Hi -
First post, so let me add some disclaimers....
Not an engineer
Am a dedicated tinkerer
Have let the magic smoke out of stuff a few times
Sometimes am more brave than smart
OK, I bought an AmpliRider for use on my motorcycle, the better to hear the MP3 player in my Nuvi 750.
It's a great piece of equipment, but I thought it would be nice if it gave me a bit more volume. I'm using Iasus X2S speakers in my helmet.
Reviewing how it was built, it uses a LM1117 chip for voltage regulation and a 4881 chip for audio amp. When I looked over the data sheet for the 1117, I noticed that the chip being used was a 2.5V Vout. The data sheet for the 4881 shows that the max rated output (200mW) is obtained with a 5V supply.
I noticed that when I turned the thing full up that there was significant distortion and it wasn't the speakers, which are rated at 500mW. I felt I must be overdriving the amplifier's input and could use a bit more headroom.
I replaced the 1117 with a 5V regulator and it seems I've gotten the results I was looking for. The fidelity seems as good as it was before (fidelity is a very relative term in a motorcycle application...) and I can't find any bad efffects. Volume is noticably increased. None of the components is getting hot, and all the magic smoke has stayed inside.
I tried to search for this or a similar topic, but found nothing. Apologies if this has been explored before - it seems like an obvious thing, so I almost feel it must have been.
Any thoughts are comments on this? Any conjecture as to why the thing was designed with a 2.5V supply? Is there a down side to this that I, as a sort of self educated tinkerer, don't understand?
Thanks,
PF
Edited by Irish - 11/10/10 at 11:55am
