tascam 38 tape heads and lifespan.

[christiandaelemans]

hey y’all!

i’ve been using my tascam 38 (which came to me virtually unused by its original owner, it was serviced and calibrated for ATR master tape and i’ve been using it that way with dbx since january) to record a 30 minute album and i’ve been wondering about the machines mortality with some of the problems i’ve noticed popping up.

i love this machine. it’s given me no heartache. HOWEVER! track 7 is a bit dull on the high end now, and i forget if it was that way a couple months ago, and track 8 is very very picky about oxide buildup and whether or not it will print hot signal to tape. usually, even if the tape path is as clean as a whistle, it’ll still be quieter than any other track even if fed the same level.

it makes me wonder about the tape heads, and whether or not i’m running them into the ground. for those with tascam 38s, how long have your heads lasted??? since my 8 channel interface has crapped out on the 2 inputs on the front, i don’t really have the option to not mix down this album from running the tape itself. this means rewinding and playing songs dozens and dozens of times. funnily enough, i use the repro head because (likely due to alignment) to mix down and digitize because the sync head always has a duller and less full sound. i heard somewhere that the sync head and repro are literally the same exact head, placed in different locations along the tape path.

here’s a link to a .wav file of a rough mix of one of my songs, you can hear the fidelity of the repro head and hopefully some mixing talent from the m512 tascam board.

song

 

[TalismanRich]

I used my old 1/4" 4 track for many years. Eventually the heads do wear, but if it was basically unused and you've only been working on this since January, the heads should be fine.

As for the Repro head sounding better, that's to be expected. A recording head should have a somewhat larger gap than the playback head which will improve the response for recording but lose high frequencies on playback. Otherwise they wouldn't have the third head. Playback via the record head is simply to avoid sync issues.

Buildup of oxide might suggest a bit of an alignment issue somewhere that is causing the tape to scrape.

Hopefully Sweetbeats will chime in here. He works with these things regularly.

 

[christiandaelemans]

I used my old 1/4" 4 track for many years. Eventually the heads do wear, but if it was basically unused and you've only been working on this since January, the heads should be fine.

As for the Repro head sounding better, that's to be expected. A recording head should have a somewhat larger gap than the playback head which will improve the response for recording but lose high frequencies on playback. Otherwise they wouldn't have the third head. Playback via the record head is simply to avoid sync issues.

Buildup of oxide might suggest a bit of an alignment issue somewhere that is causing the tape to scrape.

Hopefully Sweetbeats will chime in here. He works with these things regularly.

interestingly, the vast majority of oxide buildup occurs on the flywheel. i’ll run the tape to a gap between songs, take the tape out of the transport and run an alcohol coated foam tape head cleaner against the flywheel and it’ll pick up quite a bit of brown. the heads themselves however have very small amounts, if any.

 

[sweetbeats]

Tape heads last longer than most people realize. This, of course, depends on the material used to manufacture a particular head (ferrite or glass heads last longer than metal types), the type of machine (later generation machines with more sophisticated full servo tension transports have the potential to be more gentle on the tape and tape path), how well the machine is properly maintained (cleaning, tape head alignment, tension checks/adjustments), and how the machine is used (for instance does it do a lot of scrubbing/shuttling, and is it in a busy production environment running two or more shifts a day most days of the week, or is it in a home or project studio with more periodic use)…but a friend of mine who operated a very well-respected and busy tape transfer lab for many, many years, having a literal fleet of tape machines of all formats, the busiest of which were several 2” machines, shared the following with me when I asked him how long do heads really last: he gave the example of one of his 2” 24-track Ampex MM-1200 machines, which are not a full servo transport, and have typical metal core heads with epoxy filler…a new set of heads were installed in 2002, and after 8 years of running it often…hundreds and hundreds of reel passes…they started to show “slight signs of needing relapping.” He sent the heads off to JRF and they came back relapped with a head report showing 85% life remaining. So that’s a machine with a moderately sophisticated transport, typical metal heads in a busy production environment, and over the course of 8 years and after a relap only 15% tip depth was used up. He then said to me, regarding a near-new set of 1” 8-track heads, and me a home-based operator only using a machine periodically, “Smile. Unless you give your machine full-time use, you’ll NEVER wear them out, even if they have less than 40% life left…if you talk to JRF, he’ll give you the same practical reality.”

Your 38 has a full servo transport, has metal core heads…you can usually tell a lot about the actual wear condition on the tape path not by looking at the heads…they can be relapped and look new but only have 25% life left, for instance…and you can’t reliably tell from the guides because they can be easily replaced or rotated…but the LIFTERS…look at the lifters. Those are harder to replace, harder if not impossible to rotate, are typically smaller in diameter and therefore wear faster than something with greater surface area when shuttling, so if they’re not sleeved, and show little wear (because every pass of a reel of tape typically requires a rewind either at the end of the pass, or when re-mounting in the case of tails-out storage), then the tape machine likely has lower mileage use and wear.

So how do your lifters look? Post a pic?

Your issues could be related to bad relays or connectors on the amp cards and not be related to the heads.

 

[RRuskin]

...As for the Repro head sounding better, that's to be expected. A recording head should have a somewhat larger gap than the playback head which will improve the response for recording but lose high frequencies on playback. Otherwise they wouldn't have the third head. Playback via the record head is simply to avoid sync issues. ...

From the 80-8 forward, the Sync & repro heads have the same performance specs. The repro head was there for ease of alignment more than anything else. The philosophy was that if the same head that recorded also played back, slight alignment differences would be of little to no consequence.

 

[sweetbeats]

I used my old 1/4" 4 track for many years. Eventually the heads do wear, but if it was basically unused and you've only been working on this since January, the heads should be fine.

As for the Repro head sounding better, that's to be expected. A recording head should have a somewhat larger gap than the playback head which will improve the response for recording but lose high frequencies on playback. Otherwise they wouldn't have the third head. Playback via the record head is simply to avoid sync issues.

Buildup of oxide might suggest a bit of an alignment issue somewhere that is causing the tape to scrape.

Hopefully Sweetbeats will chime in here. He works with these things regularly.

Totally agree with all this, though just to note the 38 has identical record and reproduce heads. By the early 1980s head construction tech had advanced to the point heads could have the same gap between record and reproduce heads, and the gap length was a compromise, but the laminations were so thin by this time the HF response was still very good even with gap that was a bit too big for one head and a bit too small for the other. So on the 38 playback response should be the same between the two heads. If it’s not then yeah check for mechanical obstruction (dirt/oxide)…even the tiniest amount can substantially impact response and level…and if there’s a lot of shed happening then consider if the tape is not good (I had brand new tape once that was flaky shedding), or the tape path needs run through the mechanical alignment procedures because the tape is being crammed at the edge of one of the guides or whatever. And then there’s the whole issue with running any tape not slit on the old Ampex/Quantegy equipment on a tape path established by tape slit on said equipment. I can explain more…but said tape is slightly more narrow, so if you then run other tape on a path established by that slightly more narrow tape its bound to edge-shed.

 

[sweetbeats]

interestingly, the vast majority of oxide buildup occurs on the flywheel. i’ll run the tape to a gap between songs, take the tape out of the transport and run an alcohol coated foam tape head cleaner against the flywheel and it’ll pick up quite a bit of brown. the heads themselves however have very small amounts, if any.

The flywheel is under the capstan on a belt driven system, but tape doesn’t touch the flywheel anyway. So what part of the tape path are you calling the flywheel? Maybe post a pic?

 

[christiandaelemans]

The flywheel is under the capstan on a belt driven system. No belt on your 38 and tape doesn’t touch the flywheel anyway. So what part of the tape path are you calling the flywheel? Maybe post a pic?

that little pin roller (not the guide, but the thing next to the guide) to the right-hand side of the repro head is what i’m referring to. i had a feeling i was calling it the wrong name. but i’m pretty sure it’s always running along the shiny side of the tape, helping out the pinch roller move the tape along.

 

[christiandaelemans]

i’m not at home right now, but a month or so ago i took some detailed pictures of my tape heads. unfortunately i didn’t get a pic of the lifters, which i'm assuming should be examined from where they contact the bottom of the tape.

 

[sweetbeats]

that little pin roller (not the guide, but the thing next to the guide) to the right-hand side of the repro head is what i’m referring to. i had a feeling i was calling it the wrong name. but i’m pretty sure it’s always running along the shiny side of the tape, helping out the pinch roller move the tape along.

That’s the capstan shaft. It’s what actually drives the tape in PLAY or REC-PLAY mode. The pinch roller drives nothing. It is a passive idler that presses or “pinches” the tape to the capstan shaft. The pinch roller is rubber so that, with pressure, it deforms slightly against the capstan shaft which slightly wraps the tape on the capstan shaft, which increases the contact area between the tape and the capstan shaft, and increases friction coefficient enabling the capstan shaft grab and drive the tape. So the pinch roller helps the capstan shaft, not the other way around.

If you are getting a lot of shed on your capstan shaft there is potentially either something wrong with your tape, or the mechanical setup of the tape path, or both. What type of tape are you using? Is it new or old? Describe further how often you are having to clean the tape path and what the cleaning materials look like when done? Quantity and condition. Remember, even the smallest speck can substantially impact frequency response and signal level on a given track.

 

[TalismanRich]

Totally agree with all this, though just to note the 38 has identical record and reproduce heads. By the early 1980s head construction tech had advanced to the point heads could have the same gap between record and reproduce heads, and the gap length was a compromise, but the laminations were so thin by this time the HF response was still very good even with gap that was a bit too big for one head and a bit too small for the other. So on the 38 playback response should be the same between the two heads. If it’s not then yeah check for mechanical obstruction (dirt/oxide)…even the tiniest amount can substantially impact response and level…and if there’s a lot of shed happening then consider if the tape is not good (I had brand new tape once that was flaky shedding), or the tape path needs run through the mechanical alignment procedures because the tape is being crammed at the edge of one of the guides or whatever. And then there’s the whole issue with running any tape not slit on the old Ampex/Quantegy equipment on a tape path established by tape slit on said equipment. I can explain more…but said tape is slightly more narrow, so if you then run other tape on a path established by that slightly more narrow tape its bound to edge-shed.

That's good to know. It's been so long since I really delved into tape decks, I didn't realize that had changed. I always noticed that the sync/record always sounded duller than the play head itself but then I haven't bought a tape deck in well over 40 years.

 

[sweetbeats]

i’m not at home right now, but a month or so ago i took some detailed pictures of my tape heads. unfortunately i didn’t get a pic of the lifters, which i'm assuming should be examined from where they contact the bottom of the tape. View attachment 149620View attachment 149621View attachment 149619

The lifters are right there in all three pics. One is between the erase and record heads and the other is between the record and reproduce heads. The pics are blurry but it looks like lower than average wear. There’s no way to know without actual evaluation of the heads by a professional, but if the lifters and heads are original to the machine and I was a betting man I’d say they’ve got plenty of life left.

 

[sweetbeats]

That's good to know. It's been so long since I really delved into tape decks, I didn't realize that had changed. I always noticed that the sync/record always sounded duller than the play head itself but then I haven't bought a tape deck in well over 40 years.

Even some Otari models had dissimilar record and reproduce heads into the 1980s. The MX5050 series is that way, at least the 1/2” 8-track. My Ampex MM-1000 and 3M half track, being from the late 1960s, are definitely that way. It changes in the 1980s primarily.

 

[christiandaelemans]

That’s the capstan shaft. It’s what actually drives the tape in PLAY or REC-PLAY mode. The pinch roller drives nothing. It is a passive idler that presses or “pinches” the tape to the capstan shaft. The pinch roller is rubber so that, with pressure, it deforms slightly against the capstan shaft which slightly wraps the tape on the capstan shaft, which increases the contact area between the tape and the capstan shaft, and increases friction coefficient enabling the capstan shaft grab and drive the tape. So the pinch roller helps the capstan shaft, not the other way around.

If you are getting a lot of shed on your capstan shaft there is potentially either something wrong with your tape, or the mechanical setup of the tape path, or both. What type of tape are you using? Is it new or old? Describe further how often you are having to clean the tape path and what the cleaning materials look like when done? Quantity and condition. Remember, even the smallest speck can substantially impact frequency response and signal level on a given track.

as per the seller, i’m using 3M ATR master tape. it was manufactured in either 2022 or 2023. he told me upon buying the machine in person, “never use anything other than ATR master tape with this one.”

heres the story with the unit: it was bought by a sort of barn studio in PA in the 1980s, but was kept as a spare unit and basically not used at all. fast forward to 2024, and a company who buys reel to reels and analog equipment to service and sell bought the 38, they replaced belts, all dying caps, all components inside which were faulty or going to be faulty, and they calibrated and aligned it to be used with ATR master tape. the dude i bought it from got it for 1800 with tape, and he said he thought he was just too old to be using tape and sold it to me for much less.

before a session, i always clean the heads, guides, and every chrome part of the tape path which sees either side of the tape. usually, minimal tape residue is found. however, when i run an alcohol coated foam tape head cleaner against the capstan shaft (depending on the last time i cleaned it) i’ll usually get some brownish to dark grey/black residue coming on the foam. it’s not an endless stream, usually it’ll saturate one or both sides of the foam (i’ll usually push the side of the foam cleaner against the spinning wheel) before running out of juice and giving me no more residue.

i’ve only noticed a few times where i can audibly hear residue impacting the high end of either recording or playback. a few times when recording, i’ve heard the sync head take a sudden hit in the high end, before gradually coming back to life. though, it’s never really scared me because it always comes back and it’s only when recording with the sync head. it also doesn’t effect the recording itself that i’m laying down, which is odd. i’ve done a vocal where it happened, and the vocal was perfectly fine.

i haven’t tested to see whether the dirty shaft (har har) is what causes track 8 and 7 to be quieter and muffled when recording, or if me cleaning the shaft just happens to be what it takes for me to get lucky and lay down good signal. i HAVE heard a few takes on track 8 where the signal remains fair, but suddenly becomes much quieter and remains that way for the rest of the recording.

 

[sweetbeats]

I made a mistake…forgot the 38 has a belt drive capstan. I corrected my incorrect statement in my earlier post but wanted to flag the error and correction here.

So when you clean the capstan shaft, is most of the residue at the edges of the band where the tape contacts, or is it evenly distributed across the shaft?

 

[christiandaelemans]

I made a mistake…forgot the 38 has a belt drive capstan. I corrected my incorrect statement in my earlier post but wanted to flag the error and correction here.

So when you clean the capstan shaft, is most of the residue at the edges of the band where the tape contacts, or is it evenly distributed across the shaft?

i usually run it up and down the shaft (again, har har) so i’ve never explicitly seen where most of it is. though i always make sure to rub good against where the tape would be recording 7 and 8.

 

[sweetbeats]

Well, maybe clean it in such a way next time to try and assess if there is more accumulation at the top and bottom, or edges, of the contact band.

 

[sweetbeats]

If the problems are always with a particular track or two, and it’s consistent that way, you can swap nap cards to see if the problem follows the amp card swap. If the swap causes even new and weird problems with signal level and such, like you feel like you’re chasing a moving target, it’s usually failed relays. But sometimes it can be card edge connector solder joints that need re-flowed on the cards and the motherboard. These two areas are common issues; the relays and the edge connectors.

 

[christiandaelemans]

Well, maybe clean it in such a way next time to try and assess if there is more accumulation at the top and bottom, or edges, of the contact band.

will do. i’ve been away from home for the majority of this conversation, but im going to run some tape tonight and i’ll take a video of what the cleaning process yields.

as an aside, do the bottoms of the lifters show wear? you mentioned they are unable to be rotated, and if memory serves, they lift up and greet the bottom of the running tape.

 

[sweetbeats]

The lifters push the tape or “lift” the tape away from the heads in fast-wind modes.

Like I said earlier it’s a little hard to tell from the pics because the heads and other tape path components are out of focus, but I see a lighter than average wear pattern in the lifters from what I can tell.