A variation of this technique was sometimes known as spin echo, or repeat
With the setup as above, if you send some signal via the auxiliary send of
the Revox channel back to the tape recorder, it will feed back on itself in
a loop, causing repeated echoes rather than a single delay.
If too much signal is sent back, the level of the echoes will increase until
the signal goes into severe distortion.
This was actually a much-used technique of the Jamaican dub producers of the
1960s and 1970s.