

Mark Verhoeven

Member
Joined 2009
Bones13 said:
My DDDAC is still pretty much theoretical at this point. All the parts Doede sent are still in the bags in the box. Looking at power supplies, cases and such currently. Probably a few months from being complete. I tend to cogitate on a project much longer than I build on it.

Sorry for my tardiness. The DAC 4.1SE is no slouch, so I don't feel any pressure to hurry it along.
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O.K. good luck with the build. I assume you will post your experiences here when finished.
 
C

concept

Member
Joined 2014
mr_whocares said:
hi doede,

any feedback/suggestions to the concept's question?

best regards
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Thanks for that, but who cares right:)

dddac said:
well who cares? :p haha just kidding, why would you have a forum name like that? :D

on your question.....

basically this is what I did with my TDA1543 dac series.... still working well. point is that is difficult to build for the normal DIY. Also I wanted to have every chip a truly own power supply environment .... some times decisions are not black white, and I did like the concept of the stacked boards appealing and very suitable for most hobbyists...

what you suggest will work for sure, a nice project for the true DIY !
if it will sound better? the proof is in the eating :drink:
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dddac said:
Point is I am not 100% sure if the ref Pins can be connected together, or they need all their own resistor (in my design, the 6k one... if it would work with only one for all, this value must be 6k/ number of Chips...) for the rest it should not be an issue and value of capacitors is not critical, room for experiments I would say. R i/v is the same as for the Versions with the decks of course
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Thanks for the feedback deode, just wanted some feedback that's all. Agree that some of my ideas are not for most hobbyist but that is the fun in diy for me just to try stuff out.:D
BTW, I'm still awaiting stuff to arrive before I could try it out.

Anyway here's my messing/playing around 1 stack dddac, built around diyinhk xmos i2s board and psu.


I've removed all 4 regulators from the dac boards and directly supplying them with 3.3v for the digital section and motherboard and 8.6v for the analog section. With this I've managed to skip quite a few caps from the dac module and motherboard(the lesser components the better right...i hope:))

Why 8.6v and not 8v for the analog section you ask? Well for one thing the psu I'm using is configurable from 1.4v to 20v using jumpers and while playing music I've inserted and remove them to get instant voltage change while listening for immediate differences(not a great thing to do but what the heck:D) if any happens and after playing around with 1.4v to 10v I've settle with 8.6v since that gave me the best sound so far. I did not want to go over 10v since deode has said in his site that the pcm1794 chip smoked at 11v and did not want to cause any permanent damage and I concur with deode that above 8.6v it does not give any improvement, at least thru my listening test since I don't have the measurement gear.


I also use female pin headers for all the decoupling caps so that I could also plug and remove them at will to see if not using them would cause any effect on sq. So far from my listening test the decoupling caps for the digital section on dac is not really needed and I'm skipping that. The ones that remain are all the decoupling caps for the analog section since noise starts creeping in without those though you still could run without them. In fact I,ve run the dac without any caps and it still works to my suprise.

So for those using shunt regs to supply the dac I recommend supplying them direct at least the analog section and specifying them to output 8.6 volts to the dac chip seems to be optimum.:):)
 
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