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Old 22nd June 2008, 11:36 AM   #111
regal is offline regal  United States
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Like the XCCS - BOSOZ ?

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Old 22nd June 2008, 01:54 PM   #112
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Quote:
Originally posted by regal
Like the XCCS - BOSOZ ?


What's the point of having two CCSs in this circuit?
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Old 22nd June 2008, 02:01 PM   #113
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It`s a bad schematic, there`s missing resistor between 68 ohms source resistors...
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Old 30th June 2008, 07:37 AM   #114
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Default PLL board mods

The vcxo reclocking has been bothering me - the tonal balance was slightly too thin - so I took a look at the board to fix up the resistor at the output of the vcxo. The D1 original doesn't use this and in (mis)interpreting the notes on the product pages I'd clearly placed it in the incorrect location.

Quote:
Clock outputs: 1, can drive 3 HCmos gates. A series resistor of 22 to 47 ohm close by the VCXO is advised
I'd had the series resistor only on the line driving the D1V3 clock which after reading the above note I realised this was not what was intended! I've reworked the "board" so the resistor now is driving both the pll and clock line to D1V3 board.

From an initial listen this seems to have moved the sound back towards a far more acceptable tonal balance so it appears I'm on the right track.
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Old 30th June 2008, 12:11 PM   #115
regal is offline regal  United States
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spzk, if you come to a final solution a schemtic would be greatly appreciated. The only VXCO reclocking schematic I have found is the tent-labs DIY DAC but it seams overcomplicated.
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Old 30th June 2008, 01:13 PM   #116
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no problem
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Old 30th June 2008, 08:50 PM   #117
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Hello to all!
I am new in this forum.
I am trying to follow all the speeches to upgrade this wonderfull DAC (I am in order to buy the PCB), but my english is really terrible, and I am lost (confused) between the several arguments.
I think to have understood as follow:
- to rewire the Output Relays connections? (this OK for me).
- spzzzzkt prefers the SM5842APT digital filter and not PMD100?
- to use for DAC analog supplies from the regulated 18V I/V supplies, instead from 12v supplies?

Can someone gently confirm if I have understood correctly?

And again, can someone gently REASSUME the other modifications and upgrades necessary in order to improve the DAC to work at the best?

It would be a very important help for me.
Many many thanks in advance.
Sincerely.
Davide.
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Old 1st July 2008, 12:54 AM   #118
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Default D1V3 mods

I'd advise against doing the output relay mod as I discovered last week that my D1V3 isn't muting correctly. I need to look at this closer so see why this is happening - I sure it was working ok when first done, but can't be 100% sure. I don't think the minor gains really warrant it. Your effort would be better spent else where.

I haven't been able to get the PMD100 to work correctly to be honest. My previous dac used the PMD100 and I would be interested in trying it in the D1V3. All I can think is wrong is that the PMD100 is overloading the D1V3 output stages. I recall Spencer mentioned using different resistors to lower gain of the output stage to prevent his preamp input overloading, so possibly this is reason he hasn't seen this issue?? My aim is - partly at least - to build something close to the original D1 so the 5842 is the chip of choice for that purpose.

I'd recommend running the DAC chip supplies from the +/-18V, simply because they provide cleaner power source than the 12V supplies. I'd highly recommend that you apply the bypass caps to Radj on the LM337+LM317 regulators as these are required to get best performance from the LM3x7's. Looking at the datasheet and other sources 10uF is the absolute minimum value to use. Spencer mentions this in his thread in the marketplace.

The zener mods on the regs seem to work well, but it is very difficult to get the voltages set accurately - mine are +/- 0.2V - due to variation in the diodes. I'd hesitate to recommend doing this mod without further investigation to be honest.
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Old 1st July 2008, 12:32 PM   #119
regal is offline regal  United States
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I ordered the kit with the PMD100 and did not get the SM chip. Hopefully when my build is finished it will work. I am guessing it is one of the jumpers set wrong. The PMD should work. Pass D1 aside, it is the finest digital filter ever made. I wouldn't let its absence in the original D1 deter you.

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Old 1st July 2008, 01:53 PM   #120
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definitely not a jumper configuration issue and no bridges or open circuits on the adapter board.

To be honest the CS8412 - SM5842APT - PCM63 combination sounded far better than the CS8412 - PMD100 - PCM1702 dac i used to run even before installing the vcxo, so I haven't really felt inclined to get to the bottom of the problem I've had with the adapter.
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