I originally posted in this thread
Adding Second Amp to Technic Harness, but felt that although my question is close, I would be jacking a thread.
My statements below are based on what I have heard in my car ('11 335i e93 Premium L7) and articles I have read.
My mid-bass under seat speakers have lost an abundance of sound, because I didn't pay any attention to Frequency Ranges in my upgrades. While trying to retain the mid-range, I also wanted to increase bass response too.
Earthquake SWS-8xi frequency range is 30-200Hz. These are basically a Sub-Bass speakers. Then if you are using the Technics adapter harness, it's frequency range signal is only 30-150Hz. Which makes this a great Harness adapter if you want to add a sub-woofer or a sub-bass to get more kick and punch from your system. No doubt about that.
Now the 4" door mid-range speakers should be starting at about 400hz. So there is a hole in your sound system from 150-400hz. If you check out the charts featured below, it shows that you are missing out on most of the critical frequencies that tie in the bass to the mid-range. Like having cataracts in your ears.
References and charts from DAK.com
Bass
(Approximately 20hz-140hz)
There is little musical material with fundamental frequencies below 60hz. What is normally perceived as low bass material is actually in the 60hz-140hz range. Only a few instruments actually reach this range such as the organ, contrabassoon and string bass.
The 60hz-90hz range is where we notice the greatest perceptible changes in "bass response." Try a test tone and see just how well you hear 20hz or even 32hz, compared with the same volume of 60hz or 90hz.
Mid-Bass
(Approximately 140hz-400hz)
Mid bass has lots of instruments included in its frequency range. Cello (my instrument), Bassoon, French Horn (Freedom Horn this year) and yes Male Voice are all here. This is where most 'bass' controls really muck up your music. Overemphasizing the mid-bass range gives the music a muddy, or "boomy" quality. If the mid-bass region is underemphasized, the music sounds hollow and thin.
Midrange
(Approximately 400hz-2.6khz)
Since our ears are most sensitive to midrange frequencies, midrange has the greatest effect on the overall sound of your stereo system. Actually there is controversy among engineers and audiophiles as to what the proper balance should be in this range. Some settings are best suited to particular types of music.
The "proper" settings are the ones most pleasing to you the listener. I won't list instruments here because virtually all instruments have fundamentals found here in the midrange with the exception of Contra Bassoons, Bass Tuba and a very few others.
Attachment 1012076
Attachment 1012077
After seeing this data and charts, I can use the Technics Adapter Harness to drive the JL Audio 10W3 sub-woofer amplified by my JL Audio JX-500/1D.
I know that the Earthquake SWS-8's don't belong in my set-up. So I now have as set of Kicker SSMB8 4ohm true mid-bass capability of 80-500hz. These speakers will fill in the gap and slightly
cross-over the bass and mid range frequencies for a seamless sound.
The issue is, where do I get the mid-bass signal to amplify and drive them? Or what do I need to get it accomplished?
So, my question is, How do I get a signal to the input of a second amplifier to drive my 8" under seat speakers