Stan, a little more info. As per your suggestion, I used a 3906 and got a somewhat different result. The player played ok during it's cycle, but was still very noisy. I then played around with the player ground connection. When connected to my breadboard ground, noisy; when connected directly to an Arduino ground pin much less noisy;, and when connected to the power supply ground very little noise.
Now for the problem I can't explain. During the non-play cycle (5 sec.), the speaker clicks loudly at about a 1 Hz rate. I changed my simple program to power the Arduino and only have the output turn the transistor off--no speaker 1 Hz pops. As soon as I cycle the transistor on/off with the 5 sec. delays, the pops are back during the off cycle. I just measured the Arduino output pin state (connected to the transistor base thru the 500 ohm resistor) and it is ~ 0.17V when LOW and ~3.99V when HIGH. I don't have a scope so that's the best I can do. The only other thing I can try is to power the player/amp via a relay and use the Arduino to control the relay. If the relay chatters, I will know the problem is with the Arduino. I've included a couple pics of my 'kluge', & the Sparkfun Arudino I am using.
