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Old 29th April 2004, 06:48 PM   #21
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Hi Elso, im happy for every answer that contains some information so i could learn something.



another point: i made D1 stage and connected to the AD1865s. First they distort much if working against few negative mV, so i adjusted for +40mV instead of 0V.

Then i found they dont work as they should if i deconnect RF and Vout and Iout and summing Junction. Lots of noise if not connected. But in this circuit are all nc : http://www.geocities.com/yury_g/dac.htm

So i have jumper Vout to RF closed, and Iout, SJ and the 40mV input of D1 connected together.
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Old 29th April 2004, 06:58 PM   #22
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Quote:
Originally posted by till
Hi Elso, im happy for every answer that contains some information so i could learn something.



another point: i made D1 stage and connected to the AD1865s. First they distort much if working against few negative mV, so i adjusted for +40mV instead of 0V.

Then i found they dont work as they should if i deconnect RF and Vout and Iout and summing Junction. Lots of noise if not connected. But in this circuit are all nc : http://www.geocities.com/yury_g/dac.htm

So i have jumper Vout to RF closed, and Iout, SJ and the 40mV input of D1 connected together.
Hi Till,
I2S Direct is the most simple connection but using the CS8412 is more versatile, making it possible to use an AD1865 with a Philips transport.
For I2S Direct and the TDA1543(A) the following combinations are possible:
Philips CDP-> TDA1543
Sony CDP -> TDA1543A
I you don't use the built in IV opamp in the AD1865 you should disable the opamp in some way. I have no experience with Nelsons Pass' IV so I can't comment on that. You can use an external opamp for IV with the AD1865. Been there done that.
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Old 29th April 2004, 07:26 PM   #23
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Quote:
but using the CS8412 is more versatile, making it possible to use an AD1865 with a Philips transport.
Elso, that why i do this now. But i think Philips CD PROx must also be possible, as the transports knows various output data formats:

<I2S
mode>
I2S format mode
see SET MODE command
0 reserved
1 I 2 S - FS mode (default) DAC mode
2 I 2 S - 2 FS mode DAC mode
3 I 2 S - 4 FS mode DAC mode
4 Sony 16 bit FS DAC mode
5 Sony 16 bit 2 FS DAC mode
6 Sony 16 bit 4 FS DAC mode
7 Sony 18 bit FS DAC mode
8 Sony 18 bit 2 FS DAC mode
9 Sony 18 bit 4 FS DAC mode
81 I 2 S - CD-ROM mode CD-ROM mode
82 EIAJ CD-ROM mode CD-ROM mode


I hope one of them is ok for the 1865
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Old 29th April 2004, 07:41 PM   #24
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Quote:
Originally posted by till
i made D1 stage and connected to the AD1865s. First they distort much if working against few negative mV, so i adjusted for +40mV instead of 0V.
Some time ago I build the D1 I/V for my Sony SCD player . The differences between a dac and another they will reflect in the buffer of the D1 stage (in particular in the voltage at the source of the buffer), that's why it is more simple work without it (besides that the buffer is not essential) . So if you have too much trouble , try without the buffers(source followers) and take the output at the drains of cascode.


edit: as an example the Sony's current pulse dacs works at 90milli volt.
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Old 29th April 2004, 08:12 PM   #25
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Quote:
Originally posted by till


Elso, that why i do this now. But i think Philips CD PROx must also be possible, as the transports knows various output data formats:

<I2S
mode>
I2S format mode
see SET MODE command
0 reserved
1 I 2 S - FS mode (default) DAC mode
2 I 2 S - 2 FS mode DAC mode
3 I 2 S - 4 FS mode DAC mode
4 Sony 16 bit FS DAC mode
5 Sony 16 bit 2 FS DAC mode
6 Sony 16 bit 4 FS DAC mode
7 Sony 18 bit FS DAC mode
8 Sony 18 bit 2 FS DAC mode
9 Sony 18 bit 4 FS DAC mode
81 I 2 S - CD-ROM mode CD-ROM mode
82 EIAJ CD-ROM mode CD-ROM mode


I hope one of them is ok for the 1865
Hi Till, that's great all those possible modes.
I would choose mode # 7 for AD1865 ON-OS if that is what you are after...
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Old 29th April 2004, 08:19 PM   #26
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Exactly this would be my idea. But i want to make the controller that way i can send any Dac mode command to the transport with a menue, so it would be possible to try different modes or connect different DACs. I have half a firmware coded, and will buy a second CD PRO unit for further development when i find enough time. I dont want to put my first CDP to pieces for this, as i need it to play music every day....
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Old 29th April 2004, 08:30 PM   #27
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Quote:
The differences between a dac and another they will reflect in the buffer of the D1 stage
What would be the problem with the voltage at the source? The outputs are capacitor coupled, so what the matter with the DC level there?

It works, i cant see problems until now. It also works with 0V, but as the voltage at the input needs some time to settle / thermal drift whatever, and in the range -60 to about 0V the AD1865 makes funny noise, i thought it would be better to go for little positive voltage here.

What i dont understand is why i need to leave Vout connectet to RF and SJ connected to Iout, else i have funny noise also.

I see advantage in the buffer, i can make a volume control like in D1, and use a relais switched resistor array for this. The control of relais woul be job for the microcontroller i also need to send commands to the transport. And i can drive balanced Zen lite or SOZ with that CD player without need of any preamp. http://home.tu-clausthal.de/~tpa/CDP/CDP.gif
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Old 29th April 2004, 08:34 PM   #28
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The I2S is nice, however once you connect the ground from the CD player to the DAC you will still have abunch of noise. The pulse transformers isolate you from the CD player noise.
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Old 29th April 2004, 09:35 PM   #29
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Quote:
Originally posted by till

What would be the problem with the voltage at the source? The outputs are capacitor coupled, so what the matter with the DC level there?
Ok if it works fine for you. With sony I was experimenting too little voltage at the source of the buffer-5volt or so- and the mosfet wasn't biased properly.

Quote:
Originally posted by jewilson
The I2S is nice, however once you connect the ground from the CD player to the DAC you will still have abunch of noise. The pulse transformers isolate you from the CD player noise.
jewilson
I would like to learn more about the pulse transformers since I noticed noise too coming from the cd player mechanics .I use I2S directly .

Thanks
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Old 29th April 2004, 11:59 PM   #30
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This is what i measure at Vout of the DACs with 1kHz -0dB sine from test CD
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