Sound problems SB CT3600 @ 386 DX40 \ VOGONS

Sound problems SB CT3600 @ 386 DX40

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First post, by CJ Grass

Posted on 2021-05-10, 14:58

CJ Grass Offline

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Rank: Newbie
Posts: 18
Joined: 2010-12-02, 23:18

Hi,
I just assembled my retro kit consisting of the PC Chips M321 board with 386 DX40 processor and the SoundBlaster CT3600.
After searching for the best driver for this card, I did everything as recommended, but during diagnostics I have a strange audio dropout when testing 16 bit samples. 8 bit is OK, FM synth and AWE synth OK.
I thought that maybe something is wrong with the card and that I have one more and 100% functional (because it works in a set with a Pentium) I mounted it to 386 and the problem is still the same - the sound is interrupted on a 16 bit test or in games that use 16 bit audio (it's hard to describe, but it's more like interrupting, shutterring... something like this).
Is it a slow processor fault? Does the 386 support SB CT3600?

Reply 1 of 3, by KVM Nerd

Posted on 2021-05-10, 16:59

KVM Nerd Offline

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Rank: Newbie
Posts: 23
Joined: 2021-05-05, 20:22
Location: Germany

Just guessing, but maybe the DX40 uses another/higher clock rate on the ISA bus than a Pentium system, which may cause problems. AFAIK the bus clock is derived from the CPU clock rate. Maybe you can configure the ISA bus clock rate on the 386 board? IIRC the AWE32 needs a 386 DX33 or higher for recording, but not for playback.

Why not hook it up to a KVM switch?

Reply 2 of 3, by AlaricD

Posted on 2021-05-10, 17:53

AlaricD Offline

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Rank: Oldbie
Posts: 532
Joined: 2017-06-28, 19:11
Location: Stillwater, America

Some 386 boards are bad with 16-bit DMA transfers (like the M-321, where sometimes you can have reboots running DIAGNOSE). Try other HDMA channels; if you don't get satisfactory results, use the DMA channel for the HDMA channel (match HX to DX).

Reply 3 of 3, by CJ Grass

Posted on 2021-05-11, 09:31

CJ Grass Offline

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Rank: Newbie
Posts: 18
Joined: 2010-12-02, 23:18

Yesterday on the settings of irq 7 dma 1 hdma 5 the diagnostic tool worked without a problem (except for a crackle on 16 bits)
Today, after changing irq to 7, 10, dma to 1.3, hdma 5, 6, 7 which did not solve the problem with the crackling of 16 bit samples, the diagnostic tool hangs even with the default settings of irq 5 dma 1 hdma 5 (on the test with hdma 5).
Some time ago it was like that, but I changed irq to 7 and with settings irq 7, dma 1, hdm1 5 the diagnostic tool version 4.04 worked.
I know that the newer version 4.05 probably does not have this problem. I have to find her.
However, I still can't fix the crackle problem with 16 bit samples and games that use this mode.

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