I had exactly the same behavior.

If you have the same or similiar card to mine, just replace 74LS245 chip near LS262 chip (actually this one is YMF262 clone).
I replaced it with 74HCT245 (because I just didn't had an LS245 nearby) and FM started to sound like it should.
Two 74LS245 chips below which I desoldered were IDE CD port buffers, therefore were not necessary.

BTW, on my card in place of two capacitors below amplifier (C48 and C48) were actually soldered resistors 😀 I also replaced them based on the reference diagram.
... and added a top negative voltage regulator -9v (instead of a resistor to -12V from ISA slot) and capacitor C38.

Thanks a lot for the tipps, zyga64! 😃👍

A few years ago I encountered some audio issues with the 100+..
Maybe some of the things I found out are still helpful, not sure.
ALS120, ALS100 Plus audio fix ?

zyga64 wrote on 2022-07-30, 12:21:

I had exactly the same behavior. […]
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I had exactly the same behavior.

If you have the same or similiar card to mine, just replace 74LS245 chip near LS262 chip (actually this one is YMF262 clone).
I replaced it with 74HCT245 (because I just didn't had an LS245 nearby) and FM started to sound like it should.
Two 74LS245 chips below which I desoldered were IDE CD port buffers, therefore were not necessary.

BTW, on my card in place of two capacitors below amplifier (C48 and C48) were actually soldered resistors 😀 I also replaced them based on the reference diagram.
... and added a top negative voltage regulator -9v (instead of a resistor to -12V from ISA slot) and capacitor C38.

Thank you so much for the advice! Yeah I will have a look through my bin o parts and see what I can find. Other than that it’s a great card and quite clean pcm sound!

Thanks again!!

I know this probably doesnt help you, but the ALS100+ version has jumpers to select line vs speaker level output which cuts down on the noise a bit, or at least mine does.

drosse1meyer wrote on 2022-08-04, 02:01:

I know this probably doesnt help you, but the ALS100+ version has jumpers to select line vs speaker level output which cuts down on the noise a bit, or at least mine does.

Word of warning with ALS100+ cards though: the "74LS245" chip there isn't a regular 74LS245 like on the ALS100 cards, it's actually the OPL3 clone itself. So if you have this sort of problem and replace the "74LS245" chip on the ALS100+ card with a regular one, you will lose all FM - and might short stuff out too.

dionb wrote on 2022-08-04, 06:41:

drosse1meyer wrote on 2022-08-04, 02:01:

I know this probably doesnt help you, but the ALS100+ version has jumpers to select line vs speaker level output which cuts down on the noise a bit, or at least mine does.

Word of warning with ALS100+ cards though: the "74LS245" chip there isn't a regular 74LS245 like on the ALS100 cards, it's actually the OPL3 clone itself. So if you have this sort of problem and replace the "74LS245" chip on the ALS100+ card with a regular one, you will lose all FM - and might short stuff out too.

Yes. But only for ALS100+. On my ALS100 (not plus) card: LS245 is actually 74LS245, OPL clone is LS262 😀
BTW - real 74LS245 has 20 pins (legs), while the OPL3 (and clones) has 24 of them

On my ALS200 card that's got a DIP20 chip connecting up to the OPL3's traces, it's actually called just the "LS245". Other markings on it are "7B146M1 748".
The first post goes into impressive detail, covering what pins were removed to make it work and has some other good examples of how the OPL3 DIP-version got remarked: All the truth about FM in ALS100 Plus+ cards (includes facts, tech info and tests)

Thermalwrong wrote on 2022-08-04, 14:45:

On my ALS200 card that's got a DIP20 chip connecting up to the OPL3's traces, it's actually called just the "LS245". Other markings on it are "7B146M1 748".
The first post goes into impressive detail, covering what pins were removed to make it work and has some other good examples of how the OPL3 DIP-version got remarked: All the truth about FM in ALS100 Plus+ cards (includes facts, tech info and tests)

That is a fascinating thread and possibly one of the most interesting things I read on VOGONS since I signe d up.

dionb wrote on 2022-08-04, 06:41:

drosse1meyer wrote on 2022-08-04, 02:01:

I know this probably doesnt help you, but the ALS100+ version has jumpers to select line vs speaker level output which cuts down on the noise a bit, or at least mine does.

Word of warning with ALS100+ cards though: the "74LS245" chip there isn't a regular 74LS245 like on the ALS100 cards, it's actually the OPL3 clone itself. So if you have this sort of problem and replace the "74LS245" chip on the ALS100+ card with a regular one, you will lose all FM - and might short stuff out too.

Yep, absolutely

Also, do people not like the ALS100+? I think it sounds good. ;D

drosse1meyer wrote on 2022-08-04, 15:28:

Also, do people not like the ALS100+? I think it sounds good. ;D

IIRC, the "plus" version doesn't support High DMA, unlike the regular ALS100.

This can be problematic in some games like Duke3D, but there are workarounds.

Joseph_Joestar wrote on 2022-08-04, 15:33:

drosse1meyer wrote on 2022-08-04, 15:28:

Also, do people not like the ALS100+? I think it sounds good. ;D

IIRC, the "plus" version doesn't support High DMA, unlike the regular ALS100.

This can be problematic in some games like Duke3D, but there are workarounds.

Yea I believe I ran into this issue, had to manually edit the config file to get it to work, don't remember which game, it may have been Duke3d or ROTT...

ALS100 is good but it cannot escape it's budget roots... even on the best pcb/design there are quality issues that cannot be avoided. But it sure beats something like the CT1320/CT1600 and noisy SB16s

Thermalwrong wrote on 2022-08-04, 14:45:

On my ALS200 card that's got a DIP20 chip connecting up to the OPL3's traces, it's actually called just the "LS245". Other markings on it are "7B146M1 748".
The first post goes into impressive detail, covering what pins were removed to make it work and has some other good examples of how the OPL3 DIP-version got remarked: All the truth about FM in ALS100 Plus+ cards (includes facts, tech info and tests)

WOW! Just WOW ! Thats a truly detailed investigation !

Well that was JazeFox investigating it, the author of Unisound so it makes sense they went so in depth 😀
I've seen similar on my SB 2.0 clone card, which uses 'SC801' & 'SC802' chips, which are different pin counts but are still pin/signal-compatible with the original YM3812 OPL2 and YM3014B DAC.