Looking at the numbers it appears like the first two are the PCB revision and following that is the year and week of that revision.

Keropi had one of both major versions of the PCB some years back. Maybe he knows something about the differences?

Great observation!
It means the CT2600 (19310 and 29323) was released alongside the 07 and 08 revisions of the CT1600.
It also looks like the 07 had a major PCB layout change.

I wonder if there are substantial differences between the CT1600 revisions mainly in the audio path.

EDIT:
Yeah, it would be nice if keropi, gerwin and others will share their experience with the various CT1600 revisions.
I've seen gerwin fixing his bad 14.318Mhz oscillator on the CT1600 with a piece of wire from the motherboard.

PS. I got the 06 revision.

I no longer have the CT1600s I used to own... atm I have a 039151 card - infact I only received it yesterday 😀
is it of any help?

Great.
Yeah, any subjective experience will eventually lead to greater knowledge.
EDIT: What DSP version is the 03?

03->04 branding
04->05 oscillator for OPL
05->06 LS122 in bigger DIP packaging
06->07 major redesign
07->08 moved the model number
That's what jumps out at me.

Would be interesting to compare pre-07 and the revised layout in some detail.

James-F wrote:

By the look of it, only from revision 59 (now marked 1992) the CT1600 had a 14.318Mhz oscillator chip on board, previous revision took the clock from the motherboard(?).

Yes, 14.318MHz is a standard NTSC rate.
The ISA bus has a 14.318 MHz clock signal. The OPL2/OPL3 chip of AdLib/SB cards is timed on this, resulting in the 49716 Hz internal timing for the chip.
The SB has always had a dedicated xtal for the DAC (the thin cylindrical one near the CDROM interface).

That would imply that the 14.318MHz oscillator would only be used for the OPL3 chip on these cards, so if there are any differences in audio, then that's where I'd expect them to be.
I'm not sure why they made this decision. Perhaps as PCs got faster and more advanced, and no longer relied on the 14.318MHz oscillator for their CPU and other parts of the system, the accuracy of the clock signal on the ISA bus got worse, and as a result, the pitch of the OPL3 chip would get detuned somewhat.
In which case, you'd only notice a difference on an 'offending' motherboard. I bet that if you put them in an original IBM PC or XT, you wouldn't be able to tell the difference.

Oh, also a funny tidbit of information:
Early SB/SB Pro cards would come from the factory configured to IRQ7.
Later they changed this to IRQ5.
It seems like the 39 card was probably reconfigured to IRQ5 at some point.
The 49 one is still at IRQ7. The others are at IRQ5, which may be the factory default for these cards.

I say: put them on IRQ7. That's where the SB should be. There are a few games that are hardcoded to IRQ7, and simply won't play sound effects when you have IRQ5 configured. Stellar 7 is one of them, IIRC.

James-F wrote:

[...]
EDIT: What DSP version is the 39?

V301
tested with Halloween Harry just to be sure, it's OK 🤣

Different model, but might be of interest.

Scali wrote:

I say: put them on IRQ7. That's where the SB should be. There are a few games that are hardcoded to IRQ7, and simply won't play sound effects when you have IRQ5 configured. Stellar 7 is one of them, IIRC.

I agree 100%.
I assume nobody uses a parallel port printer these days, I know I don't.

keropi wrote:

V301
tested with Halloween Harry just to be sure, it's OK 🤣

🤣 , no clicking I assume. 🤣
Can you suggest a quick way (small soft) to check the DSP?

PhilsComputerLab wrote:

Different model, but might be of interest.

Thanks.
Looks close to the 06 with the new CT1336A chip but still the old CT1345 mixer chip.

James-F wrote:

[...]
🤣 , no clicking I assume. 🤣
Can you suggest a quick way (small soft) to check the DSP?

Yes, no clicking at all, same deal like the CT1350/CT1320

What do you mean? a program to display the DSP version?

SBCHECK might give you some info.

version 3.00 (2.7 Kbytes) determines Sound Blaster and clone compatibility with Daqarta .ADC drivers. Identifies Creative Labs Sound Blaster models by DSP version, plus CT417x ViBRA / WavEffects enhanced features. Also identifies ESS models and Media Vision Thunder Board. Now reads BLASTER environment string to get address, if not given on invocation.

http://www.daqarta.com/sbcheck.exe

kixs wrote:

SBCHECK might give you some info.

Perfect! Thank you!
I'll attach it to the first post.

It' will be great to map all DSP versions to the CT1600 Revisions.
I will update the first post.

I never ever saw a DSP version that was differing from the laser engraved version number on the microcontroller. So I assume one doesn't need a tool to readout the DSP version. One look at the IC is enough.

When it comes to the different SB Pro2 models, the CT2600 (Mitsumi CD-Interface) sounds best IMO. It may not be coincidence that it is the latest Pro2 that hit the market. Therefore, all CT2600 also feature the newer hardware mixer chip with the "S"-revision. There also are 2 different PCB qualities. One very highend looking and one that looks more like the CT1600 PCB. But the layout and components seem to be the same on both different PCBs.

The CT2600 029323 was out before the 07 redesign of the CT1600, and the two look very similar aside from the CD interface half. Same chips, same layout, some minor differences in other components.
The earlier CT2600, 019310, has the old mixer and layout similar to the 05 CT1600: http://jippel.de/sound/sound12.jpg.

Well I meant the Mitsumi-Interface version was the last realeased version, after Panasonic, Sony, SCSI and so on.

firage wrote:

The earlier CT2600, 019310, has the old mixer and layout similar to the 05 CT1600: http://jippel.de/sound/sound12.jpg.

More like a 06 with the small ceramic cap above the CT1336A Bus Interface.

That's interesting. There is another version with a different quality PCB and the "S" mixer.

James-F wrote:

firage wrote:

The earlier CT2600, 019310, has the old mixer and layout similar to the 59 CT1600: http://jippel.de/sound/sound12.jpg.

More like a 69 with the small ceramic cap above the CT1336A Bus Interface.

Right, quite. 😀

Trying to find photos of CT2600's revisions, but that's about the best one for the 02 http://www.delcolle.sk/wp-content/uploads/pho … ds/IMG_9072.jpg