multi speakers, parallel / series

[mikeoxford]

before you say it! i know i should have another amp "REALLY"

BUT, can i wire a pair of tweeters off the same wires in parallel as say my front door speakers (headunit rated at 45w per channel)

or similary, a second pair of speakers in the rear, where my headunit feeds my 7x10s

and will doing this, or wiring two pairs of tweeters or speakers front or rear or both, gradually shit me headunit up?

tah

mike

[JonL]

If you were gonna run tweeters of the same wires as your in door speakers, you would need a passive crossover, otherwise you won't be able to filter the signal going into the tweeter and it will get all frequencies, not just the high ones it needs/takes.

As for the rear addition of speakers:

Most head units have a resistance of 4 ohms, i.e. the maximum load it can output maximum power at is 4 ohms. Nearly all car speakers are rated at 4 ohms. Also the current draw of the speakers wired ina s one is 12/4 = 3 amps

If you wire the speakers in parallel then the equation is:

1/R1 + 1/R2 = 1/R3
therefore two speakers on 1 channel => 1/4 + 1/4 = 1/2
i.e the load shown to the headunit is too much, this will damage it , Voltage output to the speakers is 12 v, therefore the current draw will be
Current = Voltage/Resistance
6amps = 12/2
6 amps is too high i would say
One good point of parallel is that each speaker would be at the same level cos they'd both be receiving the same voltage, i.e 12v between 2 speakers = 6 volts each


If you were to wire in series the equation is different:

R1 + R2 = R3

therefore two speakers on 1 channel => 4 + 4 = 8
i.e the load shown to the headunit is too little , 8 ohms
Voltage output to the speakers is 12 v, therefore the current draw will be
Current = Voltage/Resistance
1.5amps = 12/8
1.5 amps is fine i would say
A bad point of series is that each speaker would be at a different level cos they'd both be receiving a different voltage, because as you go down the circuit each speaker will progressively drain voltake from the supply so one speaker will be quieter than the other e.g. (all made up figures) 2 speakers = 1 at 4 volts 1 at 8 volts.

Anyway after all this technical crap i would say that if you really want to do it, do it in series, its alot safer for your system, and won't hurt it as much in the long run, best bet is to get a cheap amp or something

HTH

Jon

[Stuart]

get a cross over or another amp.you will screw yer headunit up if you start messing about with series and parallel setups

[carltoncrazy]

depends how expensive ur headunit is,
i brought 1 for a quid of ebay,looks good.for a quid,
ment to run 2x40watts,
currently running 2 front standars+twin 10 inchs subs,
its pretty loud.
who care s if it blows up,its only a quid