Longer demonstration on how the DIY tape delay // tape echo was made. As the feedback loop is made via the RCA connectors in the back (from Left to Right) any number of pedals may be added for superior feedback control. E.g. a limiter pedal may be used for infinite feedback without overdrive. Quite a straightforward build: 1. Two mono heads mounted side by side replace the old stereo head. The left head records (soldered to "Left"), right heads plays back (soldered to "Right") 2. The Cassette tape is modified to accomodate two heads, add some foam to ensure that the tape stays close to the heads. 3. Speed: The capstan motor speed control is moved to a potentiometer on the front. 4. You have to use an old deck with Left/Right separate REC/PLAY switches (usually the long ones on the main board). Here only the Left goes to Record when pressing record (the Right stays in playback). 5. Feedback control: I added a small audio transformer in the feedback loop to eliminate hum and galvanic direct feedback (you ONLY want the tape feedback). The tape mike amplifier is used for input just as it is. I'm recording via the headphone jack on the front: Left side direct signal, Right side delayed signal. When you look for a fleamarket/ebay tape deck get an older one, they're more frequently made of metal and a lot easier to work on (easier to mount the 2 mono heads on). Mono heads may be sourced on Ebay, or e.g. in older CD-to-car-cassette adapters. Good luck!