Non Oversampling DAC-complementing CD-PRO

[rfbrw]

The circuit posted does not address the interchannel delay and a balanced dac built without addressing the interchannel delay is unlikely to perform at its best. If the stopped clock method of addressing said delay is not to your liking, one can always go down the large shift register route keeping the continuous bitclock.

ray.

[steve jones]

Interesting schematic.

But maybe I'm not seeing it correctly.

Looks like you are shifting SDATA 16 bits (2X 74HC164) so that the left channel's LSB and down-going edge of the inverted LATCH coincide. From the above I assume that it is for use with 16 bit I2S. I do believe there is a 24 bit variant, too.

But the AD1865 has an 18 bit input.

Won't the AD1865 still accept the last 2 LSBs intended for the opposite channel and add them above the MSB of the channel before the LATCH is enabled?

Don't you have to stuff an extra 2 LSBs for each channel, in there somewhere, so the 1865 has an 18 bit input register full of good 16 bit data?

Steve

[scottnixon]

SAA7372 chip. You should be able to useit in the EIAJ mode. Bypassing the I2S issue. If I remember there's a CDrom EIAJ mode that doesn't use the onboard interpolation. It's been a few years since I've played with the Pro kit. Just something to consider. CDROM/EIAJ mode with a inverted latch, for NOS cd playback?

[scottnixon]

Think those are in the newer pros.

[Peter Daniel]

Maybe the easiest way would be to use TDA 1541 then? No glue logic, direct connection and simple output stage.

[rfbrw]

It would be a pity to spoil the ship for a halfpenny's worth of tar.

ray

[guido]

Peter,

I am working on getting two TDA1541's in dual mono. That is one does left and one does right channel output. Output can be balanced by inverting one of the channels or not. In the latter case both outputs can be paralleled. This is more or less the same then as many TDA1541 designs with two in parallel. Only now left and right channel can have their own powersupply..

I posted this a while ago in this forum. Used quite a few shift registers then, but it is working fine! This is going to be only one in the future. Chipcount: 74HCT74, HEF4517 (replacing eight 8-bit registers) and a 20V8 GAL. Not too bad i think.

Maybe something to look at if you go down the TDA1541 route.
You have to check the output of the PRO mechanism. I am using the output of an old decoder in an old CD player (SAA7210 chip) and it is using 32 bit per frame, so 16 bit data and 16 bit dummies. The size of the shiftregisters depends on it.

I know not everybody likes the 1541. For me, this is the first attempt at creating my own DAC, so don't shoot me for using this chip. I was able to get two crowns for a reasonable price and this is just a start for me. On the other hand, some people like it very much.. I have no meaning yet, only have one old player with one old TDA1541 which is not modified.

Greetings,

Guido

[Peter Daniel]

Here is a filter board of my Marantz CD94 player. It uses Philips SAA7220 digital oversampling filter. If I would like to implement non-oversampling mode on 1541 DAC can I just omit SAA7220 and take signal directly from SAA7210 chip? If yes, which pins then?

[Elso Kwak]

Hi Peter,
See for example:
http://members.xoom.virgilio.it/hi_fi/com.htm and
http://members.xoom.virgilio.it/hi_fi/cd960.htm
<B>AND</B>: ( this applies to the Philips CD960 that uses the same IC's.)
Modidification to NON-Oversampling including installation of KWAK-CLOCK [version with single supply]
Color codes of wires of KWAK-CLOCK:
Red = +5V
Green= ground
Blue= clock output of KWAK-CLOCK
Remove/desolder C511; C512 & X501 (11.2896 Mhz crystal) All are on board
PD16; the board with the large IC SAA7220 (Q503); just near this IC.
Solder 11.2896 MHz crystal to KWAK-CLOCK PCB.
Connect the green wire of the KWAK-CLOCK to the negative side of C514.
Remove /desolder entire IC SAA7220 (Q503) 24 pins.
Connect the red wire to pad of pin# 24 of IC SAA7220 (Q503)
Connect blue wire to pad of pin# 9 of IC SAA7220.
With a piece of insulated wire connect pad of pin # 1 with pad of pin# 18 of IC SAA7220.
Same for pad of pin# 2 with pin# 16.
Same for pin# 3 to pin# 15 .
Please note these instructions are different from Marco Amboldi's as no tracks are cut in my modification making the modification reversible, not permanent.
Also note that with the latter modification the digital ouput is lost. You can not use a outboard DAC component. The KWAK-CLOCK output is directly connected to pin 26 of SAA7210 (digital signal processor)

[Peter Daniel]

Thanks Elso. I've got your schematic for KWAK-CLOCK2, that's the current version. I understand, I remove the crystal (11.2896MHz) from DSP board and use it with KWAK-CLOCK2.

Send me info regarding pricing for board and/or a whole kit.

You said: >The KWAK-CLOCK output is directly connected to pin 26 of SAA7210 (digital signal processor) <

Is that correct? Or is the output of a clock connects to pin 19 of SAA7210?

They recommend OP 42, OPA 604 chips for analog output. Is there any better alternative?

Thanks again for any info.

PS. One reason I'm doing that, I'd like to compare TDA1541 with AD1865 chips.