DiY Tape Delay?

Jeremy Garber · Post by **Jeremy Garber** » Mon Jul 21, 2008 2:08 pm

I've been ripping some parts from old electronic gear, that I've been keeping for years for an unknown reason (to my wife at least) up until now, some of which include old Walkmans and the like. I was wondering if I could use some of those parts to make my own tape delay. Something like mounting the cassette holder into the box, and having a variable speed control for the motor to control delay time. Of course, I haven't quite figured out how to get more than one or two delays, other than using multiple playback heads or a feed back loop to the recorder head from playback. I don't even know if this is possible. I did a brief amount of research and found what seemed to me an overly complicated approach involving two cassette players and a single spool of tape wound between two cassette chassis. I figured there must have been someone who has done this neatly before.

Any ideas, examples? I plan on doing more research when I can find time sometime this week. I just got in my first stomp pedal kit from General Guitar Gadgets (Fuzz Face), and I can't wait (plus kuddos to those guys for very quick delivery- over the weekend even). I'm just getting ideas that I'd like to work out over the next several months while I build stomp pedals from these kits for practice.

I don't think I really know what I'm getting myself into. And judging by the look on my wife's face, I don't think she knows either. heheh

Smitty · Post by **Smitty** » Mon Jul 21, 2008 2:15 pm

here ya go!

Jeremy Garber · Post by **Jeremy Garber** » Mon Jul 21, 2008 2:27 pm

Ya, that's the one I came across when I was lookin around earlier. I want something that can be contained in an over sized stomp box.

newfuturevintage · Post by **newfuturevintage** » Mon Jul 21, 2008 5:53 pm

a thought: if you can figure out how to get enough tape heads into the stomp-box sized enclosure you're talking about, old outgoing message tapes for answering machines would take care of the loop for you. I remember them being up to 3 minutes.

Jeremy Garber · Post by **Jeremy Garber** » Mon Jul 21, 2008 7:44 pm

Ooooh... I didn't even think about mini tapes. That is a great idea. I think I have an answering machine in my scrap stash as well. I would probably need to score a few more answering machines for extra heads, unless I can find them individually somewhere. That makes much more sense than using full size tapes/heads.

I was planning on removing most of the tape from within the cassette, and splicing it together so it makes one continuous loop around the inner pulleys of the cassette housing. I don't want to worry about the tape stopping once it hit 'the end" without this modification.

space_ryerson · Post by **space_ryerson** » Mon Jul 21, 2008 9:24 pm

If you can get your hands on an Echoplex, it may help you visualize how to construct this. I imagine you only need one playback head, just feed the signal back through the circuit to get multiple repeats. Also, if you can make the playback head movable, you can change the delay times like that, without having to change the tape speed.

Jeremy Garber · Post by **Jeremy Garber** » Tue Jul 22, 2008 5:36 am

Ya I should be able to find some pics online of the inners of an Echoplex. I only know one person who owns one, but I believe they live in California right now. A feedback loop would probably be easier to do than using multiple heads- also I don't think I could keep the tape in the cassette if I were to use multiple heads. A movable head assembly seems more complicated than a variable speed controller for the motor though- but it's worth looking at all avenues. One thing about a feedback loop- how do I keep it from feeding back out of control?

Jeremy Garber · Post by **Jeremy Garber** » Tue Jul 22, 2008 7:30 am

I just thought of another potential problem. How would it affect the tape if the record and playback heads were left engaged? If they need to be released when the delay is not in use, I'm going to start looking at some of the fancier home stereo tape decks which use a motorized head engagement system. I can see why this hasn't been a popular DiY project... lol

I'm not sure if there are any mini tape recorders which use a separate record and playback head, so I'm also wondering the possibility of pulling an extra head from a second mini tape recorder. Looking at my old Tascam 4trk I see it has two heads. I may have to go with the standard size cassette, but that will make the pedal larger.

space_ryerson · Post by **space_ryerson** » Tue Jul 22, 2008 8:00 am

Well, for the feedback loop, you would add a potentiometer to limit the amount of signal feed back through. As for when it is not in use, I would add a true bypass switch around the whole circuit. If you aren't going to make the tape into a loop, then you will also have to figure out a way to rewind the tape as well.

RefD · Post by **RefD** » Tue Jul 22, 2008 9:41 am

this reminds me of the Walkman Mellotron or "Melloman".

http://www.mysterycircuits.com/melloman/melloman.html

newfuturevintage · Post by **newfuturevintage** » Tue Jul 22, 2008 12:53 pm

SLEEPY BRiGHT EYEZ wrote:Ooooh... I didn't even think about mini tapes.

I was actually referring to full-sized cassettes... like on really primitive answering machines that had two tape wells, one for outgoing and one for incoming messages.

Was also brainstorming about tape path:
maybe pull the tape out after the record head, and loop that around some rollers, and across your individual tap playback heads.

Jeremy Garber · Post by **Jeremy Garber** » Tue Jul 22, 2008 2:39 pm

space_ryerson wrote:Well, for the feedback loop, you would add a potentiometer to limit the amount of signal feed back through. As for when it is not in use, I would add a true bypass switch around the whole circuit.

So the pot would basically be a volume control between the playback and record heads? How do I control the number of times it feeds back? Or would that pot effectively reduce the amplitude of the signal coming into it, so each pass it would get quieter and quieter, but new signals would be strong enough to start the sequence over. I guess fully CW the pot would allow a high amplitude to pass through, but not as high as the original (that would create an insane feedback loop- mirrors into mirrors), and fully CCW it wouldn't allow anything through, killing all feedback delays. Hmmm... starting to make sense to me. I'm a complete noob at this stuff so please bear with me.

I also wanted to add a simple EQ to the feedback loop, say a low pass filter and possibly a high pass filter. I'm trying to keep the controls minimal, but I think this is kind of important- at least the selectable low pass filter.

I would like it to have a true bypass, but I'm wondering if I'll need to keep the heads statically engaged, or if I'm going to have to figure out how to implement a trigger (tied in with the stomp switch) to move the heads in place. I know some of the nicer tape decks have electronic controls as opposed to the manual ones on most decks and Walkmans. A quick search on eBay this morning brought me to some tape deck parts vendors. It looks like I can buy complete transports (including motor, spindles, heads, etc) for not a whole lot. I would just need to hook up a way to engage the heads, and of course power which should be pretty simple. I'm wondering if the transport will work off a 9v.

----

That Melloman is absolutely great. I must have one. John Cage'ish ideas come to mind.

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newfuturevintage wrote:I was actually referring to full-sized cassettes... like on really primitive answering machines that had two tape wells, one for outgoing and one for incoming messages.

Was also brainstorming about tape path:
maybe pull the tape out after the record head, and loop that around some rollers, and across your individual tap playback heads.

Aha! Outgoing tape messages. I see. Didn't think of those. I found a UK supplier doing a brief search. I'm sure someone in the US still sells these. I wonder if they come in micro sizes.

I'm trying to keep the tape path as mechanically simple as possible. If I actually manage to build a working version of this idea, I'm sure a couple of friends will want one so I want to be able to remake it fairly easily. Hence the idea of using complete transports, whether they're bought from parts vendors or just ripped from broken decks. I want this contained in a large stomp box, not a mini briefcase like the real tape delays out there.

Thanks for all the ideas. Definitely have the gears in my head doing something...

space_ryerson · Post by **space_ryerson** » Tue Jul 22, 2008 3:22 pm

Check out some of the echoplex schematics here to give you an idea of how it would be wired up. I just had a peek at the Echoplex EP2 5939-9067 schematic on this page, and it has a pot in the circuit for echo repeats that shows what I'm not verbalizing very well

Jeremy Garber · Post by **Jeremy Garber** » Wed Jul 23, 2008 5:47 am

Thanks for that link. Lots of good stuff there.

nclayton · Post by **nclayton** » Wed Jul 23, 2008 10:43 pm

Good luck with this!

I've semi-thought about trying to cobble something like this together a few times, but never been able to think of something that would work so great it would be worth the time, so never really tried to put any notions into action. I think it would be kind of hard maybe, but maybe not if you could find the right donor parts and didn't mind short delay.

3 head cassette decks are pretty rare even in the range of hifi components. I don't know off the top of my head of any portable tape recorder with 3 heads, but there may be something. Look at Marantz portable recorders. They made some professional type recorders that might have monitor heads. You might not be able to find one for super cheap, though.

Even if you can find a portable three head cassette recorder, when you look in there, you'll see that the record and playback heads are incorporated in one thing that looks like just a single head. They're VERY close together, so you won't get much delay time unless the tape is going real slow. They have to be close together because I don't think 3 head decks were a consideration when they designed the cassette. Cassettes only have one access point to the tape. You need a pressure pad behind the tape for both record and playback, and cassettes only have one in that one spot. If you have to keep the tape in the cassette, I think you're out of luck as far as putting the heads anywhere but right there.

I'm basically 100% sure there's no such thing as a 3 head mini or micro cassette recorder.

Whatev.

Ned

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