Dual 18 Eminence Kilomax BR enclosure

[iampoor]

Hello

I am currently working on m first subwoofer design. I am new to designing speakers, but pretty experienced in all other areas of audio.

Here are my requirements.

-50-100hz useful output (trying to keep the -10db point above 40hz)
-12-13cuft box maximum size
-Sticking with Eminence drivers
-Over 130db output
-Double 18 BR design. I have built horns in the past, but never really fully understood the mathematics behind them. I am trying to build some Bass reflex cabs that I fully understand (if that makes any sense!)

I have simmed all of the high power Eminence 18in drivers in WINISD, and it looks to me like the Kilomax 18 has the highest output at maximum power. I have selected a 12cuft box tuned to 45hz. Here are the plots I am getting. My understanding is that this box has a signifcant amount of gain front the port, as the box is tubned to 45hz. Are there disadvantages to this, other than a lumpy frequency response? Port distortion? etc. I am planning on shooting for a port 1st resonance frequency of around 500hz. Will it sound like ***?


I am open to other box/driver suggestions, but I really want to stick with Eminence drivers. Thanks!

I can also send over the winisd file if that would be helpful

 

[snappyturtle]

have you experimented with a lower tune to get rid of that bit of midbass hump?

 

[iampoor]

have you experimented with a lower tune to get rid of that bit of midbass hump?

Yes I have, but then I get significantly less output. I am wondering if tuning the box this high will lead to undesirable artifacts, outside of a midbass heavy frequency response.

 

[conanski]

I have simmed all of the high power Eminence 18in drivers in WINISD, and it looks to me like the Kilomax 18 has the highest output at maximum power.

No.. the Definimax is a much better driver, the Kilo will never take it's max thermal power in the real world and for nominally flat response it requires a fridge sized enclosure(24 cu/ft). Two things you must keep an eye on with reflex designs is port air velocity and cone excursion. If you look at those graphs you will quickly see how little power these drivers take before exceeding xmax and how big the ports need to be to keep air velocity reasonable at high power levels.


I modeled them in 6cu/ft boxes(per driver) tuned to 35hz, that is nominally flat for the Definimax but you could go 40hz tuning for a little more power handling. The Kilomax response is a mess in a small box like this and as a result the Definimax has more output from 30-50hz so it's a no brainer IMO. I modeled the ports as a pair of 3x9 rectangular slots across the width of the enclosure, this produces reasonable air velocity at xmax which is 900w for the Definimax... only 700w for the Kilo. Both of these drivers will take lots more power than that on peaks(kick drum) but that's not something you can model so don't worry about it.

 

[Crashpc]

I would be skeptical. "If you tune the box somewhere, it doesn´t it will play there". No matter the sims. Can be accurate, and can be of. With my experience with weaker motor drivers, it does´t work well with the approach you have. You can do OK if the gain is at the port frequency. That´s good, and you will have resources to EQ it out.
With driver resonating way above the port tuning, while at the port tuning is flat, your driver is not only able to drive the port, but there will be audible harm in the driver response compared to larger closed box. You either do that, or replace those drivers. That is my recommendation.