Eminence Kappalite 3012LF sub project

[Defo]

Hey,

Ive modelled two of these drivers in bassbox, and I get the results shown below. Can anyone confirm that these simulations are correct, and give me a go on the project? Would love to hear some thoughts too..

[Defo]

Could anyone vouch for this project?

According to bassbox, it should be able to do 116 db at 30 hz, without exceeding xmax, and at full power... thats pretty impressive with such low mass woofers as I see it.

[CLS]

Hi,

Your tuning frequency is quite low, but with a relatively high f3...

Do remember to check the group delay curve and numbers. Doing low and loud is one thing, doing it well is another. You won't like it when the group delay is too much and/or the curve is unsmooth.

And one more thing, are you going to use this single sub box with 2 drivers in your system, or there'd be 2 such boxes? I'd prefer 2 separate boxes no matter how many drivers on them.

[Defo]

Originally posted by CLS
Hi,

Your tuning frequency is quite low, but with a relatively high f3...

Do remember to check the group delay curve and numbers. Doing low and loud is one thing, doing it well is another. You won't like it when the group delay is too much and/or the curve is unsmooth.

And one more thing, are you going to use this single sub box with 2 drivers in your system, or there'd be 2 such boxes? I'd prefer 2 separate boxes no matter how many drivers on them.

Thanks for the reply.

The rising response is of no concern as I wont be using it higher then 80hz plus eq. The idea is to make a subwoofer thats quick and punchy, unlike those high mass subs ive heard before. Its gonna be 1 wide sub placed in front between the main speakers. Its gonna work as both a sub and a rack for the components to be placed on top. Using a granite stone plate so separate them. The group delay is below. Is that acceptable? I will be using a steep subsonic filter at 28hz.

[Defo]

Dont know what happened with the pic, but here it is again.

[AndrewT]

Hi,
tuning low in a bigger than usual box gives that slow rolloff you have posted.

I did this after lots of advice and love the deep but NOT BOOMY bass that the alignment gives. Male voice sounds very natural.

I see ~ 6dB of slope over the two octaves from 40Hz to 160Hz using your little driver.

I aimed for 6dB over the 25Hz to 100Hz with a pair of big drivers.

It will be worth trying.

[Defo]

Originally posted by AndrewT
Hi,
tuning low in a bigger than usual box gives that slow rolloff you have posted.

I did this after lots of advice and love the deep but NOT BOOMY bass that the alignment gives. Male voice sounds very natural.

I see ~ 6dB of slope over the two octaves from 40Hz to 160Hz using your little driver.

I aimed for 6dB over the 25Hz to 100Hz with a pair of big drivers.

It will be worth trying.

Ill take that as an approval of the project ;D

Below is a quick drawing of what the setup will be like. The sub drivers are placed behind the "acoustic lens" as Zu audio calls it on their subs.

[Defo]

Im a bit concerned about the group delay of this project. What is normal for a ported alignment, and is the group delay of this project acceptable? I dont want slow bass...

[chris661]

The group delay is fine.

Model a 6th Order Bandpass, and see what we mean by delay (I've seen simulations of up to 4 seconds delay). But a few milliseconds is fine.

Chris

[CLS]

The group delay curve is different from what I'm familiar with.

Curves in most of the sims I've run tend to rise towards the low end -- the lower the frequency, the longer delay. Under some situations, there'd be some kind of 'plateau' shaped curves -- rising towards the low and then being constant below a frequency.... So this 'bump' shape group delay curve is new to me.

In general, in sims, I found in the same tuning frenquency, group delay is bigger when the Vb gets bigger. In the same Vb, group delay is bigger when the tuning gets lower. However I've only had 2 projects of vented boxes, so my real world experience on this is very limited.

To be honest, compared with sealed boxes, horns, and OBs, I dropped the vented box eventually Sorry for spoiling the fun

YMMV, of course.