Quote:
Originally Posted by bigaudiofanat
You can run speakers with the bose amp however it is going to cause it to fail overtime as the ohms load is different. It is like saying I ran 4 ohm speakers off a HT receiver that is only made to go to 8 ohms. It will run them but it will not do it efficiently and cause a lot more heat. You should run new speaker wire as well to bypass the factory crossovers. Just a little info  |
OK,
Bose spkrs are typically very low ohmage to maximize the power from the 12V rail. If you connect higher ohmage speakers then the available voltage is divided across a higher impedance/resistance, causing less power to be available from the amplifier. P = V2/R, so if the voltage stays the same (relatively speaking) then a larger value for R produces a lower power number. All modern car amps have switch mode supplies that take the 12-14V and produce for instance, two rails, say +42 and -42, this allows the amplifier to produce higher power using just 12-14 Volts DC input.
Bose typically doesn't do this, they use say .45 ohm speakers with 12-14V and since P = V2/R then since the Bose amp is swinging between 12-6 and 6 to 0, (center line is ~6V) then you get approx. 6V x 6V / .45 for a theoretical 80 watts, but I'm not sure what the Bose drivers in the car actually measure, BAF I'm sure knows the Bose driver rated impedance...
PS: Without going into crossover design, running any impedance other than what xover is designed for ruins the intended frequency content of the original xover to the new driver, moving it waaaay up or waaaay down, either way sounding bad. ( to some people, not to others, YMMV).
Running higher impedance speakers (bigger R number) only lessens the power output, running speakers with lower rated impedance can cause the R number to get too low and cause the power to exceed the heatsink capability of the amplifier, causing repeated thermal events and eventually damaging the amplifier.
The end goal is to select speakers that match the ideal load for the amplifier, that produce the desired frequency response, and hopefully you've selected speakers with high efficiency, i.e., if you have speakers that are 90 dB efficiency, then if you substitute 93 dB speakers, it's like getting twice the sound pressure level with the same speaker.
Also, if you have one 90 dB efficiency speaker and add another 90 dB speaker, then your SPL level will increase 3 dB.
I know this is like that person who you ask what time it is, and he tells you how a clock works! I just like folks to know how stuff actually works so they can separate fact from fiction.