Fostex analog multitracks @ 30 ips?

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

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Sonicraft A2DX Lab
Ultimate Multitrack Analog-to-Digital Transfers
http://www.sonicraft.com/a2dx
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