Otari MKIII Head spot Question and a few beginner questions

I get excited about this stuff.

I remember those days. :)
Not that I'm still not excited by audio gear...but when starting out, every new thing is a big WOW full of excitement and enjoyment.
That's how we all became gear sluts. Some people don't get it, but for some of us, audio gear can cause a lot of thrills.
 
I remember those days. :)
Not that I'm still not excited by audio gear...but when starting out, every new thing is a big WOW full of excitement and enjoyment.
That's how we all became gear sluts. Some people don't get it, but for some of us, audio gear can cause a lot of thrills.

Yep. When I brought this thing home everyone was like "what are you going to do with that?" And I was like "I'm gonna record and play some really cool high quality music on tape!" And the response was "hmm ok" with some mildly awkward silence.

We also do a 50's style diner every now and then at my church as a fundraiser for the youth group and young adults to go to special events that require high expense. So I plan on showcasing it there behind some plexiglass panels with a cool description. It would be cool to play music on it if I can get away with it, but that might be a bit much. Although I don't have any professional use planned out for it yet (it would be hard to justify in most cases) I do indeed have plans for it.:D:guitar:
 
This may be obvious but is the frequency response flat when you monitor the input directly? Are both channels set to the same eq curve? Have you tried frequencies lower than 100Hz as there can be a bit of a bump at around 100Hz - some studios would use 50 or 60Hz tones as well or instead of 100Hz to eliminate the potential head bump problem.

However, the most likely cause of this problem is a little bit of dirt on the playback head - it needs to be scrupulously clean. The other potential problem is that the playback head may not be making good contact with the tape and you may have exacerbated the problem by turning the tape guides so that the tape doesn't wrap around the head as much as it did. It is worth looking at the tape path very carefully and maybe pushing the tape gently against the playback head to see if the response at high frequencies improves.

Another possibility is that your tape is slightly wider than the tapes normally played on this machine so that the edge of the tape is riding over the edge of the worn area on the head. Some heads have small grooves at the top and bottom to allow for different width tapes to be played with no problems but your heads don't seem to have these grooves. Again, if you have adjusted the guides the tape may now be following a different path across the head which could cause this problem.

Another thing to check - have you demagnetised the heads?

That's probably enough to think about for now...
 
Great! Sounds like a lot of good stuff to go on from your post above.

I did try marking the heads with a highlighter (the only non perminant media at the time) and checked to see if contact was made evenly across the head by checking with a light. The tape wasn't even touching the very top area of the playback head and the recording head looked like the problem was there too but not nearly as bad. I had tried to check the wrap by applying pressure with a q tip around the heads and I did notice that pressure in general seemed to help quite a bit (albeit still more on one side:facepalm:

I'd say this is probably for sure all the fault of the guides being turned. The en-even, but consistant, wear is now even and consistant between the guides but the heads aren't lined up to them:( The tape is definately not hitting the edges which is probably due to all the random tapes they had to play at the station. The wear area is more than wide enough for the tape.

So, a demagnetizer and an oscilloscope is in order when I get paid this week. I'll wait a week or two to get the cal. tape. Do I need anything else to align the heads to spec.?
Also how do you put more or less pressure on the tape head?

PS: I admittedly wound up fooling with the head adjustments after seeing how out of whack the head was:laughings:.
I marked the origional position with a line in case I wanted to go back temporarily but I doubt I will.
I simply moved them for best 10khz response with decent luck. I'm not too worried since I'll have it dialed in soon anyways.

I'll run some more frequencies through as suggested and see what happens through the range now.
 
I also cleaned the heads to high heavens before even posting here (hence the initial erase head question). They could probably be cleaned again since I didn't spend a ton of time cleaning after the highlighter thing. And I did A/B the source signal to tape when running the previously mentioned frequencies through. Just to answer the above question.

I really appreciate you guys' advice. It's saved me tons already:D
 
If the heads are unevenly worn so much that the tape isn't making contact then you need to think about getting them relapped or, if really bad, replaced. If you are in the USA then the standard advice seems to be to send the heads off to JRF - Head relapping
 
I believe JRF also sells heads online as new (probably reconditioned or from scrap machines with little use). I was actually thinking about getting those but I think they are a bit under 150 usd per head, and I haven't priced relapping yet. As much as I would like to go do that, sadly I dont think I'll be able to budget them in for a bit. I'm going to need the test equipment any way you look at it so that's going to be first. Plus any stupid mistakes I do now would be on these worn out things, lol. And at least channel 2 can be made to sound really good(the jury is out on channel one) so It's not like I'll be forced to listen to garbage until then.

Does any one know what sending out just the heads would cost these days?
 
Ironically the erase head seems to be fine despite being on the worse side:confused: are those contact points surrounded by tungsten carbide or something? And for what it's worth, the tape has virtually zero noise at all at 15 ips.
 
Does any one know what sending out just the heads would cost these days?

I don't know what JRF charge but Uk prices are the equivalent of around $30-35 per head for a re-lap.

If you have an audio interface you can probably get away without an oscilloscope although there are some cheap ones that you can buy suitable for basic audio use for around $40. You can also use your audio interface as a signal generator so the only test gear you really need is a multimeter - preferably with an RMS measurement.
 
Ok, thanks. I'll have to check out the prices here. And since I don't have or need an interface personally I'll probably go with the oscilloscope. But it's good to know there are other options. And I do have a nice multimeter that's actually designed for car use. I don't think it has rms though.


Although I'm basically "blind" until I get some equipment, I ran the tape through the frequencies and the way it is now seems pretty good and consistant even in the 50hz range. It would seem that there are times the 10khz area will drop in and out though and it's not like the tape leaves the groove or anything. Maybe I messed up the tape after a ton of rewriting and really rough handling? I'm sure I'll get it eventually though.
 
Quick update...

I got the Head demagnetizer in and demagnetized the whole tape path. After running the tape on it for a few I cleaned the heads and re-demagnetized them for "kicks and giggles." Demagnetizing the heads will probably become a routine because of how much it helped. The results are a much more stable output with only a few decibels of fluctuation. The tape it's self seems to get one or two decibels louder at the end but it's much better than before.

It would also seem that the overall volume, with the tape not being the culprit, changes a tad over time. So I guess some electronics need to be checked. Overall, things are looking better.
 
hello. a basic true rms meter will not be able to sample at the high frequencies. You'll need something like the fluke 287. Although It goes for almost $500 bucks. It also reads in dB. It can show the AC mV at the same time.
 
hello. a basic true rms meter will not be able to sample at the high frequencies. You'll need something like the fluke 287. Although It goes for almost $500 bucks. It also reads in dB. It can show the AC mV at the same time.

ok, that's good to know. unfortunately it's out of my price range for a bit:( I'll consider it after I can get all I can get around the $150 usd range and under. The MRL tapes will be pushing it, but doable.
 
yeah, I need mrl test tapes too. the meter I borrowed. won't help without the tapes. But I'm practicing doing the measurements with it. Playing with a sainsmart ds802 oscilloscope also. Also not sure if the signal generator I have, tenma 72-505 can put out the sufficient mV's. I have two tascam 32's to get right.
good luck!
 
For normal calibration you only need the multimeter to calibrate the recorder's own meters so you don't need a particularly good frequency response spec for the multimeter provided it goes up to something like 400Hz or more. Once the recorder's meters are calibrated you can use those for all other measurements. There are rarely any frequency selective components in a meter drive circuit so it is fine to calibrate at a single frequency.

The test tape is probably more important than a meter or any other gear. A computer will give you all the tones you need and will allow you to look at waveforms so there's no need for an oscilloscope for any audio setup.
 
(I'm thinking an oscilloscope would also be good to have in case I advance to a level where it can be used in other areas with the calibration as a bonus. Not to disagree in any way as I am new to calibration in audio at this point. But not new to professional level audio or electronic testing exclusively.)

I do plan on using the Otari repair manual for the calibrations and what not. Which is the main reason for the scope. Would you, for example, be able to elaborate on how to align heads without one?
I'm a tad curious how you would do it.
 
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Would you, for example, be able to elaborate on how to align heads without one?
I'm a tad curious how you would do it.

Simply play back the 15kHz tone from the test tape and adjust the playback head alignment to give the maximum reading on the recorder's meter. On a multitrack where you can listen to the output from the record head you can use the same method. Otherwise you need to monitor from the already adjusted play head while you record a 15kHz tone on tape and slowly adjust the record head azimuth until you get the maximum level.

I'd suggest using 15kHz as the maximum should be more obvious than using 10kHz but if you only have a 10kHz tone then use that.

An oscilloscope is useful when there are problems but meters are fine for routine alignment.
 
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