Otari MRL and Multimeter

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thereelman77

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Ok, so I cannot seem to find directions for accurately calibrating the REPRODUCE function on my MX5050 B2-HD. The otari alignment guides online do not apply to my model. I mean, am I just calibrating 1K from the tape to 0vu on playback and then 10k for channel EQ at 0vu as well? The issue, is that when the meter gets above 0vu the peak light goes on, I'm talking if the meter "flutters" and moves just a little bit, the light goes off, which doesn't seem right to me? Or am I calibrating for something like -3vu?

Secondly, the input calibration doesn't seem to make sense. Following my manual, I calibrated everything it said to do. The only issue being that my HI FREQ EQ on channel 1 would not go above -3vu (so, in-turn I calibrated channel 2 to -3vu to be equal) But, once I've calibrated it, the issue is that when I go to record something, I get a peak reading and start to get distortion, barely hitting above -8vu. When I'm running a track from my computer or tape deck into the 2 track is when I'm having the issue. My manual doesn't state anything for calibrating the source input pots as well.....

My second question, applying above, is how do I use my multimeter for checking the voltage on the output of the deck? I mean, what mode do I set the multimeter too and then which probe (pos. or neg.) do I put where? I hope, that maybe once I can get the multimeter set, everything else will be able to be set up so that I can accurately calibrate the bloody thing already.
 
You may know this already but make sure the multimeter you are using is capable of providing accurate RMS readings at the frequencies you are measuring or none of your calibration adjustments will be accurate. Most run-of-the-mill multimeters are not going to be correct above a couple hundred hertz, and none of my cheapo multimeters (digital or analog) measure anything close to true at 1 kHz or 10 kHz. A VTVM or quality Fluke meter would be ideal but always check the specifications of your meter to be sure
 
Multimeter.webp

This is the multimeter I purchased. It is a CEN-TECH model. I can return it if it is not adequate. I have already downloaded the link you attached (which is doesn't seem to be working). The 26 page manual says to switch to NAB while playing the 1kHz tone and then to adjust for +4dBm at the rear output connector, which makes no sense to me.

That is how the rest of the manual goes = adjust to produce +4, +16, etc. from the output on the deck. What do they mean? I thought I was supposed to be looking for something like 1.23 volts from my output...Do I turn to the dB setting on my multimeter and look for 4.000 or something of the sort?
 
OK...fixed the link (I had a typo in it).
Otari Alignment Procedures
You may already have the same manual...but this the one for the 5050 BII & BIII that I use.

That multi-meter looks OK, though you should read the specs to see to what frequency it's accurate.
Also...you need more than just a multi-meter to do an alignment...so maybe that's part of your confusion.
The manual I provided has it all covered, and if you go step-by-step with the right tools, it's pretty straightforward for the most part.

If you tell us exactly at which page/step you are on...it might be easier to answer your questions.
 
Pretty much pages 10-16 (the page #s on the bottom of the scanned pages, not the PDF file pages).

According to the manual, it's accurate up to 200kHz.
 
OK...but which page and step(s) are you stuck on.

Also...when you get to page 14 and beyond, you need a scope. You can't do a complete alignment with just the multi-meter.
 
Page 11, Steps 9-12 & 15-16, for a start.
Page 13, Peak Indicator Calibration
Page 15, Steps 3-12.

These are all page numbers on the bottom of the scanned pages.

I think that is everything.
 
Page 11: Does your multimeter have dBm reading capability? It sounded like you said earlier it did...so turn to that function and adjust the VRs until you get +4 dBm readings.

Page 13: Same for this....use the dBm function on your multimeter.

Page 15: Same here....

So...does your multimeter read dBm?

But again....your are skipping around through the calibration process and just doing steps that you can do with the multimeter. That's not really doing a true calibration and set-up.
You can do just the electronic stuff...but that assumes that your mechanical calibration is already spot-on. If your REC head is off in one direction, and your PB head in the other....you end up trying to compensate for both with just the electronics...and you might get away with very minor stuff, but it's good to at least know your mechanical is as best as possible before the electronic adjustments.
Yeah...the scope portion is a PITA 'cuz you need a scope, though there are some "soft-scope" apps out there that can work, but then you introduce the whole analog/digital and digital/analog conversion process of the audio test signals, and I found that to be a PITA, and you have to be careful even more that your are using accurate signals/levels, which I've seen can be off with the A/D/A process.
 
I'm not on the scope yet. I'm just trying to test the Multi-meter and see if it will work.

I did the same for dB and got nothing and from further reading on the unit, it will not read dB from the probe, only from the mic that is built into it.
SO I'm stuck in the water.
 
Your talking dB then...and not dBm.

I think that setting on your multi is for something else....measuring sound level decibels.
 
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Yes, so I will be setting out for another Multi-meter it seems. I find it surprising that the Otari manual doesn't have you measure the voltage getting sent out vs. the dBm.....But then again, this whole thing is like Chinese in some respects.
 
Well...you could do that, measute voltage, just need to convert their dBm values to proper voltage readings, but if the multi has dBm...then it's that much easier.

I got a nice Radio Shack multi a few years back, one of their high-end models, not even thinking about dBm stuff, I just needed it for other things, and it turned out it had dBm as one of the functions.
I also have an old Loftech TS-1 that basically can just generate frequencies and read dBm or voltage....that's it, but it's just the right tool for audio purposes. I got it really cheap on eBay.
 
I would check your Cen-Tech manual again because I do not think that model reads AC voltage up to 200 kHz. It may read that high on the Frequency setting, but the manual I found for that model online at Harbor Freight says the frequency range is 40 to 400 Hz for the "AC Voltage" setting (p. 14 of the manual). I have a similar Cen-Tech model with similar specs that showed inaccurrate 1 kHz and 10 kHz measurements on my Otari MX-5050 tonight.
 
Mine is accurate to 30kHz.
Radio Shack 22-812 (but no longer available)

Oh...thanks for pointing that out, that it's an AC voltage measurment.
I said DC earlier (had a brain cramp). :)
 
Well it's going back either way. Radioshack didn't have much to offer. I can't really afford $110 on a meter, my budget won't allow it.
Is the Radio Shack 22-812 usable or should I go with something better? I'm looking on ebay.
 
I use my RS meter a lot in the studio...for a variety of things, and not just for the "dBm" function, though that has been used for calibration purposes too.
There are other brand meters, you just have to go up a bit in price, though the RS that I have was a pretty good one for an inexpensive model. Not sure why they stopped making them...but you might check your local RS store, they may still have one on the shelves even if it's not available in the RS online catalog.

The only other option is to find a used higher-end brand/model...but you need one that is accurate enough for audio calibration and that has the necessary functions.
 
Well, I guess, let me ask this question:

I'm really keen on having my 2 track calibrated perfectly for 2 purposes A: Bounce reduction mixes B: Final Mastering for Vinyl Pressing.

If the deck is not perfectly calibrated (down to the last .5 db) if I were to send the master tape off to a vinyl mastering plant, will the tape be able to playback correctly? I mean can they correct slight Stereo phasing inequality and such? I know the answer may be an obvious "no", but, that is my main concern with getting this deck calibrated. I'm nearing the mixing phase of a current record and we will need to start doing bounce reductions. For those if the deck isn't calibrated, that's fine, since it's just being bounced back to my 8 track. But for the final master, I want that to be perfect.
 
If you are concerned about using it for final mixes....you have to ask yourself....do you really want the vinyl mastering to be responsible for making up any discrepancies in your stereo mix due to tape deck misalignment.....

....know what I mean? :)

At any rate, you should ask them what they will or won't fix.
 
To add to what miroslav says, improper calibration can also futz with the sound quality of the two individual tracks beyond track-to-track phase and volume alignments. For example, depending how off the calibration is it can affect the signal-to-noise ratio, the frequency response and/or the amount of tape saturation (if any) of each individual recorded track. The effects may not be as great if the calibration is only slightly off, but without the proper test equipment there is no way for you to tell how "off" any particular stage of the calibration process may be. Unless there would be some uncompromising requirement to put a final master on two-track analog tape, I would rather do a final master to digital instead of an uncalibrated tape machine.

EDIT: Edited for grammar error.
 
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