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

Comparing the properly implemented Belleson versus the Tent versus the Salas is like comparing super-model women or Ferrari vs. Lamborghini - they all give you the ride of your life! - or so I've read.

metaphors are nice, like them. Even though sometimes it gets a bit philosophical :p I can confirm the Ferrari thing. Had a nice opportunity to do a day training on a racing circuit in Italy with one. Indeed, the ride of your life! still for daily use I prefer my Audio, which is also a bit more affordable :D

so what does that tell us? :spin:

ps, no comments on the Lamborghini and women ;)
 
I could use some help for pin 20 too. I have zero knowledge on css, fets and so on.

Aside from what James has mentioned - you may find it easier to work with LM334Z which is on TO-92 case (I do), all other parts staying the same (such as the setting resistor of 165 ohms). Umm... I just noticed nige2000 already pointed you to this part.

Other options considered this far are current regulating diodes, single n-channel JFET CCS, and some separately biased configurations. The easier to do, by far, seems to be the LM334 CCS.

So for each current source (you need 2 per deck) you will need
1 x LM334M/NOBP (there is an 'SM' version too, but this just has alternative pinouts from the chip and seems to be much more expensive, so we don't want that)
1 x 165R resistor - 1% or better
then to add the extra to remove the current variation for changes in temperature, you should also get
1 x 1N457 diode
1 x 1K65 resistor - 1% or better

You also want to get some SOIC adapter boards. They're only tiny and cheap and readily available on ebay. That just means you have something to mount it all onto.

Let me know if that doesn't make sense.
James

James - any particular reason you've went SMD on this? Is there no room, or you just prefer to work in that framework?
Radu.
 
Hi Carlsor,

Though I do not satisfied with Guido...

Chanh, a shame to hear about your experience with Tents labs. It must be hard to judge the man, half way around the world, and the holdiday periode might have had something to do with it too. But I do feel the need to counterbalance your report by saying that Guido is highly regarded in these parts and has been for a longtime and I 've not had any issues dealing with him.
 
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First of all my apologies to Doede and All for this side track out of intend!

Stijn - Perhaps this isn't a good place for detail discussion(s) per individual experience, nor should an argument be exchanging. Individual experience and business dealing are unique. You are right about long distance business dealing can sometime be a little frustrated. Perhaps you're fortunately in a better position since you're only 30mins away from his business Central and may be knowing him at a personal level? There are always three side to a story, you, me, and the truth. FYI, I don't doubt Tent Lab technology, actual fact I advocated the technology. Based on my personal experience, the business side needs be reviewing for international clients?
My sincere appology if my honest personal experience telling is offended anyone!
Please kindly PM me should this argument needs be clarified further? Going forward, could we please refocus back to enhancing this Amazing DDDAC?
Regards,
Chanh
 
No Discussion necessary, point taken, no problem.

Metal can package ICs are known to sound better than plastic packages. Might be that excess heat is able to escape much quicker not being encased in all of that plastic. You cannot go wrong with a metal can package though they are not as easy to get as they once were.

I have to assume Mr. Tent has more business than he knows what to do with and I am very happy for him if that is the case. That, at least, would explain his reluctance to answer correspondence.

I have purchased a few items from him over the years and have been happy with what I got but it can be frustrating to ask a question and never get an answer. One simply goes elsewhere - Tent is not in the vanguard now like he was ten years ago so it is baffling why he can be so hard to deal with.

I think when one has had a sour experience they should make it known. I know I am glad to hear I have not been singled out!
 
like to point you to a thread where someone is doing listening evaluation on some psu caps. as there are quite some experiments over here, I thought this might interest some of you :)

never mind the very negative comments from some other DIY :no:

http://www.diyaudio.com/forums/power-supplies/261836-some-electrolytic-caps-shootout.html

I have to assume you are being wry!

How many times have we read that thread? It has many guises but is always ostensibly the same.

The somewhat bumbling poster has to listen to the typical cacophony of the braying idiots so you end up with the deaf leading the deaf.

The sad fact of the matter is that in any given circuit one of these will sound better (to someone?) than another. Sure would be neat if there was an absolute best of anything but there isn't and there never will be.

In the long run this is comforting. Just be happy with what you have wrought. To repeat one of the great guiding principles of audio from Salvador Dali - Do not fear perfection, you will never achieve it.
 
never assume lightly! I was definitively not wry about this. I do like the empirical efforts of DIY and it is always helpful to have as many opinions as possible to build ones own. bickering who is right and wrong is the true never ending story as we all know. reminds me on the iPhone discussions going on right now, haha!

I like the Dali comment :)
 
James - any particular reason you've went SMD on this? Is there no room, or you just prefer to work in that framework?
Radu.
Just that it looked easy to make a nice neat job with minimal hassle and cost.
I can confirm however that if you use 165r to set the load, then use an extra 1n457 diode and 1k65 resistor to cancel out the tempco, you get somewhere around 850uA so I think we need to revisit the calculation there...
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An externally hosted image should be here but it was not working when we last tested it.
 
Also, this week i installed some header sockets in the main board and long arduino stacking header pins in my dac deck.
This means I can easily remove and refit my dac board if I want to try stuff.
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An externally hosted image should be here but it was not working when we last tested it.


So I decided to test out if a DAC deck with just Oscons would work well with the shunts
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I can't fault the detail of the sound, but I found it somehow grated on me and I wasn't relaxing listening to it.

So I swapped the all but the vcom and the cap closest to the digital reg out for Silmic II this evening. I also did the main board caps and put a small OSCON directly on the input of the main board reg
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.

Much better :) instantly more luscious and full sounding. Very happy with that :)

In other news, I'm also trying out a prototype jfet buffer stage to go in between the balanced outputs and my cinemag transformers. Man, that case is getting full and heavy now!
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An externally hosted image should be here but it was not working when we last tested it.

It's early days as it's burning in, but so far I'm impressed :) Makes me wonder how much of the benefit of multiple dac decks is down to an increase in accuracy from the multiple processing and how much is down to more voices equalling more balls to drive the output...
 
James, Which version LM334 did you get, are you sure the diode is in the right place it doesn't look right (but it's hard tell how the traces run)?
It was just the standard lm334m
Its a bit hard to tell from my pics as the pin numbers are different on the back of the board, but basically 165r between pins 1 and 2, 1n457 diode anode to pin 7, then 1k65r from pin 1 to the cathode of the diode (joined at pin 8 which is listed in the datasheet as not connected) then off to gnd.

It's entirely possible I've done something stupid. It wouldn't be the first time today...
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An externally hosted image should be here but it was not working when we last tested it.