| Lenin |
Having recently been gifted half a dozen PMD100 HDCD chips, I've been stroking my chin over this for a few days now.
Would it be possible to replace the SAA7220 in my 15 year-old DAC (Sony CX23053 reciever, SAA7220P/B filter, TDA 1541A) with the PMD100?
Do better brains than mine have any thoughts?:confused: |
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| JonPike |
Hmmmm.... do you have any documentation for the chips, or is it available out there?
You'ld need to find what kind of digital interface they both use, and how the data is formatted. Could be anywhere from just patch it in, to needing major retranslation.. to the point of it's more trouble than it's worth.
Likely it's somewhere inbetween, you may be needing some simple logic to handle minor differences.
Let me know if you can get the specs on the PMD100.. I'll look it over for ya..
Jon |
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| Lenin |
Thanks for the replies guys.
SAA7220 datasheet is here:
http://xoomer.virgilio.it/hi_fi/quick.htm
The results I'm hoping for are here: http://www.jeffchan.com/audio/filter-comparison.html
But being a geedy old soul, I also want to run the TDA1541 at 176.4khz.
Having only recently to read info on the 7220/1541 combo on the forum, it seems that whichever side of the OS/non-OS divide you are on, its generally agreed that one way or another, the 7220 just has to go.
As for the 1541A, it can run at 176k, opinion is that higher clock speeds result in improved sound quality (all other things being equal)
How would I go about that?
Anyone?
Henk, all but 2 of my PMD100s are spoken for/committed to projects. Lets take this off line and I'll see if I can squeeze another one out of my pal. |
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| Lenin |
Just taken a quick look at the PMD100 datasheet.
Which receiver chip would you guys recommend?
Yamaha YM3623B? CS8412? One of the Sony chips referred to in the datasheet? (More likely to be a pin for pin replacement, I guess). |
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| rfbrw |
If you want to run the TDA1541A at 4Fs or possibly 8Fs, you will have to run it in the simultaneous input mode and the PMD100 in complementary offset binary data mode (COB). See the relevant datasheets for information.
Aside from being difficult to work with as they are large surface mount devices, the CXD251xQ devices referred to in the PMD100 datasheet are not input receivers, hard to source in small quantities and have long been discontinued. Might as well stick with the CX23053. |
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| Bricolo |
| Isn't a 20bit DAC needed for HDCD playback? |
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| rfbrw |
| quote: | Originally posted by Bricolo
Isn't a 20bit DAC needed for HDCD playback?
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Read the PMD100 datasheet. |
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| Lenin |
Thanks rfbrw, will do.
Ahem... I don't suppose you have a datasheet for the CX23053, do you?
Or maybe just the pinout diagram?
Anyone? |
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| Bricolo |
| quote: | Originally posted by rfbrw
Read the PMD100 datasheet. |
What is told in the datasheet?
googling a few minutes tells that a 20 bit dac is needed for HDCD |
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| Lenin |
Hi Bricolo,
p21 of the datsheet - the PMD100 offers 16, 18, 20 or 24 bit output word lengths. |
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| Bricolo |
| ok, but do they all have the hdcd content? |
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| rfbrw |
| quote: | Originally posted by Bricolo
ok, but do they all have the hdcd content?
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Err, what is the point of having HDCD content AFTER the HDCD decoder? |
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| Bricolo |
| From what I understood, an HDCD decoder translates the information "compressed" on the 16th bit to a 20bit DAC, the 5 last bits being the HDCD data "uncompressed" |
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| rfbrw |
| quote: | Originally posted by Bricolo
From what I understood, an HDCD decoder translates the information "compressed" on the 16th bit to a 20bit DAC, the 5 last bits being the HDCD data "uncompressed" |
The mind boggles.:boggled::boggled:. Have you given this proposition a moments thought. How on earth does the HDCD decoder tell the 20bit dac that " Oi, dac, no, you are not a 20bit dac,you are a 15bit dac with 5 special bits" and what then does it do with the 5bits ? |
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| Bricolo |
Of course the dac don't know this
But AFAIK, the dac has to be more than 16bit |
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| Lenin |
Bricolo,
rfbrw's advice seems rational to me. (Thanks rfbrw).
I'll attempt to give his advice a go. (The lure of a 1541 minus the 7220, with HDCD, running at 176.4k is just too much to resist!)
Now if only I could work out exactly how I should arrange all the wire links on my DIL socket...
Advice anyone...? |
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| rfbrw |
| quote: | Originally posted by Bricolo
Of course the dac don't know this
But AFAIK, the dac has to be more than 16bit |
AFAIK Beagle 2 did not crash but was destroyed by the Mysterons on landing but my believing that does not make it so.
The choice as always is yours. You can stick to your dogma or read the datasheet and the AES paper associated with the PMD100 and HDCD in general. |
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