Hardmodding the sound cards to replace capacitors with values more in line with the datasheet specs (and sometimes even beyond to change the bass response etc.) is more common than you think. People even change things like FM synth chips, DACs and amplifier ICs from time to time.

In most cases there isn't much to do since the source of problems is inside the sound chip itself rather than external parts such as the case with MD/Genny. You can do some small mods to improve freq range but making a noisy chip less noisy is mostly impossible. Some chips to get better results when you give them nice and clean power rails but C-Media chips don't belong in that camp 🤣.
Some things that have elaborate analog sections like many SB16 cards can be improved by swapping out some of the bottom barrel parts with higher rated things and you can get closer to the theoretical maximums of the sound chips involved.

Tiido wrote:

In most cases there isn't much to do since the source of problems is inside the sound chip itself rather than external parts such as the case with MD/Genny.

Crap, so I guess the hissing background noise may just be a fault of the CMI8738 chip itself? Anybody got a legit card from C-Media to corroborate this? I wish I had taken a photo of the clone card I'm using, but the best I can describe it is, it's small enough to fit in a wallet or someones pocket. The only chips on it is the CMI chip itself and a PCI to PCIe bridge controller chip. The card is a PCIe 1x sized card. I would of figured the noise problem is due to how little components there are to the card itself.

Only the analogue outputs are wired to ports. I didn't see a SPDIF let alone a Gameport. Linux still detects the presence of both but that's obviously because it's part of the chip.

The less parts are there, the less other sources for the noise are there. 99% of that noise comes from the sound chip itself, the analog sections in it just are not good.

SPDIF comes from a certain pin on the chip, it isn't wired to anything but with a mod you can surely get the signal out and usable. Pin 98 is the SPDIF output on that chip.

Tiido wrote:

The less parts are there, the less other sources for the noise are there. 99% of that noise comes from the sound chip itself, the analog sections in it just are not good.

SPDIF comes from a certain pin on the chip, it isn't wired to anything but with a mod you can surely get the signal out and usable. Pin 98 is the SPDIF output on that chip.

Lack of components can also mean inadequate filtering of input voltage or analogue audio as well. These junk $5 PCI cards often have none of either..

Ah... heh.

I never in my life ever used SPDIF before, would the OPL3 synth output through it on these chips?

appiah4 wrote:

Lack of components can also mean inadequate filtering of input voltage or analogue audio as well. These junk $5 PCI cards often have none of either..

Even the cheapest cards have the necessary linear regulator for analog section. You need to be very incompetent to botch up a single chip design such as these C-Media things which are designed for simplest and thus lowest cost designs and even then you don't inclease hiss and whatnot, only maybe introduce buzzing noises or such.
Anything you put on the actual sound lines will not improve noise etc. without harming the actual sound itself, whatever you can hear is something that cannot be removed with useful sound itself since both coexist in same place. It is like removing an object from a painting by cutting it out, the painting won't be intact afterwards.

Since SPDIF is digital, if I can get a working port hard modded onto this clone card, I wouldn't have to worry about noise ever again right? Assuming I plug the digital source into something that has FAR better analogue outputs than this thing does.

Well, I sorta did a few years ago with an ALS1x0 card.. 😀
Re: ALS120, ALS100 Plus audio fix ?&

it's not a hardware specific mod, rather a little quick&dirty fix.
Anyway, comming up with a real mod would be possible, I believe.

The specs of most 90s sound chips aren't bad on their selves,
the issue rather lies in cheap "cost-effiicient" soundcard designs with wrong/missing parts
and the lack of shielding, noise-blocking caps and so on, I believe.

DracoNihil wrote:

Since SPDIF is digital, if I can get a working port hard modded onto this clone card, I wouldn't have to worry about noise ever again right? Assuming I plug the digital source into something that has FAR better analogue outputs than this thing does.

If the analog inputs don't go through ADC process or can be muted, the digital output should be pretty good, but otherwise you're probably got gonna get a huge improvement since a lot of noise is gonna originate from the input section and probably in the ADC aswell.

Why not just get a better card? PCI sound cards aren't hard to find or expensive. Are you attached to this particular card, or just curious about modding for the sake of it?

SirNickity wrote:

Why not just get a better card? PCI sound cards aren't hard to find or expensive. Are you attached to this particular card, or just curious about modding for the sake of it?

Because he (thinks he) can 😉

It makes a lot of sense to practice this sort of stuff with generic very expendable cards before trying it on anything of (sentimental) value or rarity.

That said, putting lipstick on a pitbull doesn't stop it being a pitbull - but when I read about the sort of things Tiido does with Yamaha-based cards (or for that matter just about any (sound) card he gets his hands on, by the sound of it), I think "I want to be able to do that too!". Wouldn't surprise me if something similar is going on here.

I don't have any money or a income for that matter right now, this clone card was given to me as a generous gift. I just happened to have been lucky that it has a intact OPL3 core, and the bridge chip doesn't interfere with the I\O ports to it. As far as I can tell from the surface the CMI8738 chip on it is legitimate.

So, I'd like to atleast get some sort of "clean digital out" so I can route it to something less noisy so I don't have this awful hiss in the background of everything, barring that I'd hope there'd be some way to make the analogue outs more cleaner.

Your best bet is to make use of that SPDIF output signal. It is 3.3V and incapable of driving a 75ohm load that normal coax inputs are on whatever you want to connect it to so there's a need for a buffer circuit.