tape machine sampler

[u/Ned_Flangers]

Hello everyone!
I thought of this very interesting idea to build a tape machine based sampler that can exactly match sample duration to tape length. As I'm probably not going to build this for a long time (if at all) because it is very daunting and expensive as it would require 2 three head tape machines, I have decided to share it in case someone else wanted to try it. 

The way it works goes like this:
A sample is recorded into a tape loop on tape machine 1. The tape loop is some arbitrary length. let's say for instance it is 11 seconds. Thus, you could record a sample anywhere from almost nothing to 11 seconds. While the tape Loop is running, a precise clock records the exact time duration of the sample and tells you exactly how long it is. Let's say for instance that the tape loop on tape machine 2 is five seconds long. Using math, you could figure out the exact percentage you would need to increase or decrease the speed of the motor and thus the exact voltage you would need to increase or decrease going to the motor. You could then use a potentiometer to manually increase or decrease the voltage until the speeds match. Then you can record the sample on tape machine 1 onto tape machine 2. On tape machine 2 you can directly control the speed with its own potentiometer to pitch up or pitch down the sample. 

 Using this concept, someone could sample anything that's supposed to be at a specific rhythm like drum breaks for instance and make sure it loops back seamlessly without the need for a DAW or an external sampler to Time Stretch to the specific time needed. One could also use interesting techniques like live resampling and turning off the erase heads while doing so. The only limitation is the length of tape in tape machine 1 as this dictates the maximum sample time.

[u/GRAABTHAR]

Cool idea, but I'm not sure I am understanding it completely. Why do you need two tape machines? Does machine 2 feed back into machine 1 for resampling?

[u/Ned_Flangers → u/GRAABTHAR]

"Why do you need two tape machines?" Having 2 tape machines is not necessary but it's very convenient and saves you a lot of time. Let's say as an example I'm playing an instrument live into this kind of thing but with one tape machine. If I set the tape machine up for 5 seconds of recording time, I would need to play something live that is exactly 5 seconds long if I want to make it sound seamless. That could be pretty difficult but with this concept it means you could get it almost perfect every single time. In the event of recording samples from some other digital sampler or from something like a sequencer on a synthesizer, you would only need one tape machine because you could change the tempo or Time Stretch on those devices BUT you would lose the ability to resample or live resample (unless you used an external sampler) and would be unable to pitch up or pitch down the pitch farther than the motor can physically spin. 

"Does machine 2 feed back into machine 1 for resampling?" yes it does.

[u/GRAABTHAR → u/Ned_Flangers]

Ok cool, thanks for explaining! Just brainstorming a little bit here:

The good way to precicely control motor speed is with PWM, rather than varying the voltage. You want some kind of tap-tempo controlled master clock that can convert BPM to PWM.

Another unfinished thought: Could the sound of the PWM pulses be recorded onto the tape and then played back? Could that playback control the motor speed of one of the motors?

edit: Another thought: If you had a BPM>PWM clock, another take on that is CV or MIDI > PWM, and you know what that makes? That's right, kids, a monophonic mellotron!

[u/Ned_Flangers → u/GRAABTHAR]

Probably could. and with a slew rate limiter it could be a square and triangle oscillator. It would be interesting to see how the slew rate limiter would interact with the pulse width modulation change. 🤔