Contour Enthusiasts Group Archives Forums Modifications Audio Rethinking subs again..need advice

Have you considered rebuilding the box and using the two speakers in an Isobaric configuration mounted face to face ?? When you run speakers arranged isobarically, you effectively cut the Vas in half, and since you are now running one speaker in the box, the effect is similar to inceasing box size by a factor of X4. What does the data sheet say about running one sub in a 4.4 CuFt box ?/

You can still run both speakers in parallel. If you mount them face-to-face remember to reverse the polarity of one speaker so the cones are moving in sync.

You will see much larger cone excursions than you are getting now. This isn't an ideal solution but it might be worth trying, if you want to trade output for extended bass.

Dave, how about an Alpine Type-R (4ohm DVC)?

Otherwise, I'm just about stumped.

I'm still doing some checking. I won't give up!

One correction to my previous post. Two speakers configured in an isobaric alignment in a 1.1 CuFt box should behave similar (with regard to box volume) as one speaker in a 1.1 CuFt box. With your current box you have 0.55 CuFt per speaker.

Damn, I am tired and keep making typos, then I can't edit them because I don't catch them 'til later. What I should have written in the original post was:

"Two speakers configured in an isobaric alignment in a 1.1 CuFt box should behave similar (with regard to box volume) as one speaker in a 2.2 CuFt box."

Next time I'll get enough sleep before loging on.

Well, I am almost convinced that you have selected the best subs for your current box, output requirements, and amp. It seems the only thing that's missing is those low frequencies in the area of 40Hz, which are lacking due to the small box size.

I've thought of another option which will allow you to keep your current subs, box, and amp:

Audiocontrol Epicenter

With the Epicenter and its frequency and sweep adjustable bass boost, you should be able to dial the extreme low bass frequencies back into your system. It'll probably take a while and pleanty of experimentation to get it dialed in just right, but I think it might be the ticket.

I haven't used one myself, but every report/review I've heard on the Epicenter has been very good.

BTW, I'm also assuming you've got the boxes heavily stuffed with polyfil, acoustastuff, or equivalent. It'll make the subs think they're in a bigger box and help to improve the low bass frequencies.

cthomp21 - Thanks so much for all your help.

The Epicenter looks really sweet and is within my budget. My only qustion is if it can really overcome the premature roll off inherant with my small box. It is my assumption that the Epicenter increases the signal at the low frequencies my system struggles with. Even with a stronger signal, is my box physically capable of playing 20-40hz bass?

Also, how can I calculate the f3 of my box (factoring in driver displacement .55 cuft3/woofer). The parameters in WIN ISD seem to be way off and when I enter my own things only look worse.

WinISD doesn't take cabin gain into account, so those graphs are probably pretty close.

Yes, you're assuming correctly. The Epicenter will boost the low bass frequencies your current box/configuration is hindering.

I can't really say difinatively how effective it will be. With the adjustments available, you should be able to produce a pretty flat in-cabin response down to its built-in subsonic frequency filter of 37Hz. You can also change the subsonic filter if you find it's too high.

The only drawback that I can see (Dave? Anything you can think of?) might be a slight decrease in the output due to the driver's higher excursions producing the low frequencies.

What I really like about the Epicenter unit is that it's completely adjustable. You can change the boost frequency, boost amount, and affected frequencies. The FPM (subsonic filter) should also help the amp put power into only audible frequencies (bass requires pleanty of juice).

After researching all of this I'm thinking of buying one for my truck. I've got a single IDQ10 in a very small box (only .4ft^3) that I'd like to reach a little deeper too. They seem to go for around $75 used on ebay, and I see them quite often on www.carsound.com in the classified section.

I'd be glad to be the guinea pig, but you'll have to wait a few months until it warms up and I tear my truck apart again.

-Colin

I just found this at PE. If I added one of these to box, would act as though it had a larger volume and thus reach lower before rolling off? I can't imagine something so simple would work...but if it did

The Scan Speak Vent is an air flow resistant, "aperiodic" damping device very useful in sealed box applications. It works by reducing the maximum impedance at the box resonance by at least 50%. This results in clearer, better defined bass, with more amplifier power and control into the lower frequencies. It also allows the use of a driver in a smaller than optimum sealed enclosure. The vent should be mounted to the cabinet back wall in a 4-5/16" (110mm) diameter hole. About 60% of the cabinet volume should be filled with damping material, being careful to leave an open path from woofer rear to the vent device. For enclosure volumes up to 1.75 cu. ft., one vent is required.

http://www.partsexpress.com/pe/showdetl.cfm?&User_ID=13501064&St=3695&St2=70038773&St3=60766601&DS_ID=3&Product_ID=7832&DID=7

Dave, is it possible that I have stumped you?