My Otari MX-80 Journey.

[thecr4ne]

I just got an Otari mx-80 for what feels like a decent price. I'm new to tape, so this will be an adventure, which I plan to document here. I picked up the machine last weekend with the CB-140 remote, and have been going through and cleaning out the dust. Downloaded the "Complete Manual" from https://analogrules.com/. Ordered a used reel of tape to test with, awaiting delivery.

Here's what's noteworthy so far:

Heads look good. Repro head has slightly uneven wear.

6 or 7 of the CB-140's Safe/Ready switches seem pretty worn, and likely need replacing. Honeywell 8V1012B might work.

Pinch roller was installed up-side-down. corrected

4 screws that secure the top cover panels to the frame are broken off in their holes (note to self: hand tools good)

Tachometer roller rubber is thrashed. $350+ core to replace from Athan.

Uptake reel is bent. Might be able to straighten out but looking into replacement.

1 VU meter lamp is out, not bad.

Chips labeled with 1989 date indicating age.

Manual indicates Serial RS232 and RS422 protocols for remote control. Remote port possibly just serial. Looking into commands for serial control.

 

[Bo Deadly]

You'll get more love on tapeheads.net. Not much about tape here.

 

[PRR]

> I just got an Otari mx-80 .... I'm new to tape

So you think you want to play with tape: An Otari Story

 

[thecr4ne]

Yeah, Yeah, I know. Tape, Ancient components,etc...

Anyway. little update.

Still having trouble finding Serial RS232/RS422 ASCII commands for this, will continue searching, would love to make a little Raspberry Pi powered serial controller as a project and a way to bring life back for machines without controllers.

Switches for controller: Originals proving hard to source, as are direct replacements. Others exist with different footprint, BUT,  BT series Toggle switches with the same footprint are still in production, so switching from the paddles to the toggles may be the solution, or maybe I'll get really lucky and they'll have interchangeable parts.  BT1D-2M4-Z and BT1E-2M4-Z $5-digikey.

got a quote from http://terrysrubberrollers.com/ for the tach roller re-do at < half the price of Athan.

My $20 reel of used tape arrived

Ordered a Han-D-Mag demagnetizer, $55 used

But my workroom has been reclaimed as a guest room for the time being so actual work will slow.

 

[Bo Deadly]

My $20 reel of used tape arrived

Next to good heads, new tape is probably the one thing that will make the largest difference in recording quality. I got LRP90 from splicit.com for my B77 and, after biasing / eq-ing for it properly, SNR leaped over the used tape that came with the machine.

 

[thecr4ne]

Next to good heads, new tape is probably the one thing that will make the largest difference in recording quality...

Of course. I need something to test with though, as my machine didn't come with tape. so for preliminary  tests, I'll work with the used reel. I also don't have an MRL tape to calibrate properly yet. Still early days.

 

[Bo Deadly]

The MRL tape is only for getting the level right so that if you move a tape from one machine to another the levels are the same. If this is just for home recording / hobbyist sort of "work", then you don't need it. Just set the output level to where the machine is comfortable without undesirable distortion and roll with that. Otherwise, MRL tapes are very expensive and just overkill IMO.

 

[radardoug]

The MRL tape is only for getting the level right so that if you move a tape from one machine to another the levels are the same. If this is just for home recording / hobbyist sort of "work", then you don't need it. Just set the output level to where the machine is comfortable without undesirable distortion and roll with that. Otherwise, MRL tapes are very expensive and just overkill IMO.

If you are serious about tape, then you need a test tape. If you dont care about quality, dont bother to get tape. Tape is an expensive exercise, so do it right or dont do it at all.

 

[Bo Deadly]

If you are serious about tape, then you need a test tape. If you dont care about quality, dont bother to get tape. Tape is an expensive exercise, so do it right or dont do it at all.

You definitely don't need an MRL tape to get a high quality recording. In fact, if you want the best possible recording quality you should just measure the distortion and set the record amp level to maximize SNR / THD for that particular machine setup and NOT use a test tape. The MRL tape is exclusively for calibrating the record level so that it matches other calibrated machines. EQ and everything else can (and IMO should) be done with a computer audio interface. Using the procedure in the manual with an AC meter is not necessary and will not produce superior results. In fact, it's inferior to getting a proper spectrum with an audio interface which would allow you to see the EQ.

 

[radardoug]

So how do you set repro frequency response without a test tape? While this idea might work for you, you are giving advice on the WWW, and its not good advice. You could be leading noobs way down the garden path.
Also, if a machine has problems like worn heads, how do you establish that without a test tape? So someone buys a machine with crapped out heads, and he can never get it recording well by your method.

 

[Bo Deadly]

I can only speak to my B77 but setting EQ on the B77 does not use a test tape. You only need a blank tape. You put in a signal that makes -20dB at 1kHz and then switch between 1kHz and 12kHz and adjust the EQ so that the 12kHz level matches the 1kHz. Repeat for fast and slow. Done.

My understanding is that the MRL tape is only for setting the reproduce amp level output. That's it. So you can set that to whatever you want as long as it yields decent SNR / THD. Or just look at the effect on level and put it in the middle. It's not going to have that much effect on SNR / THD anyway.

Yes, you are right that this is "incorrect" because it won't be the correct calibrated level. If you record something on one machine and then move it to another, the level could (will) be off more or less. But like I said, if this is for a home studio or non-super serious use, you probably only have one machine anyway! And if the heads are warn I don't understand why it would be that important to calibrate anything.

For someone learning with their first machine they don't need an MRL tape. It's just a waste of money. They're like $200 and they're all different for the machine / heads and target tape.

 

[Brian Roth]

An alignment tape is used not only for setting playback level but also for adjusting playback EQ,  The concept is to get the repro chain set to the desired operating level and have a repro frequency response that is flat as possible.  When that is done, then the record path can be calibrated.

Bri

PS, the MRL is also used to set the correct azimuth of the playback head.

 

[Bo Deadly]

An alignment tape is used not only for setting playback level but also for adjusting playback EQ,  The concept is to get the repro chain set to the desired operating level and have a repro frequency response that is flat as possible.  When that is done, then the record path can be calibrated.

Bri

PS, the MRL is also used to set the correct azimuth of the playback head.

Ah, ok. I understand. I didn't know that.

Although ... that is also really for calibration between machines so it's pretty much just like the repro level case. Meaning it would only be an issue if you moved the tape from one machine to another where the EQ would be off. Otherwise if you playback the recording on the machine it was created on, that's not really going to be an issue. Right?

 

[radardoug]

Two things. Some cheaper machines dont have adjustable repro eq, but all professional machines do.
We are talking here about the OPs experience. He has just bought a machine. Who knows what condition it is in? In order to set the machine up for the best possible response, you need to get the playback side set correctly. For this you need a reference tape.
If you are always playing the tapes on one machine, then strict level is not that important, as long as it is in the ball park.
But frequency response and azimuth are crucial to the decks performance. Lots of people tweak azimuth and frequency response without knowing what they are doing.
As to your machine, all you are adjusting is RECORD response. You obviously have no idea on what your REPRO response is.

Again, its the WWW, and you are not giving noobs good advice. And from what you have said I can read between the lines that you are not hugely experienced with tape. Brian Roth and I  are. We are old fogeys with lots of good advice for the noobs.

 

[Brian Roth]

You need a starting point to align a tape machine, and that is by setting up the repro chain.  Without doing that first step you will end up chasing around in circles. 

For instance, if the repro level happens to be too low, you have to crank up the record level to get the desired output level.  That means increased distortion as the tape has to be "slammed".

If the repro chain has drooping HF response, then record EQ must be boosted to make the overall response flat, which will also increase distortion.

If repro head azimuth is way off, that also impacts HF response.  So, you end up "cheating" with record head azimuth and/or record EQ.

Bottom line....get the repro path "happy" so you have a base reference before diddling with any record adjustments.

In a pro studio environment a fresh MRL is required.  In a home/hobby situation a used MRL is better than nothing,,,,but depending on how old/worn the alignment tape is you might be stabbing in the dark.

One possibility for home/hobby is to find a pro studio that is properly set up with a same-format recorder and have them print you set of tones onto fresh tape.  Better than nothing.....at least in the ballpark.

Goto the MRL website.  They have many interesting papers discussing the issues.

https://mrltapes.com/

And before getting serious with the new machine, buy fresh tape.  Ebay stuff may be old and sticky/shedding.

Bri

 

[PRR]

> If you are serious about tape, then you need a test tape.
> You definitely don't need an MRL tape to get a high quality recording.
> you probably only have one machine anyway!
> set the correct azimuth of the playback head.
> He has just bought a machine. Who knows what
> you are not giving noobs good advice.
> We are old fogeys

Didn't you have this argument a couple months ago?

 

[radardoug]

Probably. Its hard to train on the WWW.

 

[thecr4ne]

Thanks Everyone.
I have an idea of what I've gotten myself into, and know old used tape has the potential to be problematic. For now I'm still diagnosing the state of the machine, so I just need something to play for now to see if I even get signal flowing.

Proper setup is the goal, but for now I'm in no position to buy a fresh MRL tape. If my refi closes monday like it's supposed to and my tax returns don't take too long, I might be better positioned to order one, but I've gotta get things cleaned and lubed and rollers replaced and the damned thing wired up to a mixer first....with the whole quarantine situation, I might actually get some of it done.

Then there's the whole recapping thing, and if that's needed...

baby steps.

 

[radardoug]

Glad you are getting to it, it can be a long road. On the cap thing, look on Ebay and buy one of those cheap component testers. Then pull a couple of caps and test them. If their values are right, then dont bother recapping. There is a lot of crap talked about recapping.
As to when to get an alignment tape, use your cheap reel to do all the deck adjustments and getting a feel for the machine. Dont worry so much about actual recording. Although once you get the deck running nicely, try recording and see where you are in the ballpark.
On your used tape, if you see any sign of shedding or sticky action, lose that tape. You usually need a work reel for testing, so theres no reason not to buy a new reel and dedicate it to testing.

 

[thecr4ne]

Thanks Doug,
Appreciate the support and advice on checking caps, I'll go that route when I get there. As for the tape, I'll get a fresh reel at some point, but as you said, this is really just to get started. 

Any  recommendations on lubricants for the moving parts?

-Chris