[Coco] Buzzing sound in Arkanoid?

[Steve]

Arkanoid is one of the few CoCo 3 games that uses full analog readings 
from a joystick port while doing full 6-bit audio.  Since both systems 
use the same 6-bit DAC, there is bound to be audio issues.

In most games, the Joystick is treated like a digital input and only 
needs one fast read for each axis.  In the case of Arkanoid, the full 
analog joystick (aka paddle) requires 6 reads to get the value of 0 to 
63 and this takes much longer.

The CoCo has a system of turning off the DAC output to the TV sound.  
This is used so you don't hear the DCA while reading Joysticks or saving 
data via a cassette recorder.  This sound on/off system is not perfect 
because it can make a little "click" sound and this is what you are 
hearing.  The longer you turn off the sound as in full analog joystick 
read, the stronger the click.

But some Cocos, the click is worst than others.  But what makes a real 
difference is the audio system you are using.  Some amps and speakers 
system tend to boost the click sound and this is why you may have never 
noticed the click sound before.

Switching to another sound system or better yet, adding a notch filter 
will fix your audio problem.

Steve Bjork

On 3/12/2014 5:20 AM, jeremy michea wrote:
> Decided to play some coco 3 carts and noticed that Arkanoid seems to 
> emit a bit of a background buzzing sound. Never noticed it before and 
> seems to happen on more than one coco 3 machine so it doesn't seem to 
> be the coco 3's themselves. It's similar to the sound at 24:07 of this 
> video:
>
> https://www.youtube.com/watch?v=--pBWsS867s
>
> Even though it's emulated in the video the sound is similar and only 
> in Arkanoid, not in any other coco carts. Is this normal? Like I said 
> I don't remember hearing this before when playing it. Not many coco 
> arkanoid videos for comparison besides mine (atarileaf) and coco 
> forest which is a filmed screen and hard to hear.
>
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