Need to smooth upper bass of sub response...

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....I'm using an Adire Tumult with my Magnepan MGIIIA speakers. They complement each other much better then my last setup of my 100 db PA speakers and the Tumult. The Maggies are in the range of 85 dB efficiecy and I believe the Tumult is right around there. Im now using an Adcom GFA2535 4 channel amp with 2 of the channels bridged running the 2 voice coils of the Tumult in series. I'm using this configuration because this ensures both voice coils are getting = power and material.

The sound- well takes some getting used to since I'm used to the extreme power of the PA system that was there before hand. This system is much more detailed and bad recordings are much more obvious. Also the amplifier is dead quiet, unlike the PA amps which had fans that turn on and buzzing huge iron core transformers. I kinda miss the punch and slam of the PA system but this system is geared entirely different.

Now, heres what I'm getting at- from listening and from my RTA the upper bass is kinda weak. My X over is 90 Hz with a Linkwitz-Riley alignment. 60 Hz comes up kinda weak (it did in the car too when I used this woofer in the car), as indicated by RTA and my ears. I want to boost this up. Should I make the box smaller?

The box is sealed, its a sonotube enclosure. 2.5 cubic foot after driver displacement. And I did do the phase reversal to make sure it wasnt phase cancellation.
 
My guess is that you're discovering the difficulty of successfully mating two different technologies of speaker, ribbon vs. dynamic, line source vs. point source...etc.

Check out the difficulty in measuring the true response of the Magnepan in a room, and you'll get an idea of what you are in for. Don't get stuck on setting the high-pass and lowpass xovers at the same frequency or slope, and be prepared to experiment A LOT.

http://www.stereophile.com/showarchives.cgi?303:6

Scott
 
Yeah I'm actually replacing my old sub that I had going for the past 5 years. It was a 12" Cerwin-Vega car audio sub, but I tuned it to "home audio" specifications in a 5 cubic foot vented sonotube enclosure. Surprisingly, it integrated very well and I was very happy with the sound to my ears and on RTA. I might redo that enclosure again as I pasted 2 sections of tube together.

Right now, the 2 different types of speaker is painfully obvious. Theres alot of 50 hz and below energy, so everything rumbles and you can feel that subsonic energy. Its fine for movies, but listening to other music where you expect the "punchiness" in the upper bass, with the Tumult's lack of 60 hz and the maggie's dipolar nature, the sound just doesnt integrate. Its even worse on music that contains a variety of bass material.
 
Why not try the Tumult as a dipole?

Just build a simple baffle like the one here:

http://www.linkwitzlab.com/proto.htm#PW1

Of course you'd need two if you want to go stereo, plus dipole EQ, but just this simple baffle will give you an idea what to expect.

IMHO, you will get better results by having the same radiation patterns throughout the range, and dipole bass is excellent in any case.

Steve
 
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