Neo Newbie needs MVS help

I recently purchased a 4-slot but am having problems with the sound. On the Neo GEo boot up screen not all the channels seem to be sounding and in the games, some effects(particularly high tones) sound horribly scratchy. I have it running on a jamma cab btw, not a supergun. I dont have any jamma boards to test the speakers with, so it could end up being that... Im just wondering if this is a known problem and what possible troubleshooting steps I should take.
Thanks to all in advance.

I am having the exact same issue.

Does it have to do with the fact that multislot boards are "not exactly" JAMMA?

I am using a Jap cabinet, and a Jap 4-slot that was modded to USA. I bought the 4-slot from MD Game Sales.

In the Neo Geo "jingle", some of the sounds are missing, and there seems to not be any real 'volume' to the sound. There is not really any bass or midrange when playing the
games.

Thanks for any help...

Maybe to shed some more light on it,

I went to the HW-test menu (dip 1) and went to sound test.

If I select either left or right sound channel test, sound comes out of BOTH speakers on either setting, like it was setup for mono sound only.

however, if I select center, sound comes from NEITHER speaker.

Which leads me to believe that I have a harness problem, and that when sound is sent to both stereo channels, it gets cancelled out somehow.

Any clues?

Eek, I figured it out...

Looking at the jamma pinout for the MVS multi-slot boards (1-slot doesn't have this problem), the Left audio channel is on the same pin that Jamma speaker ground normally is.

Which means that the right channel only is playing, and it's being grounded through the left channel output.

This is NOT a good thing and will blow the amp. Needless to say I'm looking into alternative. I think I'm going to set up a full stereo system with external amp in my cabinet, and use the headphone stereo out for the output, and cut the jamma altogether. I only play Neogeo and CPS2 games anyway, and CPS2 has line-level outputs too.

Hope this sheds light on the sound problems for somebody..