Mixer and High-Pitch-noise [solved!]

I post this also on AW.net:

I figured out that whenever starting Mixer, it set up a high-pichting-noise on the left Audio-Channel. You can hear it when wearing Headphones and turn your Amplifiers Volume to 50% Volume.

Maybe it set some registers on the SAM440ep Soundchip?

I had similar problem almost since the first Mixer version i tried (Sam Flex 800 here) so if i have for example TuneNet open with a song in playing and then i open Mixer, my volume will go up ...

Check what the mixer is actually mixing.

Perhaps you are hearing interference from an unconnected CD input? (or aux or whatever other unused input's you have?)

Mute anything you are not using.

Ok, i will try that and inform here what was the reason.

There was another discussion somewhere(?) about Mixer.
Mixer and AHI are independent of one another. In simple terms
the mixer controls/modifies the hardware registers for input and
AHI is looking at the hardware output.

So when you start Mixer it changes the values in the hardware and
of course this is reflected in the AHI output. Known issues.

A temporary solution that I'm using is to start Mixer, start AmigaAmp3,
start playing a small mp3, move the PCM slider on mixer just slightly,
stop Play on AmigaAmp. This holds a channel open in AHI and stops those
annoying POPS whenever a new sound stream starts. It's also a pain in
the neck.

If you check AmigaAmp prefs>Audio, you will see a setting for-Keep AHI
Unit Open.

I do not have, and can't make my system, produce this nasty noise on
either channel. It could also be a bad shield somewhere in the wiring,
but you have probably ruled that out already.

Of course an easy solution to that left side noise is to turn the headphones
around.

Side note*

Would anybody like to try Timidity? I've done some work on the configuration
files and it should be easier to setup properly now. I would have to email
you a file.

I got the same with the onboard via686b audio chip on the XE board, although its not a high pitch but just a loud dissortion when the chip gets initialized.

I have set everything not needed to MUTE, need to try to set all of the channels to MUTE for testing but i fear the dissortion comes from the hardware and not Mixer

I have now found out that the AUX-Input made this terrible high-pitch noise, if i mute this input-channel all right now!

Did you have anything connected to this input?

Best regards,

Niels

@fingus

Ahh, thanks for the hint, it was AUX for me aswell
Dissortion and crackling on startup gone

edit: too early, dissortion comes from the hardware and not from Mixer.
Mixer kicks in much later after the crackling is already done.
I remember Davey telling me no chance of fixing it on the XE, ah well

@nbache

It doesn't matter (for me at least).
I had nothing plugged in AUX and i got the dissortion.
Right now i have the cable from the double SID chipped Catweazle on and still get the crackling/dissortion on startup, but now it's muted.

I only unmute AUX when i start VICE (specially built version to use the SID chips) - with a special script that unmutes AUX in Mixer and mutes it again when it quits - otherwise i get a very bad bus noise, even on moving a window around, which can only be silenced by setting the volume for AUX in mixer to lowest or mute

Quote:

No.
On The Sam440ep is it a pin-header on the Motherboard. Maybe a missing Grounding cause this, because there´s nothing connected to it (No Cable or Jack...)