Tape delay experimenting

[AdamB]

Hi,

I've been wanting to attempt a DIY cassette tape delay for a while now, but haven't been able to find a 3 head deck to cannibalise.

However there's loads of cheap 2 and 1 head machines available for very cheap so I got to thinking of ways to make this work without a 3 head deck.

I remember back when CD players first became a thing, you could hook a portable CD player up to a car cassette deck using one of those little tape-converter/adapter gizmos. Digging into it, it appears how they work is they're just a little tape head that butts up against the read head in the deck, so that it "writes" the incoming signal straight into the read head in the deck.

What I'm trying to figure out is if I can repurpose the "write" head in one of those little converters (turns out these are still readily available for cheap on Amazon) to add a write head to a 1 head deck?

I tried a simple experiment of just taking the write head out of the cassette adapter and gluing it in place over the tape before the read head and then feeding it a signal off my phone's jack output to see if it'd write to tape. That don't work, I'm assuming either a) these write heads are a different kind to what you'd find in a tape deck or b) I need to put in-front a preamp that converts the signal into something that can be written to the tape.

I found some interesting reading online about write heads needing a pre-amp that generates a high frequency (somewhere up around 30KHz?) AC signal and then modulate it's peaks by the audio signal in order for writing to work well (called AC biasing), but I was still surprised that it didn't write any info to the tape at all when being fed without this, not even some distorted noise.

So wondering if anyone else has any knowledge/experience with this that might help me out?

Thanks!
-Adam

[AdamB]

Actually moments after I posted I found this thread that has a lot of info, doh!
https://www.diystompboxes.com/smfforum/index.php?topic=125076.msg1192277#msg1192277