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Discussion Starter · #61 ·
Luke am I understanding this right. You fill the entire enclosure up with the poly just leave barely enough for the driver to fit in?

Yep, pretty much.
 

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Time for another trip to MN. We haven't been since the last time I was there! My wife was just looking at flights a couple days ago for school break, but it was super expensive with the Canadian dollar in the toilet right now.
I want to make sure I can make it down when your able to visit. Would like the chance to meet you.
 

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I was expecting it to be a little smoother.
For comparison here is the MalX-21 nearfield on a FP14k.

With full-power it gets close to 140db nearfield.
HzHorn in blue.


Green is HzHorn @ LP with basic EQ and Smoothing applied, which extends the knee to 14hz -3db, with useable output to ~12hz.
Purple is all subs @ LP (sealed LMS-18's and MalX-21's and HzHorn etc etc), with basic EQ and Smoothing applied, as well as delay.

Even with this aggressive infrasonic boosting the HzHorn barely reaches 4mm's of P-P excursion out of 80mm Mech at THX levels (or beyond...)
I can overheat the LMS-18's coil with 5kW, but for the life of me I cannot bottom it out while the HPF is in place!
Excursion minima is 14.5Hz and maxima is 22hz. (Maybe with a high-powered sinewave focused at 22hz it could get moving, haven't tried it...)
 

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I was expecting it to be a little smoother.
For comparison here is the MalX-21 nearfield on a FP14k.

With full-power it gets close to 140db nearfield.
HzHorn in blue.


Green is HzHorn @ LP with basic EQ and Smoothing applied, which extends the knee to 14hz -3db, with useable output to ~12hz.
Purple is all subs @ LP (sealed LMS-18's and MalX-21's and HzHorn etc etc), with basic EQ and Smoothing applied, as well as delay.

Even with this aggressive infrasonic boosting the HzHorn barely reaches 4mm's of P-P excursion out of 80mm Mech at THX levels (or beyond...)
I can overheat the LMS-18's coil with 5kW, but for the life of me I cannot bottom it out while the HPF is in place!
Excursion minima is 14.5Hz and maxima is 22hz. (Maybe with a high-powered sinewave focused at 22hz it could get moving, haven't tried it...)
Both these NF measurements look like they have nearby reflections still. How far are you guys placing your mic. Should be like an inch from the dust as. I wouldn't use the for comparison purposes.

The near field output is meaningless.
 

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With the subs stacked so closely together, if you're only driving one box for the nearfield measurements, I'd think the other unpowered subs would be acting like bass traps. Could even be getting some loading on the drivers from the tight spacing as well, based on the photo with all four subs stacked against the wall. Not that a close-mic'd measurement of the subs really matters that much at the end of the day.
 

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Discussion Starter · #70 ·
I think I'll series the Othorns and put them on a single bridged CC5500, move the SP2-12K to 4 of the 21s and buy another SP2-12K for the other 4. I sold the 7.5 and I'll also sell the other CC5500 to help fund this.
 

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Both these NF measurements look like they have nearby reflections still. How far are you guys placing your mic. Should be like an inch from the dust as.
If I put it in the middle of the room and remove all nearby objects and place the mic as close as humanly possible, the MalX-21 gives me this:


Mine aren't dual-opposed boxes so I don't have the problem of a 2nd driver interfering with the sweep. That's perhaps the ONLY downside of DO boxes: a small delay between the two sides!
 

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Discussion Starter · #73 ·
For comparison here is the MalX-21 nearfield on a FP14k.

With full-power it gets close to 140db nearfield.
HzHorn in blue.


Green is HzHorn @ LP with basic EQ and Smoothing applied, which extends the knee to 14hz -3db, with useable output to ~12hz.
Purple is all subs @ LP (sealed LMS-18's and MalX-21's and HzHorn etc etc), with basic EQ and Smoothing applied, as well as delay.

Even with this aggressive infrasonic boosting the HzHorn barely reaches 4mm's of P-P excursion out of 80mm Mech at THX levels (or beyond...)
I can overheat the LMS-18's coil with 5kW, but for the life of me I cannot bottom it out while the HPF is in place!
Excursion minima is 14.5Hz and maxima is 22hz. (Maybe with a high-powered sinewave focused at 22hz it could get moving, haven't tried it...)

Those excursion minimums and maximums are very similar to the Ghorns. I could get excursion really high between 22-25hz with ~2kw, but at 15hz I could dump the entire CC5500 into it and couldn't even get close. It'd heat up the coil pretty good though!
 

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Discussion Starter · #74 · (Edited)
So, the million dollar question:

Can you feel the low stuff now? If that setup doesn't get it done, it just ain't possible.

Are those drivers available to anyone?

How'd I miss this post?


I've done some spec labs with stuff like EoT and HTTYD dragon crash and there's no question I've gained a full octave+ over the low end of the Ghorns.

I am a little disappointed my riser doesn't resonate quite how I hoped it would, but I was just discussing with Mike today some plans to measure it's current resonant frequency and how I might add mass to lower it. Should be fun.


EDIT: And yes, these are available to anyone.
 

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Luke Is your front baffle made of Baltic Birch or did you use MDF? I like your approach of mounting the drivers with screws rather than inserts and screws. Much faster and simple to get right. I bought the inserts and screws and am not sure if I can switch to your approach and use screws. I don't know if a screw will hold on mdf? My panels are cut and am starting the assembly in the morning. Thanks in advance.

MARK
 

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Luke Is your front baffle made of Baltic Birch or did you use MDF? I like your approach of mounting the drivers with screws rather than inserts and screws. Much faster and simple to get right. I bought the inserts and screws and am not sure if I can switch to your approach and use screws. I don't know if a screw will hold on mdf? My panels are cut and am starting the assembly in the morning. Thanks in advance.

MARK
They will hold fine in Mdf. Just make a pilot hole first. Also, you can take pieces of plywood and glue them in behind your mounting baffle for extra bite if you want.
 

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Discussion Starter · #77 ·
Luke Is your front baffle made of Baltic Birch or did you use MDF? I like your approach of mounting the drivers with screws rather than inserts and screws. Much faster and simple to get right. I bought the inserts and screws and am not sure if I can switch to your approach and use screws. I don't know if a screw will hold on mdf? My panels are cut and am starting the assembly in the morning. Thanks in advance.

MARK

The entire enclosure is MDF, and I pre-drilled. Baffles should be an minimum of 1.5" thick.

They will hold fine in Mdf. Just make a pilot hole first. Also, you can take pieces of plywood and glue them in behind your mounting baffle for extra bite if you want.

^^^
 

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Here's impedance and FR measurements of an Infinity 1260w in a 1.4 CF sealed box with different amounts of fill. Fill is standard arts-and-crafts fluffy polyfill. FR measured close-mic'd with sub on its back, driver facing up, and the mic on a stand pointing down at the driver, so I could slide the mic out of the way when adjusting fill without changing height of the mic. I took these last spring.

Red - Empty box, Qtc 1.185
Orange - .5 lb/CF fill, Qtc 1.059, fill was loose in the box, box was not filled to the top
Green - 1 lb/CF fill, Qtc 1.065, was enough fill to fill the box
Blue - 1.5 lb/CF fill, Qtc 1.018, lightly packed into the box
Black - 2 lb/CF fill, Qtc 1.049, fill was heavily packed into the box, had to jam it into the corners, density of the fill was probably pretty uneven in the box.

It does look like the box picked up some efficiency with the fill. The difference between red and black at 20 Hz is about 1 dB. And once the fill started getting packed into the box, it had less effect on the impedance sweep and Q of the sub. It'd be interesting to try it with other types of fill, especially if something like rockwool were more dense without being packed.

 

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