[XtremeRevolution]

Talk to any experienced SQ car audio guy and he'll tell you: cone area is king. The more cone area you can afford, the better. Think about an indoor rock concert. You have a 22" kick drum that pounds away and PA speakers that send shockwaves through you with tight, precise bass that you can feel in your jeans. The only way to really reproduce that effect is to get more cone area.

Take the Image Dynamics IDQ15 V2 for example; it's one of the best SQ subs built in the last 10 years. Low moving mass, great motor strength, incredible frequency band, and works in 1.55 cubic feet! That's 1.55 cubic feet, for 840 square cm of cone area! There are some 10" SQ subs out there that need 1.8-2.0 cubic feet, and those are half the cone area. With a typical 8" sub coming in at 220 cm2, a 10" sub coming in at around 330-350 cm2 and a 12" sub coming in at around 480-520 square cm, you really start to appreciate the air hammer that 840 cm2 can be.

Still, even with the likes of the IDQ15 V2 working in such a small box, you find out that if you want to get louder, you still need a big box. Two IDQ15 V2s are 3.1 cubic feet. That's a lot of box, and a lot of weight. Still a lot of cone area, and you'll probably get the impact you're looking for at incredibly high volumes.

But what if you're crazy? And I don't mean crazy in the sense of wanting a ported box, one note wonder SPL sub that will make you vomit and break your windshield glass with a 40hz tone. I mean crazy in the sense of "maybe 1680 cm2 of cone area just isn't enough." Maybe you don't want to feel an air hammer when a kick drum beats. Maybe you want to feel freight train-sized kick drums. Maybe you want to feel like you're in the first row of a rock concert.

If that's who you are, then maybe...just maybe...you might understand why my IDQ15 is getting sold and is being replaced with not one, but two 18" Peavey "Black Widow" Low Rider subwoofers.

 

[tecollins1]

AND IT BEGINS!

:bowing:

 

[4piecekit]

18? Wow. I can only imagine that diameter because one of my floor toms is an 18...dang. I am very curious as to how this build is going to look. Can't wait. Don't tease too much.

 

[EcoDave]

 

[XtremeRevolution]

LOL!

Keep in mind, I'm going for impact and accuracy at loud volumes, not just raw SPL at one specific test tone. Furthermore, this will actual result in a net gain in trunk space from my current IDQ15 (which is has a very small footprint for such a big sub), a net reduction in weight, and the only compromise will be the inability to have quick and easy access to the pass-through of the trunk. I hope to be able to create a system that allows me to quickly and easily remove the trunk baffle so I can use the pass-through.

 

[obermd]

And here I though you meant Winter was over and Road Cone season had begun. :th_coolio:

 

[tecollins1]

I guess the other chevy will be the "material haul vehicle" don't think you will be able to get a couple sheets of MDF in your car without cutting them before hand


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[iKermit]

Off topic: I read the thread title as "North Kore is King" wtf?

On topic: This will be epic... Update us with more teasers im a ***** for teasers...

 

[1990tsi]

How are you going to block the rear deck 6x9 holes?

I used 1/4 mdf, 'no nails' wood glue and it's still holding great. (I had plans of IB but never got around to it!)

 

[jakkaroo]

you wanna sell me that 15 with box?

 

[XtremeRevolution]

How are you going to block the rear deck 6x9 holes?

I used 1/4 mdf, 'no nails' wood glue and it's still holding great. (I had plans of IB but never got around to it!)

1/2" MDF, gasket tape, and sheet metal screws. Makes it easily removable, and I can drill out the holes from the screws to make them look prettier if I ever want to reverse it. For the smaller holes, I have some CLD tiles left that I can use to cover them up, and I may even get some MLV and CCF to cover the deck just for good measure.

I've been thinking about how to make the whole thing rigid yet easily detachable, and I think I just figured out how. Bike axles with quick-release levers.

Sunringle Cam Skewer Quick Release > Components > Wheel Goods > Quick Releases | Jenson USA Online Bike Shop

If designed correctly, 6 of those should be enough to hold the baffle in place and allow easy removal when I need to remove them to use the pass through.

 

[XtremeRevolution]

you wanna sell me that 15 with box?

I have a guy who already called dibs on it, but if that falls through, I'll let you know.

 

[jstoner22]

I'm excited to see this!

What are you powering these with?
What are the specs on them?
I could have passed right over it, but it sounds like you are going infinite baffle?


Also, I'd hold onto the 15" for now personally. It is a fairly hard sub to find, and until you hear the results of this new endeavour, I wouldn't part with it.

good luck!

 

[XtremeRevolution]

I'm excited to see this!

What are you powering these with?
What are the specs on them?
I could have passed right over it, but it sounds like you are going infinite baffle?


Also, I'd hold onto the 15" for now personally. It is a fairly hard sub to find, and until you hear the results of this new endeavour, I wouldn't part with it.

good luck!

Powering either with my Alpine MRP-M1000, or with a pair of Kenwood amps. I may spring for a Boston Acoustics high powered 2ch amp if I don't like the Alpine. I will probably end up selling the Alpine to go Class AB.

Specs are in the link I posted. Super low moving mass, 9.6mm xmax, low Qts. Matt Borgardt approved.

Yep. Infinite Baffle is indeed the intention.
I love the IDQ15, but I want to head away from boxed subs for a number of reasons. I would have gone IB with two IDQ15s, but in the year I've been searching, I couldn't find one. Worst case, if I hate these (unlikely), I'll replace them with the new 15" IDMax or another SQ sub. I also have two IDQ12 V2 subs sitting in my garage without a home.

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[XtremeRevolution]

Sold the Alpine MRP-M1000 amp that I was using with the IDQ15. I needed a Class AB amp, which has an inherently better damping factor than Class-D amps. It's not really an issue with a boxed sub, but it's more important for this type of install.

The replacement amp?

Boston Acoustics GT-2300. Bridged, this will provide 1000W @ 4 ohms, which is the load I'll be giving it with the two subs. The ingenious cooling design allows me to mount it anywhere and in any orientation.

22-1/4" in length, 9" in width, and 2-3/8' in height

Built in Q-adjustment will allow me to effectively tune the subs to simulate a given sealed box volume.

At nearly 2 feet long, I'm not yet sure where I'll mount it yet...

 

[XtremeRevolution]

By the way, just so people understand why I decided to go with a Class AB amp, there are two primary reasons.

1. I wanted more power @ 4 ohms. My Alpine MRP-M1000 provided 600W @ 4 ohms, and the Boston Acoustics GT-2300 provides 1000W @ 4 ohms.
2. Damping factor. See the following link:

www.crownaudio.com/media/pdf/amps/damping_factor.pdf

 

[Smurfenstein]

AND IT BEGINS!

:bowing:

With me following close behind

I mean someone's gotta rep the west coast haha.

 

[Smurfenstein]

Sold the Alpine MRP-M1000 amp that I was using with the IDQ15. I needed a Class AB amp, which has an inherently better damping factor than Class-D amps. It's not really an issue with a boxed sub, but it's more important for this type of install.

The replacement amp?

Boston Acoustics GT-2300. Bridged, this will provide 1000W @ 4 ohms, which is the load I'll be giving it with the two subs. The ingenious cooling design allows me to mount it anywhere and in any orientation.

22-1/4" in length, 9" in width, and 2-3/8' in height

Built in Q-adjustment will allow me to effectively tune the subs to simulate a given sealed box volume.

At nearly 2 feet long, I'm not yet sure where I'll mount it yet...

Can the cooling work properly if its enclosed on all sides? If so you might be able to fit it under the trunk floor and simply remove some of the foam. Although i'm pretty sure the foam is only a little over an inch thick, two max. But its an idea. Could work with some tweaks.

 

[XtremeRevolution]

I think that might insulate it too much like a blanket. You at least need to keep the heatsink clear, even though it is internally fan cooled. If anything, I'll put it in the hole in the floor of the Eco's trunk if I want it out of sight.

 

[jstoner22]

I understand the power, but infinite baffle or not, the relevance of dampening factor is debatable.


Here is an excerpt from a recent write up by Steve Mantz

"Damping Factor - This amplifier specification has been blown out of all proportion. What it means is the ability of the amplifier to resist a change in it’s output voltage. The formula is DF= Speaker Z / Amplifier output Z (where Z is impedance). So many manufacturers have claimed ridiculous, and often false damping factors. A damping factor of 1000 implies that the output impedance of the amplifier is 0.004 ohms (4 ohm load). The only way to attain this figure is to apply masses of negative feedback (or use positive feedback) and too much feedback makes amplifiers sound harsh and clinical. Alsodamping factor changes with frequency. The lower the frequency the higher the DF number. Typically the DF can be ten times larger at higher frequencies.
Let us take this amplifier whose output impedance is 0.004 ohms (Zout). The speaker circuit is a series circuit and the following impedances(resistances) are in series with this 0.004 ohms. Let us assume that this DF measurement was made at the amplifier’s speaker terminal. The first extra contact resistance is the speaker wire to the speaker terminal (WT ohms). Then there is that of the wire itself for two conductors (W). Next is the contact resistance of the wire to the speaker terminal (WS). Next there is the contact resistance of the wire from the speaker terminal to the voice coil (WV) and lastly there is the DC resistance of the voice coil itself (DCR). So what we have is a series circuit with the following resistances in series and adding up. WT+W+WS+WV+DCR+Zout. WT,W,WS,WV and Zout are very small indeed. Certainly less than 0.1 ohms. Whoa, look what has happened the EFFECTIVE DAMPING FACTOR has been reduced from 1000 to
40 by just taking into account those pesky unavoidable contact resistances. Now for the cruncher, remember that the DCR is also in series and is typically 3.2 ohms for a nominal 4 ohm speaker. So we must add 0.1+3.2 = 3.3 ohms and now EFFECTIVE DAMPING FACTOR is now a magnificent 1.212! (4 divided by 3.3)This is the real world. We see that the DCR of the speaker swamps all other resistances in the speaker circuit and the 0.004 ohms amplifier output impedance is almost meaningless. It has been found that a DF of about 20 is quite sufficient to dampen the voltage spikes from the speaker. An eye opener this one is it not? Good tube amps sound marvelous - low damping factors!!"


Here is a link to an article by Richard Clark
http://www.monstercable.com/mpc/stable/tech/A2412_Damping_Factor_Article.pdf


Here is a recent write up from Andy Wehmeyer
"Damping factor is hogwash, pure and simple. There is no appreciable cone control provided by low amplifier output impedance.

Here's the short story. The preposterous arguement for damping caused by amplifiers is based on the idea that the output impedance of the amplifier causes the energy stored in the inductive component of the moving speaker to be dissipated more quickly, because the current flow is greater from the speaker to the amplifier if the amplifier has a lower impedance. The problem with that BS theory is that the speaker's DCR is in series with the amplifier's output impedance and is always MUCH greater than the output impedance of the amplifier. Therefore, the speaker's DCR is what controls damping in the electrical circuit and not the amplifier. "

and his recommended source reading ... http://www.diyspeakers.net/Articles/...G%20FACTOR.pdf

These are just a couple of 'pioneers' in the car audio game. You will not find more reputable sources than these. There are a plethora of people that agree that damping factor is near irrelevant in modern amps (as they all boast a sufficient value...in quality amps anyways)



Regardless, I like the amp choice. Very nice.

I'm sure you have looked into it, but what kind of draw will there be? (seeing as it is a high powered A/B)