l 2, it would be OCR1B.</span></div><div class="line"><a name="l00020"></a><span class="lineno">   20</span>&#160;<span class="preprocessor">#</span><span class="preprocessor">define</span> <span class="preprocessor">AUDIO_CHANNEL_1_OUTPUT_REGISTER</span> <span class="preprocessor">OCR1A</span></div><div class="line"><a name="l00021"></a><span class="lineno">   21</span>&#160;</div><div class="line"><a name="l00022"></a><span class="lineno">   22</span>&#160;<span class="preprocessor">#</span><span class="p