Fostex alignment

[fred s.]

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.

[SteveMac]

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.]

The manual lists
MRL 21J103 as an option, and something about it having 3.5 dB lower output than the 9100A Fostex tape.

Originally Posted by SteveMac

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.

[SteveMac]

Originally Posted by fred s.

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 s.]

Heres a scan of the manual sections...i dont know how to post images so just follow the links.

http://i55.photobucket.com/albums/g1...tone23/2-1.jpg

http://i55.photobucket.com/albums/g1...tone23/1-1.jpg

Originally Posted by SteveMac

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.

[Beck]

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

[fred s.]

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!!

[fred s.]

...just an update, I ended up getting the MRL tape 21J303, no hope for finding the fostex or basf.

[Beck]

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.

[A Reel Person]

Originally Posted by Beck

The Fostex Model 80 is factory set to 320 nWb/m (+4) @ 0 VU.

#21J303 from MRL

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

~Tim

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.]

...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

Originally Posted by A Reel Person

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.]

Originally Posted by fred s.

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.

[goldtopchas]

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.]

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?

Originally Posted by goldtopchas

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.

[cjacek]

Originally Posted by fred s.

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/downloa...tandalone2.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.

[cjacek]

Originally Posted by goldtopchas

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.

[Beck]

Originally Posted by A Reel Person

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.

Originally Posted by fred s.

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.blueyond...are/audio.html

~Tim

[fred s.]

Beck and cjacek, THANKS for the info and those links!

[cjacek]

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!

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

[cjacek]

Here's some good reading I found, which may be of help:

http://www.johnvestman.com/alignment.htm

http://www.johnvestman.com/azimuth.htm

[SteveMac]

If you use a shareware osciliscope on your pc, what do you use for inputs? do you need stereo inputs on the computer? Not that I necessarily plan on using the osciliscope yet. Also Tim, what do you personally use when the instructions call for a 20k tone. I have the Fostex TT but it doesn't have a 20k tone.

[fred s.]

I have a question, is it absolutely necessary that I get a multi-meter? Would there be another way to check the computer's output? Maybe on a VU meter or something? I actually have a USB interface with rca ins/outs for sending signals from the computer to the Fostex and back, so I was thinking maybe if I send the computer output into a mixer or something...and check the VU meter.

If this doesnt sound like such a great idea can you recommend a multi-meter that is inexpensive and will get the job done? Are the ones from Radio Shack any good? I'm just trying to keep costs down, after spending all that money on the MRL tape

Originally Posted by Beck

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).

[Beck]

Originally Posted by cjacek

Tim,

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!

*** LONG ANSWER ALERT ***

(short answer in bold below)

Don't worry, a lot of people have a hard time with this wide awake.

The calibration tape is necessary for tape operating level, EQ, and as you mentioned mechanical head alignment. It can be confusing because there are two different levels to deal with and people call them both operating level.

The amplification line level of the machine (what’s going in and coming out) will either be -10 dB or +4 dB (usually). However, the magnetic flux level applied to the tape is the same no mater what the line level is. So for example, a tone recorded @ 0 VU on a semi-pro half-track set for 250 nWb/m will playback at 0 VU on a pro half-track set for 250 nWb/m. It doesn’t matter that one machine has a -10 dB line level and the other has a +4 dB line level.

So, there are two independent systems to be adjusted, though they interact. The key is you can’t determine a deck’s flux level by measuring voltage at the outputs, because that voltage will be (should be) the same for a given machine no matter what the flux level is.

For most semi-pro machines you use a 1k tone @ -10 dB to confirm the signal level coming from the RCA outs is the same as that going into the RCA ins.

After that is established you play a calibration tape with a known flux level (e.g. 250 nWb/m) to make sure the output reads -10 and the VU meters read 0 for that flux level.

If you use a machine of unknown condition to record your own calibration tape, that tape will be off to the degree the machine is out of spec.

Making your own calibration tape is like making your own scale without knowing the weight of the objects you are using to balance the scale.

However, once your machine is calibrated you can make a reference tape for checking and adjusting flux level in the future… but, once your heads become significantly worn from that state you must have a full-track MRL tape again.

If you buy a typical deck off of eBay, all bets are off – it might be at factory spec, but it could be set @ 250, 355, or even 500 nWb/m for +9 tape. Also, if any of the channels are low, you can’t tell if it’s on the record side or the repro side without an MRL tape.

(By the way, if you buy from a knowledgeable seller that knows the machine and spend a little more, you can be hundreds of dollars ahead in the long run. The ending bid price is just the beginning)

Buying or borrowing a standard calibration tape is even more important now since most decks are pre-owned.

~Tim

[cjacek]

Excellent, Tim. Thank you!

[fred s.]

Well I spent most of my day adjusting this thing...it's pretty much doing what I think it should

It was my firdt time doing this, so I think that's why it took so long...

It was pretty a draining task.