Exodus Audio Maelstrom-X Pre-Order Thread - Page 3

Well, hoffman is here all along, the idea though is that you can pump more power into the motor and it will deliver the output while maintaining a nice frequency response. It really doesn't have much to do with bullying hoffman as it does getting a system that can translate lots of power into a usable frequency plot with a small box.

For a fun experiment, take a bunch of widely differing subs and throw them all in a X size sealed box and power them all with Y watts of power, see what they do down low, the similarities between them is frightening. When it comes to delivering output in a small box, its pretty much all about how much power your throwing at it, efficiency is pretty moot since your working against the enclosure and the driver's light mass, easy suspension and loads of flux are all thrown against the confines of a small box.

"Its important to note that while stuffing lowers tuning, it doesn't provide the low end sensitivity boost that a larger box would provide."

Hmm, really?

I guess that would be because the effective volume increase, which is what lowers Fb, is offset by lower box Q?

This is actually a point I'm not clear on; how can sub-20 Hz sound be absorbed, given the difficulty of building effective bass traps at that freq, i.e., needing several feet thick of compressed fiberglass.

I guess it's because inside the box the SPL and air velocity is much higher, with consequent frictional losses from air and stuffing movement.

Gotcha

Well, thats why you don't want to pack your stuffing too well, it can really start to absorb your sound and actually become a large resistive place where all your power and output is dumped.

That's what I was thinking above, about $500 with another Behringer/2400w. What's your take on comparing the performance of each option?


Noah, what are you comparing here?

YES my two Maelstrom-X are paid for...including shipping and the works.

This will be a killer of a driver,with class leading displacement.Anyone considering a serious sealed or vented sub should not be without this beast...or two or more.

"Noah, what are you comparing here?"

Sorry, bad editing; comparing with Ava 18.

Bummer. Dual 4's would'a been nice for those with CE4000's or other nice amps.

Buy a pair.... then you have dual 4s.

It doesn't matter to me......I just can't wait! All this performance in a smaller box is absolutely fun! These have so much displacement........I may just do 'em sealed in 4-6 cubes per sub with 1800 to 2500 watts each (LT'd of course) and forget about it.

So whats the right amount ?

That is an excellent question. It'd be nice if someone would experiment while taking measurements. IMO (which again is My Oppinion and not based off any testing or evidence...so essentially nearly asinine), I wouldn't fill a box more than half way with fill. If you need more space, build a bigger box. Too must fill traps heat around the driver.

Couldn't find a live link to its home, but I found the text of Nousaine's article on stuffing posted in a few places when Googling.

http://www.diysubwoofers.org/talksho...ages/41415.htm

"Dual 4's would'a been nice for those with CE4000's or other nice amps."

Not sure I agree, CEE4000 rating only goes from 1200W/ch@4 ohms to 1400W/ch@2 ohms

Re stuffing and resistive loss, foam may be better than fibrous material to minimize it.

That's with 110v. 200v or greater it's rated at 1800wpc@2ohm. Not that much of a jump, but still enough to give the Mal-x's a workout.

"Stuffing doesn't absorb those wavelengths its mode of operations is to slow the speed of sound and cause losses through heat."

Sound speed is irrrelevant.

Stuffing for mid/woofers is to absorb sound, which it does by being converted to heat.

Stuffing for low freq is to increase the effective box volume, the mechanism being absorption of heat from the air during compression, which would otherwise allow a greater heating of the and consequent pressure rise resisting motion of the driver trying to move inward, and returning it to the air during rarefaction, where otherwise nthe cooling air would lower the pressure, again fighting the driver which is now moving outward.

Uhhh slow the speed of sound!? Uhhhhh... Speed of sound is constant unless you have modified the very air and are using a gas to sustain life I do not know about.

"The speed of any wave depends upon the properties of the medium through which the wave is traveling. This small change aids the box appearing acoustically larger to the driver than it really is."

It's irrelevant in the boxes we're talking about because at the lowest freq the box dimensions are a tiny fraction of the wavelength.

It does matter in a xmission line where you're aiming for a particular pipe resonant frequency.

No reason to believe it would, yeah? 3.5 ft^3 looks like a sweet spot for this driver, an LT, and a bridged Behringer 2500. Good-looking excursion utilization, and ~100dB anechoic on tap @ 10Hz.

Of course the speed of sound changes lots with pressure/altitude relative humidity, resistive mediums, ect. The concept of CHANGING speed of sound is prolly what threw him off, but yes aurthur, it is indeed possible to control variables such as box stuffing to change the speed of sound.

"it is indeed possible to control variables such as box stuffing to change the speed of sound."

What's the point?

The speed of sound has reached Mach two...in my old Mach Two speakers.

+1. What's the point?

The compression of trapped air inside the box is determined by the box size for a given driver and heats the air molecules proportional to the compression.

The stuffing reduces the temperature of the compressed air by heat dissipation, making the trapped air behave as though it's under less compression, as in a larger volume of trapped air for the given driver.

As the driver heats the air inside the sealed box due to prolonged high SPL operation, when using the types of driver/amp combinations we typically use, the benefits of stuffing to apparent box size decrease. But, this effect will be seen regardless of stuffing and box size.

In a sealed system 1/2 of the total output of the driver is radiated into the trapped air in the box and momentarily stored. Some of that stored energy will be released through the vibration of the box panels. Some of it will be released through the drivers cone, which is the weakest link in the sealed box. Some of it is absorbed and dissipated as heat by stuffing.

In both cases, reduction of the temperature of the trapped air and conversion of stored energy to heat, stuffing is an effective solution to varying degrees.

Under normal use (not prolonged high level operation), the stuffings effect is predictable on both counts and therefore a smart choice because latent release of stored energy is a bad thing and a physically smaller box that is apparently the larger target size box via stuffing is much easier to build with reduced box panel vibrations.

Speed of sound inside the box is irrelevant.

Bosso

Did I say there was a point? Aurthur questioned whether you could change the speed of sound, I said you could change certain variables to do just that.

I try to keep fill to around 1lb/cubic foot, others push that 1.5lb per cubic foot which would see around a 20% increase in effective volume.

bosso,

I don't mean to be a monkey on your back, but...

"As the driver heats the air inside the sealed box due to prolonged high SPL operation, when using the types of driver/amp combinations we typically use, the benefits of stuffing to apparent box size decrease."

Air temp inside the box isn't relevant to the effective volume increase.

"But, this effect will be seen regardless of stuffing and box size."

That I agree with

"In a sealed system 1/2 of the total output of the driver is radiated into the trapped air in the box and momentarily stored. Some of that stored energy will be released through the vibration of the box panels. Some of it will be released through the drivers cone, which is the weakest link in the sealed box. Some of it is absorbed and dissipated as heat by stuffing."

The first sentence is correct as fas as acoustic output, but that's about 1% of the energy the driver is putting into the box air.

The other 99% is the going into compressing/rarefacting the air spring, and on every half cycle it's dissipated as heat in the voice coil (mostly) and amp output transistors.

"In both cases, reduction of the temperature of the trapped air and conversion of stored energy to heat, stuffing is an effective solution to varying degrees."

Again, I don't think these have anything to do with stuffing, other than the stuffing is good insulation and will impede heat xfer to the outside.

Maybe he's meaning the stuffing gets too saturated with heat that as the pressure changes, the change in temperature still increases because the stuffing can't absorb the extra energy?

If the stuffing were hot enough to significantly change the specific heat (heat absorption capacity per unit mass) and thermal conductivity, which are what determine the stuffing effectiveness (other than fiber diameter which affects the important surface area/volume ratio), the voice coil would already be cooked.

Haha, then I'm going to assume that's NOT what he was meaning