Wow, that Creative/Tandy Multimedia Audio Adapter is something that I'd very much liked to try. But one of the cards I'm sure I'll never going to get.

I just had to try CT1770 as well. When I previously tested it, I thought it was much less noisier than I expected. I remember testing some other CT17xx once, maybe CT1740 or CT1750 and it was noisier than later Sound Blasters.

But this CT1770. I think it is very good, even better than the CT1680. No bus noises at all and very little anything else. But it has the DMA clicking bug. Also compared CT1600 and cT1680 again, this time with Pentium Classic and Pentium MMX (previously I had K6-3+ installed). But the CT1600 is noisy and has lots of bus noises and the CPU did not make a difference, at least nothing I could hear.

CT1600 isn't just one card either, there are revisions.

On my SB Pro 2 (CT1600) the "thinking noises" are mostly routed via the FM circuit. If I mute the FM chip in the mixer, the card is considerably less noisy.

Here are better pictures of the CT1600 and CT1680 if someone wants to do comparisons.

CT1600 rev 4

CT1680 rev 1

aitotat wrote on 2023-04-24, 10:35:

Here are better pictures of the CT1600 and CT1680 if someone wants to do comparisons.

Bruno Putzeys wrote a good article about ground connections in circuits with low levels signal (i.e. audio)
https://www.diyaudio.com/community/attachment … ord-pdf.886214/
In short, approaches have changed a lot, and now just an ground plane is absolutely not enough.
It prevents a very bad result when tracing the board, but does not guarantee a perfect result.

Since I recently got a Sound Blaster 16 MCD (CT1750) I figured I'd share my experiences here. In case it matters my particular card seems to be of a slightly later revision as it has DSP v4.12. It also came with the ASP/CSP chip installed, which the SBBASIC.EXE drivers detected automatically, so CSP.SYS was loaded by default.

Anyway, after setting the OPSL and OPSR jumpers to the Line Out position, as instructed by Cloudschatze here, and using his optimized mixer settings, this card has almost no self-noise. It also doesn't pick up any interference over the ISA bus e.g. during heavy disk activity or high CPU utilization. Even the CD audio header doesn't introduce any additional noise that I can hear. So yeah, it's definitively not a "noise blaster" when configured properly.