LEFT - STEREO - MONO - RIGHT Switch

[Michael Maurice]

Over the years there have been several threads asking for help on the track switching arrangements for the Akai 3000D and 4000D / DS and their derivative tape recorders.

This simple switching box should help you overcome this without modifying the Akai machine.

It can also be used with any other tape recorder or cassette recorder

it is easily built, the 3 pole 4 way rotary switch is readily available.

[Dave Moll]

Is it good practice to connect left and right channels direct to one another? I understood that it is normal practice to include a suitable resistance in each channel prior to mixing - which could easily be achieved in the wires going to position three of the left and right channel switches. I'll leave it to others to recommend a suitable value.

[Paul Stenning]

Should there be resistors (around 1K) in series with the inputs so the outputs of the source device aren't shorted together when switched to MONO? It's not an issue for line level outputs as they normally have significant impedance but could be for headphone outputs on MP3 players etc.

[Michael Maurice]

1970s/1980s amplifiers did just that, connect left and right channels together. The Switch was designed around these tape recorders but Dave and Paul are correct, if you're using headphones out say on MP3 players or to be safe, insert a 1K resistor between each of the left and right inputs and their respective switches.

[Jimmyhaflinger]

i have an Akai CS-34D cassette deck that's extremely unhappy to have its outputs shorted together in mono, it distorted heavily when i once tried to do this without putting resistors between the outputs

[majoconz]

I found that if you have a mono recording on a stereo machine and then you join the two outputs together on playback, then there's all sorts of funny phasing effects.

[Michael Maurice]

That is because the azimuth of the heads on either the recording machine or playback machine is out of alignment

[paulsherwin]

Indeed, practically all domestic cassette decks will exhibit this behaviour to some extent when replaying cassettes recorded on something else (including commercially recorded cassettes). It's a matter of precise vertical head alignment rather than simple azimuth. The phase error is largely undetectable when listening in stereo.