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Thread: Fostex Model 20 Alignment: Practical vs. Ethical

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    A Reel Person's Avatar
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    Exclamation Fostex Model 20 Alignment: Practical vs. Ethical

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    I'm going thru alignments on a Fostex Model 20 mastering deck.

    The manual states that 0VU is referenced to 514nWb/m! This would strike me that it's factory set and intended to use +9/185 high output tape, (499, 996, etc.), and the 0VU is set on the hairy edge of MOL! Being that's what the manual states, it strikes me as funny anyway. However, using this deck at 15 IPS on +9 tape must sound very clean, punchy and impressive! (Just don't hit it too hard above 0VU!)

    The practical thing is the bulk of my tape is +6/185 tape, 456/equiv (031 media), or standard 457, 3M 226, some 806, other various standard or lower output tapes (can't remember them all), and yes, some Quantegy 480 and 3M 996 high output tape in smaller amounts. I am ready to recalibrate and I can't decide what standard to use. The (lower) practical one for my own purposes, or the (higher) one that's stated in the manual?

    The ethical twist is that after calibrating I'll likely be selling this unit to locals via Craigslist. Just to set it for factory and tell the next owner to get some +9 tape, or set it to +6 (@MOL) and recommend using 457 all the way across? The Model 80 8-track is set for G320, which would be like running 456/457 with 0VU at the hairy edge of MOL. Again, that seems odd, but it's FOSTEX, and they were definitely marching to the beat of their own drummer.

    If there's a small chance it won't sell at all, I will be keeping it, nonetheless.

    I can't decide. I know what seems expedient to me, (lower levels using +6 tape), but to just set it to factory specs to hand it off to the next user and tell them to use +9 tape or let them make adjustments as they see fit?... (seems "right" vs "expedient" or "comfortable")

    Mastering to a +9 tape doesn't sound like a bad idea, but my stocks of +9 on 7" or 5" reels are minimal, and my estimate is that +9 tape is more expensive than +6 tape to buy at the dealer level.

    The Fostex Model 20 was designed for and factory set for +9 tape, so anything less would not be using the hardware to it's greatest advantage... is the most common sense idea I can draw about the situation.

    If I could decide, I could move onto the calibration and be done with it!

    Any input or recommendation, tapeheads? For some reason, this question has me way outside my comfort zone! I typically don't use +9 tape. I'm not used to it, but tape is tape, and I can read the manual! Aaagghh!! I think I'm having "analysis paralysis"!

    Thanks!

    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    Beck's Avatar
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    Dave, I know it is funny to see those levels, but they're based on European (IEC) standards rather than NAB, and are meant to be used with the recommended 457 class tape. +9 tapes weren't available yet when the Model 20 was introduced.

    G320 (German 320) is closer to 280 nWb/m NAB. It's a different scale altogether.

    Edit: Actually I worded that wrong. G320 is equivalent to 280 nWb/m NAB or IEC because of the different way we measure compared to German. Jay McKnight has a good explanation somewhere here on my overly crowded hard drive. I'll try to find the link.
    Last edited by Beck; 05-07-2013 at 20:50.
    "If you canít make a hit record with a Tascam or a Fostex,
    then youíre not going to able to do it with a Studer or Otari!"
    -David Mellor

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    A Reel Person's Avatar
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    Exclamation Yes, and...

    Thank you. I also determined from what I read, reference info, etc., that G320 was somewhat lower than 320. The Model 80 refers to 320nWb/m, and with all things considered I determined it to be calling for G320. G320 was referenced in lots of the white papers I've read. I set my Model 80 to G320 using -4VU and a 185nWb/m cal tape, but what of 514nWb/m?

    The Model 20 manual refers to the Fostex 9102A cal tape, or STL 53-1. Referencing an MRL 21J205 (15 IPS @ 250nWb/m) and would read -5.5dB below 0VU. The equivalency charts I'm reading would be somewhere just below 500nWb/m.

    Choosing and Using MRL Calibration Tapes for Audio Tape Recorder Standardization
    *I see G320 referenced, but nothing about 514, except in other tables a G510 reference is 450nWb/m and +8 over 0VU@185. I've read the dc-vs.-ac measuring method to arrive at these standards is appx. 10% difference. However, as my opening thought indicated, 450's just a hair below MOL for a +9 tape.


    Tape Flux Measurement Revisited*
    "the old German measurement is 10%less than the stated value--tapes identified as 320 nWb/m are actually 288 nWb/m". (the rest of this paper is very technical!)

    That info still indicates that the Fostex Model 20 was set up for high output tape. It's modern enough. It's the A2/A8 that probably predates +9 tape.

    I think I'm being too obsessive about this. I think it breaks one way or another on whether I want to do my own thing in my own way, or just follow the manual, use +9 tape and live with it. I think if I'm passing it on to a new user and I'm going thru the trouble to calibrate it, setting it to factory seems most proper. Once I found the reference equivalencies, it makes more sense, but yet to make that final decision.

    Thank you !
    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    Beck's Avatar
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    Yep, you pretty much found all the info I remember McKnight covering in one of his papers. The M20 is a strange beast for reference level IMO. The A2 (1982) and the E2 (1986) were both referenced to 250 nWb/m NAB, but the one in between, the Model 20 (1985) has this funky 514 nWb/m flux reference. I'm no expert on the Fostex machines, but I do have the original brochure, which also lists that 514 nWb/m reference @ 0VU and recommends Ampex 457 or 3M 227 tape. Of course 3M 227 all went sticky so today's options would be Quantegy 457 or RMGI LPR35.

    The Model 20 came out about 1985. The first +9 tape was 3M 996, introduced in 1990.

    I see other decks come up with the 514 nWb/m, like the Tascam BR-20 if shipped to Europe, but the heads are slightly different too... DIN vs NAB. And they all recommend 456 (+6) tape or equivilent. It's been a while since I looked into all this so I can't speak about it off the top of my head as much as I would like.

    But the bottom line is the Model 20 Brochure and manual say 514 nWb/m and they both recommend Ampex 457 tape... so that's what I know, whatever that's worth. Sorry I can't be of more help.
    "If you canít make a hit record with a Tascam or a Fostex,
    then youíre not going to able to do it with a Studer or Otari!"
    -David Mellor

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    Exclamation Omg!

    Thanks for pointing that out. I'd just glossed over it way before. The manual recommends 457 or 227, then in the specs says it's ref. 0VU=514nWb/m. There has to be a contradiction there! I don't feel so bad now about splitting the difference, or just shooting for a ... wait.... I'm still confused.

    The service part of the manual states that using a 250nWb/m cal tape shoot for -5.5db/VU.

    That, with the recommendation of 457 tape,... means they're running the 457 really, really HOT! However, it would be ideally located to run 996 in it's optimal range.

    MAYBE,... the Model 20 may have been updated in the 90s, technical specs, etc., updated in the 90s, but they just forgot to update the paragraph referring to 457 or 227 tape? That seems to make more sense.

    ANOTHER difference between what the manual states and reality, is you should be able to get to all the cal points by removing a bottom cover plate. However, there was an additional RFI shield over the REPRO set of adjustments, requiring me to remove the entire top/back bonnet and the RFI shield. That was not referenced in the manual at all. ** MAYBE they added the RFI sheld around the REPRO section when they bumped up the operating level to 514nWb/m?** The pieces of the puzzle are falling into place now.

    I'll be honest, IMO*, Fostex really had some innovative devices and ideas, but somehow really didn't have their shit together in the implementation phase.

    That says nothing about the Model 20, itself, which from all indications is a phenomenal device! IT's the references and manual that somehow leaves me scratching my head!

    I am inching closer to just doing a straight "follow-the-book" calibration and in the turnaround using +9 tape. That really seems easiest, but it's made me put my thinking cap on to work through all these conflicting ideas!

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    Last edited by A Reel Person; 05-07-2013 at 22:23.
    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    Beck's Avatar
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    Myself I would be inclined to set the left and right tracks to standard 320 nWb/m NAB (not G320) and the center time code track to 250 nWb/m. I would do this for North American compatibility and use 457 or equivalent. It may not matter as much to home users with a closed shop, but to those who may be sending out mixes on tape for mastering or just using them on other machines I still think standardization is a good practice. In North America both 250 and 320 nWb/m are common. I have my Tascam 32 set at 320 nWb/m Nab for that little extra so I don't need noise reduction. Something to consider anyway.

    But have fun experimenting and let us know how it all turns out. Cheers!

    P.S. Yeah it could have been updated at some point, but my Model 20 manual has a print date of 1985. I agree it is a bit confusing.
    "If you canít make a hit record with a Tascam or a Fostex,
    then youíre not going to able to do it with a Studer or Otari!"
    -David Mellor

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    Exclamation Yes,...

    Some other very good things to point out!

    My PDF manual copy has the same print date. It's a download from the Fostex site.

    There are 2 points that specifically refer to running the M20 at appx. +9/185, and the cal instructions support that. Recommending 457 is dubious under those conditions. You'd be well in the audible distortion range. 499 or 996 would be just humming along, not breaking a sweat.
    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    Thrust is offline Senior Member
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    Now Im really confused. I had my model 20 aligned once in about 97 or 98 and the tech suggested 456, 457. Now im wondering should I experiment with some RMGI 900?

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    Exclamation And so it goes for my...

    dilemma.

    I'm not finished with this process. It's sat idle for a few days. In my mind it crystallizes that you set ref fluxivity by the book, then bias, etc., and run a +9 tape. Despite inconsistencies and perhaps some conflicts in the documentation, that seems to make most sense.

    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    Beck's Avatar
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    Whoa! Hang on guys! You're still not quite getting the difference between peak flux level as measured by German standards and average flux level as measured in North America. It's a different animal. The Model 20 calibration and tape recommendation (Ampex 457 1-mil) is not inconsistent with other decks from other manufacturers calibrated for Europe, including Studer-Revox, Otari and Tascam. The 514 nWb/m peak flux level with a recommendation of 456/457 class tape is not unusual. And remember there was no +9 tape when that deck came out and that version of the manual was printed.

    I'd spend more time in the research phase, focusing on the difference between European and North American calibration methods and standards. Also keep in mind that even with North American standards you won't see a 3% distortion level until above 1000 nWb/m @ 15 ips with Ampex 456 or equivalent tape.

    Edit: One more thing... there's also no 1-mil +9 tape, except for a special run or two of certain sizes. 1/2" that I know of by EMTEC that used SM900 oxide on 1-mil tape. And 1-mil tape is consistent with all the other smaller Fostex machines, before, concurrent and after the Model 20. Ampex 457 was recommended for the A2, A8, Model 80, and R8 as well.
    Last edited by Beck; 05-10-2013 at 21:12.
    "If you canít make a hit record with a Tascam or a Fostex,
    then youíre not going to able to do it with a Studer or Otari!"
    -David Mellor

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