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Directing PA Speaker Energy
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Raptrox View Drop Down
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Joined: 07 October 2020
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Points: 4 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Raptrox Quote  Post ReplyReply Direct Link To This Post Topic: Directing PA Speaker Energy
    Posted: 07 October 2020 at 11:51pm
So this is probably a dumb question. I built a 2 way full range speaker and it sounds okay, but all of the air moving/chest thump energy is on the sides of the speaker and the front sounds weak, where is my (probably stupid) mistake here? I can feel the power on the sides of the speaker so its there, just not at the front of the speaker. I have put it in different locations so its not the room.

Drivers 
Eminence Delta Pro12A
APT 150 Supertweeter

Amp
300W rms to LF
100W to HF
crossover at 3.5khz 24dB slope
filter at 50 hz

Front ported tuned to 55hz, everything is sealed besides the ports
Volume is ~2.7 cubic feet, made with 3/4" Birch ply

I haven't put any bracing or damping in the speaker yet, could this be the issue? It's a well sealed and solid cab, the panels do resonate a bit though.

I can get pictures if needed
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Greg32 View Drop Down
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Points: 116 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Greg32 Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 12:51am
2.7cubic feet seems very large for a pa 12"mid woofer, I would think 1/2 that volume would be ample. And maybe raise the tuning to maybe 65hz, your best bet is to simulate the alignment in one of the speaker box programs like winisd etc. Greg
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Points: 532 		Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 1:15am
My first thought would be that 50hz-3.5khz is a lot of bandwidth for a 12 inch driver. You will find that directivity higher up will be very narrow and down low it will be very wide. This means that if you EQ it to sound good off axis, it will not sound good on axis and if you EQ it to sound good on axis, it will not sound good off axis. 

Hope that helps
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Raptrox View Drop Down
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Points: 4 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Raptrox Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 1:51am
Hey greg, thanks a lot for your input! The reason i went with 2.7 was because of the recommended volumes on the Eminence website ranged from 1.1 to 3.2 cubic feet and i got the best curve on WinISD from 2.7 I'll definitely try a smaller box next time
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Conanski View Drop Down
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Joined: 26 January 2006
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Points: 2537 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 5:28am
Originally posted by Raptrox Raptrox wrote:

I can feel the power on the sides of the speaker so its there, just not at the front of the speaker.
While music is playing mute the compression driver, does your impression of bass energy in front of the speakers improve or is it the same?

Originally posted by Raptrox Raptrox wrote:

I have put it in different locations so its not the room. 
The room is always a problem when it comes to bass, how big is this room? Have you tried putting the speaker right into a corner?


Edited by Conanski - 08 October 2020 at 5:29am
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Chris Grimshaw View Drop Down
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Points: 281 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris Grimshaw Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 2:15pm
My bet is the amount of bass is roughly the same all around the speaker, but the dramatic increase in mid-high energy when in front of the cabinet is what gives the impression of relatively weak bass.

So long as you're not hitting the limits of the woofer, it's safe to throw some EQ around.

Chris
Quality sound from Sheffield
www.grimshawaudio.com
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Conanski View Drop Down
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Points: 2537 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 3:04pm
Yep that is exactly what I was thinking, speaker bass output is omni directional so it should be much the same all around the box, but baffle step loses combined with the drivers natural midrange response rise means EQ will be necessary to get balanced sound.
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Raptrox View Drop Down
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Points: 4 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Raptrox Quote  Post ReplyReply Direct Link To This Post Posted: 08 October 2020 at 7:07pm
Thanks for the help guys! Got it sounding solid and still getting high spl before any limiting/distortion.
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