Pass D1V3 DAC - build thread

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
Pass D1V3 DAC - build thread

Hope this isn't considered too marginally Pass for the PL forums...

I'm curious to see how others are progressing with Spencer's "NP D1 clone with enhancement" see here. It seems like quite a few boards have been sold to members but there hasn't be much said about build progress.

I received my pcb and bags of parts from Spencer early in the week and was very impressed with the quality of the board. The parts supplied look to be good industrial quality - Panasonic FC caps, S&M (siemens??) film caps, Linear Tech reg's, etc etc, and everything came neatly bagged and labeled.

The board is very densely packed in places, and is a bit daunting when you come to locate the correct location for many of the resistors and caps. I've had to resort on a number of occasions to searching the schematic pdf to locate the context of a part number before I could find it's position on the board. :xeye:

I've managed a few soldering sessions and have roughly got to midway through step 3 in Spencer's suggested build sequence - surface mount regulators, resistors, diodes, jumper pins, and ic sockets, plus 75% of the 0.1uf film caps are mounted on the board. I've also soldered a surface mount cs8412 onto one of Spencer's 8414 adapter boards.

A nice, no-bs guide to smd soldering techniques can be found at http://www.infidigm.net/articles/solder/

I'll try to get some pics of my efforts so far posted tomorrow.


cheers
Paul
 
I was following Spencer's thread with great interest even knowing I couldn't tackle it with my lousy eyesight. It is a quite daunting project. I did try his I/V boards in a player with PCM63s and they are very impressive, totally transparent, no grain at all.
I don't believe he's making a dime on anything he's selling.

Best, Bill
 

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
Still no pics, but have had a couple of good soldering sessions over the past fews - vastly improved by an extractor fan. well really just a portable fan blowing away from the work surface :)

I've completed the first 17 stages in the suggested build and test sequence. I'm now at the stage of testing and adjusting the JFET I/V power regulators. The 50VA 18V + 18V transformer I'm using - left over from an old DIY modular synth PSU - is putting out a little over 27V+/- at the designated test points. This slightly higher than the maximum of 25V+/- indicated in the original build thread. I suspect this isn't a real issue as the earliest board revisions used higher voltage secondaries, and the main side effect is higher dissipation in the regs.

A quick check of the reg output test points shows everything is operating ok with voltages ranging between 18.0V and 18.4V prior to adjusting the pots.

I curious if anyone has used Visaton MKP crossover caps for coupling. I've seen a comment in the archives that they are far better than the Wima MKP. They are certainly far easier and cheaper to find here in Australia. Any experiences?
 

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
Board overview

Board stuffed to analog power supply testing stage.
 

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spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
The pics are a bit low res I guess... the pads are definitely gold plated, and the "bling" white solder masking is very thin and scratches off pretty easily to show gold underneath. Personally I'd have preferred blue or green solder mask and tinned pads.

Attached is a pic of the unused xo clock section showing some pcb bling. When compared to the D1 or Tent Labs dac clocks the xo clock section on the board seems to be missing some essential circuitry to allow the xo clock timing to be adjusted vs the recovered clock. This lack apparently results in clicking on the output when using xo clock. I'm not sure how feasible it will be to implement a piggyback board to get the xo clock working correctly.
 

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spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
Managed to spend some time working on the D1V3 this afternoon.

Picked up a cheap 20VA 2x9V trafo from local electronics "junk" retailer Jaycar, and was able to run thru the test procedure to check the 12V digital power supplies. The raw 12V section was fine but the 5V regs were putting out 1.33V. The problem was traced to an incorrect resistor at the LM317 - pays to never assume resistors are correctly packaged no matter the source!! I didn't have the required 120R on hand so have replaced with 100R after calculating the resulting output and checking the LT1117 datasheet for input voltage.

Once that was sorted, the rest of the final testing and adjustment procedure was straight forward. I seem to have some oscillation on the output but haven't got the Visaton caps installed yet and still need to source some copper foil to shield the output caps.

Unfortunately the replacement resistors for my aleph 30's got sent to the wrong address :\
I have to see if I can recover them in the next couple of days, otherwise it's another long wait until I can actually listed to the D1V3.
 

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
Personally I don't think it is especially difficult. But that really depends on your building experience!

The parts count is quite high, and the JFET I/V sections are very densely packed, which looks quite daunting, and the parts identifiers can be a bit hard to find on the silk screening. Some part numbers are illegible and you need to resort to the pdf of the silkscreen to confirm what the actually number is.

The build instructions seem to be based on Spencer's personal build notes and there are a few steps that I'd do in a different sequence and other small things that he doesn't mention. For instance I discovered that the transistors for the mute relays aren't shown in his pics, nor mentioned in the notes but the outputs are muted unless they are installed.

Parts quality is variable: the many of 0.1uF film caps had rusty leads and required a careful clean before soldering. Some values of panasonic fc had pre-cut leads and I had to hold these caps in position while I tacked one lead into place.

But I think if you are comfortable with soldering a densely packed board, and reading the schematics to confirm parts locations and values, then the assembly becomes simply a matter of being methodical and careful in component placement.

hope this helps...
 

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
Awesome!! Finally got my Aleph30 monoblocs back in service a couple of days ago, and sounding fine. Today I mounted the trafo's and D1V3 pcb on a test base and hooked it up to the system.

I'm really stunned by the sound I'm hearing. It's the first time I've been conscious of the soundstage extended past the speakers, and the imaging has sharpened up compared with my Assemblage DAC 2.0. I think for the first time I could distinguish the exact positioning of tabla's and the sound of the hand strikes. The at beginning of "Epiphany" on Nicky Skopletis & Raoul Björkenheim's Revelator cd, this really jumped out, and startled me.

Still haven't put the Vistaton MKP's in to replace the axial mkt's, but nonetheless it's a stunning sounding DAC. In contrast with the DAC 2.0 it is in a completely different league, and the sound is simply superb. The first thought that popped into my head was "this is absolutely gorgeous"!!!

off to listen to some tunes :)
 

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
sklimek,

Yes, I'm very happy with what I'm hearing. It's a clear upgrade from my present DAC so that is a good outcome.

I haven't tried to use the XO section that's on the board. I don't actually think it can work without clicking as the clicking is caused by drift between the XO and the recovered clock. The advantage of the VCXO is that it can be adjusted to keep the two clocks locked to the same frequency. When I get some time I'll take a look at making up a daughter board with a VCXO similar to the original D1. I believe this is the only way to solve the clicking problem Spencer described in his thread.

The daughter card really only needs a handful of additional components to adjust the VCXO frequency to match the recovered clock. There is a dedicated 5V psu for the XO on the main which can be tapped for the daughterboard. Spencer has suggested that the DIR9001 is a better low jitter alternative, but I believe jitter can be further reduced by an order of magnitude by implementing the VCXO. The minicoax was a thought I had for jumpering the recovered clock across to the daughter board as cleanly as possible.

How is your build progressing?
 

spzzzzkt

Disabled Account
2005-05-21 4:24 am
Melbourne
D1 Reclocker

I finally got the copper shielding in place on the output caps last week, which doesn't seem to have made a significant difference to the sound in my D1V3. My setup with CS8412 and SM5842APT was showing no sign of instability without the shielding. I was having major problems when I replaced the 5842 with a PMD100 filter, the D1V3 was displaying all the traits of instability described by Spencer: extremely loud, distorted output. This needs further investigation.

In the mean time I'm very happy with the original Pass D1 "line up" of 8412/5842 but I would like to address the lack of reclocker on the D1V3. I'm waiting on delivery of a tentlabs VCXO but have begun building a slightly modified version of the reclocker shown in the D1 service manual. It seems fairly straight forward, although I am uncertain of the purpose of the +5V power supply feed via a 2.2M ohm resistor (R7) into the PLL loop. My best guess is that this is to bias the 4.7uF cap in the filter circuit. If anyone can shed some light on this point I'd be very most appreciative!!

cheers
Paul
 

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