Using 41J326 alignment tape on a 1" 8 track???

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vinyvamos

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Hi guys,

I'm currently looking for an alignment tape for my Otari MX70 1" 8 track but simply cannot afford to buy one new from JRF. I might be able to get a 41J326 tape 2nd hand quite cheap but will it work ok on my machine? (pending the tape's condition). This tape is made for the "denser" 1" machines (16 & 24 trackers) whereas mine is an 8 track "pro" machine. I will be using RMG SM900. Will the 41J326 tape at 320 nWb/m (+4 DIN) be ok for this tape and for the MX70?

I am relatively new to tape recording and this will be my first go at aligning a machine. All the machines I have bought had elec. problems to start with and have fixed them so I'm not afraid of a scope and PCBs full of pots ;-). The other problem is, I don't have much time before the first session for aligning this machine! Is there any easy way of testing the machine to see whether it is far off alignment? The tapes will only ever be used on my machine so I assume as long as it plays back at the same levels (@ 100Hz, 1K, 10K) as I had recorded then I should be ok??? The first session is a dirty 8 track-only punk session so a little bit of wobble might not be noticed.

Any advice you guys have would be much appreciated! Thanks!

Vinny
 
You can get some vague idea of whether the levels are consistent by recording test tones, flipping the tape over and playing it backwards. That way, track 1 will now be playing the track recorded by track 8, 2 plays 7, 3 plays 6 and 4 plays track 5.

If the playback levels are the same as when played forwards, the machine is lined up uniformly (or at least, the opposing tracks are doing the same thing, whether or not it is correct!).
If some of them aren't, you're going to have a horrible job working out which channel is doing it wrong. At least until you can get a test tape.
 
OK I'll try that thanks! Regarding recording EQ & levels vs. playback EQ & levels would I not also need to playback the tape in the normal direction and make sure that if I've recorded at 0VU that I'm playing back at 0VU? Not that the volume matters too much as I can always compensate on the desk at mix-down. The method you suggest would also test for tape path misalignment, am I correct? I haven't a clue when it was last aligned in any way. We're gonna do a trial run this evening during rehearsal so I'll see how that goes and I'll put a few test tones onto tape too...
 
vinyvamos said:
OK I'll try that thanks! Regarding recording EQ & levels vs. playback EQ & levels would I not also need to playback the tape in the normal direction and make sure that if I've recorded at 0VU that I'm playing back at 0VU?
Click to expand...
Yeah, you'd play it forwards first, and then compare with it in reverse. Like I say, all it really does is compare two tracks against each other with the same signal, but it's a start.

If you have access to an oscilloscope or some decent 'scope software, you could probably test for alignment in the traditional 2-track way, by working on the tracks two at a time. Might be worth doing it against the edge tracks, or 2 and 7 - I've not tried this on a multitrack myself so I'm not sure which would work best.

On a 2-track deck, you'd record a 0VU tone on both channels, and check the playback head. Set the 'scope into X-Y mode, and feed one channel in on X and the other on Y. You should get a thin line at 45 degrees - if it's ellipsoid or circular, the alignment is off.
Again, this is usually a test you'd perform with a calibration tape, so I'd probably avoid adjusting it until you have one, but it shouldn't hurt to see how it's going.
 
Hi Vinny

That 41J326 alignment tape will be ok, but read on. One question first - does the MX70 use IEC equalization? If it is NAB, then you will need to compensate for that at HF and lF. There is a chart on the MRL web site.

Be aware that the older G320 tapes MRL tapes had the frequency response run at -10dB relative to operating level. If this used tape you've found is one of these then most of the action is going to happen near the bottom of the VU meter scale, which will make your life difficult. If the tape has an "a" suffix then all the tones are at operating level. I got all this from the MRL web site, and there is lots more info there.

Good luck

David
 
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