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Old 11th February 2008, 10:32 AM   #11
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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.
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Old 11th February 2008, 12:09 PM   #12
icewall is offline icewall  Sweden
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Hi,

Just a question about the dificulty level on this project. In your opinion, spzzzzkt, how hard is it to assembly this DAC? I'm thinking of ordering a kit for my own birhtday - as a gift to myself
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Old 11th February 2008, 08:08 PM   #13
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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...
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Old 17th February 2008, 10:54 PM   #14
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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
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Old 18th February 2008, 01:57 AM   #15
sklimek is offline sklimek  United States
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Congratulations! You sound truly pleased.

Are you using the XO and were you able to resolve your concern with the output clicking from the XO clock, did your mini-coax do the trick??

Stan
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Old 18th February 2008, 03:58 AM   #16
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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?
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Old 18th February 2008, 04:58 AM   #17
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Default D1V3 hooked up...

and making some noise!!
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Old 18th February 2008, 06:40 AM   #18
sklimek is offline sklimek  United States
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It looks great!

I've acquired everything and hope to start stuffing when I get some down time around 3/15. Thanks for starting the thread!

Stan
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Old 17th March 2008, 11:03 PM   #19
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Default 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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Old 18th March 2008, 05:33 AM   #20
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The answer according to someone who should know is that the voltage is a prebias for the VCXO and the value was selected to minimize jitter.

guess I need to google a bit to find out how this will play with a tentlabs vcxo.
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