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Nice post but.....

come on Qusp, Ive' heard all this before, digital noise.... smd... through the hole.... legs like radio receivers.... Quite possibly I am truly deaf as a post, because I just don't get all this noise from my tinkering, or its very convenient for companies to let us believe that convenient manufacturing is better for our ears.

The day I pick up a whole sack of noise from 'a through the hole mod', I will rip that mod out and try SMD. There are just more quality 'through the hole' components around.

I'm a leg man.

Good job Wood with the VR's. Harmonic complexity reproduced in a convincing manner is part and parcel of getting closer to the "I'm feeling like this is a real event" rather than 2D reproduction of such.

Are you experiencing any front to back layering improvements with this latest addition ? I would love to hear this DAC vs the REF 1 (which can be switched into NOS mode by flicking a dip switch on the DSP1 processor pcb).

Are those Texas instrument TX resistors slit foil types ? Could you point me in the direction of a pdf or data sheet for them please Wood. I would appreciate that greatly.

Peete.

Hi Peete, loads of info on them here

Texas Components - Precision Resistor & Microelectronics

Ignore the Vishay ones on this site, just look for Texas, and Audio resistors. They sell them for about 10 bucks apiece. Oh and qusp they do smd as well

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Yes its coming together, layering was already there but more like cardboard cut out, like 3d glasses. With these VR its tangible. Nice thing is about this dac is its aproaching the kind of uncanny level of detail of a modern dac but hanging on to that seductivness, bit like a properly implemented Tube amp.

I think the ideas you and qusp are generating on PSU, will bring it along nicley as well, thanks for chipping in there!

Cool, thanks Wood for the link and the thoughts. One suggestion don't get caught up in the "modern" DAC designs being automatically superior myth...many of the modern designs are because of cost cutting measures rather than sonic improvements over the older DAC chips. A great example of older being much better besides the TDA series are the AD1865,PCM63K and PCM1704UK R2R ladder designs. They are infinitely better chips than anything being made today (but difficult and expensive to produce) which is why so many of us covet vintage gear or look for new stuff using old technology. Of those chips only one has been put back into production (form sheer demand) the pcm1704. I hope TI continues to produce these for years to come.

My dac is a perfect example of using the best of the old (which still rules the roost technically and sonically speaking) incorporated with the best of the new (ACSS/CAST and DSP1 digital processor) using solid design principles (discrete regulated supplies, discrete analog stages), etc...

Hopefully some of my hair brained ideas will bear palatable fruit. It certainly compelled QUSP to add some terrific suggestions and to point what I had suggested that was in error in a better direction which should benefit those thinking about the next step

Peete.

Hey wood,

The difference I noticed with the direct wire mod, improved clarity, and bass, i could hear more texture in the bass. I did test for noise, and heard no difference, it was quiet either way.

Im not a big fan of the socket, and the jumpers, and was the main reason I did this(also reduce the number of solder connections from 5+ to only 2. If you hook it up the same way I did, you will not be able to use the Reclocker board, I did not mention this because I thought it would be obvious. But just an FYI.

Well, you could jump your wire from the input board to the asynch board to the DAC board and back and forth. so you could make changes but it has to include the iron.

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Yes indeed, so I will hold Mikes mod in reserve, the fat lady singing mod, cos I will solder to the pins. But I still want to play with the dac some more. The Dac is very good for showing the character of different caps. So Its a good opportunity to get that first hand experiance rather then rely only on second hand opinions (valuable as they are). So as much as I like the MKP1837 (my new toys) I will still try other low value caps in this position and may even settle with a mixture eventualy, who knows?

I got my Russian Teflon caps in the mail today, I installed them just now. I may have put them backwards though, mine appear to be opposite of the markings on Pat's. Does it matter ?

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No, they are bipolar film caps. Give a couple at least of weeks Teflon are very slow to burn in, and are not at there best before.

Cool, im listening to them now, I can't hear alot of difference either way. At least I don't have the desire to immediately rip them out, like most bypass caps i've tried here will let them burn in for awhile. I forgot to put my FRM back in and was dazed and confused for a moment when listening to it.. that mod makes a huge difference.

I do have 2 extra teflon's (bought 4) i wonder if they would make a positive change if I bypassed the Wima FRM caps with one. hmm..

Im still undecided if I should put a heatsink on the DC30W or not. I've let it run for 3 days without any sign of problems. The voltage drops from 8.20 to 8.18 on the dac board after it's been powered on for a few hours, but im not really concerned with that. The case temp maxes out around 48c and stays there. This is the hottest part of the case, measured directly above the transistors.

Little update on the MKP1837, 24hrs in. Most of the changes are architectural at this stage, like the soundstage is more solidly structured, but delicate with it and in addition there is a euphonic touch, harmonics I guess. Very nice, but whats missing at this moment is colour.... Its not exactly black and white either, more dark gray and white, a typical SS amp sound. Quite amazing that these little 10n caps can have such an effect on the 47uf caps which have 4700 times more capacitance. The wimas in comparison started warm (too warm) and stayed like that, lets see if these MKP1837 change, will see in a couple of weeks. But I have no doubt now that the choice of decoupling caps are as critical in this dac as the output caps.

Hello to all TeraDak friends,

can anyone help me to implement a transformer output on my Valab 2.1 DAC (1:1 transformer or anything else).

Probably i can wrong on wiring my transformers in parallel with I/V resistor and without caps and 47k resistor.

thanks and good music! ,
Andrea

You see the output caps where you have the wires going to + and - ?

You will keep the caps in place but detach the - connection.

You will take the + and - of the primary of the transformer and connect to the caps + and the boards -.

then take the secondary of the transformer and connect the + wire to the center of the RCA and the - to neg tab of the RCA.

Do that for both transformers.

You may want to drill a hole on the side or top of the chassis to mount the transformers outboard - not enough room inside the box for them.

very Thanks!
I will try!