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Author Topic: Yet another Kilomax post  (Read 12179 times)

Paul Walters

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Yet another Kilomax post
« on: July 31, 2010, 05:18:17 pm »

Before I get flamed for not searching, I'll say that I have and as such have gained lots of information about these subs. However, this was not enough to answer my specific question. It's a fairly unique situation and hopefully you can help.

First off, I received (for free, beggars can't be choosers) a pair of Eminence Kilomax Pro 18s in a pair of Peavey Subcompact 18 enclosures (  http://www.peavey.com/assets/literature/manuals/80301953.pdf  http://www.peavey.com/assets/literature/manuals/80301953.pdf), each 7.6 cubic feet (measurements based off the external dimensions, actual volume will be a bit less).

From what I've read on the site, the Kilomax should be loaded into a box roughly the size of a "refrigerated shipping container" in order to function properly.

I've also seen lots of conflicting information on the power handling of this driver. Some say it needs "1800 to 2000 watts to keep it happy", others say it can't handle 600w without exceeding xmax.

I'm also wondering about the effect of the enclosure's tuning upon the driver's performance. The box tuning is 170Hz and 62Hz.
The original driver's frequency response +/- 3db was 200Hz to 47Hz. In addition, its power handling was 350w RMS/ 700w program.

The plan is to use a single Crown XLS 802 (it's what I can afford, I'd buy XTIs if I had the cash for them) on each driver in bridge mode. This would deliver 1600w to each driver. This plan is based on the rule of thumb "safe range", but for the record I know nothing at all about enclosure construction, tuning, and the like. ALL of my experience to this point has been with factory spec enclosures, and when I've replaced drivers I have matched the original specs as closely as possible.
Something about this pairing of driver and enclosure seems a bit whack, and I'd like your advice on how to best utilize the equipment I have without destroying any of it.

Edit: Also I forgot to ask, what should the hi pass be set at? I was looking at a dbx 234 crossover with a fixed 40Hz hi pass filter, would this be adequate?

Thanks for your help!
Paul Walters
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Paul O'Brien

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Re: Yet another Kilomax post
« Reply #1 on: August 01, 2010, 01:07:00 pm »

If I remember correctly the driver loads at an angle at the bottom of this PV box and if so this couldn't be a better example of the absolute worst possible driver/box combination. The Kilomax driver has some potential but this box does not, you will never get any respectable lowend output(by modern standards) from this box no matter what driver are loaded, so you have some choices to make.

A. Scrap the boxes and build or buy something more suitable to the Kilomax. You end up with much larger boxes with decent low end but there's still no getting past the poor driver design that will only take 600w before exceedig xmax.

B. Modify the boxes so they're at least usable with the drivers, that means gut and install a new baffle to mount the driver flat at the front with a couple ports making it a traditional reflex box. That gives you boxes that will go to 40hz but they will still only handle 600w with these drivers.

C. Sell the Kilos and buy the drivers the boixes were designed for.. PV BlackWidows. That gives you low power handling bass bins that can't even be considered a true subwoofer by todays standards.

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Paul O

Art Welter

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Re: Yet another Kilomax post
« Reply #2 on: August 01, 2010, 03:11:26 pm »

The Peavey  Subcompact 18 lower Fb of 62 Hz would require a HP of about 55 Hz for high power applications. The 40 Hz HP you use probably will keep the Kilomax under Xmax to 600 watts at 40 Hz.

Excursion limits are determined by box size and are frequency dependent.

You can look at different box size, tunings and excursion here:
eminence.com/pdf/cab-kilomaxpro-18a.pdf

You basically have the choice of a high F3, high power small box, or a flat response large box that runs out of Xmax well before running out of power, but makes some low bass, or something in between.

index.php/fa/31737/0/

Note the 10.65 cubic foot box has as much 40 Hz output using only 450 watts as the 4.2 cubic foot small box has with 1250.
High power operation makes for power compression, the small box will not actually put out as much level once the voice coil heats up, and the small box would need a 40 HZ HP to not run out of Xmax at that power.

Each choice has advantages and disadvantages.
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Paul Walters

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Re: Yet another Kilomax post
« Reply #3 on: August 01, 2010, 03:37:31 pm »

Is it then your opinion that the maximum power that should be delivered to this driver is 1250 watts? (Ignoring the box, if that's possible for a theoretical situation.)

Why did I see posts about this driver needing 2000 watts? Is the practice of doubling RMS power not applicable to this particular driver?

Also, I would love to toss these enclosures and build a new one, but it might be more economical to simply buy something like a Peavey SP218 used and sell what I have.

Alternately, would it be possible to buy a dual 18 enclosure with blown subs and install these drivers?

If I do have to run these subs for a while, would it be safe to run each at 500 watts and a 40Hz hi pass filter and crossover at 100Hz?

Thanks for your help thus far! Sorry that I'm so new to subs, but I'm here to learn!
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Duane Massey

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Re: Yet another Kilomax post
« Reply #4 on: August 01, 2010, 03:54:34 pm »

If you have decent carpentry skills you should be able to build acceptable boxes for less than $ 150 each, depending upon the coating and hardware you choose.

I would think this would be the most economical solution, but there's no guarantee that it would be cost-effective in the long run if the performance was not at least up to your minimum needs.
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Duane Massey
Houston, Texas, USA

Paul Walters

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Re: Yet another Kilomax post
« Reply #5 on: August 01, 2010, 04:07:08 pm »

Hardware would be recycled from the existing cabs. It should work just fine. As far as fasteners go, I have a lot of stuff here at work that I could use.

Here's the question: the medium vented box on the Eminence site handles 700w and has a similar volume to the box I have +/- .5 cu ft. It is tuned 10Hz lower than mine. Would it be possible to increase the size of the vents in my enclosures in order to lower the tuning from their 62Hz to the 37Hz of the medium vented box?
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Art Welter

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Re: Yet another Kilomax post
« Reply #6 on: August 01, 2010, 04:36:29 pm »

Paul Walters wrote on Sun, 01 August 2010 13:37

Is it then your opinion that the maximum power that should be delivered to this driver is 1250 watts? (Ignoring the box, if that's possible for a theoretical situation.)

Why did I see posts about this driver needing 2000 watts? Is the practice of doubling RMS power not applicable to this particular driver?

Also, I would love to toss these enclosures and build a new one, but it might be more economical to simply buy something like a Peavey SP218 used and sell what I have.

Alternately, would it be possible to buy a dual 18 enclosure with blown subs and install these drivers?

If I do have to run these subs for a while, would it be safe to run each at 500 watts and a 40Hz hi pass filter and crossover at 100Hz?

Thanks for your help thus far! Sorry that I'm so new to subs, but I'm here to learn!


Drivers don’t “need” power, they require power to deliver sound output.

You can’t ignore the box, the driver’s excursion is controlled by the box.

If you study the various boxes, you will see the relationship between excursion and frequency.
You will see excursion is at minimum at Fb, rapidly increases below Fb, and has an increase above Fb that reduces again at higher frequencies. Smaller boxes limit the excursion above Fb.

The Kilomax voice coil can handle 1250 watts. Like any other decent LF driver, it can easily handle musical  peaks of two  or more times that.
If you were to run a sine wave, or severly compressed music, 1250 watts would be all the voice coil is rated for.
But most music has less than 1/3 the average power as peak, so the speaker seeing 1250 watt peaks is probably getting less than 400 watts average.

The Kilomax Xlim, the maximum mechanical limit, is 19.2 mm.
If the power is sufficient to reach Xlim, the speaker may be torn up instantly, hence the need for a proper HP filter.
If you look at the excursion vs. power, you see that very little power is needed to reach Xlim below the box tuning, Fb.

Power between Xmax and Xlim will not tear up the speaker instantly, but will make distortion rise rapidly.

As far as safety at 500 watts and a 40Hz hi pass filter and crossover at 100Hz, power up the cabinet and measure the peak to peak cone motion and divide by 2. A dot of white paint can make the cone excursion easier to read.

If it is less than Xmax (10mm) 3/4” peak to peak, the cone is safe from excursion damage.
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Jeff Wheeler

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Re: Yet another Kilomax post
« Reply #7 on: August 01, 2010, 10:41:00 pm »

Paul O'Brien wrote on Sun, 01 August 2010 12:07

A. Scrap the boxes and build or buy something more suitable to the Kilomax.

We have two of these at my friend's bar.  They are absolute junk with the OEM drivers, and I can't imagine a random driver that is not intended for this type of box being any improvement.
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Jeff Wheeler, wannabe sound guy / moonlight DJ

Elliot Thompson

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Re: Yet another Kilomax post
« Reply #8 on: August 02, 2010, 07:08:35 am »

Paul Walters wrote on Sat, 31 July 2010 22:18



I've also seen lots of conflicting information on the power handling of this driver. Some say it needs "1800 to 2000 watts to keep it happy", others say it can't handle 600w without exceeding xmax.

I'm also wondering about the effect of the enclosure's tuning upon the driver's performance. The box tuning is 170Hz and 62Hz.
The original driver's frequency response +/- 3db was 200Hz to 47Hz. In addition, its power handling was 350w RMS/ 700w program.



Hi.

In the correct cabinet the Killomax will perform well. Unfortunately, the majority of Killomax buyers are mesmerised with large wattage figures and, pay no attention to the TS Parameters of the driver.

I do remember years ago simulating the Killomax 18 in my double eighteens and, received 32 Hz @ - 3 dB (normalised gain). Bear in mind my Double Eighteens are roughly 20 cubic feet.

The Killomax Xmech Peak to Peak is 38 mm (19 mm one way). It will not destroy itself exceeding the 9.8 linear xmax rating. What will occur is more distortion.

I believe the problem with the Killomax is it’s low sensitivity  (94 dB) in which many need to drive the speaker harder to attain more upper bass (60 Hz up wards) where the driver is the least sensitive. Compared to the standard 18 inch driver which offers anywhere from 98 – 99 dB, in addition to inserting it in the wrong cabinet (It appears the majority tend to insert them in horns) it is obvious why there many blown Killomax floating about.

If you are looking for a driver to go low, the Killomax will perform well based on its QTS. However, if you are looking for the driver to make a lot of noise from 60 Hertz upwards, it may be best to explore another driver.

Also, the original Killomax 18-inch driver was rated 1000 watts. Throughout the years the wattage has increased, however based on the TS Parameters, I cannot locate any improvements mechanically that would lead in a higher wattage figure. Possibly steeper filtering upon testing.

Best Regards,



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Elliot

Paul Walters

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Re: Yet another Kilomax post
« Reply #9 on: August 03, 2010, 01:09:57 am »

I'd like to build one if these http://forum.speakerplans.com/beyma-sb18-building-pics_topic 34250_page8.html
Thoughts on Kilomax compatibility?
If that enclosure won't work are there any small vented box plans I could have? I've been looking through plans today and haven't found a whole lot to my liking.
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