Something a little different: modifying an R2R deck into a musical instrument

In a fit of overt fanboyism of the Radiophonic Workshop, I now have it in mind to try modifying a reel-to-reel tape deck into something that behaves like a musical instrument. The idea is that the tape playback speed would correspond to the note being played, thus creating an interesting natural portamento lead instrument using tape loops of whatever I might record.

I have two questions:

1) What kind of deck should I be on the lookout for? I figure 1/4" 7.5ips will be the most common finds. I want to get something cheap, as I don't want to potentially ruin a nice, sought-after piece of gear. I'm a bit rusty with my motor control knowledge, but my understanding is that they're usually regulated with a PWM signal. Are there any other methods I might run into?

(As a side note, I seem to be running into a lot of 60's era Wollensak tape decks for pretty cheap on the local Craigslist.)

2) Relating to #1, one issue I see with this type of instrument is that I want to somehow "latch" the last note played. In other words, if I simply let off the note, the sound will go away, but the tape will continue on at that speed until a new note is played. That way, I'm not limited to legato-only playing styles. I suppose the method I choose to do this will depend on how the motor is controlled, but I'm thinking a microcontroller might be the order of the day here. That way, I can MIDIfy my final instrument, too.

Thanks for the help, and for indulging this increasingly desperate DIYer.

Cheap (and some not-so-cheap) tape machines just used AC fan-motors which, when lightly loaded, run at wall-outlet frequency.

Anything pulse-controlled is potentially valuable.

So your first hack is to lash a 100 Watt audio amplifier into a 24V:120V 100VA transformer, and feed it with 30Hz-120Hz sine-wave to make a variable-frequency wall-outlet. Ideally you find the motor main power feed so you can keep the electronics on direct wall power. (Tip: look to see if the tape-break switch simply kills the motor.)

Well, the old Wollensaks were battery-powered portable units, so I don't think they used the 60Hz wall outlet as a clock. I do like the idea of a variable frequency wall outlet, though, not only because it would be a great source of engineering humor, but also it wouldn't require any modification to the tape deck itself.

EDIT: The more I think about the idea of a variable frequency wall outlet, the funnier it gets. Also, for a tape deck regulated in such a way, it's a doable solution. At this point, I'm going to hunt for a deck and see what particular model and design I end up with. Thank you for the help!

Hi,

you could use a Tapemachine, like the Telefunken M15A. They have Varispeed as an option. There, the speed is controled using a normal poti. You could replace the Poti with a keyboard...

I think Studer and the like have a varyspeed option as well.


Peter

Well, that kinda goes against the "not wanting to potentially ruin a valuable old piece of gear" guideline I established earlier. I got this whole idea, actually, because I saw someone modify a walkman for vari-speed playback, and it turned out to be quite easy to do (there's a speed regulation trimpot in your average walkman). I was also amazed at the huge range of speeds he was able to achieve. Of course, I could always make a tape loop-based instrument out of a walkman, but that wouldn't look nearly as cool as an old reel-to-reel would.

I like this idea a lot, if only for shits and giggles, but I don't think you would be able to have much control over portamento time if you only deal with capstan speed. The transition time would be a matter of tape tension and reel loading, and would probably vary across the tape length according to these factors.

Of course you could build reel compensation into your controller if you wanted to go that far - this might be where PWM comes in handy.

Well, the whole idea is to build something quirky that has its own behavior that will force me to use it as it is and be creative with it, warts and all. I have an old tabletop cassette recorder that I'd thought about modifying for this purpose as a prototype, but it occurred to me that the two builds, cassette deck then up to reel-to-reel, would be different enough that one can't really serve as a model for the other. I've been on the lookout on Craigslist and other place for some good working decks, but I seem to have hit a dry spell for now (they were all over the place a month ago).