otari mx5050MKIII-4

[FALKEN]

so I got a 1/2" 4 track otari about a month ago. The person who sold it should get an award - for worst packing job ever. not only was it shipped in packing peanuts, but somehow a good amount of sawdust made it in there as well. this was all over the insides of the machine. So the first thing I did was completely vacuum the insides. I cleaned all of the parts, and the knobs, etc, etc. The pinch roller was sticky so I sent it to terry and had it re-built (now its perfect). I made all of the cables necessary to use the machine. Now is where the fun starts.

I loaded the MRL (370 nWb/m) and calibrated all of the outputs to read +3 while getting 1.58 volts at the output. so far, so good. Removed the calibration tape, and loaded a blank tape (456). Playing a 1 khz tone I adjusted the bias to a 5db drop past peak. Then, I attempted to calibrate the input level to read 0db. This is where I ran into trouble. One of the input tweakers couldn't get all the way up to 0db. Additionally, a second input tweaker does absolutely nothing at all. But it was still in the ballpark.

So I decided to record a practice. The results were very good, save for two issues. 1 - more hiss than you would expect, 2 - intermittent clicks and pops (which are now on the tape).

The heads look almost new, although the lifters are worn down pretty good. I am wondering if the lifter is worn enough could it be scraping the tape and causing the pops? Another thought is maybe I screwed up the soldering job on one (or more) of the cables. Or perhaps there is a bad card or something? (it seems like there were more and more pops the more I played the tape, but I'm not sure) As for the hiss, maybe the heads are more worn than I thought, or perhaps I did something wrong in my calibration? Maybe I should just run it hotter? (I tried to stay between -3 and 0 on the meters) As for the input tweaker which does nothing, perhaps I should try touching up some of the points around that on the channel card with a soldering iron? maybe the whole unit needs to be re-touched?

Thanks in advance for any advice. I can post pics later if it would help.

 

[The Ghost of FM]

I think you may have gone astray in your calibration procedure and that may account for the odd levels and hiss issues?

Would not a 320nwb calibration tape referenced to 0vu be more in order to get the rest of it to line up with 456?

Cheers!

 

[FALKEN]

yes. However, my tape is 370 (355), so I referenced it to +3. is this correct? I poured through many old threads while contemplating this....

 

[The Ghost of FM]

yes. However, my tape is 370 (355), so I referenced it to +3. is this correct? I poured through many old threads while contemplating this....

In theory that might seem like the way to go but I don't know if you can trust the meters on a recorder to be that accurate at that end of the scale keeping in mind that the extra 3db on the meter may not in reality equal the extra 50 nwb's in reality?

The hiss levels you're experiencing are definitely telling me that you've got the 456 record levels way too cold for what they're showing up on, on the meters.

Cheers!

 

[FALKEN]

I think you might be right. I played the mix today on the stereo and it sounded fine. (hiss not as bad as on the monitors). It sounded pretty amazing actually. I think some hotter levels and the hiss might be fixed. I'd still like to know where I went wrong with the calibration..... and what might be causing this popping?? could it be the lifters? should I send the whole headstack to ATR? should I attempt to rotate the lifters? I took a look at it and it seems as though I would have to disassemble some pretty tricky parts.

 

[The Ghost of FM]

As to the popping, I can't say with any certainty? It could be any number of things including possible mis-settings in your calibration that may now have certain gain stages operating beyond their normal thresholds.

As for the heads needing a relap, no one here could make an accurate judgment sight unseen but in either case, worn heads alone wouldn't cause those popping sounds. Worn heads would show different symptoms in things like an uneven performance in response in level and eq and fresh tape would shed oxide more quickly on them as their flattened shape will be more abrasive to the tape's oxide layer. The heads on my 16 track showed all of those signs prior to them being relapped a few weeks ago but I never experienced any popping sounds prior to that procedure.

Rotating guides is also never a bad plan as worn edges on them will also be more unkind to your tapes.

It all kind of points back to the calibration you performed as near as I can tell. Perhaps investing in the proper MRL tape for 456 might be a wise pursuit or perhaps getting a roll of 499 and calibrating the machine from scratch for that formulation...that's for you and your wallet to decide at this point.

Let us know how it turns out.

Cheers!

 

[Beck]

yes. However, my tape is 370 (355), so I referenced it to +3. is this correct? I poured through many old threads while contemplating this....

The math is right as far as using that tape for that level. It sounds like you could have some oxidation on the trimmers. If you’re turning, but the meter isn’t moving you might have to either clean that trimmer with Deoxit or replace it.

Popping and crackling can be from badly magnetized heads, bad capacitors, poor circuit grounds, among other things.

 

[FALKEN]

of all the threads I referenced to do the calibration none of them mentioned specific voltage levels. it now occurs to me that maybe I should have used +3 db over +4 dbu or 1.73 volts on the output. then on the input I should calibrate 1.73 volts to +3 or 1.23 volts to 0. is this correct?

 

[FALKEN]

ok I think I've got a grip on this thing. I re-calibrated including the eq and got everything pretty darn close to where it needs to be. some of the tweakers still don't do what they're supposed to but without getting down n' dirty the settings are still pretty close. And I was able to rotate all of the lifters, so hopefully there won't be any more orange streaks....one final question.....

when recording a 1khz tone and monitoring the repro, the levels are fluttering. I cannot determine what is causing this small flutter. I tried oiling the capstan, rotating the lifters, etc, and to no avail. The pinch roller is brand new. I cannot figure this out, but I fear it will require a tension adjustment. does this sound about right? or is a small amount of flutter on playback of a tone normal? this sound isn't audible, its just visible on the meters. THANKS!!

 

[FALKEN]

bueller? .

 

[FALKEN]

could this be caused by an out-of-round pinch roller? My new pinch roller seems like it might be off by 1/16 of an inch...but its hard to determine....

 

[evm1024]

ok I'm sitting in a mall and perhaps not tracking you right but....

1.58v is + 4dB (over 1v) so to have the output read 1.58v is to have 0 vu for this deck.

Next. if you want to have your deck calibrated to you test tape (at 370 nW/m) you would set your meters to read 0 VU and the output to read 1.58v.

Otherwise if you want your deck calibrated at another fluxitivity than 370 you would offset your output and meters to read high or low as required (if your tape is hot by 2 dB you would set the output to +6 dBv (+1.995 v) and the meters to read + 2VU). Got that?

Then proceed to the rest of the calibration.

Regards

 

[FALKEN]

Thanks, I eventually figured that out....

here's what I eventually came up with:

ch1 ch2 ch3 ch4​

rep lev 1.73 1.73 1.73 1.73
sel lev 1.73 0.62 1.73 1.73

10k 5.5 5.5 5.5 5.5 (+2.5 / 3)
100hz 1 1 1 1 (-2 /3)

bias (10k) -4db -4db -4db -4db

input 0 0 0 1
rec level 0 0 0 1.5

low rec -7.5 -7.5 -7.5 no effect 0.519 100hz
high rec 0 0 0 0.25 0 10khz

as you can see I ran into some issues on a few channels but the differences are not ridiculously bad. the channel 4 rec level pot had no effect but wasn't so far off. 2 channels were spot on and 3 if you don't use the sync head for playback. the 4th is within a db or so. right now I am more concerned with the fact that the levels are moving up and down slightly...still sounds really good though.

 

[The Ghost of FM]

ok I think I've got a grip on this thing. I re-calibrated including the eq and got everything pretty darn close to where it needs to be. some of the tweakers still don't do what they're supposed to but without getting down n' dirty the settings are still pretty close. And I was able to rotate all of the lifters, so hopefully there won't be any more orange streaks....one final question.....

when recording a 1khz tone and monitoring the repro, the levels are fluttering. I cannot determine what is causing this small flutter. I tried oiling the capstan, rotating the lifters, etc, and to no avail. The pinch roller is brand new. I cannot figure this out, but I fear it will require a tension adjustment. does this sound about right? or is a small amount of flutter on playback of a tone normal? this sound isn't audible, its just visible on the meters. THANKS!!

Oscillating levels might be due to mechanical alignment or tape tension issues.

If the tape is physically moving up and down along with the level changes, some skewing alignment issues might be at play.

The possible un-trueness of your new pinch roller might also be a possible factor where its gripping strength varies and possibly pulls tighter in part of its rotation thusly creating a different pull through tension on the tape against the heads causing level fluctuations.

Does the rate of level change share any relation to the turning rate of the pinch roller?

Cheers!

 

[FALKEN]

Does the rate of level change share any relation to the turning rate of the pinch roller?

they seem to be in sync...........

 

[The Ghost of FM]

they seem to be in sync...........

You might want to see if you can get that roller exchanged then....unless the level changes aren't audible right now. Then again, if you wait too long, you might exceed the grace period from the vendor if they even have a grace period?

Cheers!

 

[tascamman]

Hi All, I've been hanging here for quite a while but never posted. I've been following this 5050 problem and there seems concern about the pinch roller being the problem. I've read many posts about Terry and I'm sure he will take care of it if theres a problem. Hes a very personable and replacable person. Have him at least check it.

 

[MCI2424]

so I got a 1/2" 4 track otari about a month ago. The person who sold it should get an award - for worst packing job ever. not only was it shipped in packing peanuts, but somehow a good amount of sawdust made it in there as well. this was all over the insides of the machine. So the first thing I did was completely vacuum the insides. I cleaned all of the parts, and the knobs, etc, etc. The pinch roller was sticky so I sent it to terry and had it re-built (now its perfect). I made all of the cables necessary to use the machine. Now is where the fun starts.

I loaded the MRL (370 nWb/m) and calibrated all of the outputs to read +3 while getting 1.58 volts at the output. so far, so good. Removed the calibration tape, and loaded a blank tape (456). Playing a 1 khz tone I adjusted the bias to a 5db drop past peak. Then, I attempted to calibrate the input level to read 0db. This is where I ran into trouble. One of the input tweakers couldn't get all the way up to 0db. Additionally, a second input tweaker does absolutely nothing at all. But it was still in the ballpark.

So I decided to record a practice. The results were very good, save for two issues. 1 - more hiss than you would expect, 2 - intermittent clicks and pops (which are now on the tape).

The heads look almost new, although the lifters are worn down pretty good. I am wondering if the lifter is worn enough could it be scraping the tape and causing the pops? Another thought is maybe I screwed up the soldering job on one (or more) of the cables. Or perhaps there is a bad card or something? (it seems like there were more and more pops the more I played the tape, but I'm not sure) As for the hiss, maybe the heads are more worn than I thought, or perhaps I did something wrong in my calibration? Maybe I should just run it hotter? (I tried to stay between -3 and 0 on the meters) As for the input tweaker which does nothing, perhaps I should try touching up some of the points around that on the channel card with a soldering iron? maybe the whole unit needs to be re-touched?

Thanks in advance for any advice. I can post pics later if it would help.

If the machine pops and clicks in the record/playback mode, it is possibly dirty relays on the channels. These relays get oxidized and don't completely close nicely. They cause real problems from pops and clicks to "The Wind" sounds on real BAD ONES. I would clean and Deox them as a matter of peace of mind before I did any thing else.

 

[FALKEN]

oh man;

i've been trying to track this down. I've been working with a really good tape and what has happened is it started out sounding perfect. I had chalked it up to bad tape. After playing through and rewinding a few times, I have come to notice that the pops are coming from where I had pressed transport functions. basically, there are a lot of clicks and pops in the first song from hitting stop on the rewind back to zero. Would cleaning the relays solve this perhaps? what do they look like? ??

 

[Dr ZEE]

what do they look like? ??

I've never been inside otari, but they may look like these boxes (found here)