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Keystone Sub Using 18, 15, & 12 Inch Speakers
Keystone Sub Using 18, 15, & 12 Inch Speakers
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Old 10th September 2019, 09:56 PM   #1241
Brian Steele is offline Brian Steele  Grenada
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I'm surprised that no-one's pointed out that you made those cabinets with MDF instead of birch-ply...

MDF is bludy heavy, and even a little bit of moisture can destroy your creation. It's not really the best choice for PA subwoofer boxes. Painting them inside and out might reduce the moisture problem.
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Old 10th September 2019, 10:30 PM   #1242
daneo is offline daneo
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Brian,
Yes I knew they were going to be heavy but choose MDF for a couple of reasons.
1. It is actually MR (moisture resistant) MDF.
2. Used good quality Duratex paint for extra protection.
3. Where I live, Birch-Ply was more than 3x the price of the MR MDF.
4. Even with Birch, they are still heavy, and I will only be moving them a few times a year. So I think I can deal with the bit extra weight.
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Old 11th September 2019, 01:37 PM   #1243
weltersys is offline weltersys  United States
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Quote:
Originally Posted by daneo View Post
But I did find the culprit for the mistake (see pic)

Art, I'm not sure how close to 1500w RMS my amps will really output. I think probably closer to 1000w, but that is still too much if sustained. I will mostly be playing Rock/Metal, so a little less demanding then EDM.
Is it possible to set approx limits by ear? I mean listen until it starts to sound a bit distorted, then back it off a little?
The DR260 does have a RMS limiter and a Peak Stop limiter, but from what I have read it aint that good. Without proper RMS limiters I'm kinda guessing anyway I suppose.
Dane
Dane,

That "culprit" didn't drink itself

Most of us can accept quite a bit of LF distortion before finding it unacceptable, by the time you would reach even 10% THD, a sustained tone could fry the coils. An AC voltmeter and sine wave tones will be needed to set the voltage you decide to let through.

The DR260 limiter has an attack .01 to 200 m Sec, the speed at which the limiter starts to limit the signal once it has crossed the threshold. If set to the longest attack time with a relatively low threshold, it should clamp down for sustained tones, yet still allow peak impact.

Cheers,
Art
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Old 11th September 2019, 05:57 PM   #1244
BP1Fanatic is offline BP1Fanatic  United States
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Lol @ the "culprit" didn't drink itself!
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Old 11th September 2019, 07:56 PM   #1245
daneo is offline daneo
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Originally Posted by weltersys View Post
Dane,

That "culprit" didn't drink itself
Pretty sure I remember it pleading with me to drink it. It's exact words... " I love you, drink me". SO it is its fault
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Old 11th September 2019, 08:01 PM   #1246
daneo is offline daneo
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Ok hearing distortion not a reliable way. Thanks
I wasn't sure about the AC multi-meter test. I'll work on using that method.
Dane
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Old 4th October 2019, 02:21 AM   #1247
wreckingball is offline wreckingball  United States
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Too many replies to sift through to find the actual quote.
But I distinctly remember that a KS utilizing a 15 could be made 20% less wide...(.though lower dB)...but still have the same FR.

Just checking into this thread to make sure I'm not imagining things...

Btw, I built two KS subs using the b&c 18s (non-neo)..and before break-in, I almost wept thinking things weren't right...but after a week of solid break-in...these things are beasts!
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Old 4th October 2019, 03:07 PM   #1248
weltersys is offline weltersys  United States
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Originally Posted by wreckingball View Post
But I distinctly remember that a KS utilizing a 15 could be made 20% less wide...(.though lower dB)...but still have the same FR.

...but after a week of solid break-in...these things are beasts!
A 20% reduction would be a 21.2 inch wide cabinet, your distinct memory might be dyslexic ;^).
The cabinet could be reduced in width, utilizing 15" or 18" drivers with a reduction in output, but the Keystone exit would have to be adjusted to retain the same frequency response. I doubt the adjustment of the exit would be linear to the width reduction to maintain the same frequency response.

Seems most of the people building the Keystone run them at levels that would "break in" the driver in a few hours, but glad to hear yours are housebroken!

Cheers,
Art
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Old 4th October 2019, 03:24 PM   #1249
BP1Fanatic is offline BP1Fanatic  United States
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Lol!
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Old 5th October 2019, 12:59 AM   #1250
wreckingball is offline wreckingball  United States
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LOL Indeed! ..good stuff Art..

But dyslexia it sorta was, the 20% figure was for an increase in size, using dual 15's, not a reduction for using one.

Original quotes from post #1, and post #168 in case someone else runs into same question:

Quote:
Making a slightly wider cabinet would allow two 15 inch speakers to fit, which would probably allow about 3 or 4 dB more output at the low corner, and 5 or 6 dB more upper level with only about 20% increase in cabinet size.
Quote:
Reducing cabinet width may actually be an improvement for a 15", but you will need to experiment with the exit size. As a starting guess, I'd reduce the exit dimensions by the same % as the cabinet width and height are reduced.
And bolded ..is this still your starting guess? I'm still considering experimenting, so clarification would be great.

As far as breaking the B&Cs in, I must not have hit them with much power then...
Haven't measured anything yet...just playing tunes through an old AVR I have in my shop, feeding the sub-outs into a NU-6000, solid lights on bottom 2 LEDs, and kick-drum blinking the 3rd.
Even after about an hour of that (loud to my ears), the motor structure is cool as can be, no warming whatsoever.
Speaking of which, can someone point me to a thread or link that spells out what I need to determine how much voltage/wattage I'm feeding to a driver in a high-power/PA type scenario, and for testing them in general for that matter.. (?)
I have REW, 2 measurement mics (usb and XLR with cal files), but have only really tested on a low-power/home type scenario, so jumper-wires, resistors etc. are of that same low-power variety.

Enough now, the 'cousin of culprit' is knocking on my door, and it's Friday..
Have a great weekend all.. -Steve

Couple pics here, really like this Herculiner polyurethane paint, tuff stuff!
Attached Images
File Type: jpg Finished Keystones.jpg (680.6 KB, 49 views)
File Type: jpg Keystone Back.jpg (370.6 KB, 49 views)
File Type: jpg Keystone & Ported EV Design.jpg (577.4 KB, 49 views)
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