Eep386 wrote on 2021-02-13, 16:23:

I think what fixes issues with OPL3, is to increase the number of 8-bit ISA wait states (sometimes called 'I/O Recovery Time') in BIOS. Some lame-ass BIOSes (typical of OEM systems) don't allow you to change the wait states, however. For those that do allow the option to be changed, I usually ramp em up all the way to 8 or so if the system's a 'fast' one (say, Pentium 200).

Also, I'm beginning to think that the DAC chip has less to do with self-noise, than whether or not the cards have floating op-amps. Creative's left a number of quad amps on their cards with one or more sections of certain amps floating, which is terrible for noise and power consumption. I have a first-revision CT2760 with a CT1701 DAC, that had *six* sections of op-amp floating. I tied the amps down and the hissing doesn't seem any worse than is typical for ISA sound cards, at least to me.

Creative ISA Sound Card Floating Op-Amps Running Log/List

technically I/O recovery time isn't the same as wait states - wait states are inserted within an access cycle to allow for the target device to decode address or whatever, I/O recovery time is waits inserted between consecutive access cycles

All the same, increasing that *usually* helps fix glitchy OPL3 sounds on some faster systems, provided the BIOS actually allows access to said setting.

Eep386 wrote on 2021-02-13, 21:41:

All the same, increasing that *usually* helps fix glitchy OPL3 sounds on some faster systems, provided the BIOS actually allows access to said setting.

Yes I agree, especially with OPL2s which are even more speed sensitive

This thread should be stickied!

Especially the flaws that can be fixed.

Cheers,

maxtherabbit wrote on 2021-02-13, 16:03:

interesting, my ALS007 worked just fine with DOTT

yes, MAYBE i have an ALS007 somewhere? one thing is for sure, the ALS007 is definitely not the same chip as the ALS100 with a different marking; the Windows drivers have different INF files:

5118 05-15-96 17:41 ALS007.INF
5069 05-15-96 17:36 ALS100.INF

so, uh, maybe the ALS007 is an ALS100 but a little better?? i have no idea honestly. the lineup is incredibly messy and confusing: ALS100, ALS007, ALS100+, ALS120, ALS200, and who knows what else...

Eep386 wrote on 2021-02-13, 16:23:

Also, I'm beginning to think that the DAC chip has less to do with self-noise, than whether or not the cards have floating op-amps. Creative's left a number of quad amps on their cards with one or more sections of certain amps floating, which is terrible for noise and power consumption. I have a first-revision CT2760 with a CT1701 DAC, that had *six* sections of op-amp floating. I tied the amps down and the hissing doesn't seem any worse than is typical for ISA sound cards, at least to me.
Creative ISA Sound Card Floating Op-Amps Running Log/List

I think you are onto something here but actual measurements of the different cards would be the best way to improve the chart. The problem being here that different systems will result in different results. The best way would be if one person could measure all (or the most important) cards in one system with the same settings.

I'm hoping to add to my running log of Creative cards with floating amps as I find Sound Blaster 16s. I was shocked to see floating amps on my Pro 2 as well - might have had something to do with its output noise.

I have questions to the Vibra 16XV CT4170.
The list says that it doesn't have the hanging note bug.
Here on retronn.de it says that it has DSP V4.13.
So that card must be have the hanging note bug?
But i read also that some other cards have DSP V4.16.

And what's the difference between the chipsets CT2511-SAT and CT2511-SBT?
Maybe...
CT2511-SAT=4.13?
CT2511-SBT=4.16?

Far as I can gather, ViBRA16s don't have hanging notes regardless of the DSP version they claim to have. Instead, they have other problems (ringing/hissing artifacts after samples play, etc).
The -SAT and -SBT have no really tangible difference between them that I can tell, a CT2511 is a CT2511 unless someone else can tell me otherwise.
Though I cannot substantiate it, I wonder if the ringing/hissing artifacts (and lack of popping/clicking artifacts) is due to altered/removed muting circuitry on the ViBRA (probably inside one of the big chips) as opposed to on the non-ViBRA cards.

Not true, a lot of Vibras have hanging note issues. I'm not sure why CT4170 is marked as not having it though. I have one, but never tested it.

Regardless, there are several revisions of the CT4170 with different components on different (but similar) PCBs. Some have newer revisions of CT2511 with colored jacks, some with older revisions with black jacks. Mine is one of the former, I may plug it into a system and check the dsp sometime.

zoinknoise wrote on 2021-02-14, 01:09:

yes, MAYBE i have an ALS007 somewhere? one thing is for sure, the ALS007 is definitely not the same chip as the ALS100 with a di […]
Show full quote

maxtherabbit wrote on 2021-02-13, 16:03:

interesting, my ALS007 worked just fine with DOTT

yes, MAYBE i have an ALS007 somewhere? one thing is for sure, the ALS007 is definitely not the same chip as the ALS100 with a different marking; the Windows drivers have different INF files:

5118 05-15-96 17:41 ALS007.INF
5069 05-15-96 17:36 ALS100.INF

so, uh, maybe the ALS007 is an ALS100 but a little better?? i have no idea honestly. the lineup is incredibly messy and confusing: ALS100, ALS007, ALS100+, ALS120, ALS200, and who knows what else...

Going a bit off-topic here, but no, not better. Only the ALS100 supports high DMA. ALS007 shows same behaviour as ALS100+, so reports as SB16 but, uses same DMA channel for low and high. Some games are OK with that, some aren't.

They share the same DOS driver/init program, you simply don't get the option for high DMA in the 007 where you do in the 100. But I think this discussion would be better continued here: Sound Blaster 16 Clones

appiah4 wrote on 2021-02-25, 21:06:

Not true, a lot of Vibras have hanging note issues. I'm not sure why CT4170 is marked as not having it though. I have one, but never tested it.

Right, I am thinking of the single-cycle DMA clicking bug, which ViBRAs don't seem to exhibit. I don't generally use my SB16s and ViBRA16s as MIDI output devices proper, beyond the on-board OPL3 FM synthesis.
That being said, doesn't the CT4170 use a newer chip with a higher DSP revision, or something? Not that I actually have one to test.

My source regarding the CT4170 HNB is the article on Amoretro:

https://translate.google.com/translate?sl=de& … cts-ct4170.html

You can forget about DSP version information on Retronn - they are mostly copy and paste errors.

Thanks for the replies.
In a offering i saw a screenshot that the card with colored jacks have surely the DSP V4.16.
I won a auction today and got a CT4170 with colored jacks for 10,50 Euros incl. shipping.
I hope the price is ok.
The card seems to be a decent SB 16.
Then i can also check if the card has the clipping issue.
Is there a special audiofile to check it?

anakin94 wrote on 2021-02-26, 14:14:

Then i can also check if the card has the clipping issue.
Is there a special audiofile to check it?

Doom, WarCraft 2 and Skyroads seem to be good test cases for the Vibra distortion bug.

Check here and also here for distortion examples documented by James-F.

anakin94 wrote on 2021-02-26, 14:14:

Then i can also check if the card has the clipping issue.
Is there a special audiofile to check it?

The chaingun in Wolfenstein 3D is also very good to check the clipping issue.

I found it easy to play this WAV file back on the target machine. It is a sine wave with maximum amplitude. It should sound like a soft hum, the same hum as the mains in Europe makes. When your sound card clips, it sounds harsh instead. You can compare with any modern computer, it should play correctly on that.
I find the difference quite distinct, because 50 Hz is low enough that it is barely audible on average speakers, but when it clips it because much louder because the overtones are well within the range of the average retro PC speaker.

Salient wrote on 2021-02-26, 19:55:

The chaingun in Wolfenstein 3D is also very good to check the clipping issue.

Joseph_Joestar wrote on 2021-02-26, 15:05:

Doom, WarCraft 2 and Skyroads seem to be good test cases for the Vibra distortion bug.

Check here and also here for distortion examples documented by James-F.

I can test only Doom, i don't have the other games.
The examples are very clear, interesting.

digistorm wrote on 2021-02-27, 09:55:

I found it easy to play this WAV file back on the target machine. It is a sine wave with maximum amplitude. It should sound like a soft hum, the same hum as the mains in Europe makes. When your sound card clips, it sounds harsh instead. You can compare with any modern computer, it should play correctly on that.
I find the difference quite distinct, because 50 Hz is low enough that it is barely audible on average speakers, but when it clips it because much louder because the overtones are well within the range of the average retro PC speaker.

Great, i will check it out when my card arrived.

anakin94 wrote on 2021-02-27, 10:54:

I can test only Doom, i don't have the other games.
The examples are very clear, interesting.

Skyroads has been made free by the original developer. You can download it from their website.

WarCraft 2 had a shareware demo back in the day. You can still find that demo on archive.org.

Thank you.
Now i'm prepared.