John, thank you for your detailed answer. My few experiences with F-1 tapes have been nightmarish. Everything is fine, until you hit that one spot where it just won't track..I applied the skew method. twist the knob left or right until the lights look good, remember where you started, and do it again for real. When it works, it sounds great, when it doesn't... Ugh..
-Matt Sohn 


On Thursday, December 11, 2014 10:10 PM, John Gledhill <[log in to unmask]> wrote:
  


Tom -
o    The tape are recorded in the 14 bit mode with TOSHIBA DX-900. They 
actually have FM tracks of the same material
o    I am capturing both the FM and PCM

To David Glasser
o        I understand re the sample rate.
o      live performance recordings - 6 hours per tape

I have the 14 bit recovery working well with the EP tapes and have a 
solid right green on (or flashing) MOST of the time.
I just wanted to know the significance of the LEDs

I actually record a new tape through the coax in from a CD player to the 
601-esd (16 bit) , and then played the tape back and captured through 
spdif to compare the waveforms. I think the the 601 saturates slightly 
before 0x7ffff (around 0x7fef) but the lower values were a bit for bit 
match.

To Rob Poretti
o I agree re the 14 bit versus the 16 bit - if  the 601-esd does not 
like the VCR then more error correction will win.
o However, from watching the screen it is no 1 party bit versus two 
parity bits.
I think all of the stuff on the right hand side of the screen is error 
correction data. Each line has 3 word pairs and a huge pile of ECC . 
Roughly 3 * 15.75 minus the time lost during the vertical will give you 
the 44.056 This is also confirmed by the fact I can pop up the on-screen 
diiplay from the VCR and mot hear any errors,. Like a CD the ECC is 
spread over tape space = time to work around dropouts

Is it  important to correct for a 1/2 sample offset. Is this not the 
same as moving one speaker in a stereo pair 3mm  further back.

Slightly interesting aside.
While doing my experimenting for this I tried feeding the video from a 
vcr through a time base corrector to clean it up before going to the 
601-esd. Video looked much more stable on the screen but the 601-esd did 
not like this arrangement and the tracking bar stayed on the left. 
Perhaps it was the digital re-sampling in the TBC that cause this result.


Anyways - I am getting very clean audio back from the ep tapes and 
wanted to know about the lights.

I might guess that the guy who designed the LSI to do the decoding put 
the logic outputs there for his own diagnostic purposes and a bright 
marketing guy said "we have left oer LEDs - lets use em" with no one 
really writing down what they meant.





On 12/11/2014 7:44 PM, Tom Fine wrote:
> Hi John:
>
> My experience is that NO F1 decoder works well with 16-bit recordings 
> made at EP speed. I also think that later VHS machines with 
> auto-tracking may not align best for F1 recovery because they were 
> designed to also take into account VHS-HIFI signal. A 
> professional-quality VHS deck, even a late-era VHS-HIFI deck, will 
> have a tracking control, but the consumer models lost the tracking 
> control shortly after VHS-HIFI was developed.
>
> I'm curious, what sort of material are you working with and how many 
> tapes?
>
> -- Tom Fine
>
> ----- Original Message ----- From: "John Gledhill" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, December 11, 2014 4:45 PM
> Subject: [ARSCLIST] Sony 601-esd pcm audiio processor decoder
>
>
>> I am recovering sony F1 type audio (PCM and ECC in the video image) 
>> from some VHS tapes (ep speed 6 hr per tape)  - it was actually 
>> recorded with a Toshiba version.
>> I have the manual for the Sony 601-esd and I think is says the boobie 
>> lights (Red, FlashRed, FlashGreen, FlashGreen, SteadyGreen) is a 
>> logical procession from poor signal to good signal.
>> Additionally there is a tracking indicator (bar graph moving to the 
>> right)
>>
>> I can see from the schematic the LED's are driven from the decoding 
>> logic (didn't really need a schematic for that one).
>>
>> However, I an not find out at which point errors are still being 
>> corrected (apparently a few red flashes are fine) and at what point I 
>> can not count on the data.
>> I am recovering through the spdif -> PC.
>>
>> I am hoping there there is a audio archivists list with somebody who 
>> used these 30 years ago and thought to ask Sony exactly what was 
>> being measured with the lights.
>>
>> P.S. I found the Sony 601-esd encoder/decoder is not a good match 
>> with most later model VCR's and ep tapes. (the data on the back of a 
>> VCR switch disappeared years ago).
>>
>> -- 
>> John Gledhill
>> BIT WORKS Inc.
>> 905 881 2733
>> [log in to unmask]

>>
>>
>

-- 
John Gledhill
BIT WORKS Inc.
905 881 2733
[log in to unmask]