Reel Repeats

Tape delay interface

Reel Repeats is an audio interface module designed to connect your Eurorack system up to an external tape machine turning it into a REAL TAPE DELAY!

The input signal is routed to the tape machine via the SEND phono / RCA connector on the panel to be recorded.

At the same time the playback output of the tape machine is routed back to the module via the RETURN phono / RCA connector. Using the mix knob you can blend between the input signal and the playback to monitor your recorded signal.

With the repeats knob at the top of the module you can control how much of the playback signal is sent back to the tape machine input to be re-recorded. This feedback creates delay and echo effects.

The delay time depends upon the distance between the record and the playback head and also the the speed of the tape. By introducing more feedback the delayed signal is re-recorded creating the effect of repeats.

In school we are taught A+B=C but we were never told C in turn affects A......

By including the tape recording and playback process in a feedback path its nature and character become amplified. It's limitations and imperfections shape the feedback giving an effect so much closer to real natural behavior that a digital emulation can never truly capture.

To do this you will need a three head tape machine like a Marantz PMD 222 or a reel to reel like a AKAI 4000DS. Machines that have three heads will with have a record monitor feature where you can listen to your recording as it is being made.

The module also works with standard single head machines but you will only be able to record or playback....

If you have a desktop mixer with sends and returns you can make a feedback path by sending some of the output back to the input of the tape recorder but with reel repeats you can do this straight from your Eurorack system and with CV control.

I feel this module is the best of both worlds, the flexibility and control of modular with the sound and nature of real tape from a tried and tested three head tape machine.

To control the feedback the module includes a repeats CV input and a repeats KILL input. Using your modular system you can use 0-5V signals to the repeats CV input to increase the feedback.

You can use 0-5V signal to the Repeats KILL input to kill the feedback and stop the repeats. These inputs works up to audio rate.

To experiment with using other eurorack modules to control tape feedback a modular send and returns jacks have been included. By using these we can process the SEND signal before it goes to the tape machine to be recorded.

By routing to a filter makes it possible to select the frequencies that are recorded or rerecorded via the feedback. Using a VCA we can open and close the feedback path.... so many options.

I've tested the circuit with a Marantz PMD222 and adjusted the circuit so that the levels are balanced around the middle setting for the record level input to give clean repeats.

Managing feedback

There are three controls for the amount of feedback.

Turning the top knob clockwise will increase the feedback.

The Middle top Jack socket is a CV 0-5V which increases the feedback.

The middle bottom jack is also 0-5V and kills the feedback.

Connecting to your tape machine

Most tape machine use phono / RCA sockets so I felt it was only appropriate to add some to the panel. The right socket is send and the left is the return.

Mix

The mix knob blends between the audio in and the tape machine playback.

Max/Kill switch

The switch either kills or maximizes the feedback path just like the CV inputs. The Max function only works if the Repeats knob is not at absolute minimum.

Gain knob

Sometimes you just need a bit more gain as levels can vary with tape machines and tape brand/formulations.

So far I've also tested the circuit with an Akai 4000DS and will make a video about that in the future.

VU 

GREEN, AMBER AND RED level monitoring of the SEND signal level.

https://beepboopelectronics.co.uk/product/reel-repeats-eurorack-tape-machine-audio-interface/