Re: Mockingboard output through IIgs internal speaker?

[mjmahon@aol.com (Michael J. Mahon)]

Hidehiko Ogata wrote:

>Is such thing feasible?  Skimming the schematics
>("http://apple2.org.za/gswv/a2zine/Docs/IIgsMotherboardSchematics/";,
>part 8-A&B), the juncture of SR1 (MegaII speaker output) and SR53
>(Ensoniq output?), just upstream of LM12 (software volume control
>opamp?) seems like a good place to go, but I'd appreciate any comment
>by you experts ;).  Or, Apple being Apple, perhaps there is a proper
>tapping point on the mobo already?

Yes, this looks like a good place to mix in another audio source.

Since the Mega II speaker output is a 5v peak-to-peak signal, and
is mixed in with a 470K resistor, and the Mockingboard output is
about 1v peak-to-peak (and adjustable with "hard" volume controls),
I'd use a couple of 100K resistors to mix in the two Mockingboard
channels.  IIRC, they are already capacitively coupled on the
Mockingboard.

Although this should work fine, it, of course, mixes the stereo
Mockinboard down to mono.  And the internal speaker won't
do justice to the output the Mockingboard is capable of (anymore
than the internal speaker does justice to the Ensoniq output  ;-),
but you can always plug in headphones or an external speaker.

-michael

Check out amazing quality sound for 8-bit Apples on my
Home page:  http://members.aol.com/MJMahon/