first post, so I hope this isn't TOO stupid a question. I am planning on building this circuit:


which eventually outputs 3 audio signals from three pins on the YM2149 chip (see top right).

On the original I think these are just wired so that one is on the left of the stereo signal, and the other two on the right (? - correct me if I'm wrong!)

Ideally would like to complete the circuit with one 1/4" jack that outputs all three signals in mono, and then three separate jacks that output each pin separately.

Is there any issue with simply "tapping off" the signal from each pin post resistor to a separate output, before they go to the "all in" jack?

Would I need to add anything else?

thanks in advance for any help offered - I think other questions on here suggest it should be fine, but these mostly involve "Y splitter" cabling rather than actual circuit building.


1 Answer 1


The 1k series resistors are needed if you are summing any of the chip outputs together. This isolates each output from the others.

You can add 3- additional mono outputs if you wish: connect another set of 3- 1k resistors between each output jack and the chip pin.

If you want a total of 4 jacks: 3- mono signals plus a mono sum of all of the signals, do the 3- individual jacks as I have described above. Then connect 3- separate isolation resistors from the mono sum jack to the chip output pins. Ideally, these 3 resistors will be about 3k3 in value rather than the 1k you are using for the individual signal jacks. The higher-value resistors provide greater isolation (minimize cross-coupling of the individual outputs).

The combined mono-sum output still has a similar output impedance to the individual output jacks (1k vs 1k1).


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