Fostex alignment

fred s.

New member
I've decided to check the alignment on my Fostex Model-80

The instructions in the manual seem pretty clear and easy to follow to me. I've never done this, but do generally have a lot of experience in fixing and setting up my own musical equipment (guitars, amps, a few minor pedal repairs/mods, etc...).

So just to make sure I have a clear understanding on what I need to buy,

The manual suggests using either Fostex 9100A, BASF 45513/2, or MRL 21J103 calibration tape, for checking the reproduce alignment.

So far I haven't been able to find either of these tapes. Are they still made?
I don't mind buying used at all, but I coundn't even find them on ebay.

For checking the record alignment the insructions say to

"apply a 1kHz signal to the recorder inputs at nominal -10 dBV level. The meters corresponding should indicate 0 dB..." then to record, and playback should be at 0 db.

then to "record tones from 20 Hz to 20 kHz. Playback the recording and check the frequency response, if it's not in the specified performance adjust the recording EQ, and fine tune bias..."

I read before that you can send those signals for checking the record alignment from you computer? But I'm not sure how that works. Any info and tips would be great! Thanks.
 
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The original Fostex tapes will probably be impossible or hard to find but Most likely you'll want a +3, 250nWb, IEC tape. You can look that up on MRLs website. I know this because I've been looking into it all lately and that is what the Fostex A8 uses, most likely the 80 does too. It should say in your manual.
 
The manual lists
MRL 21J103 as an option, and something about it having 3.5 dB lower output than the 9100A Fostex tape.

SteveMac said:
The original Fostex tapes will probably be impossible or hard to find but Most likely you'll want a +3, 250nWb, IEC tape. You can look that up on MRLs website. I know this because I've been looking into it all lately and that is what the Fostex A8 uses, most likely the 80 does too. It should say in your manual.
 
fred s. said:
The manual lists
MRL 21J103 as an option, and something about it having 3.5 dB lower output than the 9100A Fostex tape.

It's listed here I guess it's a 200nWb tape. Your manual should have more specifications on it. Did you look at the spec page. It should say.
 
Fred,

The Fostex Model 80 is factory set to 320 nWb/m (+4) @ 0 VU. The 9100A calibration tape is 320 nWb/m. MRL used to record all tones except 1kHz on their 320 tape at –10 dB. This may be why Fostex said to use the MRL 21J103 in the 1980’s.

MRL now records all the tones at 0 dB, so the tape you need is MRL 21J303, which is 320 nWb/m just like the Fostex 9100A. Other than the higher flux level the 21J303 is the same as the 21J103 in every way.

You can use tapes of any flux level for calibration as long as you compensate for the difference during adjustment. However, since you don’t have a calibration tape you might as well get the right one, and the price is the same for either.

#21J303 from MRL

http://home.flash.net/~mrltapes/

~Tim
 
Great thanks for the info! The site has 21J303 tape at $105...
Actually it's listed as 21J303a I dont know if that little "a" at the end makes a difference but I'll probably end up with this if I cant find any used Fostex or BASF tapes on ebay...

How about for checking the recording alignnment?

I need to send 1kHz signal and tones from 20 Hz to 20 kHz to the Model 80.

Is it possible to do this with my computer? I couln't be more confused on that part...I'm not even sure how I would connect to the Model 80 from my PC's soundcard?

I'm sure there are more things to do to have a perfect recorder, but I just want to get these basic things done as suggested in the manual so i can at least start using and enjoying this thing!! ;)
 
Good deal. You'll be glad you did. The Fostex and BASF tapes are no longer made, and very rarely do I see them on eBay. :)
 
...and if you do ever get around to it, you might want to contact me because I dont think I'm going to keep the 21J303 very long after my work is done ;)

A Reel Person said:
No telling if/when I'll ever get 'round to calibrating my Fostex r/r's, but that handy research is good to keep on file!!

(PS: I have the manuals, so it wouldn't have taken me that long on my own, but thanx for the tip in advance!)
 
fred s. said:
For checking the record alignment the insructions say to

"apply a 1kHz signal to the recorder inputs at nominal -10 dBV level. The meters corresponding should indicate 0 dB..." then to record, and playback should be at 0 db.

then to "record tones from 20 Hz to 20 kHz. Playback the recording and check the frequency response, if it's not in the specified performance adjust the recording EQ, and fine tune bias..."

I read before that you can send those signals for checking the record alignment from you computer? But I'm not sure how that works. Any info and tips would be great! Thanks.

...still hoping someone can shed some light regarding my questions on checking the recording alignment.
 
Not sure if it helps, but I found some test tones on the web somewhere once.
I downloaded them and burned an mp3 of assorted tones (freq.s as well as white noise, pink noise etc. I used these to "calibrate" an old A8 that I got real cheap. I basically just recorded the tones one at a time on each track, and played with the bias,Eq,levels etc. till it sounded equal on all tracks.

It took a long time and I know it's probably not to spec.' but it seemed to work well.
 
That might work. Basically I have the machine (model 80), I have the MRL tape, and I have my pc...I'm hoping to just run and check the test tones from my computer...that's everything I would need to do this, right?

is there any specific software I should look at/download?


goldtopchas said:
Not sure if it helps, but I found some test tones on the web somewhere once.
I downloaded them and burned an mp3 of assorted tones (freq.s as well as white noise, pink noise etc. I used these to "calibrate" an old A8 that I got real cheap. I basically just recorded the tones one at a time on each track, and played with the bias,Eq,levels etc. till it sounded equal on all tracks.

It took a long time and I know it's probably not to spec.' but it seemed to work well.
 
fred s. said:
That might work. Basically I have the machine (model 80), I have the MRL tape, and I have my pc...I'm hoping to just run and check the test tones from my computer...that's everything I would need to do this, right?

is there any specific software I should look at/download?

You may want to directly download a free test tone generator from here:

http://vincent.burel.free.fr/download/generator_standalone2.zip

It's excellent and has lots of features but is easy to use. Has presets or could be dialed in to whatever you want.

I just burned about a minute of each of the following tones onto CDR (to copy the Fostex TT-15): 40Hz, 400Hz, 1k, 10k and 15k.

If you have a quality soundcard then I guess you could do it from your pc as well. ;)
 
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goldtopchas said:
Not sure if it helps, but I found some test tones on the web somewhere once.
I downloaded them and burned an mp3 of assorted tones (freq.s as well as white noise, pink noise etc. I used these to "calibrate" an old A8 that I got real cheap. I basically just recorded the tones one at a time on each track, and played with the bias,Eq,levels etc. till it sounded equal on all tracks.

It took a long time and I know it's probably not to spec.' but it seemed to work well.

So basically you tried to match (by tweaking all of the above parameters) the source and what you were getting from tape ? That's interesting.
 
A Reel Person said:
No telling if/when I'll ever get 'round to calibrating my Fostex r/r's, but that handy research is good to keep on file!!

You’re welcome Dave. :)

fred s. said:
Great thanks for the info! The site has 21J303 tape at $105...
Actually it's listed as 21J303a I dont know if that little "a" at the end makes a difference but I'll probably end up with this if I cant find any used Fostex or BASF tapes on ebay...

How about for checking the recording alignment?

I need to send 1kHz signal and tones from 20 Hz to 20 kHz to the Model 80.

Is it possible to do this with my computer? I couldn’t be more confused on that part...I'm not even sure how I would connect to the Model 80 from my PC's soundcard?

The “a” suffix on MRL 21J303a is to differentiate the newer tapes from the older ones mentioned above, so you have the right one.

You can generate test tones from your PC. For the 1kHz operating level it’s handier to buy a pocket size tone oscillator, like the Fostex TT-15 or TEAC TO-122a. I see them quite often on eBay.

The dedicated tone oscillators are precisely set and switchable for standard levels such as -10 dB and 0 dB… 316 mV and 775 mV, respectively. The 1 kHz operating level tone must be a precise value.

Using your computer you would need to adjust the output level. Not all sound cards are the same. Even if you have an oscillator program set at -10 dB, what is really coming out of the sound card depends on its nominal output level.

For setting input/output levels (not flux levels) you would need to adjust the PC oscillator. To do this, generate a 1kHz tone while measuring for the correct output voltage with a multi-meter that can measure mV (milivolts).

The connection goes from the line-out (or speaker out if no separate line-out) on the sound card to the input of the recorder. You can buy a stereo miniplug-to-RCA Y-cable adaptor from Radio Shack. You only use one line, either left or right from the stereo output.

The 20Hz to 20kHz sweep is for checking crosstalk between tracks on the Model 80 and R8. Fostex has a rather unusual way of doing it. It’s normally measured with a single tone.

There are free oscillator programs on the web you could use for the 1k tone and the 20Hz to 20kHz sweep, such as SweepGen below.

http://www.david-taylor.pwp.blueyonder.co.uk/software/audio.html

~Tim
:)
 

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Just thinking out loud .....

Tim,

It's quite late, my brain is kinda clumsy now and so excuse the poor choice of words but I do have a question. How silly it may be after I have a good night's rest is open to debate but here goes: Would it be feasable and I'm not suggesting in any precise way (but inexpensive and workable) to do as "goldtopchas" suggested and run a bunch of test tones (and other sounds) and tweak all parameters (by ear) to more or less callibrate a machine for one's tape choice, less of course the mechanical adjustment, so that the "source" and "from tape" monitoring sounds matched ? No MRL tape and no other tools than a blank tape, service manual and a source of test tones and sounds. A poor man's callibration perhaps ? No laughing please! :eek: :D ;)

Btw, here's what the screen shot looks like of the test generator from the link I gave.
 

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