Reply 260 of 354, by 640K!enough
darry wrote on 2020-10-29, 01:58:
The DreamBlaster X2, when playing through the Orpheus digital out actually has more audible noise than when playing through the Orpheus analogue out . To be clear, I do need to apply a high degree of gain on my headphone output to perceive a difference. The noise, which is present even when nothing is playing and muting the synth mixer input eliminates it (all other analogue inputs are already muted).
This may be entirely avoidable. There are a few possible sources of this noise, and they should be mostly manageable in software.
The CS4237 offers quite a range of gain values on most audio sources, but beyond a certain point, it is analogue amplification, which tends to introduce a certain amount of noise. I don't think there is any amount of careful layout/routing work that will eliminate that, but managing the range of available values in software should help. Have you been using UNISOUND exclusively for DOS?
The other problem is, in part, due to the fact that the CS4248 and CS423x lines have quite a long history, with new features regularly "stapled" on (sometimes somewhat awkwardly), in an effort to preserve "perfect" compatibility. In general, this works relatively well, but creates challenges when trying to manage the later chips' features to extract more quality and capability. When using software that mostly treats the chip as one of its predecessors (like Crystal's own tools) or takes certain shortcuts (because that's "good enough"), the result can be added noise. Managing the register values carefully can go a long way toward minimising that noise, but can be a rather tedious process to find just the right balance of quality, features and simplicity (for the people who will use the card, not its creators).
So, if you've been using CWDMIX for DOS, stop that! 😀 That nasty kludge can be a source of all sorts of noise. The next thing to try for now is to reduce the input volume on the synth/wavetable header to a maximum of a few notches (or percentage points) below maximum. See if that helps a little. If you have time to test some more, please continue sharing your experiences. All constructive feedback is helpful.