Magnetic tape gurus, I konw you are out there! DIY TAPE DELAY ideas

'morning engineers,
I woke up with the insane idea of making a tape delay and, as unemployment stands firm, is the perfect time to build something cool.
(my girl works so don't send me money please, just infos!!)
I've found this block schematic of  the Roland space echo which is very helpfull to this project, but contains 2 modules in particular that i would like to understand, the  MOTOR DRIVER and  the BIAS OSCILLATOR+BIAS TRAP.
Both are all discrete design on the original, and i wonder if there is a way to  simplify them with ICs, the same i want to do with the whole machine..
Second, the mechanics.
the main question is: do i need just one point on the tape loop where the motor spins or i need that both the capstain and one reel are coupled to the motor?
last thing: which heads are suitable for that job? and who sells them?
Any information or link on the subject is really welcome,
and thanks in advance to everyone who shares his knowledge on this forum,
you are the best!
if somebody is interested in this project, plesase keep in touch around here.

sandro

Full schemo is there http://www.scribd.com/doc/17560989/Roland-Space-Echo-201-Service-Manual?autodown=pdf
The motor control is essentially a temperature-compensated variable regulated DC supply.
The oscillator is a two-transistor job. The bias-trap is a resonant LC circuit tuned to the oscillator frequency.
I don't think you can get much simpler than that.
On the 201, the tape is looped in a cassette with no reels. The tape must be thick enough (50 um) and lubricated.
I don't think audio heads are manufactured anymore (except for cassette), but you may find some there
http://www.jrfmagnetics.com/

Great! thanks so much! everything is clearer.
The only thing i still can't understand is where i want to transmit the movement to the tape..
sorry for my poor english, but i mean if it is sufficient to drive it from the "reel" or it should be controlled by a motor coupled capstain as well to keep a constant tension.
i think they call the way to control tape movement closed loop or open loop or something like that, which type of loop is ok for that job?
thanks for the answers,
sandro

On the 201 (and most of the tape-echo units - Watkins, Echo Phonic, EchoRec,...) it is capstan driven, no reel. It's a closed-loop, but this word has different meanings in different areas.

Buliding a DIY tape delay unit from scratch will most likely be a big and maybe impractical build due to the mechanical pieces involved.  You'd probably have to do custom metal fab.

It may be easier if you use a preexisting tape machine.  Any 3-head reel to reel would work. Depending on the physical layout of the machine you could probably squeeze a few extra head stacks to the right of the playback head and wire them as delay taps.  Headstacks can be harvested from beater decks. Consumer decks should be a good plentiful and cheap source for these.  Many of these may be better than what was used in the Roland unit. A custom JRF headstack would probably be quite expensive and somewhat overkill for a funky 'ol tape delay.

Plus, with a 2-speed machine you get double the delay time selections. May even be able to rig up a varispeed on the proper capstan motor for even more control. 

There's a interview out there somewhere with Les Paul where he discusses doing something similar to this - may have been in Mix magazine.

good reading here though Fripp was doing something a little different:

http://www.elephant-talk.com/wiki/Interview_with_Robert_Fripp_in_Guitar_Player_(sidebar_article)

Totally.
Building a tape delay from scratch would be very difficult, and surely will come out more expensive than buying a Roland unit from ebay. If you want to mess with tape delay on cheap, you have to find a tape machine with 3 heads and just fit a "feedback" resistor on it, and BAM! bam! bam! bam! bam!
You have a working tape delay!
I did it myself in highschool.

abbey road d enfer said:

I don't think audio heads are manufactured anymore (except for cassette), but you may find some there
http://www.jrfmagnetics.com/

Click to expand...

Better Akai Hifi used to have heads made from glas that probably last forever (at least I have not yet seen them wear out), maybe there are cheap ones on ebay? Then again, it might be the easiest to score some old tape machines with varispeed and multiple tape speeds?

Michael

hi everybody,
i totally agree that the mechanics work is gonna be the hardest, but i'll not give up before speaking with a friend who owns and works in a metal workshop in my city, and listen his opinion about making pinch rollers and capstans with the machines they have there.
for the magnetic heads the first thing i thought, when i saw the prices of the pro ones, was to cannibalize some cassette player as you said.
but i don't like the idea of messing with that tiny tape that sticks to everything it touches and tends to twist, so the other option would be an old reel to reel machine,
BUT
think about a VHS video recorder, is full of pieces that maybe one can use. (capstan, rollers, head mounting hardware & co)
what you think about it?
i'm thinking to that because the video tape is really better mechanically than a cassette tape..
and if is there any chance of using a video head as an audio one,
or use just the audio section of the VHS head, i'll go right away to open the one i have around here!

Basically, no.
VHS tape is too thin and is much worse for the application.
Also there is really no parts you could use in the VCR...
Your best bet will be a reel-to-reel tape and you could use parts from one if you are determined to build a stand alone unit.

1/4 inch format is what you want. Virtually all of the hundreds of commercial 3-head tape recorders use this format and knockabout tape is easy and cheap to source.

On the subject of sourcing new headstacks I overlooked a possibility-

check out this unit here:

http://www.fulltone.com/images/SSTE%20proto.jpg

They must be sourcing their heads from somewhere and I doubt they're costing what a set of JRFs would.
Always the possibility that akai, sony, teac, or pioneer have a backstock of heads in their surplus lots. I know Kenwood has an online store that sells their backstock components. 

i was thinking the same about Fulltone heads, in their website they talk about "proprietary heads",
but i can't find anything about the company that actually builds them.
the only cheap and easy to find heads are the cassette ones...that i don't want to use mainly for the size of the tape they work with.
i'll take a look to the kenwood online store you said and will let you know.
there is also a guy who sells Copicat parts replacements, but he asks about 50€ for 1 head...too much for me.
thanks to everyone!

when you say commercial 3 heads recorders you are speaking of a cassette machines, right?
so how can we use a 1/4 tape with a head of that size?
if the cassette ones are suitable, this shop sells cassette heads at very low price..

http://www.donberg.ie/search?query=cassette

benidubber said:

when you say commercial 3 heads recorders you are speaking of a cassette machines, right?
so how can we use a 1/4 tape with a head of that size?
if the cassette ones are suitable, this shop sells cassette heads at very low price..

http://www.donberg.ie/search?query=cassette

Click to expand...

No. Talking about stuff like these:

http://cgi.ebay.com/OLD-MAYFAIR-1020-B-7-INCH-REEL-TO-REEL-TAPE-RECORDER_W0QQitemZ130359552164QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item1e5a08e8a4

http://cgi.ebay.com/TEAC-A-2300S-REEL-TO-REEL-STEREO-TAPE-DECK-RECORDER-NR_W0QQitemZ220542909053QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item335961ba7d

http://cgi.ebay.com/Retro-Panasonic-Reel-to-Reel-Tape-Recorder-RQ303-Japan_W0QQitemZ300386424455QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item45f06d1687

There's gobs of them. I'm not sure that all of these have 3 heads - the teac for sure does.  A common mishap of tape recorders is that someone drops them and one of the reel hubs gets badly bent - I've come across several of these - perfect parts machine.  Check thrift stores and the backrooms of music stores. 

This is a great book for info on the commercial/consumer type machines:

http://www.amazon.com/Evolution-Audio-Recorder-Philip-Praag/dp/0965734404

Lots of great pics and specs.

great links! let's take a look

I'm out of town and can't send you a pic, but I have an Echocord Super 76 tape delay that has the echo rate function on a linear sliding arm, i.e. the playback head slides along a straight piece of rod and the tape loop itself is fixed tension, unlike the roland that has it all coiled up in a cassette type case. this seems like a simpler mechanical design, less need for tricky capstans etc.
its a much bigger box than the roland, a full 17" width.
good luck with this

I did this with an ancient Sony tube deck. Notice the head mounted to the side of the case? It is from another junked deck. The signal from this head goes thru a tape preamp sitting on top of the deck( the gold box) and then is fed back into the deck while recording. It sounds way cool, and quite a long delay also. I use the output of the deck to feed my recording gear.

very nice.  I bet you get some interesting depth folding the signal back in that way. 

Sony Tape Echo!!
that's a nice piece of equipment man, compliments!
i think i will end up building one of these, as all of you have being saying from the very first post.
it seems that this solution (modified reel to reel) is the easiest for the mechanics setup, and even cheaper than buy 3 magnetic heads and a motor..
it would be nice to build a Sony/teac/fostex tape delay (like Dspruill's one) with the playback head sliding on a rail to change the delay time, like the Sleeper's one (and like HH delays or the new Fulltone as well).
anyway i'm a bit sad that for the moment the tape delay (as a stand alone unit) is not an affordable project, the cheapest way would be to buy spare Copicat parts from Watkins and put them together, but that is still too expensive..
thanks to everyone here,
bye sandro

walkman-delayman:

http://www.flickr.com/photos/xelent/2455014579/in/pool-make/

My 'liil sketch:



For fancy feedback to a stock deck try Echo-matic:

http://www.moosapotamus.net/IDEAS/Echo-Matic_a.gif

http://www.moosapotamus.net/IDEAS/Echo-Matic_b.gif

It would be simpler to rig up a torsion arm type tensioner, rather than a sliding spring like in your drawing. If you want to get real funky and low-fi (maybe medium-fi), get some old VCR heads, you could have like, 5 of them on the playback loop and mix however many of them you want for delay repeats.

This thread has my gears turning... hope you keep with it.