Tape echo capstan / splice jump

Steenamaroo

Steenamaroo

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Hello folks..
Not often I'm in here..Hope you're all well! :)

I've acquired a little WEM Watkins copicat mkIV. It's the later solid-state copicat tape echo.

It's all looking and sounding good. I've cleaned the heads and path with 99% and all moving parts seems clean and free too.
However, every time the splice goes over the capstan I see and, more importantly, hear a little wobble in the tape.

At first I assumed it was just less than suitable tape weight or a bad splice but I have since bought proper pre-made loops for the machine and am having the same issue.

Ok, I'm going to fail at describing this but the wobble appears to be at the edge of the tape closest to the machine.
By that I mean it's an uneven wobble.

Where do you start with something like this?
I've tried three or four of the premade loops. They are the proper type self lubricating tape and the splices all look perfect.

Putting a little bit of extra pressure on the tension arm doesn't help so I don't think it's a tension issue there.
Is it possible for the motor to be weak? I can halt the capstan by grabbing it with index finger and thumb, but it's not a pushover.
Unfortunately I have no point of reference, so I don't know if that's normal or not.

Any help at all is much appreciated, chaps! :)
 
I can hear the splice ever so faintly on my tape loops with my Multivox tape echo....which has the "endless tape" tray, where the excess tape is loose in the tray. It has a 16 foot loop, so there is plenty of time between them, and it's not an issue...unless I do a lousy splice when making them.
I also use the BASF/EMTEC 911 or 468 1/4" tape, which has the back-coating, and it's smooth as silk.
Maybe you can try a different tape and see if it helps...?

Not sure how many feet of loop yours has to work with or if yours is a constant tight loop...?
Anyway...it sounds like the splice point is enough to make it wobble no matter how clean it is...which could be the tension on the arms or pinch/capstan...and it's probably not as adjustable as tape deck with all it's calibration points...but there should be some tension adjustment capability.

Mark every nut/screw with a perma-marker so you can put it back...and then start messing with it. :)
 
miroslav said:
I can hear the splice ever so faintly on my tape loops with my Multivox tape echo....which has the "endless tape" tray, where the excess tape is loose in the tray. It has a 16 foot loop, so there is plenty of time between them, and it's not an issue...unless I do a lousy splice when making them.
I also use the BASF/EMTEC 911 or 468 1/4" tape, which has the back-coating, and it's smooth as silk.
Maybe you can try a different tape and see if it helps...?

Not sure how many feet of loop yours has to work with or if yours is a constant tight loop...?
Anyway...it sounds like the splice point is enough to make it wobble no matter how clean it is...which could be the tension on the arms or pinch/capstan...and it's probably not as adjustable as tape deck with all it's calibration points...but there should be some tension adjustment capability.

Mark every nut/screw with a perma-marker so you can put it back...and then start messing with it. :)
Click to expand...

Hey Miro,
Thanks for the reply.
Yeah, unfortunately it's a very simple machine. I don't think anything can be adjusted at all except for the tension arm.
The heads can't even be aligned. They're just bolted where they are.

Initially I was using some old (good) quantegy and home made loops.
See, the first one I made was perfect and the rest thereafter wobbled. As I say, I've since bought loops made specifically for the machine so tape type, length, and splicing are all good.

I don't hear the splice, as such. I hear the pitch tremolo because the tape wobbles as the splice passes it.
Maybe that's the same thing and what you mean, but I'd take hearing the splice to be a thump or click or something. There's none of that.

For what it's worth, though, I did try a whole array of light and heavy, dark and light, tape. Even tried some tape from an 8 track cartridge having been lead to believe it's self lubricating and, therefore, ideal for this machine.
The loops are 23" long or thereabouts so, yeah...the wobble comes about once every few seconds.

There is no pinch - It's just 5 heads, a tension arm, a guide, and a capstan.

I considered that the capstan (and motor) might be off alignments slightly. I mean, you could bend the whole faceplate by leaning on it.
I can find no pressure point which helps, but plenty which make it worse. :p
 
Update, just rolling the capstan round by hand, I can actually see the tape move away from it slightly just as the splice tape comes across.
It's exactly what you'd except if the splicing tape was too heavy or the motor and tension were both weak.
 
Are you using the EMI tape loops, out of interest? And do you have a sound clip of the problem?

Mine's in less than perfect condition, but I don't remember any noticeable pitch issues.

Any idea which version yours is? There's a history of them here... mine's clearly a MK4: The Watkins / WEM Copicat
 
Hey JP,
Yes, it's definitely a MKIV, transistor model.
i bought the tape loops on eBay - qistar.
He's claiming them to be just right for the machine and there's enough good feedback out there to suggest they're OK, at least.
I'm pretty certain it's not the tape, though. I've spliced loops from maybe 10 different brands and types, and tried 4 of the premade loops I bought from qistar.

I can do a sound clip for you. It's just what you'd expect, though. The tape takes a little buckle as the splice goes over the capstan, and the pitch jumps and drops back every so slightly with it.

Not sure how well I described that above, but I feel like a collar on the capstan making it a little bigger would solve it. There's obviously 'proper' solution, though.
 
I just removed the heads and single guide to see what it did, and it still kicks the same way.
Just with capstan and tension roller, it kicks as if the splicing tape is too heavy.

Really don't get it - It's designed for a spliced loop.
 
Steenamaroo said:
Hey JP,
He's claiming them to be just right for the machine and there's enough good feedback out there to suggest they're OK, at least.
I'm pretty certain it's not the tape, though. I've spliced loops from maybe 10 different brands and types, and tried 4 of the premade loops I bought from qistar.
Click to expand...

Mine have no backing but do have 'EMITAPE' printed into it at intervals. I got them about 10 years ago, though. I seem to recall the machine didn't like it much at first when I was using 406, it was too thick.
I can't see what kind of stock this guy is using from the photos.

Not sure how well I described that above, but I feel like a collar on the capstan making it a little bigger would solve it. There's obviously 'proper' solution, though.
Click to expand...
I tried that it one point, didn't work as well I'd hoped, it will also slow down the tape, changing the echo timing and sound quality. Not sure how important that is to you, though.

AFAIK the only real tension control is the power of the spring in the tension arm.

Talking of which I should probably try some of the qistar stuff on mine, the current loop is getting pretty worn.
 
You're in Wales UK? PM me your address and I'll send you one to try if you want. I think 10 is his minimum order.
I bought 25 still not having learned any life lessons at the age of 30.

Damn, this thing is really pissing me off. Would you mind giving me some points of comparison, since you have the same unit?

If I look at the head surface, my tape always wants to pull up a little, away from the faceplate. It rides the edge of the guide.
Does yours run clean through the guide without touching the sides?

If you let it free wheel, observing the motor speed/pitch, then stick a tape on, does the speed/pitch drop much?
 
Here's a quick video of mine running. The motor generally makes a ticking sound which I'm not convinced is right but so far hasn't been enough of a problem for me to investigate.
When I first started out it seemed to have a really awful wow effect. Then I remembered that it was routed through a chorus pedal. Once that was in bypass, I was reasonably impressed by the pitch stability of the thing. As a rule I use it for vocals rather than instruments which have a fixed tuning to them so I haven't generally been bothered by pitch variation.

https://youtu.be/Kxyou1_NFgk

This is using a new EMI tape loop from the set I got in 2005 or whenever. They have been creased but it seems to be reasonably happy with it regardless.

The last part of the video has the capstan on and off load. There's a slight variation in motor pitch but nothing major. It's a bit difficult to tell.
 
Oh wow, thank you so much for going to that trouble!
Yes, yours definitely runs much better than mine. Compared to mine, I'd say the pitch of yours is totally stable.

In the meantime I got bored and made some progress.
The motor seemed to run very hot - I had suspicions it might be on the way out, so I stripped and cleaned it.
When I put it back in it seemed to run stronger, but definitely cooler!

The kink seemed nowhere near as bad on reassembly and I think I've figured out how to eradicate it completely by raising one of the motor mounts a hair.

Seriously, thank you much for that video! Would you like a loop or two? to try?
 
Ok here's a video of mine in return.
You can still see the little skip when I finally get a decent view of the capstan.

Putting a washer under two of the motor posts (mentioned above) helped that little bit as you can see.

I got a less than flattering reply on GroupDIY basically saying these are badly made and they 'all do that' so I guess that they all kink or skip like that since the tape goes round most of the capstan and it's quite a bend, but mine was making the most of that design flaw by pulling the tape out of head alignment and slowing down as a result of a weak/dirty motor?

The tape runs perfectly through the guide post now without touching the sides and it sounds pretty good to me now.
Not perfect but it's a 60s consumer tape delay. Perfect would be no fun.

Thanks for your help! :)
 
Well, a little playing with the tension and it just gets better and better.
She runs well with my quantegy, used 8 track tape, and the tape I bought on eBay.

Happy ending, folks. :)
 
Good stuff! Glad you got it going. And yes, I should probably look at checking the motor on mine sometime, see if I can stop that clicking.
As for tape, I still have three of the EMI ones left so I'm good for now...

EDIT: In case you noticed, someone modded mine to add a defeat switch for the motor. I think the original purpose was to save wear when it wasn't being actively used, but it can be fun to shut the motor down while it's running. You can get some nice effects that way especially if it's put into feedback and then shut down.
 
I did notice! I forgot to mention it with the other stuff going on. Great idea! :)

Yeah, your clicking..That's got to be something simple. I don't know if you've opened the unit and looked at the motor but it's so basic.
The tolex was loose at mine near the capstan (under the faceplate) and it causing a bit of a noise by rubbing against moving parts. It could be as simple as that or something similar.

If not, dismantling and cleaning the inside of the motor is a gift.
Sorry, I bet I'm teaching my granny to suck eggs here - I'm not aware of your history.

I don't suppose you know anything about the possibility of varispeed? Is that a feasible mod for a unit like this?
I like what it does and expect I'll get a lot of use out of it, but varispeed could be very cool, even if it was a limited range.
 
Steenamaroo said:
I did notice! I forgot to mention it with the other stuff going on. Great idea! :)
Yeah, your clicking..That's got to be something simple. I don't know if you've opened the unit and looked at the motor but it's so basic.
Click to expand...

I haven't taken many motors to pieces, but as you say it should be fairly simple since it's an induction motor. I shall do that at some point. I should also look into recapping it.

I don't suppose you know anything about the possibility of varispeed? Is that a feasible mod for a unit like this?
Click to expand...

Not easily. It's a synchronous motor so the only real way to do that is to vary the mains frequency into the motor. Something like a variable frequency drive should do the trick but it doesn't seem to be easy to get such things.

IIRC the IC400 does have varispeed, but it does so by using a DC motor instead.
 
jpmorris said:
I haven't taken many motors to pieces, but as you say it should be fairly simple since it's an induction motor. I shall do that at some point. I should also look into recapping it.
Click to expand...

Cool. Good luck. I have partly recapped mine and it did make a good difference to general noise and hiss.
I have a few more awkward-to-get-at caps that I'll get around to some time.

Incidentally, there's a reasonably large electro cap tacked on to the underside of the main board on mine.
It looks a bit suspicious to me, like a mod. Please don't open it up just for me but if you do ever get curious could you see if yours has a cap in the same place?
It's pretty obvious - sticks out like a sore thumb.

jpmorris said:
Not easily. It's a synchronous motor so the only real way to do that is to vary the mains frequency into the motor. Something like a variable frequency drive should do the trick but it doesn't seem to be easy to get such things.

IIRC the IC400 does have varispeed, but it does so by using a DC motor instead.
Click to expand...

Ah, ok. Sounds like it's best left alone. ;)
Thanks again. :)
 
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