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

[markie83]

the cassette might work.....you could vary the motor speed to control your echo time. If you record and play at the same speed it should sound fine so changing the motor's speed should allow you to control the dwell time. 

[Enzo]

You can't reasonably move the heads in a cassette deck, but changing motor speed does the same thing, and would be easy.  After all, the delay is time between record head and playback head.  CAssette deck motors, at least anything remotely recent, will be DC motors, but they often are not simple motors.  That is, they may not adjust by just changing voltage.  Many have little support circuits inside that regulate speed.  It would be hard but not impossible to crack one open and remote the speed trim, I guess.  SOme do indeed operate on voltage/speed.  One could remove the other type and replace with one of those.

Tape tension has nothing to do with motor speed or the pinch roller.  Tape decks have back tension, to keep that taut against the head, and takeup tension to collect the tape as it spools past the capstan.  Back tension is nothing more than a little drag, maybe a felt slip washer under the reel hub.  Take up tension works similarly.  Ther wil be a belt or idler tire spinning the takeup reel support, but another clutch disc means it slips over so much tension.  SO it is a matter of drag on either end that keeps tape tight, not motor speed.

Fancy three motor reel to reel decks may have back and forward tensions determined by motor servo, but I think that is way past the scope of the original post.

Since the record head and playback heads are against the same tape, it is simple to maintain the same tape speed for both, in fact it is darn close to impossible to have different tape speds betwen the two unless you loop the tape out betwen them and feed it back through at some odd rate.


Audio doesn;t record directly to tape, it is combines with a high frequency "bias oscillator" signal, I forget now  50kHz?  100kHz?  A plain old erase head uses the same oscillator without mixing in any audio.  The HF bias oscillator scrambles the oxide particles in the tape coating, while the audio modulating it creates a pattern in it.  So a missing bias can leave a tape deck able to playback but not record.   Fancier decks, and mostly reel to reel have separate erase heads before the record heads.  Smaller gear can have combined heads with an erase and a record head in the same "head." Tape is erased just as it is about to reach the record head.  One can just bias the erase head to blank the tape.  Erasing is the same as recording "nothing."

Tape speed determines the repeat rate, arrange whatever dry/wet balance you like, and feedback level of output signal to input determines the number of repeats.

[beans_amps]

The Fender delay reminded me of a project I saw where a guy had taken a turntable, glued a piece of 1/4" tape onto a disk, and then mounted the disk onto the turntable.  He then attached the record and play heads on the circumference of the disk.  One (or bothe) of the heads was movable. 

The disk may have been made of foam.

I do not recall if the motor speed was variable other than 33/45/78 maybe a 16 1/2 on the low end with no 78.  It was an old style portable school record player.

Food for thought.  May be easier to kludge up than a hack into a cassette machine using standard tapes.

Sean

[wavley]

The Fender delay reminded me of a project I saw where a guy had taken a turntable, glued a piece of 1/4" tape onto a disk, and then mounted the disk onto the turntable.  He then attached the record and play heads on the circumference of the disk.  One (or bothe) of the heads was movable. 

The disk may have been made of foam.

I do not recall if the motor speed was variable other than 33/45/78 maybe a 16 1/2 on the low end with no 78.  It was an old style portable school record player.

Food for thought.  May be easier to kludge up than a hack into a cassette machine using standard tapes.

Sean

That's pretty much how the Binson works...

[beans_amps]

Hey your right.     I guess the guy was trying to copy an Echorec.  I had totally forgotten about the Binson.  I have never seen one in person.  That looks like an easier kludge up than trying to use a cassette recoder. 

Sean

[jbgron]

I have a sickness, I collect tape delays.  I have a huge collection of Echoplexes, Space Echoes, Univox and Melos tape delays.  I think I've got more than 20 but less than 30.  If anyone needs any gut shots or voltage measurements etc PM me and I'll see what I can do.

[jubal81]

Some quick Google-fu gave me this really neat nugget:  "using some pretty basic electronics, to turn a regular floppy drive into a controllable tape-style delay and echo/reverb."

http://www.synthgear.com/2010/diy/diy-floppy-drive-echo-delay/

[danielzink]

There's a similar thread over at FSB - search "Echo-Matic cassette deck tape delay"

googling brings up this thread: http://homerecording.com/bbs/general-discussions/analog-only/home-made-analog-cassette-tape-delay-project-157157/


and then on our own board here: http://www.diystompboxes.com/smfforum/index.php?topic=80091.0



Dan

[dogenigt]

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.

I managed to build a lo-fi tape delay based on two microcassette dictaphones some while ago. I love it, it works with a single playhead and feedback.


You can find more info, video/sound documentation and a description of how it works and was built on my site:
http://www.dogenigt.com/2013/03/microcassette-tape-delay.html

[Mark Hammer]

Brilliant!

[tubegeek]

Brilliant!

Indeed! I've been contemplating how one might do this lately myself and I was hoping to figure out a cheap source of 1/8" full-track heads....
Nothing could be much cheaper than The Zone Of Broken Toys in my upstairs room. I have some microcassette stuff up there!

[wavley]

Brilliant!

Indeed! I've been contemplating how one might do this lately myself and I was hoping to figure out a cheap source of 1/8" full-track heads....
Nothing could be much cheaper than The Zone Of Broken Toys in my upstairs room. I have some microcassette stuff up there!

Space echo heads are stereo heads wired in series for mono so stereo heads are not out of the picture.

[tubegeek]

Space echo heads are stereo heads wired in series for mono so stereo heads are not out of the picture.

I know, but generally stereo heads would be only 1/4 of the width of the tape (typical use is 2 tracks thataway and 2 tracks thisaway.) Mono full track could be a much better way to go.

[wavley]

Space echo heads are stereo heads wired in series for mono so stereo heads are not out of the picture.

I know, but generally stereo heads would be only 1/4 of the width of the tape (typical use is 2 tracks thataway and 2 tracks thisaway.) Mono full track could be a much better way to go.

I don't think those heads care which way they're going, I'm pretty sure that portastudio heads are just regular thisaway thataway heads wired to all go thisaway.  Maybe a series parallel arrangement would work for any heads out of anything that has auto-reverse.  Maybe we can find a use for the useless.

[PRR]

Direction does not matter.

Most consumer formats are "half width" so you can flip it over, use the other side, and double your time per tape-buck. (1/2tr mono, 1/4tr stereo, etc.)

Unless you can salvage some pro gear, you have to get by with half the tape width.

You can get back your S/N by doubling tape speed. In a loop, that only means you need twice as much loop storage. And must replace worn tape twice as often; unless you drop acid and play loopy 13 hours a night every night this is not an issue.

Or, since most of these half-width formats *were* "acceptable", just go with it.

[wavley]

My concern about anything cassette based would be the amount of moving parts making it pretty unreliable.  The most classic and reliable tape echoes have a minimum of moving parts that need to be synchronized, the space echo is just an open tray and capstan/pinch roller and works brilliantly.  With the number of neglected and useless consumer 1/4" reel to reels out there it just seems that the motors and heads are kind of the least of our worries making something like this, it's really fabricating the mechanical part that's the hard part.

This guy looks like he's on the right track http://www.ghostvibe.com/  Once I was checking out a Shadows forum and there was a guy that had made a beautiful all tube Copicat clone with like 7 or 8 playback heads, I wish I could find it again.  I actually have a couple of old decks sitting around waiting for me to take on this labor of love, I already have 101 and 501 space echoes so it keeps getting put on the back burner. 

I certainly applaud the efforts to use all those cassette heads for something and saving them from the landfill, I have to say that it is hard enough to get 1/4" tape to behave.  1/4" tape is much less prone to stretching, tangling, and breaking.  I'm just saying that in 25 years of owning a space echo I've had tape wrap around the pinch roller and break more than a few times, they are especially terribly behaved if it's really humid... the dozen years I lived in Tampa required almost constant cleaning and tape changing, you better learn to splice a tape and keep plenty of loops handy or you're going to be poor.

That said, there are a lot of microcassette recorders out there that are mono with auto reverse which probably equals a 1/2 track stereo head which can then be wired for mono use of the whole tape and will probably sound pretty good with guitar.

[amptramp]

Has anyone tried to use the relatively large number of VHS video record / playback machines out there?  You could put two of their heads together, one for record and one for playback and get something with excellent high frequency response.  Reliability is one of the reasons they are available used for so little, but for just audio, they might be OK.

[tubegeek]

amptramp: VHS machines have a relatively complex tape path. Video record/playback happens with a rotating drum that spins at an angle to the tape, not a stationary head, and there is a loop of tape pulled away from the cassette when it loads if I remember correctly.

Having said that, I think the AUDIO track may actually be parallel to the tape, not at an angle - I'm off to google a bit....

EDIT:

Hi-fi audio on VHS tape is some crazy technology!
But it is as I said for the video track - helical scanning on a drum.
The parallel audio track is low fi and mono.
Check it out:
http://repairfaq.cis.upenn.edu/sam/icets/vcr.htm

[timd]

Its cool that you guys are trying to make tape echos with post consumer gear. I really want to work up to that, but so far, all I have done is circuit bend tape players. Just this last week I was doing some recording to tape (there was a bunch "new" tapes in packaging at the Goodwill) and came up with some good results. VHS was just mentioned for its audio portion. Could one have good results recording just audio to VHS? Never thought of that before...

[PRR]

> Could one have good results recording just audio to VHS?

Some VHS recorders won't even record without sync-pulses (a real TV signal).

The Hi-Fi (embedded on video) audio tracks are not awful.

There once was a slick system which digitized audio and dressed it up as "video" so it would pass through the very wideband video channel, then decoded it for play. Target fidelity was comparable to CD. As it was several years before CR-R audio recorders existed, and far cheaper than the early DAT, this was the bees-knees of perfect/cheap audio in its day.

But the topic of this thread is "echo". For that you must record and playback the same tape at the same time. Consumer video decks do one OR the other, never both at once. We could try two decks and hacked-open cassettes to bring tape through one deck then the other. But with the complex VHS (or Beta or Umax) tape path, and slow speeds, it isn't so much an "echo" as "instant replay" (many seconds after the event).

The no-fooling way is a *3 head audio recorder*. Record at the record head, play at play head, the delay is about 100mS-200mS at 7.5ips. At high speed you can push the Haas Effect (well known before Hass from transcontinental telephone). For Seconds of delay you grub another playback head at an appropriate distance from the record head.

To keep going longer than one reel you make a tape-loop. Jigger the safeties so the deck will run, do something to keep slight tension on the loop for good head contact.

BTW, you don't have to use tape for looping. I had a mystery mechanism which looked like a 12" record turntable but with "tape heads" riding on the rim on spring-arms. It recorded on solid iron (like the first magnetic recorders, or later "metal" tape). You'd capture a second and then repeat it over and over. The rest of the contraption tuned a variable filter leading to a stylus which rubbed on wet fax paper wrapped around a cylinder mounted on the turntable. There's an iPod app for that now. But anyway.... you could probably record on a brake drum or disk if you are handy enough.