[sak333]

Hi, ive got logic 7 underseat subwoofers(2ohms) that are wired in parallel to door speakers(4ohms) as standard powered by a vibe powerbox 65.4 amp but the door speakers are making “farting/clipping noise” even after i upgraded the speakers. More so the front than the front left.

Im assuming because the logic 7 are pulling to much current which runs through the 4ohm speakers.
Is this correct?

If it helps i have the base audio system with a professional headunit.

Amp spec
Frequency Response - 20Hz-20KHz
Peak Power - 520 Watts
RMS Power - 4 x 65W

Also would anyone like to swap subwoofers with me must be 4 ohm.


Thanks

[sfinxvc]

You're probably just over-taxing the amp.

4 ohms and 2 ohms in parallel is 1.33 ohms, this is what your amp "sees" but it's rated only for 4 ohms.

If you want to parallel two speakers and end up with the 4 ohm load your amp can drive, you want 8 ohm speakers.

The general rule of thumb is to halve impedance and add 6db sensitivity for speakers in parallel, provided the amp can push that halved impedance.

This is the formula for calculating impedance when combining speakers...

[ctuna]

Split the front channels so the doors and floors are not in parallel
and run one channel of the amp to each speaker location.
This is a standard lower cost solution to the base system.
Forget amping the rears if you aren't going to buy a 6 channels amp.

https://www.e90post.com/forums/showthread.php?t=1816904

Read this so many similar threads.
links in entry 7

[sak333]

Originally Posted by sfinxvc

You're probably just over-taxing the amp.

4 ohms and 2 ohms in parallel is 1.33 ohms, this is what your amp "sees" but it's rated only for 4 ohms.

If you want to parallel two speakers and end up with the 4 ohm load your amp can drive, you want 8 ohm speakers.

The general rule of thumb is to halve impedance and add 6db sensitivity for speakers in parallel, provided the amp can push that halved impedance.

This is the formula for calculating impedance when combining speakers...

I might just try a 4 ohm sub see if the amp can handle it. Anyone know any cheap easy to fit sub under the seat. I dont want to buy new door speakers because i just bought a pair of eton’s.

I have logic 7 subs if anyone wants to swap..?

[sak333]

Originally Posted by ctuna

Split the front channels so the doors and floors are not in parallel
and run one channel of the amp to each speaker location.
This is a standard lower cost solution to the base system.
Forget amping the rears if you aren't going to buy a 6 channels amp.

https://www.e90post.com/forums/showthread.php?t=1816904

Read this so many similar threads.
links in entry 7

This seems abit too technically advanced for me.


Thank you for the reply guys

[BMW33]

Originally Posted by sak333

I might just try a 4 ohm sub see if the amp can handle it. Anyone know any cheap easy to fit sub under the seat. I dont want to buy new door speakers because i just bought a pair of eton’s.

I have logic 7 subs if anyone wants to swap..?

Did you ever get to the bottom of this issue? I'm in somewhat a similar situation.

I have vibe amp 65.4m and have changed the door speakers to two way ground zero 60rms ones so far and when I turn up the gain anything more than a quarter I seem to get the same clipping noise as I increase the volume. It's coming from the speakers not the subs.

I have tried playing around with it but cant seem to see what's happening.