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Old 26th May 2003, 03:18 PM   #11
PMiczek is offline PMiczek  United States
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Default I2S signals

I think Peter Daniel meant you need to add three wires to make a connection from the circuit board in a consumer CD player to a new DAC chip you are adding.

What this looks like and where the circuit traces are on your board would depend on what CDP you have, and what DAC chip is on the board. You would find the datasheet for your DAC, and start by identifying the pins with the correct signals.

This is really not such an easy modification to do in a new product if you do not have some experience dealing with small circuit board traces and SMT (surface mount) components.

Maybe post a question to find out if anyone has modified the CD player brand and model you have, and what the results were.
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Old 27th May 2003, 04:17 PM   #12
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mb,

I also own a CIA VDA-1 DAC and would be interested in the mods you performed on yours if you would be willing to share. These mods may also be relevant to others designing their own, or modifying eval boards.

David

Quote:
Originally posted by mb

The CI was not stock, but has the sonic signature of the stock unit, plus perhaps more control and better extreme top end. The mods were not out of the ordinary - diodes + caps. Some tuning by ear (not all mods were synergistic).
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Old 28th May 2003, 11:50 AM   #13
miguel2 is offline miguel2  Portugal
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My cdp is a marantz cd48. It uses a bitstream dac. Anyone knows where I can find the I2S signals?
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Old 28th May 2003, 04:21 PM   #14
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Koinichiwa,

Quote:
Originally posted by miguel2
My cdp is a marantz cd48. It uses a bitstream dac.
No, it does not use a Bitstream DAC, it uses "bitcheck" conversion using the TDA1545 DAC.

Quote:
Originally posted by miguel2
Anyone knows where I can find the I2S signals?
Not at all. The CD48 uses the 4 X Oversampling Digital Filter of the CD Decoder Chip. The Signal after that Decoder/Digital Filter is still I2S, but at 176.4KHz and with a Digital Oversampling Filter already applied. If you where a cynic you could use a 192KHz capable DAC Chip with internal 4/8 Times oversampling from BB/TI or Cirrus Logic (aka Crystal) and claim you modded CD Player does syncronous upsampling to 176.4KHz and then further 4/8 Times oversampling.

Sayonara
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Old 28th May 2003, 04:33 PM   #15
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: Simple, good quality DAC

Koinichiwa,

Quote:
Originally posted by jnxw2

I would really like to upgrade my CD player with an external DAC, however I fear that my electronics skills would not be up to anything more sophisticated than building a power supply...
I am quite familiar with the abilities of both CD63/67 and CD6000 from Marantz. With some modifications they can offer very high sound quality, not easily exceeded with any of the common modern external DAC's, especially not with those found on cheap EVAL Boards.

If you could actually build a Powersupply for an external DAC that will perform well then you should have little problems building a simple DAC from scratch (after all, the Powersupply of any given circuit is about 50 - 80% of the sound).

If you want a sound that actually offers a sonic perspective that is notably different (I shall not say "better", as this is a matter of taste) I must strongly support Peter Daniels recommendation of the TDA1543 (or TDA1545) used in non-oversampling mode.

For someone with limited DIY experience you might find Scott Nixons DACKIT a good choice.

What is this DacKit thing? - http://www.scott-nixon.com/dac.htm

I used to have the earlier version of this approach based on Kusonoki San's 4 X TDA1543 DAC from MJ 1996 since late 1997 and found it a great choice and much better to my taste than my modded Marantz CD-67 CD-Player, as well as my modded Pioneer DV-505 DVD-Player (this is a surprisingly good CD-Player as it has Pioneers best but one Legato Link DAC Chip).

BTW, just as an aside, the Burr Brown PCM1716 and Cirrus Logic CS4329 DAC Demo Boards both where much worse than my modded Marantz Player.

Sayonara
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Old 28th May 2003, 04:52 PM   #16
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I just modified my Marantz CD-94 and as a stand alone unit it is better than used as a transport feeding my recent CS8420/PDF1704/parallel PDF1704 DAC. I'm still using original PS inside the player, while my DAC had 8 transformers and at least 13 local PS based on LT 1035/1085 (or whatever numbers) chips.

The only thing I did to Marantz was bypassing digital filter, simplifying output stage to a single OPA627 per channel, removing DC reducing resistors network right at DACs output, changing all electrolytics to HFQ and Cerafines, adding local bypassing (Goudreu triplets). Well, the results are impressive and that player is producing the best bass I've heard so far. Sometimes simple ways are better indeed.
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Old 28th May 2003, 05:49 PM   #17
miguel2 is offline miguel2  Portugal
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Quote:
Not at all. The CD48 uses the 4 X Oversampling Digital Filter of the CD Decoder Chip. The Signal after that Decoder/Digital Filter is still I2S, but at 176.4KHz and with a Digital Oversampling Filter already applied. If you where a cynic you could use a 192KHz capable DAC Chip with internal 4/8 Times oversampling from BB/TI or Cirrus Logic (aka Crystal) and claim you modded CD Player does syncronous upsampling to 176.4KHz and then further 4/8 Times oversampling.

Hey Kuei,

I understand that if the I2S signal is already oversampled, a simple TDA1543 design is out of the question. And as I am not a cynic (I guess) I have to ask you if using a 192KHz chip would increase sound quality significantly. And which chip in which configuration (a schematic here would be just great)? Do you remember the exact chip of Decoder/Digital Filter, so I can spot it on the cdp and see where I can get the I2S?

Miguel
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Old 28th May 2003, 05:52 PM   #18
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Thanks for all the suggestions!


The Dackit looks pretty good but I think i would prefer to use the TDA1543 if only because I reckon I could learn more..
I had a look at Peter Daniels Schematic of the TDA1543 circuit and PS, and I think I could do that easily enough, the only thing i dont know is where do I get the input signal from?


Thanks

jnxw2
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Old 28th May 2003, 06:12 PM   #19
Previously: Kuei Yang Wang
 
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Koinichiwa,

Quote:
Originally posted by jnxw2

The Dackit looks pretty good but I think i would prefer to use the TDA1543 if only because I reckon I could learn more..
Ahhm. The DACKIT is based on the TDA1543 and uses in fact the same circuit. I did not recommend buying the finished product, just the PCB and maybe chips... ;-)

Quote:
Originally posted by jnxw2

I had a look at Peter Daniels Schematic of the TDA1543 circuit and PS, and I think I could do that easily enough, the only thing i dont know is where do I get the input signal from?
Peter AFAIK works without receiver, which means you need tap off the I2S signal inside the Marantz CD6000. Get a Service Manual and work it out if you like.

The DACKIT PCB includes space for an S/P-DIF receiver, in this case you simply plug it into the Digital (Coax) Output of your CD6000.

Sayonara
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Old 28th May 2003, 06:26 PM   #20
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ahhhhhh, hence you see why I didnt think I was up to building a DAC

jnxw2
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