Tascam 388 studio 8 recording problem

[Alexwfm2030]

Hello,

I'm trying to get this recorder back to work as it doesn't look in too bad condition and the heads seem to have some life left in them. At first it needed a belt change, so now I'm on the sound tests.

Unfortunately I don't have a test or alignment tape, so I've been recording a 440hz sine on all 8 channels at once for a few minutes and listen back. I'm using the recommended tape from the manual, UD-35 (second hand but looks ok)

What I notice is that there is there are spurious interruption of sounds across all 8 channels but especially on 1 and 8. I did take a look close up on the R/P head but it doesn't look worn to the point of explaining this issue. I'll attach an audio file of CH1-8 which then changes to 2-7 after about 25 seconds.. if you were to look at the waveform you could see how it looks more like signal dips, but I'm not sure what is causing them. My initial thought is dust on the tape, but I can't see how that wouldn't be the case all the time. The noise happen at random times on all channels and it can't be heard/seen at the test point just before the bias trap.

--------in the audio file you might hear a break every 8 seconds, it's cause I'm using a sampler which loops a sine. Not the best way to test but it's quite distinguishable from the actual noise which is on continously.

I've tried demagnetising but not with a very fancy demagnetiser.

Attached are also close ups of the R/P and erase head with and without tape. The machine is all plugged in and ready to test if anyone has any ideas on things to check!

 

[sweetbeats]

What do the guides look like?

Even the tiniest bit of debris can cause significant variances in record or reproduce level, and by variances I mean up to a complete drop-out.

If there is a wear pattern in the guides that was established by Ampex tape then the Maxell may be slightly wider causing edge shed. Or the Maxell tape is just shedding on its own. Feel free to post pics of the guides. Try some Ampex/Quantegy tape preferably 457 (that’s what the machine was designed around).

Is this just a reflection?

 

[Alexwfm2030]

The guides don't look too bad, I think you can see the wear pattern on them and the dummy head. and that yes is just a reflection.

In terms of dust, I'd be having the issue right after cleaning the heads, I'm not sure if the tape could already be dusty by itself?

 

[sweetbeats]

There are many kinds of shed…sticky shed, flaky shed, edge shed…and the thing I’m talking about with the established wear path is a real thing. The machine was designed around Ampex 457. Ampex, among all other tape manufacturers, had issues with the consistency and precision of their tape slitting machines. In order to avoid the possibility of their tape ever being slit too wide (we are talking 0.001~0.003”), they purposely slit it slightly undersize. So that means if your machine has a wear path establish by Ampex/Quantegy tape, and then you put another brand on there, generally the tape path is slightly too narrow…again it may only be 0.001~0.003” difference, but on guides or heads without relief slots cut, that means the tape edges are running up against a sharp edge and this often creates some edge shed that affects edge track performance…not a big deal usually on a wider track machine, but the 388 track width is similar to cassette 4-track and the edge shed is problematic. If it was me I’d find some non-sticky Quantegy 457 and try it out and see if it performs better. If it does then you’ll want to use that tape, or maybe since the wear seems fairly limited, you might be able to get away with rotating the guides to a fresh surface and use the Maxell unless there is the same wear path established in the R/P head…couldn’t tell from the pics. If you rotate guides and do nothing else just bear in mind this *does* affect the geometry of how the tape mates with the heads…not a big deal on the erase head but may be on the R/P head. Ideally when you rotate guides you’re also realigning the heads or most ideally relapping the heads and I always use JRF Magnetic Sciences to do that though there are other vendors. Your wrap angle is already slightly off on the R/P head and the guide rotation wouldn’t further that, if anything it might slightly correct it. But my point is you have an established wear path, and any changes you make to one or more components in the tape path establish a new wear path. And this is bad. But not terrible if the wear is minimal. It’s just not ideal. And there may be minor performance issues until the new wear path is fully established.

That was a lot of info. But there’s a lot to think about when messing with your tape path, especially on a 388 where there are no new heads available, and no other machines besides 388s from which to pull spares…the erase and R/P heads on a 388 are 100% unique to the 388. And prices for anything 388 are crazy.

Here’s one more thing you can try. I actually had success doing this and others have as well when the wear path is minimal…I had a 388 with a wear pattern established by Ampex/Quantegy tape. I wanted to use BASF LPR35 which is precision-slit to the industry standard. I was having edge shed on track 1 or track 8. So I took a reel of the LPR35, threaded it up, defeated the lifters and put it in FFWD all the way to the end of the reel, then REW back the other way; did that a couple times. The idea was to use the tape to dress up the edges of the wear path to hopefully mitigate the ongoing edge shed. By defeating the lifters and fast-winding the tape the tape is fully seated in the tape path while fast-winding. Did it work? Yes. No more drop outs from debris. Was it a little cruel to that one reel of LPR35? Sure. But it was worth having all 8 tracks perform appropriately, and any debris that was on the tape from the dressing procedure I wiped off by gently pinching the tape between my thumb and fingers using a soft lint-free cloth while play spooling. There wasn’t much. So that might be something else you can try. This all assumes I’m correct about my hypothesis. But remember even the tiniest speck can have an impact. Clean the whole tape path. Thread the tape up. Play it for 5 minutes. Stop the transport. Turn the reels so you can lift the tape away from the heads and clean the path again. Is there any debris in the tape path? Heads? Guides? If so I bet I’m right.

 

[Alexwfm2030]

Thanks for all the precious info Sweetbeats. I'm going to try to see if I get any shed using your method, anyway I'd mention that when I took those close up pictures the machine had already been playing for I'd say 30min in total since the last clean, without showing clear shed. But I also understand that it's not about the head being completely covered but could be just tiny particles.

Is there much difference between the LPR35 and the UD35 I'm using? I think I've read this second one might have a better wrap since it's slightly thinner. The only reason I got this reel is cause it was suggested in the manual of the machine. I'm looking for a 457 reel but from what I'm slightly hesitating because of the cost, if it ends up not being the issue, but I might be able to borrow one for tests. I quite like the idea to use the UD35 to "carve" a new path. I'm assuming after doing that the tape reel would probably be unreliable for sound tests?

If there was any adjustment I would do that would be the RP head wrap angle. The light could be deceiving but it looks like it's slightly to the side. I think the erase head is worse but that's probably less important.

I'm not too sure what the previous owner used but I got given all types of tape with it, which sounds worrying.

The only other tapes I have now are quantegy 632 and BASF SPR50LH

 

[sweetbeats]

Reply part 1 of 2…

Thanks for all the precious info Sweetbeats. I'm going to try to see if I get any shed using your method, anyway I'd mention that when I took those close up pictures the machine had already been playing for I'd say 30min in total since the last clean, without showing clear shed. But I also understand that it's not about the head being completely covered but could be just tiny particles.

You’re welcome. And yes…I’m not exaggerating. My experience with my own 388s I’ve owned over the years is even a particle almost imperceptible to the eye deposited on the R/P head can make a track inaudible or nearly so. The other thing that can happen is lifting or curling at one or more edges due to the wear pattern being just slightly more narrow than the tape. This is the same as what I was talking about earlier, but in this example there may not be an issue with edge shed, but rather just slight lifting or curling of the tape at the edges and that’s all it takes. So I’d definitely try the edge dressing method I mentioned in my last post. You could do it with the Maxell or the BASF tape. I’d do the BASF tape you have because that’s lower quality tape in terms of maximum operating level, print-through, etc.

Is there much difference between the LPR35 and the UD35 I'm using? I think I've read this second one might have a better wrap since it's slightly thinner.

I’m not familiar really with the Maxell tape because it was developed for the consumer market…maybe somebody else that knows more can comment on that…that doesn’t mean it’s bad and I think they are both +6 class 1mil tapes? You’ll definitely want to check bias, which is a pain on the 388 because the instructions in the Service Manual are all designed around 457, and the bias setting for LPR35, for instance, is substantially different. I have no idea what it is for the Maxell tape and if it was me I’d be quantitatively figuring that out if I was in your shoes…I don’t know if you have the means to do that or not. Correct bias setting has a significant impact on distortion level and HF performance, and the adjustment range is very narrow for proper performance. You could look at the spec sheet for the Maxell tape and maybe find some guidance for proper bias you can apply to the 388 using the traditional over-bias method, which, again on a two-head machine is a bit cumbersome, but at least it’s only 8 tracks!

To your statement the Maxell might have “better wrap because it’s thinner”…I don’t know where that ideology comes from but I don’t agree with it. While it may philosophically be true, operationally it’s not going to have any consequence…no wrap-related performance advantage between different 1mil class tapes of slightly different overall thicknesses, or even between 1mil and 1.5mil class tapes. The tape path and wrap around the heads is going to either be defined by the specific tape path and available adjustments, or determined using the instructions in a machine’s service manual to the end of achieving performance within the parameters of the machine. The 388 has semi-fixed heads. There’s no adjustment for zenith or wrap depth. You have azimuth and wrap angle. That’s it. And the guides are fixed. So it is what it is and a few micrometers difference in tape thickness will matter to nothing. The main pros and cons to 1mil class tape compared to 1.5mil close tape are:

Pro: 1mil class tape has longer play time for a given reel size of tape compared to 1.5mil class tape…thinner tape means more tape footage can fit on a given size reel. Teac selected 1mil class tape as the standard for the 388 because of the 7” reel size used by the machine in order to maintain longer record/play time.

Con: thinner tape typically equates to less or no back-coating and consequentially greater risk of print-through. This boundary really starts to get pushed when we’re talking about +6 operating level class tapes that can handle higher signal levels before saturation than lesser class tapes, but that hotter print to tape and the thinner tape means more print-through potential.

Bottom line, Teac picked 1mil class tape for the longer play time.

The only reason I got this reel is cause it was suggested in the manual of the machine.

Can you tell me where that is? I’m not questioning you, I just can’t find it and it would be interesting to know that. Years ago I had phone conversations with analog support techs at Teac in Montebello, CA, before they dissolved that department altogether, related to the 388 and setting bias. They clearly stated the 388 was designed around using 457, and the specs in the manual and settings for bias were based on 457. And in my memory 457 is listed in the manual, but now I can’t find that or ANY reference to a particular tape type lol! But they told me the bias setting was for 457 and if I was using LPR35 the bias setting would be significantly different. And I conducted my own tests and found that to be very true.

I digress.

To be continued…

 

[sweetbeats]

Reply part 2 of 2…

I'm looking for a 457 reel but from what I'm slightly hesitating because of the cost, if it ends up not being the issue, but I might be able to borrow one for tests.

Up to you…tape is expensive. Now that I know you have other tapes on-hand like the BASF tape I’d use that as your “shop tape” and give that a few passes at fast-wind speeds with the lifters defeated.

I quite like the idea to use the UD35 to "carve" a new path. I'm assuming after doing that the tape reel would probably be unreliable for sound tests?

Again, see comment above. Now that I know about your other options, don’t use your Maxell tape as your “shop tape.”

If there was any adjustment I would do that would be the RP head wrap angle. The light could be deceiving but it looks like it's slightly to the side. I think the erase head is worse but that's probably less important.

Don’t touch it. Understand the wear path is flat. If you move that head now without a relap you will start a new wear path and potentially, until the new wear path is fully established, which can take a long time, be unable to get the machine to perform within spec. I said this earlier: once a wear pattern is established on a headblock assembly, it is highly recommended to make no changes or adjustments aside from azimuth unless the wear pattern is extremely light, or you are sending the assembly in for a relap and optical alignment. I’ve had a couple headblock assemblies for my MM-1000 with extremely light wear either on fresh heads or relapped heads, but was making changes to the guides and also had removed scrape flutter idlers for servicing. ANY changes to ANYTHING on a headblock will change the geometry of how the tape mates with the wear pattern on the heads so don’t do it unless you have the means to properly align the heads (and I don’t touch this area…the value of a tape machine is in the heads…I do not cut corners where it concerns setup and alignment of a headblock assembly), or the wear pattern is extremely light. On those Ampex assemblies I sent them to John French to reassemble and make the guide changes and optically align the assembly as close as possible to the existing light wear pattern. And even somebody like John with all his experience and equipment will tell you “I can’t get it perfect but I’ll get it as close as I can”, which is good enough for me when the wear pattern is very, very light. If the wear pattern is beyond that he won’t even do it. So…yes, I mentioned earlier your wrap angle is off. It’s not terrible. You need to decide if you want to set it right now, and disrupt the wear pattern, but you may not be able to do it because you set it by adjusting the head for maximum output, which is a pain on a two-head machine, but with the established wear pattern as you rotate the angle of the head you may disrupt the tape-to-head contact giving you false feedback on level and you end up with it still maladjusted. JRF would optically align it which means they can do it without using signal and get it right, but you still have the issue of establishing a new path and potentially disrupting performance in the meantime. I might be splitting hairs because it’s hard to see the wear pattern in your pics being so close up. They are really good pics for seeing a lot of things I don’t usually get to see when people post pics of heads and ask for opinions, but the close up shots straight on actually don’t give the perspective of the relief of the wear pattern.

I'm not too sure what the previous owner used but I got given all types of tape with it, which sounds worrying.

The only other tapes I have now are quantegy 632 and BASF SPR50LH

I wouldn’t call it “worrying”, but those are more affordable tapes which are also not going to perform as well. So the clue there is the previous owner wasn’t invested in paying the cost to get the correct tape class for the machine. Lots of people do that and we’re all on a budget, but lots of people get into tape thinking they’re going to get some magic result and their machine is going to magically work perfectly without any ongoing maintenance or fixes or using the correct tape; that what they read or are told won’t or doesn’t apply to them and they don’t really need to have a good tech or have their own skills and equipment, which typically costs hundreds of dollars at minimum; that they can cut corners without consequences but then come complaining their machine isn’t working right when they cut those corners. My firm sense that’s not you, but it’s a lot of people. Owning and operating a tape machine is a serious commitment and takes time, money and expertise.

Do this: clean the tape path really well, and run some tests with the Quantegy 632. That tape is slit on Ampex slitters and is slightly undersize compared to the industry spec. Is your edge track performance better or no? If yes, dress the tape path with the BASF tape, clean it up good and run some tests with your Maxell tape. Report back.

 

[Alexwfm2030]

Thanks sweetbeats. I went trying the 632 tape just now, after making sure everything is clean. Track 8 now is sounding good, as well as 2 to 7. Unfortunately track 1 still had the same issue, as well as a weird intermittent very periodic cut out of sound. I found later the reel had an indentation on the side, so every once a while one side of the tape will have a small outward "edge". I wonder if that wasn't the case if track one would have sounded ok. I think I might just order a 457 and see.
You can see the indentation in the pictures attached.

On the other pictures there's a photo of the head after a 5min recording with the UD35 tape, which seem to have some debris from the tape. On another picture you can see an interesting coloration of the plastic around the tape counter wheel, which I wonder is caused by!

The theory about thinner tape better wrap angle is something I've read on a reddit post, which you might agree is not the most reliable source..

I also can't find where I've read about the maxell UD35, but from what I remember it was in a scan of either the manual of the machine or a quick tech spec, I might try to look for it.

Anyway it seems I'm on the right path using the 457 slit type tape. I'll wait for it to come in and will report back then!

Cheers

 

[sweetbeats]

Hi. So, just to be sure, since you didn’t specifically mention it in your last post, am I correct you ran the BASF tape in fast wind forward and back with the lifters defeated a couple times through the pack?

And yeah the 632 is garbage with that deformity through the pack. I’ve run into that before.

I have no idea what that colored ring around that roller is. Maybe residue from some type of lubricant.

I’d be interested to see the documentation regarding the UD35 if you can find it.

Reddit…yeah…dunno. But “wrap angle” means two different things…the angle resulting from tape bending around tape path components, and specifically stationary components. The total wrap angle is the sum of the angles in a given tape path the tape wraps around stationary components, and that sum, along with the total as well as individual lengths of unsupported tape in the tape path between each tape path component, is a critical factor determining scrape flutter frequency and other tape path performance outcomes. Less is better for both. “Wrap angle” also refers to the perpendicularity of the centerline of a head to the tape. It should be 90 degrees. Thinner or thicker tape has nothing to do with impacting either of these. Tape will wrap around stuff. And the wrap angle is mechanically set/adjusted on a machine. It’ll be the same if it’s 1mil or 1.5mil tape or if you use paper…doesn’t make a difference.

 

[Alexwfm2030]

Sorry I wasn't very clear. Before doing the FF thing with the BASF tape I thought I'd do some tests with the 632 which was supposedly brand new unused. After I've realised that the 632 didn't have a noise issue on track 8 I thought I'd skip the BASF fast forward step and just order the 457 and see how that sounds.

That's good info about the wrap angle, in my head I've imagined a thicker tape to be less bendy therefore wrap less around the head. But then considering the tension the tape is subject to I guess any tape will just bend at all corners the same. As you suggested, even though I'm really tempted to play around it's probably better if I don't mess around with the wrap angle adjustment.