Tascam 58OB Heads

snellular5

neil young whore
Hey all! I have a chance to pickup one of these machines locally. Its even got the remote with it. Ive been looking for a machine like this for a while. I don't really know what Im looking for when it comes to head condition. Ive tried reading up on it but I'm still not sure that I can judge the heads properly.

I know a picture isn't exactly the best way but here are the pictures I got from the owner. How do the heads look to you? Owner also stated:

"They don't appear warn to me. But, its likely that track 1 record head is warn because it records at a lower volume than the other 7. However I was able to adjust the record volume on track 1 so it now records at the same level as the others."

Should I be worried about the above statement? I don't really know anyone who knows tape machines near me that could come and help with the purchase. I also know its hard to tell without actually having the machine in hand. But just from the info given above and the pictures. Do you think this is a wise purchase? Or will my needs for the machine outlive the heads quite fast.

Thank you so much in advance!

Matt

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I've seen worse. The guides look reasonably good too, though they might have been rotated. If it were me I'd seriously consider it. The heads are the same as used on the 38 and TSR-8 so it's not like they're unobtainable if push comes to shove.
How important is it that track 1 is in tip-top condition? The edge tracks tend to be the least solid anyway...
 
Ok awesome. Ya it does seem that there's quite a few Tascam 38's out there as parts machines that I could snag a headstack off of.
I would be using all 8 tracks most of the time but you are right its an edge track and I dont mind having to make up for it with a bit more input.
 
Hey, Matt...

I concur with jpmorris...the 58 uses the same 8-track headstack as the 38, 48, 58, TSR-8 and ATR60-8...You may even still be able to buy them new from Teac. And unless you are using a machine 24/7 heads last quite a long time especially if its just home or project studio use...lots of opportunities for spares out there for those headstacks.

To be honest, those heads look good. I always look at the lifter posts...you can't typically rotate the lifter posts, or if you can its not at all easy, so unless the lifters have been replaced or have had sleeves put on them (and you can usually see a sleeve...not very common), I usually look to the lifters as a key clue to whether its a low, nominal or high-mileage machine, and I don't get more granular than those categories because the ONLY way to know the life remaining on a set of heads is to send them off to somebody like John French at JRF Magnetics and have them analyzed. Period. That's it. Everything else is, at *best*, a bit of an educated W.A.G. But if the lifters look like they've got low miles on them I look to see if that wear corroborates with the guides...and yes, as jpmorris points out, guides can typically be easily rotated (and this is true of the 58), so its easy to hide ugly wear. So I try to look all around the guides for wear paths. But if the lifters look like they've got low mileage, and the guides show the same (if there are multiple wear paths then kind of add them up in your mind), then its usually relatively safe to assume the heads are the same. The caveat is you can replace the guides and lifters. I bought a new set of guides and lifters for my first 58...never installed them...I still have them...will likely put them on my second 58 when it comes time for a relap...anyway...I'm not meaning to be complicated here but want to make sure I cover the caveats because they are many...heads can look great but if they are relapped and have had new edge slots cut, well...they can *look* brand new but have 50% or less life in them, or less...often less. I sort of did a poor man's optical analysis once on a 2" 16-track "black-face" Ampex headstack...its in one of my threads around here. That's the only head I've ever had that one could even do anything like that because there isn't any material in between the head coils in the stack...where the guard bands are...so you can actually see the head coil tip, and that's the only way to know the actual wear...you have to know how deep the tip depth was when new, and optically measure the existing depth...divide the existing tip depth by the original tip depth and you have your percent remaining. I have a near new 1" 8-track "black-face" Ampex headstack (same construction between the 2" 16-track and 1" 8-track stacks) and used a magnifier, really good light, and a feeler gauge to compare the depth of the new headstack to the depth of the worn assembly and estimate the remaining life, but I still had to assume a large margin of error to the lab equipment John French uses. but it was effective enough to answer what I needed answered...I bought the 2" 16-track headblock assembly with a return guarantee, and after determining that, for certain, the headstacks had considerably less than 50% life remaining, I returned them for my money back...seller said he thought they were "near new"...and they did look nice...but they had been relapped...another obvious giveaway sometimes is there will be a sticker on the heads they've been relapped. JRF has a "relapped" sticker. But its a sticker...they can be removed. But I digress...You can't do any of this poor-man's optical analysis with the Teac headstack anyway.

So from what I can see (and I kind of don't like passing judgment from a couple pics online...you are getting my unprofessional opinion only here and YMMV, buyer beware, etc.), the lifters have light wear, the surface of the guides that is visible appears the same...the profile of the wearing face of the head coils has a very similar profile to the surfaces outside the edge slots, and the edge slots are still deep (again, if a relap is done right on these headstacks the edge slots are re-cut, but that's not always done so sometimes you can identify heads have been relapped because the edge slots are shallow and narrow)... I don't see any keystone or hourglass wear pattern on the face of the headstacks [EDIT: scratch that...see wkrbee's comment below...he caught the trapezoidal wear on the record/sync head...I missed it...but see my additional comment after that below]...in fact its hard to see any wear path from the pics...I don't see any open coils...I also don't see a bunch of nasty crud built up on the mounting block...based on what I see I'd say that machine has relatively low miles, has not likely been relapped, and looks like its been maintained.

I wouldn't worry about track 1 being low output...understand it is best to assume you *will* have repairs and maintenance to do before the machine is 100%...just expect it...then you won't be disappointed when you are faced with the reality. If you aren't comfortable repairing, setting up and maintaining something like a 58, then strongly consider finding a tech within reasonable driving distance from you. But track 1 being low output could be:

1. A speck of something on the head (it takes *very* little foreign matter to considerably diminish the output level)
2. The machine needs calibrated (somebody didn't do it right and one track is vastly different than the others...it happens)
3. A relay is going bad
4. The amp cards need re-seated

If you get it, first thing to do is to clean the tape path, re-seat the amp cards and roll some fresh tape...see what you bought. Next up is a full calibration. Then you *really* know what you have. If the heads are near end-of-life you'll have a difficult to impossible time getting the record and reproduce frequency response dialed in within spec.

But if the price is right...I think it is far from being a train-wreck, that machine.
 
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The only issue is the second head from the left in the second picture shows a trapezoidal wear pattern.The "tilt" is not correct on that head.It's tilted back at the top.
 
The only issue is the second head from the left in the second picture shows a trapezoidal wear pattern.The "tilt" is not correct on that head.It's tilted back at the top.

Yeah I see that, but I'm not too concerned about that as a deal-breaker...its pretty light at this stage don't you think? The tape path needs setup...the heads are semi-fixed...zenith is fixed and azimuth is semi-fixed...I don't believe the head is tilted. I've seen that wear before on the semi-fixed heads but it was related to the guides not being setup right and improper tensioning...the 58 is tricky to setup because the roller guides on the tension arms and each of the three fixed guides in the headblock assembly are all height adjustable, and there are specific instructions for setting up the fixed guides and then the tension arm guides and finally the reel table heights. It took me *hours* on my first 58 the first time I did this. But if the guides aren't right the tape can skew slightly and pull tighter at the top or the bottom...and if the tensions are off this can exacerbate the issue.
 
All good points Sweet.The tilt can be adjusted-within reason- with the two set screws on the head.Uneven tape contact could be causing the trk 1 problem the OP is talking about.I saw a number of 8 tracks come out of the factory with the head tilt not set correctly-must have been on the first day back after Golden Week.It's better to take care of it now with maybe a light re-lap/dressing,than to let it go until the head is worn enough and cannot be lapped.
 
All good points Sweet.The tilt can be adjusted-within reason- with the two set screws on the head.Uneven tape contact could be causing the trk 1 problem the OP is talking about.I saw a number of 8 tracks come out of the factory with the head tilt not set correctly-must have been on the first day back after Golden Week.It's better to take care of it now with maybe a light re-lap/dressing,than to let it go until the head is worn enough and cannot be lapped.

The head-mount screws are only azimuth-related. I’m not challenging you, wkrbee, as I know you know precisely from experience what you are talking about. I just want to make sure I understand. There are 3 screws per head:

* one larger center screw that fastens the head to the mounting block, and
* two smaller socket-head set screws on either side of the center mounting screw for fine-set azimuth adjustment.

When you say “tilt”, are you referring to zenith tilt (front-to-back tilt) as opposed to azimuth tilt (side-to-side)? And if so are you saying that those fine-set azimuth adjust screws can impact the zenith of the head? Like, and I don’t have a 58 headblock assembly in front of me, but I can see if the center screw is not fist tightened securely, and if the azimuth adjust screws are not lined up fore-aft with the centerline of the larger mounting screw, those azimuth adjust screws would effect the zenith of the head. Is that what you are saying? If so, that’s interesting/valuable/insightful info. On my 58 and my 48, prior to checking/adjusting the azimuth, I always loosened the azimuth adjust screws all the way, and made sure the center mounting screw was firmly fastened, then put tension back on the azimuth adjust screws, then proceeded with checks/adjustments. I can’t recall if I ever found a center mount screw less than firmly fastened.
 
Wow amazing replies! Thank you so much for all of the input. I think I'll go through with it!

Sweetbeats you're a wealth of analog knowledge :)
 
Wow amazing replies! Thank you so much for all of the input. I think I'll go through with it!

Sweetbeats you're a wealth of analog knowledge :)

Thanks...I am a collective of info from smart guys like wkrbee. ;)

May I ask what the seller is asking for the bundle?
 
Hard to really tell from the photos, BUT one very important point and something that no one thus far has picked up on.

The seller has stated that the record level on Trk 1 is somewhat lower than the rest.

If the tape guides, head azmuth, etc are all correct, then the passage of the tape over the heads should be exactly the same and the record level on all tracks should be the same, so if Trk 1 is lower and all the above are correct, then if Trk 1 is lower in record volume it could be that there is something wrong with the coil, etc associated with that particular track's head, OR that there is something wrong with that track's record or playback amplifier. This could be anything from the amplifier's electronics to something wrong with amplifiers bias/level settings.

As a result, it might not be the record head that is at fault, but rather electronics, settings or even the re-play head.

Can I suggest that you try to obtain a legitimate test tape and play it back to see how the levels of every track compares in playback mode.If all are the same (or very close), then you can eliminate the playback head and its electronics.

Also, if you connect a good test tone generator to the units inputs do the individual Vu meters indicate the same volume when not recording and if you then are able to do a recording and read the Vu meter on each of the tracks, does Trk 1 show the same level as displayed in non record mode or does it show a lower level. If this is the case then as the levels were all the same in non-record mode and on playing the test tape it proved that Trk 1 on playback was OK, THEN it indicated that the problem is most likely to be within the actual record head.

Although a bit jumbled in presentation (!!!!!) I hope that the above gives you a bit more to work on. By the way, I have used professional multi-track tape recorders (including one that is the only one of its type ever built) for more than 55 years and have never seen only one track wear out, unless the take guides were out of alignment, BUT if so, it was very soon discovered because the sound was wrong on playback.

David
 
The heads have a like wear pattern to one I see often. The head mounting system was not the best to get the heads straight as much as they think it was so. What you are looking not to have is black spots in the center area of the head which are open gaps. The higher up tascams have more trouble with relays that anything else- I have had to replace hundreds of them. That and the Tachometer rollers seem to always decay as to the rubber.
I am waiting on two of them now. If yours is sticky then might as well send it to Terry right away. I have seen some so bad that they leave decayed rubber on the tape and then it transfers to the heads and lifters in little black tracks.

Those heads should be usable for a long time yet and I would try and correct the tilt so that the top channel gets more pressure. These assembly line guys seem to do plenty of sloppy work. I get X1000R decks in all the time with no one ever touching them that only go up to 9KHz and after I correct them they go above 20KHz. The 58 is a top notch unit and I don't think heads will be a problem for a while as they don't get used all that often unlike the 388 which is a joke to start out with. When I say used I mean bought for replacement.
 
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