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GRS 12PT-8 12" Woofer Bass Simulation - Looking For Extended Bass

Pete B

Pete B

AK Member
Subscriber
The GRS 12PT-8 is a 12" prosound woofer that is optimized more for bass extension than for
very high efficiency. This is a rare type of driver since most prosound types start to roll off
usually above 50 Hz and often far above there.

Note: TODAY I NOTICED THAT THE GRS Xmax SPEC ALREADY HAS SOME OVEREXCURSION IN
THE SPEC, I SHOULD HAVE REDUCED THE AMOUNT IN THIS PROGRAM TO 1.2. FOR NOW
JUST ASSUME A 150 to 200W LIMIT AS MAX WITH MODERATE DISTORTION FOR VENTED.
SEALED WILL PROBABLY TAKE 250W PEAKS AS SHOWN ALSO WITH MODERATE DISTORTION.

Here are some sims in Unibox:
Advertised parameters entered:
GRS 12PT-8 SIM1.PNG

======== 4 cu ft VENTED BOX TUNED TO 35 and F3=35 OBVIOUS B4 ALIGNMENT:
==== USE 2 cuft for a B6 ALIGNMENT Fb=35 AND 6dB BOOST AT 35 TO RECOVER OUTPUT:
==== OR PERHAPS ROOM GAIN WILL BE ENOUGH FOR NICE TIGHT SOUND. RESPONSE WILL
==== LOOK AND SOUND MORE LIKE A SEALED SYSTEM. 3 cu ft IS A FINE COMPROMISE
GRS 12PT-8 SIM3.PNG

WOOFER EXCURSION:
GRS 12PT-8 SIM4.PNG

======== 3 cu ft VENTED BOX TUNED TO 38 and F3=39 CLOSE TO A B4 ALIGNMENT:
GRS 12PT-8 SIM7.PNG

==== 3 cu ft VENTED EXCURSION
GRS 12PT-8 SIM8.PNG

======== 2 cu ft VENTED Fb=35 F3=49 NOT THE BEST EXTENSION BUT B6 TYPE BOOST WILL RECOVER IT
GRS 12PT-8 SIM6.PNG


======== CLOSED BOX IN JUST OVER 1 cu ft THAT'S SMALL, USE EQ TO RECOVER DEEP BASS IF NEEDED:
==== F3=68 Hz, NOT VERY LOW BUT IT WILL TAKE SOME EQ
GRS 12PT-8 SIM2.PNG

==== SEALED EXCURSION AT 250W and 1.5X OVEREXCURSION ALLOWANCE
GRS 12PT-8 SIM5.PNG
 
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Assuming this is for a home system, what would be the advantage of going with a prosound driver rather than a consumer level driver optimized for low end extension?
 
I'm simply looking for good Econowave woofers, but I prefer ones that will provide deeper extension for
use without subs. I think we found some.
And this being listed under prosound made us think that it would be in the 93+ range, but we know that
a woofer like that is not going to go deep, so really this might be just right.
HiFi woofers and especially subs are getting more and more inefficient so, it is nice to see these with above
average but still having decent extension.
 
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Hey Pete, the 3 cu ft box is calling my name. Possible to change the port to a slot port?
 
Slotted is fine, perhaps better than round. I've been wanting to use one but have never gotten around to it.
If I were doing it, I'd make your boxes fairly tall to get the horn at ear level. Use a port calculator to figure
out the length and area. If possible bevel the board that makes the slot inside and outside.
If you can measure do a test fit and measure Fb, cut as needed test again.

Anyone know of a good slotted port calculator?
 
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At the resolution of the work right now, ISD can do that stuff. If it gets more real about actual geometry and baffles and boundaries and standing waves, Akabak is your friend.

Edit: Add url to WinISD ref.
 
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Apology, Pete. Fixed post. It's what it is and there's no changing end corrections and there are other bugaboos. If you can run the old Akabak, I can get you started offline, too.

slot_scr.png
 
@loaded This was a 12" Econowave project of mine. I used a Dayton subwoofer (DCS305-4) with
throw on the shorter side that makes it more like a high output woofer with fairly good response into the lower midrange.

Rectilinear III Econowave

I'm talking about just using a highboy or lowboy box for a 2-way Econowave. Anyone?
www.audiokarma.org
To be honest, I was just too busy to measure them. I used a miniDSP for baffle step and a 1200Hz crossover, they sound good.
This was at Frankenfest and they kicked some serious butt in that big room, people were impressed:
I think that I just want more, and that's the reason that I'm looking at 15" in 6-8 cuft:

These are recycled Rectilinear III Highboy boxes, I reused the front baffle as a test, I should have started from scratch on the front
baffle and placed the horn higher up, and the woofer as close as possible to the horn. I read that these are 3 cuft boxes but when
I measured them myself I think it came out closer to 2.5:

You can't get this horn (B52 clone of the 152i) or driver, Peerless DFM2535 anymore, NLA:
index.php
 
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Pete B said:
ISD? Would like to learn Akabak but not anytime soon.
Click to expand...
I was going to ask if the port detail in WinISD is good. I have used your detail above to set up a 3 cu ft box in WinISD lets you change to a slot port.

I love that waveguide... tried to find some but there are none for sell, just like most other parts mentioned in the old econowave threads! Some day, I hope to have the room to do a giant pair of speakers with 15's, but for now, it has to be the 12's and 3 cu ft is just about the limit of the space I have.
 
Oh, good about WinISD.
We've been mentioning that the EV ELX112 horn clone performs well and is almost as large as the 152i.
And its cheap at under $20. Earl has one and I'm curious to see what it will do with the D230ti bolted to it,
getting us back to seriously Econo.
 
Pete, did you recess the GR 12 speaker slightly or just flush mount? Did you use a LPC to it and at what freg? Thanks Dave
 
That's a Dayton woofer, I did these sims just to see what this GRS woofer can do have not used the GRS 12
but I do currently have the GRS 15.
The Dayton is mounted in the original hole in the baffle from Rectilinear and it is partly recessed, I think
that the original woofer didn't have the paper gasket that I should just remove from the Dayton.

LPC?
I showed that picture just for the waveguide that is NLA.
It is crossed 4th order with a MiniDSP at 1.2 KHz.
 
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