How can I convert SPDIF to EFM (RF) signal, to use a cd player as a DAC ? - diyAudio
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Old 27th January 2009, 10:07 PM   #1
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Default How can I convert SPDIF to EFM (RF) signal, to use a cd player as a DAC ?

Hello

A friend of mine do have a kenwood DP-460 cd player with a dead laser, it was a very good sounding cd player, he ask me to modified this kenwood into a DAC.

So, to use a SPDIF signal, the only thing I should need to do should be to use a SPDIF to EFM (RF) signal convertor ?

I presume that the converted signal, after SPDIF to EFM (RF) convertion, should go to pin 29 of the TC9200AF data processor Ic ?

Any simple circuits suggestions for convertion of SPDIF to EFM (RF) signal and how to use it ?

Btw, using google, I can not find anywhere the data sheet for the TC9200AF and the TC9201AF, anyone do have them ?

Here is the part of the schematic of the kenwood DP-460 cd player.

Thank

Bye

Gaetan

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Old 28th January 2009, 04:21 AM   #2
amc184 is offline amc184  New Zealand
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No, a S/P DIF to RF converter is not how you would do it. You would use a S/P DIF reciever IC to convert S/P DIF to the digital format that the DAC IC (TD6709N) accepts. Everything before the TD6709N would be bypassed.

An IC like a CS8414 might work, but you would need to know what format(s) the TD6709N accepts, and to know that you need a datasheet.

Any way you go, it is going to take a lot of time and effort to do what you are proposing. I don't think it will be worth your time.
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Old 28th January 2009, 04:50 AM   #3
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Looking over the schematic, there's not much there to salvage. The njm4558 are not very good op amps, and there's muting transistors in the signal path, I could go on. 95% of what's in the diagram would not be used. The only parts that would be reused are the DAC IC301 and the components in the lower right side corner of the diagram.

IMHO, almost anything you buy or build will sound better than this circuit as a DAC. Buy one of the DAC's from Brian at Twisted Pair or something else instead. By the time you build out the digital receiver circuit and it's associated parts, you will probably realize it's not worth the effort.

Someone in the trading post had an Adcom GDA700 for sale that will blow this CD player into the weeds.

I hope this does not sound harsh, but it's really not worth the effort - even for tinkering.

-David
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Old 28th January 2009, 05:55 AM   #4
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Quote:
Originally posted by amc184
No, a S/P DIF to RF converter is not how you would do it. You would use a S/P DIF reciever IC to convert S/P DIF to the digital format that the DAC IC (TD6709N) accepts. Everything before the TD6709N would be bypassed.

An IC like a CS8414 might work, but you would need to know what format(s) the TD6709N accepts, and to know that you need a datasheet.

Any way you go, it is going to take a lot of time and effort to do what you are proposing. I don't think it will be worth your time.

Hello

Here is the only data sheet that I have for the TD6709.

With this data sheet can you find out the format(s) ?

Thank

Bye

Gaetan

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Old 28th January 2009, 05:26 PM   #5
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Hello Gaetan,

This is a very old 16-bit DAC and nearly any current DAC chip will blow this chip into the weeds. Checkout the schematic for Peter Daniel's DAC using the 1541 chip or any number of AKM 4396 designs. They are simple to make and would involve the same level of effort or less than converting this CD play into a DAC.

-David
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Old 28th January 2009, 07:48 PM   #6
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Hello

Anybody find out the format(s) by looking my data sheet image of the TD6709 ?

Thank

Bye

Gaetan
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Old 7th February 2009, 11:11 PM   #7
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Hello

Looking again at the schematic of this kenwood DP-460 cd player, it seem to be non-os with a kind of analog brick wall filter, L101, L201 and IC102 ?

Since I will not need to fix his Kenwood, I could use some parts, how about using this analog brick wall filter for a non-os dac (replacing the 4558 op amp by a better one and taking out the emphasis and mute transistors) ?

Thank

Gaetan
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Old 8th February 2009, 06:24 AM   #8
jaycee is offline jaycee  United Kingdom
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The format is described by the timing chart.

It looks like Right Justified Mode might work, but the chip would only accept 16 bit. Attempting to send anything else would result in static.

You could use CS8416 as an SPDIF reciever.

Personally, I think if you are going to go to this effort, you might as well grab a newer DAC - see what you can get from TI or Analog as a sample part The only downside is that these are all SSOP package parts, very small - but you could use a converter board used for prototyping to change them to DIP format.
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Old 8th February 2009, 06:40 AM   #9
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Quote:
Originally posted by jaycee
The format is described by the timing chart.

It looks like Right Justified Mode might work, but the chip would only accept 16 bit. Attempting to send anything else would result in static.

You could use CS8416 as an SPDIF reciever.

Personally, I think if you are going to go to this effort, you might as well grab a newer DAC - see what you can get from TI or Analog as a sample part The only downside is that these are all SSOP package parts, very small - but you could use a converter board used for prototyping to change them to DIP format.
Hello

Is it Standard Japanese input format ?

I have some DIR9001 receiver chip, can it work for it ?

Thank

Bye

Gaetan
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Old 8th February 2009, 07:25 AM   #10
jaycee is offline jaycee  United Kingdom
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Looking at it, no... the nearest mode would be FMT1=FMT2=0, but the bits are clocked in the wrong way round and the LRCK is inverted to what the DAC requires.

It could be that TI and Toshiba use different meanings and it would actually work. You would need to invert LRCK from the reciever to feed it to the DAC, which is simple enough with a 74HC04 or similar.

I think if you are really keen, you need to try it. Make a small test board with just the DIR9001, and hook it to the CD player's board. Cut the traces to the DAC that bring in BCK, LRCK and DATA (pins 3, 7 and 8) and connect them to the outputs on the DIR9001. Remember LRCK would need to go via an inverter, or your channels would be swapped.
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