Hammond 307A Transformer in audio splitter application

[gman7]

If the primary impedance of the transformer is actually around 500-600 ohms, connecting your guitar to it will produce close to nothing on the secondary. Your guitar's output impedance is likely very high ( 250K ), loading it with a 500-600 ohm transformer winding will effectively short the output.

[R.G.]

You need to buffer the guitar before going into the primary of that particular transformer; otherwise, you're likely to have big losses in treble and possibly level.

Something like this:


This setup was solving a different problem (using a cheap, cheap, cheap transformer to isolate with good frequency response) but the approach is something like what you need. The IC buffers the guitar signal so that the transformer loading does not suck treble out. The transformer then gives ground isolation.

[R.G.]

Here's another isolated thought.

Along with an isolated 9Vdc *output*, how come guitar amps don't have a buffered, transformer isolated *output* of the input signal available to drive other stuff?

I know the answer, of course. It's because we are living with almost a century of guitar amps being a standalone item, and designed to be so, instead of playing nice with the increasingly complicated multi-electronics setups we use now. But it still comes up in my mind.

[Jayz]

Thanks. I think the preferred method for receiving a guitar signal for recording and often for live sound is still to place a mic at the speaker output.