I have no idea if all GF1 chips are interchangeable, I do hope that isn't the problem. I had speed issues myself with my GUS ACE, but they were caused by:
1) Matrox videocard with digital output @60hz. Timings derived from the video signal were all messed up;
2) CuteMouse interfering with music playback. Seen another issue on this forum with SoftMPU.

Also try trackers like Impulse Tracker and FT2. AFAIK they approach the hardware in a somewhat different manner and can help pinpoint the issue if they work normally.

Edit: didn't read your post correctly

Rawit wrote:

I have no idea if all GF1 chips are interchangeable, I do hope that isn't the problem.

Yeah, I'm hoping that's not the problem. Apparently both ICS1614 and ICS11614 are used as GF1 chips. Both of them are used on cards which otherwise appear to be the same so I have no idea if there's any difference. Regardless, the new chip and the old chip on mine are both ICS1614.

I did some more testing:

- The speed is actually normal after all, everything just plays at a lower pitch which made me think it was also too slow.
- I was wrong about the sound effects being normal. They also play at lower pitch. Everything the card outputs is like that.
- Impulse Tracker is also affected.
- Tried it in a different computer, made no difference.

Seems like it has to be a hardware issue.

Is it possible to post an example? There are some recordings here to compare with:

Need help repairing a Gravis Ultrasound Classic 2.4!
https://soundcloud.com/advancedgravis

That Vogons thread is dealing with out-of-spec crystal issue which might be related.
Impulse Tracker being affected would exclude PAT problems. In Impulse Tracker there is a driver section where you can enable some debug info like sample rate. Activate that and try a 4-channel (or < 14 channel) MOD / IT / XM file. It should provide you with the actual sample rate, which should be 44100 when playing a file with less than 14 channels.

Edit: do you use a 16-bit DMA or 8-bit?

Here's a recording of Doom:

https://www.youtube.com/watch?v=QaNuXontLIs

I wasn't able to find the driver debug section in Impulse Tracker. Do you know where it's hidden?

The settings automatically chosen by the Ultrasound drivers are ULTRASND=260,1,1,7,5 which means it's using DMA 1 for playback.

For Impulse Tracker I need to check it when I'm back home. I checked the video and it seems some parts of the FX are also cut off. Did you try reseating the memory?

Yeah, I've reseated and cleaned all the contacts on the memory. I also tried with just a couple of them installed in case some are dead but that made no difference.

After re-watching the video, I think I was right originally that it's slow, not just reduced pitch. Some of the sounds are so slow that they stick out and sound obviously wrong. When I said that the speed was normal, that was based on Impulse Tracker playback which as you said doesn't use the same hardware access method.

To me it does sound like a reduced pitch, I've heard Doom's E1M1 track quite often. Do you have printer ports enabled and do they sit at the same IRQ as the GUS?

Well, I fixed it.

I replaced the crystal with a new 20MHz one and now the sound output is perfect. The old crystal must have become out of spec and was running the card at too low of a clock speed or something.

The thread linked further up says that the crystal should be 19.7568 MHz (the markings on my old one are worn off). Does anyone know where I can source one of these rather than using the 20 MHz one I've got? Can't find them for sale anywhere.

seanneko wrote:

The thread linked further up says that the crystal should be 19.7568 MHz (the markings on my old one are worn off). Does anyone know where I can source one of these rather than using the 20 MHz one I've got? Can't find them for sale anywhere.

In that thread, Ozzuneoj mentions having a source for the crystals. Maybe you can send a message to enquire about placing an order and sharing the costs? From evidence in that thread, a 20 MHz crystal will still not give the correct results, either; the pitch will still be slightly off.