SID still sound after a note off?

[tom303]

When i play a note i still hear the tone after the note off. Very quiet but the sound is still there.  ???

It's like the gate is not closing totaly.  :-/

Anyone know what this could be?

Greetings,

Thomas

[Dr_Nick]

Hi Thomas!

The sound leakage of the SID chip is a known problem.

Back when the chip was designed, Bob Yannes (the creator of the SID) had only little time to develop it. Even though the SID is quite a remarkable little device, it has it's flaws.

Bob Yannes once said in an interview:

"If I had had more time, I would have developed a proper MOS op-amp which would have eliminated the signal leakage which occurred when the volume of the voice was supposed to be zero. This lead to poor signal-to-noise ratio, although it could be dealt with by stopping the oscillator."

So probably Thorsten could add some code to stop the oscillator if no notes are played.

If you want to know more about the history of the SID, you should check out the complete interview with Bob Yannes at http://stud4.tuwien.ac.at/~e9426444/yannes.html

Regards,

Dr. Nick.

[tom303]

Thanx,

then i don't have to search for a problem in the circuit. - Cool.  :D

Maybe there is a way to add a hardware gate addon that close the output when the signal is lower than...?!

Regards,

Thomas

[TK.]

...do you really want to disable this unique feature of the SID? Shame on you!  ;)

Best Regards, Thorsten.

[tom303]

Ok, but a SID bug on/off would be nice.... :D

Best regards,

Thomas