What would it take to make a cassette based tape echo?

[Hides-His-Eyes]

I'm serious; what part doesn't exist that we'd need? 3D printing and laser cutting are the cheapest they've ever been (eg ponoko). Even the cheapest tape echo units here in the UK cost £150-odd for a working one and they're bigger than my laptop. You can get a hell of a lot for £150 DIYing, right; two cassette players (one to donate a record head), a nice sheet metal enclosure... Hell, you can get a cassette fourtrack for the price of a good cable these days. They have record heads.

Infinite loop cassettes are available cheaply in standard and micro sizes. That's easy enough and there'd be no need for rewinding.

The driving and recovery circuits can't be all that. Are there specialised ICs? Is there more to it than just impedance?

I have no idea how the motors work in a tape player. Is it geared or just hooked straight in to the rotating bit? Could you control the speed with PWM?


I'm picturing a plastic frame from a 3D printer etc. that sits in the enclosure and holds the rollers, motor and heads in place.



If I had £10k, nothing else to do and no plans for next year I'd apply for a patent (lol) but since I don't, do you think we here could come up with a project for the DIY community? It's not just guitarists, I'm sure the synth guys etc. would love something like this.

[joegagan]

this is a great idea. other people have done it here, but it has been a while. if the info is in the archive , you might save some headaches in figuring out the details.

a good quality cassette would sound a ton clearer than some of the crap analog delays people covet around here. plus, you would have tape tone. let us know how it goes, please.

[Mark Hammer]

Actually, I'm not sure how long it would sound good.  While it is/was possible to get fairly robust 1/4" tape, good sturdy cassette-sized tape that can live up to the rigors of a loop of decent length may be tricky.   That thin stuff doesn't pack a whole lot of oxide on it.  If you can live with answering-machine quality, great.  Maybe I'm out to lunch, but I can't see it getting much better than that.

[Hides-His-Eyes]

I've seen loops of several minutes, designed for waiting room muzak. How many passes do you think it would hold up?

I've opened up an old walkman here and it's geared with a drive belt. Guess the motors are too fast without. However, the whole assembly (motor, head and roller) came out as one. No room for a second head there though.

Here's a tape motor on ebay:

http://www.ebay.co.uk/itm/CCW-2400-RPW-DC-6V-Cassette-Tape-Recorder-Micro-Motor-/130559236956?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e65efdb5c
Is that 2400 revolutions per week I wonder!

[Taylor]

Answering machine quality but with sound on sound and long record times would be awesome to me.

I don't have much DIY time these days, HHE, but I support the idea and would love to contribute whatever I can so I can have a DIY tape looper in a reasonable form factor. If you needed others to sign on to get costs lower for your Ponoko or other making projects, you can count me in.

But, I'm not positive that would be the easiest way to go about it unless you're heavily concerned with having it look slick. Standard parts that don't need o be hacked can sometimes make a project more doable, but in this case aligning the mechanical parts and heads properly and getting them set up may end up being such a massive amount of work that it's not worth it. Using ready-made cassette player/recorders, and hacking in the necessary electronics for driving them and doing sound on sound, would likely be a much simpler angle.

As far as driving them, the basic technique is dynamic high end boost in front of tape and dynamic high end cut or de-emphasis after tape. A simpler approach is simply to boost frequencies above 1k before the tape and then cut that same band by the same amount before going to the output, without the compression aspect.

Some experimentation would be good to determine whether the emphasis/de-emphasis works best as a wrapper around the delay, or in the feedback path so it happens each time around. Each would have unique and useful sounds.

I tend toward weird and junky sounds more than hi-fi stuff if I'm bothering about tape or analog, so a simple approach is cool with me.

[frequencycentral]

When I was a teenager I was very into tape. I had a Teac 3 head cassette deck, which means that the playback head was immediately after the record head. I used to feed the output into a mixer and back into the input. very short delays with regen were possible, no control over delay time. Another thing I did was to take two cassettes apart, and have one spool in the first housing, the other spool in the second housing, put two cassette recorders side by side, on on record, the second on playback, run the output of the second back into the first via a mixer, stretch the tapa around the room. Seriously long delays were possible, like minutes. Cassette Frippertronics. I also abused WEM Copicats - by sticking bits of bent card over the record and/or erase heads you could create semi permanebt loops. A couple of years ago I picked up a cheap WEM Copicat and hacked in a DPDT to disable the record head, so you could 'save' a loop of whatever you'd recorded. I did try to control the motor speed with a pot, unsuccessfully - AC motor.

Anyways, the simplest way to go would be to get hold of a 3 head machine and cludge some control over the motor speed. I'm interested but not neccesarily in!

[lion]

From the world of emulating vintage Meazzi type echoes - as used by The Shadows back in the 60's:
http://charliehall.proboards.com/index.cgi?board=project&action=display&thread=6155&page=1

Erik

[wavley]

Answering machine quality but with sound on sound and long record times would be awesome to me.

I don't have much DIY time these days, HHE, but I support the idea and would love to contribute whatever I can so I can have a DIY tape looper in a reasonable form factor. If you needed others to sign on to get costs lower for your Ponoko or other making projects, you can count me in.

But, I'm not positive that would be the easiest way to go about it unless you're heavily concerned with having it look slick. Standard parts that don't need o be hacked can sometimes make a project more doable, but in this case aligning the mechanical parts and heads properly and getting them set up may end up being such a massive amount of work that it's not worth it. Using ready-made cassette player/recorders, and hacking in the necessary electronics for driving them and doing sound on sound, would likely be a much simpler angle.

As far as driving them, the basic technique is dynamic high end boost in front of tape and dynamic high end cut or de-emphasis after tape. A simpler approach is simply to boost frequencies above 1k before the tape and then cut that same band by the same amount before going to the output, without the compression aspect.

Some experimentation would be good to determine whether the emphasis/de-emphasis works best as a wrapper around the delay, or in the feedback path so it happens each time around. Each would have unique and useful sounds.

I tend toward weird and junky sounds more than hi-fi stuff if I'm bothering about tape or analog, so a simple approach is cool with me.

The later space echoes used an NE570 compander pre and post delay to do the noise reduction thing and that's pretty easy to add.  I think this would be simpler and more durable to build using radio station carts, a dc motor to control speed, and 1/4" tape deck heads kinda like the Univox units.  Personally I'm more fond of the open tray multi-head Space Echoes, but that might not be the way to go for a first try.  I have an old ratted out consumer, but tube, Ampex deck with good heads that I've been meaning to do this to for years, but my house and more important projects always get in the way.

[Hides-His-Eyes]

So a cassette has three access points like this:



If I set it up to be a one head delay with electronic feedback feedback like this:



One could run the tape extremely slowly; using PWM and a DC motor. I don't know what kind of frequency you'd need but I'm sure a 555 could handle it?

Then the quality of the tape becomes much less of an issue at longer delay times.

You could also if you were feeling particularly clever run the thing in actual stereo. put the two in series for a half/fulltime switch or even have ping pong.

[EATyourGuitar]

this has been done before but I think the problem you will have with the tape on the cassette is that you can't move the heads like a real tape echo. only one of the heads needs to move. you should make sure that they get as close as possible at one extreme so you can get ultra short delay times. you can still buy endless loop cassettes in 30 second on the web. there was everything from 30 seconds, 1 min, 2 min, up to 5 minutes. they are getting rare now since they are out of production and people throw them out. you might want to put a buffer so the guitar is going into a high z input. you can have a separate knob for saturation and feedback attenuation. you'll also want a clean blend or you wont hear the clean till it hits the playback head. its a good idea to get the right stuff for cleaning tape heads. they are old.

[wavley]

The way you have it labeled looks like it might work pretty well.

Most traditional tape delays use a mono head or stereo wired for mono and use the the whole 1/4" tape to get the limited fidelity that they do.  I'm not saying that cassette based is going to sound like crap, but it's going to have extremely limited fidelity especially at longer delay times because slower speeds = more high frequency loss, that's why studio machines run at 30 ips or 15 ips if you want fat bass.  Cassettes are extremely thin tape but can last a long time when used at a constant tension, start speeding up, slowing down, and stopping and you're looking for trouble, it may work, but it might not be as reliable as you would like, good thing is cassettes are cheap so it doesn't matter unless it quits in the middle of a song and wraps around the pinch roller.  Even the more heavy duty machines are notorious for this behavior that's why the later Space Echoes like the 501 don't start and stop, the tape just runs continuously but that only solved the start/stop problem and not the speed up/slow down.

Don't get me wrong, I'm not trying to poop on your parade because I would love to see somebody get on of these cassette tape delays running someday.  I'm just trying to share some knowledge from years of owning tape delays/repairing them for a living

[Hides-His-Eyes]

this has been done before but I think the problem you will have with the tape on the cassette is that you can't move the heads like a real tape echo. only one of the heads needs to move.

Why? Easier to control the tape speed.

you should make sure that they get as close as possible at one extreme so you can get ultra short delay times.

I'm not trying to make a flanger!? I don't care if it goes super short.

you can have a separate knob for saturation and feedback attenuation.

"saturation" how?

The way you have it labeled looks like it might work pretty well.

Most traditional tape delays use a mono head or stereo wired for mono and use the the whole 1/4" tape to get the limited fidelity that they do.

Heck, you could easily put a switch for long short that would let you choose between parallel for quality and serial for length!

I'm not saying that cassette based is going to sound like crap, but it's going to have extremely limited fidelity especially at longer delay times because slower speeds = more high frequency loss, that's why studio machines run at 30 ips or 15 ips if you want fat bass.

If it's not much worse than a PT2399 I wouldn't be arsed!

Cassettes are extremely thin tape but can last a long time when used at a constant tension, start speeding up, slowing down, and stopping and you're looking for trouble, it may work, but it might not be as reliable as you would like

I didn't know that, but like you say they're cheap enough.

, good thing is cassettes are cheap so it doesn't matter unless it quits in the middle of a song and wraps around the pinch roller.  Even the more heavy duty machines are notorious for this behavior that's why the later Space Echoes like the 501 don't start and stop, the tape just runs continuously but that only solved the start/stop problem and not the speed up/slow down.

I'm not convinced tape ever has a place on stage tbh. I more see this as a novelty for those of us that think this weird way! I'm not trying to emulate anything, I'm trying to make something new based on an old idea. I'm not anticipating it replacing anything

Don't get me wrong, I'm not trying to poop on your parade because I would love to see somebody get on of these cassette tape delays running someday.  I'm just trying to share some knowledge from years of owning tape delays/repairing them for a living

And it's much appreciated.

[pinkjimiphoton]

google is your friend...there are several different projects concerning this out there on the net that i've read several times...but, too lazy..

[Hides-His-Eyes]

Lots involving 3 head equipment (usually massive AND requires guitar pandering circuitry in addition) or spliced tapes (god help me and my fat hands)

Can't find much about this particular direction we're looking at with the stock cassette.

oh wise men; how does a record head control the wiping? Is there a DC signal required on one of the pads or is it a bit more complex?

[pinkjimiphoton]

i wish i could remember what the keywords were, but basically i think it was like popular electronics or something, they used a double cassette deck and had an interface where it would feed back one side into the other..giving repeats and echoes...basically almost just literally patched together. if i find it, i'll try and post it.

[Hides-His-Eyes]

i wish i could remember what the keywords were, but basically i think it was like popular electronics or something, they used a double cassette deck and had an interface where it would feed back one side into the other..giving repeats and echoes...basically almost just literally patched together. if i find it, i'll try and post it.

I know the type. I'm looking at something a tenth of the size if I can get what I'm thinking working.

[runmikeyrun]

One year I got to make the soundtracks for different rooms in the haunted house I worked at.  Being that it was 1999 I made the soundtracks in Acid but recorded them to 3 minute endless loop tapes in tape decks for each room.  Those were then connected to a stereo system.  Anyways, my point...  the tapes held up good for a while... but by the end of the season they were pretty shot.  Mind you, they were running for 6+ hours 3 nights a week for 5 weeks.  Not sure how hard it is to find endless loop tapes now, let alone good quality ones.  I'm also not sure how much you'll be using them.  For all intents and purposes though they should be ok for your application.  I'd be more concerned about using good record and playback heads, as well as good motors to cut down on wow and flutter.

[Taylor]

cut down on wow and flutter.

I'm not sure I can speak for HHE here, but all the quirks like wow and flutter are precisely why I'd want to do this in the first place. Plain jane delays and even loopers are pretty cheap these days, so if you wanted something straightforward, a cassette tape delay would be completely the wrong way to go about it. 

[Hides-His-Eyes]

Yeah, if I wanted a digital delay I'd use a PT2399. Unpredictable wow and flutter would be a godsend, not a problem!

[wavley]

Yeah, if I wanted a digital delay I'd use a PT2399. Unpredictable wow and flutter would be a godsend, not a problem!

That is precisely the reason to own a tape delay.

If you're using a battery powered motor from a portable deck then I'm gonna guess that it's a DC motor already, just vary the voltage to change the speed.  I think that the capstan/pinch roller might be a real problem when speeding up/slowing down because if it doesn't keep the exact same tension as your spindle then it will eat your tape.  Speeding up/slowing down is the other reason to own a tape delay.  Check out the schems for Tascam Portastudios, maybe they will have a clue as to how you might achieve a vari-speed. 

Or you could ditch the whole cassette part, disassemble the cassette and take the loop out, ditch the spindle, drive the whole thing with just the capstan/pinch roller like a big machine, and use an open tray.  Then you have the option of multiple fixed heads like a space echo or korg stage echo, or a single movable head (now you don't have to fuss with tape speed so much)

The Fender Tape Echo has a really simple path with a tensioned loop and a movable head, but the tape loop length needs to be fairly precise.


The Space Echo uses an  open tray and it doesn't really matter how long the loop is, you change time with head selection and tape speed.