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Fostex analog multitracks @ 30 ips?

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Anonymous
June 26, 2005 10:26:08 PM

Archived from groups: rec.audio.pro (More info?)

Hi --

I'm hoping someone can help me with some questions about Fostex analog
multitrack machines running at 30 ips. Some background first:

Our business is high-quality multitrack analog to digital transfers. For a
quick technical overview, please see:

http://www.sonicraft.com/a2dx/a2dx_tech.html

When we set the lab up initially, we were planning to focus exclusively on
formats where track density did not exceed 4 tracks for every 1/4" of tape
width.

Now that business is in full swing, we're learning that some very nice
projects have also been done on formats like 1/2" 16-track and 1" 24-track.
Furthermore, many of the same folks who send us work on formats like 2"
24-track also want to send us projects that used these smaller, denser
formats. So, we've started to gear up and can now transfer most of these
tapes.

Recently, we got a tape in that was done in the 1/2" 16-track format but at
30 ips. After a bit of research, I learned that the E16 Fostex machine had a
jumper on the capstan motor that would kick it up to 30 ips and that perhaps
Fostex had even issued 30 ips E16 machines.

By putting a jumper on the capstan where someone could crack the machine
open and change only the capstan speed, Fostex has created an interesting
problem for me. If a job comes in on 1/2" 16-track tape at 30 ips, I now
have to figure out whether the tape was made on:

(1) a properly modified or factory built 30 ips machine,

(2) a hot-rodded 15 ips machine (where the only change was to bump up the
capstan speed) and some attempt was made (through bias, record, and playback
re-alignment) to get a stock 15 ips IEC EQ machine to "work" at 30 ips

or

(3) a hot-rodded 15 ips machine where all that was changed was the capstan
speed jumper to make a 15 ips machine move tape at 30 ips.

I think the E16 (G16?) machines were built using either Dolby C or Dolby S
NR. So, figuring out how the tape was made gets even more critical if the 30
ips tapes were made using the machine's built-in noise reduction system.
(Yes, some people actually run 30 ips *with* noise reduction.) Stated in a
simplified way, if the playback EQ we use isn't reciprocal to the original
record EQ, the noise reduction decoding will suffer.

I'm also wondering whether or not the 1" 24-track Fostex has a similar
jumper and/or was capable of 30 ips operation from the factory.

Also, while we're here, what are the differences between the E series and G
series Fostex machines in sound quality and build quality? Which models
supported which noise reduction systems?

Are there any Fostex mavens out there who can help me out with some answers?

Thanks!

-- Steve

=================================================
Sonicraft A2DX Lab
Ultimate Multitrack Analog-to-Digital Transfers
http://www.sonicraft.com/a2dx
=================================================
Anonymous
June 29, 2005 8:01:08 PM

Archived from groups: rec.audio.pro (More info?)

On Sun, 26 Jun 2005 18:26:08 -0400, Steve Puntolillo <spunt@comcast.net>
wrote:

>
> By putting a jumper on the capstan where someone could crack the machine
> open and change only the capstan speed, Fostex has created an interesting
> problem for me. If a job comes in on 1/2" 16-track tape at 30 ips, I now
> have to figure out whether the tape was made on:
>
> (1) a properly modified or factory built 30 ips machine,
>
> (2) a hot-rodded 15 ips machine (where the only change was to bump up the
> capstan speed) and some attempt was made (through bias, record, and
> playback
> re-alignment) to get a stock 15 ips IEC EQ machine to "work" at 30 ips
>
> or
>
> (3) a hot-rodded 15 ips machine where all that was changed was the
> capstan
> speed jumper to make a 15 ips machine move tape at 30 ips.
>
> I think the E16 (G16?) machines were built using either Dolby C or Dolby
> S
> NR. So, figuring out how the tape was made gets even more critical if
> the 30
> ips tapes were made using the machine's built-in noise reduction system.
> (Yes, some people actually run 30 ips *with* noise reduction.) Stated in
> a
> simplified way, if the playback EQ we use isn't reciprocal to the
> original
> record EQ, the noise reduction decoding will suffer.
>

It looks like you probably know as much as I do about adjusting the E
series Fostex's to work at different speeds. Do you have a service manual?
I don't remember any mention in the service manual of any component
changes for 30ips so I suspect that any changes in eq that were necessary
can be made using the standard preset pots.

E16's were Dolby C only and it would be rare to find that it wasn't used -
even at 30ips the noise would have been fairly apparent.

I'm going away for a couple of weeks at the end of this week but if you
need any info from the service manual then send me an email and I'll see
what I can do.

Cheers.

James.
!