I have bought a little micro class D amp for my car 4 x 65 w rms ( vibe powerbox 65.4 )
the amp connects to the speaker outputs on the head unit then boosts the output to the speakers the amp is 4 ohms stable
But the problem is my car front factory fit speakers each side piggy backs of a sub under the seat see hand drawn pic
so the amp sees 2 ohms and at high level starts to distort the door speakers
seeing the door speakers have a bult in crossover the 4.7uf caps i only need a 2 way 4 ohms crossover which i can connect near the subs which is what the head unit feeds first
would the last pic be any good ?
20240110_165346 by glenn jarrett, on Flickr
20240111_120059 by glenn jarrett, on Flickr
20240111_122530 by glenn jarrett, on Flickr
the amp connects to the speaker outputs on the head unit then boosts the output to the speakers the amp is 4 ohms stable
But the problem is my car front factory fit speakers each side piggy backs of a sub under the seat see hand drawn pic
so the amp sees 2 ohms and at high level starts to distort the door speakers
seeing the door speakers have a bult in crossover the 4.7uf caps i only need a 2 way 4 ohms crossover which i can connect near the subs which is what the head unit feeds first
would the last pic be any good ?
20240110_165346 by glenn jarrett, on Flickr20240111_120059 by glenn jarrett, on Flickr20240111_122530 by glenn jarrett, on Flickr
Yes, that seems the way to go.
The least you need is a capacitor in series with the mid (between sub and mid) as well as the one in series with the tweeter.
Are you in the position to calculate the component values?
Last edited:
It appears from your sketch that the mid (4.5" door speaker) is currently unprotected from the bass frequencies by a capacitor.
That would explain the distortion the door speakers are experiencing.
You can try simply placing a capacitor between the sub and the mid (4.5" door speaker). I'll come back with a suggested value.
That would explain the distortion the door speakers are experiencing.
You can try simply placing a capacitor between the sub and the mid (4.5" door speaker). I'll come back with a suggested value.
I can't find any info on the subs but the mids say 140hz
could I use an online crossover calculator
this is what i intend to do but not sure how to work out the values crossover freq etc
20240111_155552 by glenn jarrett, on Flickr
could I use an online crossover calculator
this is what i intend to do but not sure how to work out the values crossover freq etc
20240111_155552 by glenn jarrett, on Flickr
You could simply try a single 100 uF non-polar electrolytic capacitor in series with the mid.
The impedance seen by the amp will be that of the sub, i.e., 4 ohm.
The impedance seen by the amp will be that of the sub, i.e., 4 ohm.
I assume the capacitors in the pic are non-polar, AKA bi-polar, as indicated by the BP printed on the side.
Give them a try. We can look at the more complex solution if required.
Give them a try. We can look at the more complex solution if required.
Here is a suitable calculator if you wish to go down the more complex path:
https://www.omnicalculator.com/physics/crossover
Select Number of speakers 3, 1st Order, 4 ohm, low crossover frequency 300 Hz, high crossover frequency 4000 Hz and 3.0 octaves.
The nearest standard component values would be:
C1 = 10 uF (although the current 4.7 uF may be preferable).
C2 = 82 uF
L1 = 0.15 mH
L2 = 1.2 mH
And a UK supplier:
https://willys-hifi.com/collections/electrolytic-capacitors-non-polarised
https://willys-hifi.com/products/monacor-audio-inductors-air-core-1mm-ofc?variant=33569754480699
That's probably overkill for your application, but you now have the information you asked for! 😎
Last edited: