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| Interesting audio issue |
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| Breaker:
Hello all, I've just noticed an odd issue with the audio on my (almost) completed CAB. While doing some final testing of my wiring I noticed what sounded like a high-pitched whine from my speakers while playing some games. After further testing I noticed that the whine was synchronized with the 'Numlock' indicator on my keyboard. As a result I surmised that the whine was related to those games with lighted Player 1 and Player 2 switches. The whine is not present when I first start up a game (using MAMEWAH) but, as soon as I coin-up, the whine changes to a beeping which coincides with the flashing of the Player 1 and/or Player 2 start buttons; once I press Player 1/2 to begin a game the beep changes to a steady whine (for those games that keep the Player button on during the game). At this point it seems like my audio system is somehow picking up a tone related to the LED control feature on my IPAC. I thought I'd post to see if anyone else has experienced this problem and has a solution? Anyone have any thoughts? Cheers, Breaker. |
| NickG:
Some stuff to try: --eliminate suspicion of an audio system ground loop by temporarily substituting unamplified headphones. --eliminate suspicion of the keyboard and the Ipac by removing them temporarily from the system. --still hear it? It may be motherboard related, especially if you are using onboard sound. install a dedicated sound card. Sometimes this can stop (nearly eliminate) chip-set crosstalk. If you are still using that old broken ASUS board then you cannot do this step, but, well, there you are. |
| Breaker:
Thanks NickG, Here are the results of some further testing: a) if I eliminate MAME/MAMEWAH by going into Windows and hitting the 'numlock' key while IPAC is connected-> whine is present b) if I disconnect the IPAC and connect the keyboard directly to the computer -> 'numlock' produces no whine c) unamplified speakers (using MAME/MAMEWAH/IPAC) -> no whine I should note that I am using a set of Logitech speaker and have hacked the remote that comes with the set in order to place a volume control on my CP. At this point it looks like it's a combination of a bad ground and/or something the IPAC is kicking out when it turns on the 'numlock' LED on the keyboard. One last test will be to attach a different (unhacked) set of amplified speakers and give it a try. If the whine persists, it points to the IPAC, if it goes away it must be my hack job. I'll do some more testing and report back. Breaker |
| Breaker:
...OK, IO tried another set of amplified speaker (with MAME/MAMEWAH/IPAC) and no whining. Looks like my hack is the issue...hopefully I can return the remote control to it's original state and use Oscar's volume control design instead. Breaker. |
| Zebidee:
You could try using USB for your IPAC instead of PS2. USB has better 5v reliability, apparently. Might be too much hassle though. |
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