As I already mentioned in an earlier blog post, I aim to expand the unit with either a Spring Reverb or a Tape Delay by the end of the third project semester. For the reverb, my main idea is to build an add-on tube-driven spring reverb module based on the classic Ampeg and Swart-style circuits. The advantage of these circuits is the relatively small number of parts required. Besides an enclosure, a handful of components, and a valve socket, the only costly item is the reverb tank itself, which I already possess.
My main reference for the tape delay effect is a DIY project by Matsound, that combines a Marantz PMD430 portable cassette player with the Echo-Matict, a simple circuit that can turn any 3-head cassette recorder into a tape delay. The 3 head design allows for the separate use of record and play head, meaning that it is possible to record and playback from the tape simultaneously. The Echo-matic circuit splits the incoming signal and routes it both to the output and to the tape machine with a mix blend control. The delay effect is produced by mixing the dry input signal with the one going through the cassette tape. Initially, the delay time is fixed by the distance between the record and play heads, but by adding a voltage control to the motor its speed can be altered, and thus the delay time can be adjusted.
Cary, J., 2021. Echo-Matic (DIY Tape Delay). [Blog] Proto-Schlock, Available at: <http://proto-schlock.blogspot.com/2015/04/echo-matic-diy-tape-delay.html> [Accessed 12 December 2021].
Effects, S., 2022. DIY Tape Delay? The Echo-Matic!. [online] The Gear Page. Available at: <https://www.thegearpage.net/board/index.php?threads/diy-tape-delay-the-echo-matic.1822557/> [Accessed 12 December 2021].
Hawkes, R., 2019. DIY CASSETTE TAPE GUITAR DELAY. [Blog] Hackday, Available at: <https://hackaday.com/tag/cassette-tape/page/2/> [Accessed 12 December 2021].
freestompboxes.org, 2017. Stompboxology Echo-Matic DIY Tape Delay. Available at: <https://www.freestompboxes.org/viewtopic.php?f=28&t=28316> [Accessed 12 December 2021].
Price, H., 2019. HOW TO BUILD YOUR OWN SPRING REVERB UNIT. [online] Guitar.com | All Things Guitar. Available at: <https://guitar.com/guides/diy-workshop/build-tube-spring-reverb-unit-amplifier/> [Accessed 19 December 2021].
Accutronicsreverb.com. n.d. The History of Spring Reverberation. [online] Available at: <http://www.accutronicsreverb.com/main/?skin=sub03_01.html> [Accessed 19 December 2021].