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Portable DAT modded to 24-bit?

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jefflester:
There's a taper "BobS" sharing some of his DAT masters from the 2000s on Dime and he was calling them 24-bit so I pointed out that the "M1" was 16-bit DAT recorder not 24 and he says it was modded. I could maybe see possibly a home deck (playback is on a Sony 7040) getting modded to 24-bit playback but have a hard time believing such a mod could be done on a small deck like an M1. Anyone ever hear of such a thing or how it could have been done?

http://www.dimeadozen.org/torrents-details.php?id=680320

Jeff Beck
The Greek Theatre
Los Angeles, Ca.
2006/09/28

Source: AUD (BobS)
Sec.B row A 10’ off center
Recording gear: DSM6-EL>M1 DAT with Sonic Studios pre amp mod at 48/24
Transfer deck: Sony PCM-7040 out 48/24
Processing gear: Audition, Izotope RX7 advanced, Ozone 9 advanced, various parametrics and notch filters.
Exported at 44.1



#8400232 by bobs23 at 2020-06-05 14:43:13 GMT
[avatar inaccessible]    

In comment #8399978 tdcrjeff wrote something like this:

"Recording gear: DSM6-EL>M1 DAT with Sonic Studios pre amp mod at 48/24
Transfer deck: Sony PCM-7040 out 48/24 "

There were never any 24-bit DAT portable recorders, and certainly not the "M1", which presumably means Sony PCM-M1. AFAIK, the only DAT machine that ever did 24-bit was the $2000 Tascam DA-45R 3U deck circa 1999 , which ran double-speed for the increased word depth - only 1 hour recording on a 2 hour tape.



Having worked in the entertainment industry in LA for a very long time, I have some very smart friends that have the ability to not only fix gear, but to modify it as well. The A/D's and associated circuitry were moded to make this happen. Take it or leave it.

Craig T:
The stock PCM-M1 used the AK4520A a/d chip, which was 20bit.  My guess is that the modification was to replace the AK4520A with a 24bit a/d chip.  I'm sure the modified M1 was still recording at 16bit.

jerryfreak:
id call BS on that

as you mentioned, you'd literally have to mod both the ADC circuit writing to the DAT, and either insert some novel compression algorithm between the ADC and the tape, or as you mentioned, physically speed the tape up, to fit the data on it. Thats a ton of changes in a deck of that size (remember how small the M1 was relative to the D8?)

reading the tape back would require a custom DAC to decode this mysterious, non-standard 24 bit data

more than likely this guy dumped his entirely 16-bit signal path into a 24-bit soundcard with 8 empty bits (or worse, into a non-bit accurate soundcard that filled up 8 bits with noise). The fact that the guy doesnt even understand how critical the soundcard is, and doesnt list it in his lineage, is also a red flag

none of it makes any sense. doing any mod like that would be prohibitively expensive and money thrown at better mics or a real preamp would return far greater results. And its not like there werent real 24bit recorders in 2006

jerryfreak:
also i vaguely remember some 20 bit or 24bit mods to equipment of that era.... sbm maybe. but i think it was just to use better chips, not necessarily all the bit depth

my $50 sony voice recorder uses a SoC capable of 32bit/192K, but only utilizes 16/44

Scooter123:
Nah

The SBM dithered and truncated down the signal to 16bits.  I've used it extensively when I transcribed somewhere in the neighborhood of 1,000 DATs a couple years ago.  However, there is a HOSA equivalent which does the same thing but outputs to SPDIF, a preferred cable, rather than the Sony 7 Pin. 

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