What is 4DAC ?

[Late Boomer]

I have a question fully phrased here about a particular CD player that I've bought recently. I more or less understand what MASH is, but not sure about 4DAC label. Thought this subforum gets more views. Thanks!

 

[ProBlogger]

See this thread: https://audiokarma.org/forums/index.php?threads/technics-panasonic-mash-cd-players.825663/

 

[Late Boomer]

I've read that thread, did not help me much.

In the end, MASH chips were basically four bit DACs

Are all MASH chips 4-bit? Are there datasheets to prove this? Where should I look in a datasheet? Does it mean 4-bit in the "old" sense, that is, 4 DACs, each processing 4 bits of a 16-bit word, or in post 1-bit DAC sense? I don't really know how modern multi-bit DACs are different from 1-bit DAC, but I presume they use the same bitstream concept, which is completely different from the pre-bitstream idea of separate resistors per binary digit.

The front says "4DAC 18Bit", but inside they secretly employ a MASH DAC

My CD player does not say "4DAC 18Bit", instead it says "MASH 4DAC".

Again, I am not looking for what does "MASH" mean, I am curious what "4DAC" means.

 

[ProBlogger]

MASH is the noise shaping system that Panasonic used. 4DAC is for the 4 bit D/A converters that they used, as opposed to Sony’s 1 bit system.

 

[Late Boomer]

4DAC is for the 4 bit D/A converters that they used, as opposed to Sony’s 1 bit system.

Please, explain. I would appreciate links to reliable sources.

 

[pete_mac]

Hmmm... I'm not sure if the 4-bit reference is correct.

From what I can ascertain (and as per the extract below), the 4-DAC gear literally had four DAC chips (two per channel):

 

[Late Boomer]

The manual says this is what my CD player has (it is made in 1991):

I could not find datasheets for these ICs, but I think there is just one of each, not four. Weird.

It seems that MASH and 4DAC are mutually exclusive.

Should I accept the point already stated in the other thread that "The front says "4DAC", but inside they secretly employ a MASH DAC". Why would Technics do that? Were "1-bit" or "delta-sigma" dirty words at that time?

 

[pete_mac]

Hmm, that's an odd one!

I was trawling through some old catalogues on hifiengine for info, but have exceeded my daily download quota of manuals/brochures.

I did find this:

 

[Hyperion]

I did find this:

Looks like you nailed it.

 

[Late Boomer]

^ AFAIK, this is Matsushita's older technology. Not MASH.

 

[Andersonix]

The SL-P370 from 1990 is the same way: says both MASH and 4DAC, but is not actually....