Problems with SC-55 in DOS/Win 3.1

[hagmo]

Hi everyone,

I recently got a SC-55 mkII module to complement my MT-32 for retro gaming, but I'm having difficulties getting it to work properly on my vintage DOS/3.1 computer.

The SC is connected to the joystick port of a Sound Blaster card. At first I used an AWE64, but I have tested with a SB16 Vibra card (also PnP) just to see if it was the particular model that caused problems. But the symptoms are identical for both cards.

In DOS, I get stuttering sounds and extremely low performance whenever digital audio is played, but the games work fine otherwise (i.e. when using the Sound Canvas only and selecting "No DAC capability" or similar in the set-up).

In Windows, I can use the module if I tinker a bit with the MIDI mapper. But some notes seem to linger, resulting in distorted music. It's extra obvious if I pause a song in Media Player, where the notes will keep playing for about a full second before the synth turns silent. I've heard of the well-known problem dubbed the "hanging note bug" with some SoundBlaster cards, but I don't know if that's what I'm experiencing. I think I read somewhere that the AWE64 models didn't have this problem?

Of course, everything works beautifully on a modern PC with a USB-to-midi cable and DOSBox, but I don't really want to have spent lots of time and money on a vintage PC just to play my old games on a tiny laptop monitor.

Does anyone have any ideas what's going wrong here? Weird that the MT-32 doesn't cause any problems at all and then all this with the SC-55.

Cheers,
hagmo

[hagmo]

I had time to experiment some more today. I don't know if it means much, but here goes.

I tried running a few games with the SC-55 in stand-by mode. They all ran smoothly. That is, the choppiness only occurs if the module is turned on and receives data. As soon as I turn it back on, the problems are back.

I get the same amount of lag if I use the games' MT-32 drivers (with the Sound Canvas still connected), so it seems that the problem lies with the device itself, not with the General MIDI drivers that the games use. If I connect an MT-32 module - using the same cable - I get no lag, no matter if I use it with the MT-32 or the GM driver.

I really don't know anything about the inner workings of these devices, so I might not be on the right track at all. I'm thinking of installing both soundcards in the machine at the same time, and let one of them deal with the synth only and the other just use the DAC. Is this possible? Is there any chance it might fix the problem? It seems a bit overkill, yes, but at this point I'd be happy if I can just get the games working.

[Cloudschatze]

I tried running a few games with the SC-55 in stand-by mode. They all ran smoothly. That is, the choppiness only occurs if the module is turned on and receives data. As soon as I turn it back on, the problems are back.

This is strange. I imagine you are using just a single MIDI cable, connecting the MIDI OUT from the SB (joystick/MIDI adapter) to the SC-55's MIDI IN port, and there are no return connections involved?

[hagmo]

I imagine you using just a single MIDI cable, connecting the MIDI OUT from the SB (joystick/MIDI adapter) to the SC-55's MIDI IN port, and there are no return connections involved?

Well, actually... I've been assuming that the SC-55 would connect the same way as the MT-32. That is, In->Out, and Out->In. (I later read somewhere that one of the connections wasn't necessary, but I could never remember which one, so I kept connecting both - as long as it worked, why fiddle with it? )

But, yes, this seems to have been the problem. I omit the MIDI IN part of the cable and the games don't lag anymore. Brilliant. Thank you for not assuming too much about a stupid layman's do's and don'ts!

Yes, I feel silly now for not trying this earlier, going out of my way to find more and more far-fetched solutions. But in my defense, the MT-32 has no problems with having both cables plugged in, and the same goes for the USB interface.

I still find that the notes get stuck briefly when I pause a MIDI file in Windows, or when I exit KQ6. However, the songs seem to play fine now: no more strange-sounding chords outside the Castle of the Crown for example. So it seems both problems have been solved. Thanks again!