All SB16 from the first CT1730 to the last CT2950 have the DMA clicking issue.
Some Vibra cards on the other hand do not have this problem, but have ringing and distortion problems.
The question is whether a SB16 card exist that doesn't click, ring, or distort and has a real OPL3.

Recorded the Alien Carnage music and Skyroads explosion on my CT2940. Mixer settings per James-F's earlier suggestion (My Sound Blaster 16 CT2230 Review).

I don't think I hear anything wrong there.

Thanks firage!
I don't hear anything either, there is no DMA clicks bug nor Distortion, and a real OPL3 (very rare) with your CT2940.
It could very well be that the CT2502 chip is actually the best SB16 if you can find one with an OPL.

firage, can you please record a minute of game-play of Wolfenstein3D without Adlib music.
Gerwin complained about faint ringing which happens on his CT2940, and my CT2890, mainly after a PCM sounds like killing an enemy or opening doors.

Did a quick test with a SB16 Value CT2770 (rev 019423) and it also has the Alien Carnage issue ... (CT1745-S , 4.12 DSP , integrated OPL)

This is what Nerdly Pleasures has to say about the CT2502 chip:

CT2502
I have never seen this chip branded with the ViBRA logo, and it is not a home-grown Creative Labs chip, as it contains technology licensed from Crystal Semiconductor.

That is funny, it's the only chip not designed by Creative, and the only one that has not DSP bugs. 🤣

The clicking DSP bug is not only in Alien Carnage, but in MANY old games, like Mortal Kombat 1, Supaplex, Jill, Skyroads, Prince of Persia 1/2, and many more.
Anything that uses single-cycle DMA mode, which probably a lot older SB1/2 games.

James-F wrote:

Thanks firage! I don't hear anything either, there is no DMA clicks bug nor Distortion, and a real OPL3 (very rare) with your CT […]
Show full quote

Thanks firage!
I don't hear anything either, there is no DMA clicks bug nor Distortion, and a real OPL3 (very rare) with your CT2940.
It could very well be that the CT2502 chip is actually the best SB16 if you can find one with an OPL.

firage, can you please record a minute of game-play of Wolfenstein3D without Adlib music.
Gerwin complained about faint ringing which happens on his CT2940, and my CT2890, mainly after a PCM sounds like killing an enemy or opening doors.

Of course nothing's ever perfect with Creative. 😀
Besides the hanging note bug, the OPL3 chip (that you can only find on a part of these) is the later YMF289 model which uses a new clock source resulting in slight detuning and possible artifacts.

I''ll check for the ringing deal soon, but this recording setup isn't good for fine details.

Edit: Added the recordings from Wolfenstein 3D and Tyrian setup to check for ringing/whistling(?). Also grabbed samples from X-Wing setup and Melt.amd for any YMF289 vs. YMF262 comparisons.
Lossless flac's up on Mediafire if needed: https://www.mediafire.com/folder/7684ejys1d9jh/ct2940

Thanks you for these recordings firage!
Yes, the CT2940 also rings but more faintly than the CT2890.

As I thought, the DMA clicking and Ringing problem are actually related and only happen with single-cycle DMA sounds.
The SB16 cards that click, do not ring.
The SB16 cards that ring, do not click.
It seems that residual ringing is heard because the DSP does not mute the signal and keeps the audio channel open.
The click is actually a closing of the channel as it should be, but it is not silent.

Now it is official, there is NO bug free SB16 and I'm not talking about MPU-401.
This is my personal opinion, if you don't need 16-bit sound in DOS games (hardly), I would stay away from the SB16 altogether, it is a really bad egg.
If you need 16bit sound in Windows 9x, there are MUCH better ISA cards than the SB16.
But if you must have one, I can say the CT2940 with YMF289 OPL is the most acceptable SB16 card if you find one.

Thanks for all your work on this subject, James. It's fascinating and really useful info! 😀 You should somehow compile this into something more permanent than a couple of threads--Vogons wiki maybe?

Yeah, thanks for doing the work on uncovering the mysteries. 😀

I wonder if the AWE64 is clear of these issues with digital sound.

The AWE64 is clear of the DMA issues but lacks an authentic OPL3, no Wavetable header, and still has the stuttering MPU-401 bug in Duke3D and Tie Fighter.

Thank you all who helped me figure out and lay down all the issues "on paper" for future reference.

James-F wrote:

The early AWE32 CT2760 which came in 1994 use the noisy CT1703-T DAC.
Later AWE32 had the quiet CT1703-A but also omitted the real OPL3 chip.

Actually only CT3990 (the very last revision) of AWE32 uses CQM. I consider the CT3980 the best model of AWE32 that delivers the best features the most purists look for: True OPL3, low noise. The only downside is to be PnP, what demands CTCU to work properly on older machines.

Damn, James-F, you're right about the CT1703-T being a noisy POS.
I just got a CT2770 SB16 Value (CT1747 chip) and it came with a CT1703-T, and it hissed like crazy. Replaced the chip with a CT1703-A taken from a dead AWE32, and the hiss was cut by 50%. Now only the PCM volume slider hisses when I don't mute it.

Looking at the op-amp section, there's a corner of the TL074C that is left floating, which is a *huge* no-no. I'll terminate that uncommitted op-amp and see what that does for noise.

Update: Terminating the op-amp still didn't totally get rid of the PCM hiss, but I feel better for having doing that so I'll leave it terminated. I suspect that, at this point, it's a combination of too high gain someplace and generally poor layout and circuit design that's causing the hiss. It does sound much better than how it did at first, though.

James-F wrote:

(...) CT1703-T is the noisy DAC appearing only the CT2230 (19413) and (29417) but not on the CT2290, also on the first revision […]
Show full quote

(...)
CT1703-T is the noisy DAC appearing only the CT2230 (19413) and (29417) but not on the CT2290, also on the first revision AWE32 CT2760.
CT1701 is the oldest and noisiest appearing on the first SB16 CT1740 cards.

The early AWE32 CT2760 which came in 1994 use the noisy CT1703-T DAC.
Later AWE32 had the quiet CT1703-A but also omitted the real OPL3 chip.

My CT2760 has CT1701-T. And what now? ;]

Hello all
You can see that I have two sb16's (one CT 2230 with asp chip and one CT 2950).
As you all guys are more experienced than me which one should I use for a better sound and music ?

The image quality is quite poor, so it's hard to see some specific details, but the first card, the CT2230, is definitely the better option. It has real OPL3, whereas the CT2250 seems to lack the Yamaha YMF262 chip (which means that the CT2950 is probably the CQM version). The 2950 has both the Type 1 & 2 MPU-401 hanging note bugs, so MIDI playback will be an issue with many games (if you are interested in that). Also, a bit harder to tell from your picture, but the DSP chip on the CT2230 seems to be either the CT1703-A or the CT1703-T. If it's the "-A" version, it's one of the better, quieter cards. If it's the "-T" version, it will be quite noisy.

Thanks for info @bloodem

You're very welcome 😀

Thanks for the review. I have received a similar card, the CT2290 and found it to be excellent;
- line out with extremely low noise, even with volume at maximum
- does not pick out the electric noise from the CPU activity unlike my CT1750
- CT1741 DSP 4.13 without hanging note bug, functional WaveBlaster header
- modern CD-IN connector, again unlike the CT1750 (it does not block the DreamBlaster X2 which works fine)
- ASP chip
- real OPL3 (CT1747 clone)
- not speed sensitive (works with Athlon XP)
Overall it seems to be a great choice for a SB16. Also see: https://sites.google.com/site/soundcardcomparison/

cde wrote on 2020-12-06, 18:05:

- ASP chip

Not all CT2290 have an ASP/CSP chip, some just have an empty socket where it should be...

That's correct, my second CT2290 doesn't have the ASP/CSP chip. It otherwise seems to perform the same 😀