Eye should probably think about making Teac AX10 clone
The Model AX-10 Sound-On-Sound & Stereo Echo Unit is designed to adapt a stereo tape recorder so that it can make sound-on-sound recordings (mixing and recording from one track to the other) or apply echo effects during recording in stereo.
Either process is simply carried out by depressing the red buttons
singly or in proper combinations.
This unit is adaptable only to stereo tape recorders which feature the ability to record on one track while playing back the opposite track. In addition, decks with separate record and play heads and electronics are essential for the echo function.
The AX 10 unit is nothing but a controlled loop around device that allows one to take a input and output (stereo) and apply the input signal to the recorder but also take a portion of the output when the red switches are down to apply back to the input for echo type control. This is mostly useful in a deck with three heads and when the deck is recording and monitoring off tape not source.
Then the delayed tape output of the machine gets mixed in with the input to make the echo effect. You can control the amount of insertion but not the delay amount. That is determined by the tape speed. The 15 IPS will be a shorter delay than the 7.5 IPS speed. These were made for decks like the A3340S type machines where recording with mics may have needed a echo added in.
The inputs go into the AX10, the cables go to the recorder L,R, then the output cables go to the recorder and the outputs to your mixer or amp come out of the jacks on the AX-10 box.
The unit adds an echo or sound on sound (less of an echo), to a recording by way of the difference in space between the record head and the play back head. Can be used only on 3 head machines. It sends what is being played back to the record head, which causes delay (echo), when it is recorded on the tape. The differrence in the space when between playback head and the record head causes the echo effect. If you you use the 3.75 speed the echo is increased. The Unit matches the impedence and adjusts the amount of echo.