Impedance issue adding speakers to car

So i have four 6.5" woofers that came out of some yamaha ns-300 towers. I want to fit them in place of stock speakers in my ford ranger front and rear doors and maybe fit an amp that gives 180watts at 2 ohms. The issue i have, is that the yamaha drivers are 12ohm impedance, which is too high. The doors have tweeters in them which as far as i can make out from researching, are 4ohm with capacitor added for crossover.
If i wire the woofer and tweeter in parallel, according to parallel speaker calculator i will get total impedance of 3 ohms which is great and 120watts total power from amp, but the issue is, that it says the power will be shared at 30watts to woofer and 90 watts to tweeter. So either will blow tweeter or at least will have very weak woofer output and massive top end.

Does anyone know a way around this?
Ive seen it is possible to put high power resistor across woofer but would lose sound quality. I wondered if it may be possible to remove voice coil from some old 100wat 8ohm speakers i have and put it across the woofer? That would give me 2.18ohms total imp and share power at 75woofer 90tweeter which is better.
Dont know if its possible to do that.

Does anyone in the know have any ideas?

Ideally i want to get a 4 channel amp and have a woofer and tweeter on each channel. Any help would be gratefully accepted. Cheers
 
Yea i wondered about a series resitor between woofer and tweeter. In theory that would reduce the power going to the tweeter. Not sure what value and power of resistor i would need tho. Would i just add the resistance to the impedance of the tweeter and work it out as whatever value that is in parallel with my 12ohm speaker. So if i added an 8ohm resistor in series with the tweeter would that effectively make my tweeter 12ohm, so in parallel with 12 ohm woofer would give me 6ohm total with 50/50 share of power.
 
This isn't a perfect world and you have to make compromises where resources aren't infinite.

I don't know what you consider a loss in quality. Adding the resistance in series with the tweeter could make is sound better or worse, depending on the tweeter and it's impedance curve... and your preferred overall sound.

The power sharing with the series resistor would share power equally woofer vs tweeter circuit but the tweeter wouldn't get 50% of the power. The resistor would be wasting much of the power.

Have you asked around to see if you had a friend that had a small amp they would give you (or sell it to you for cheap)?

The L-pad is used (when all terminals are used) when you have a passive crossover and don't want the frequency of the tweeter/midrange to drift, due to the change in impedance (due to the series resistance) of the circuit.
 
  • Like
Reactions: Audio>X
I do have an old 2 ch amp that is 180W peak into 2 ohms. I was going to use it as a test bed. I have an impedance meter so i can use that to see my true Z.
Maybe a proper 2 way passive xover is way to go, but would need 4. My headend has no built in xover. Stock system is obv designed to work with tweeter and woofer combination.
It was just an idea really as the yamaha speakers ive got are good quality and didnt want to spend a lot of money on it.
 
No it only has settings for hp or lp filters on each channel, so would work if i use one chanel as lf output and other channel for hf, but then im using 2 channels just to drive one set of speakers. Realistically not gonna work for all 4 sets.
 
The speaker only provides an impedance load to the amplifier in the frequency range its operating in.

So. If you have a 12 ohm speaker playing to 3k and a 4 ohm tweeter playing from 3k+. You're still only loading the amplifier with 12 ohms at low frequencies.

Adding a resistor just to load the amp to make more power doesn't make sense. The amplifier output voltage won't increase by adding the resistor. It will draw more current. Which creates more distortion. The extra current being supplied by the amplifier will just be dissipated by the resistor.

Just run it as is until you can find some proper speakers. Midbass speakers don't need as much power as you think. People used to run a single 50wpc amp to their entire system including woofer in the 90s.

If that speaker is 12 ohms. It's probably not designed to take much power anyways.
 
Today car speakers and amplifiers are designed to be Low impedance & High current.
For results you would like, I would not use the Yamaha woofers at all.
Stick with 4 ohm drivers intended for the use of Car Audio 🙂
PS.
You could use the Yamaha woofers for a new & interesting 'non car' speaker project.
 
Last edited:
  • Like
Reactions: sesebe