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Discussion Starter · #1 ·
Hi Shack members.. I have decided to take on a 12” SDX PR build and thought I would share it over here at the Shack. It’s a design I never have built before or listened to for that matter, so I’m keeping my fingers crossed and hoping for the best. I’m going with the 12” SDX dual PR build because I have a 15” SDX and have found the driver to be a very nice option along with having been quite impressed with it. I’m going to go with a design that CSS suggests and take it from there. Everything is due to land this Tuesday. I have noticed the shipping weight at 85 lbs, so after enclosure it’s going to weigh about the same as a ported option although it will come in smaller.

http://creativesound.ca/pdf/Q12XD.pdf


http://www.creativesound.ca/pdf/SDX12.pdf


 

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Discussion Starter · #3 ·
With the cone excursion being 75% of rated Xmax on a XBL2 driver this will be a very low distortion design. I'm hoping to build one of these subs for my son in law in the near future so I'll be watching this build closely. Post lots of build pics! :T


Hi Mike, Thanks for stepping in and your interest in the project. I just came across your 10” SDX dual PR build yesterday and found your impressions very encouraging. This project is much different than the ground I have traveled in the past, so I’m just going to jump in and see what shakes out? You don’t know until you know! I have no doubt about the driver though. Anyway you indeed can count on plenty of pics and hopefully a few graphs. I will post a pic of a LLT sono using the 15” SDX that met my expectations very well.



 

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Intriguing build. I've never heard a high power 12" with PRs in person. I'd suspect the overall size will be quite small considering the low LF extension and SPL it should be capable of. Good luck with the build!
 

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Discussion Starter · #5 · (Edited)
Thanks Russ! Unless I make any changes I think I’m looking at 1.5” thick, 17.5 W, 20.5 H and 21.5 D. Since it’s getting on the heavy side I’ll most likely leave the amp out and take up the space with a little more bracing. If I understand things correctly this is about as large as a guy wants to go considering the PR’s can be driven to max, or very close anyway in a enclosure this size with the SPA1000. All washers will be used for lowest tune.

The Quartet 12XD uses the DaytonSPA1000 subwoofer amplifier with two APR 12 radiators. The SPA1000 has a highpass infrasonic filter set to 18 Hz with a Q of .7 which helps to tame
over-excursions However, with 1000 Watts over-excursions of the passive radiators are still possibe. To reduce this risk all of the supplied washers should be installed on the APR12 radiators. In this
arrangement the tuning is below the cut-off frequency and excursions are much more controlled. Bass extension is still very deep (17 Hz cut-off) and maximum travel of the APR12 radiators is peaking
at 29.4 mm at full power. This tuning produces a more gradual initial roll-off. When typical room gain is included the result is a very flat and very high output subwoofer with extension in room to 15 Hz
while maintaining good control and very low distortion. Your home theater will never be the same.
This sub will be going in a bedroom, so I'm expecting very high output and extension for enclosure size, but also think it should be worthy of other considerations/applications.
 

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You'll probably be safe since in that environment it should get blasted too loud. I would be kind of worried about over driving a PR. I believe their excursion limits are hard mechanical limits, meaning exceeding them would probably start to cause damage.
 

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Discussion Starter · #8 ·
You'll probably be safe since in that environment it should get blasted too loud. I would be kind of worried about over driving a PR. I believe their excursion limits are hard mechanical limits, meaning exceeding them would probably start to cause damage.
Duly noted, that’s my understanding anyway.

Mike P> I modeled the above design in WinISD and I'm not getting the PR excursion as shown in the PDF. Must be a difference in modeling software.
Mmmm, I dunno, I hope it's all good?
 

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Discussion Starter · #10 ·
The PDF shows 29.4 mm and I get 22.6 mm for the PR's, either way it's within the stated Xmax. As far as I know the amp has a 3rd order HPF and that's what I modeled with.


Yes it’s actually tuned a little lower than the HPF so their thinking is it ought to be good albeit be close under extreme conditions. Certainly don’t want to leave anything on the table as they say. Thanks Mike
 

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Discussion Starter · #11 ·
The PDF shows 29.4 mm and I get 22.6 mm for the PR's, either way it's within the stated Xmax. As far as I know the amp has a 3rd order HPF and that's what I modeled with.


Yes it’s actually tuned a little lower than the HPF so their thinking is it ought to be good albeit be close under extreme conditions. Certainly don’t want to leave anything on the table as they say. Thanks Mike
 

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WOW!! Seems like a lot of sub for a bedroom?

Looking forward to seeing the pictures.

I understand from your correspondence with Al that we may be able to tempt you with some other designs in the future. Stay tuned.

Bob
 

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Discussion Starter · #13 ·
WOW!! Seems like a lot of sub for a bedroom?

Looking forward to seeing the pictures.

I understand from your correspondence with Al that we may be able to tempt you with some other designs in the future. Stay tuned.

Bob
Nice to see you step-in Bob and Thank you for your support. Yes I would definitely think this build would be a very nice option or worthy in a much larger room if all goes as anticipated. Always interested in what you come up with next though, no matter what I have on hand.
 

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Discussion Starter · #14 ·
Everything landed today and this 12” SDX is one very serious 12”. I just weighed it and it comes in a 40 lbs. A perspective on that would be one of my 18" mae-x's I have comes in at 50 lbs. So yeah it’s a 12” but it’s one high excursion heavy duty 12”. Here take a look in the old farm house.




PR




SDX




 

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So that's as far as you've gotten? The enclosure isn't built yet? What a slacker... :D
 

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Discussion Starter · #16 · (Edited)
So that's as far as you've gotten? The enclosure isn't built yet? What a slacker... :D
:rofl: Hi Jim.. I hurt myself taking it out of the box so it might be awhile before I can actually start on the enclosure now. The doctors said it’s a definite extreme case of a hernia from lifting up something terribly heavy.:flex:

EDIT> When I allude to the weight of the SDX, I’m paying it a BIG compliment.. this is no cheaply built driver. The engineering is off the charts!
 

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Discussion Starter · #17 ·
One of those days.. not really any headway except a trip to HD to pick up a trim-bit and 1 1/4” course wood screws. I’m going to order some cherry veneer after this post, so I should be sitting good to start the build tomorrow morning. :)
 

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Discussion Starter · #18 ·
The enclosure I’m going to start building today is going to come in at 19H X 17W X 19”D. Being I want the driver and PR’s close to flush, I’m going 1.25” on the L, R and the baffle. The rest of the enclosure will come in at 3/4 due to wanting to keep the weight at a minimum. The enclosure will have the terminals on the back for the amp. The leads inside the enclosure will be a extra 10-12” long for ease of pulling the driver. I absolutely hate short leads. Since I want to hide the edges of the ply, and don’t want to employ trim or band for my own reasons, I’m going with veneer. I just thought of another way to hide the edges but the veneer is ordered, o-well.. still wouldn’t come out as good as cherry veneer anyway. I also have a few other ideas that are going to have to evolve as I build and try them out.
 

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Discussion Starter · #19 · (Edited)
Well I got a little done today. I would think it’ll be finished tomorrow except for the veneer. The veneer wont get here until next Wed so that’s a bummer. Figured three days but it's not to be. Anyway building a sub this size seems really weird, I’m so used to larger enclosures.

EDIT> In the past I have always used MDF to build a sub and this causes a sub to get very heavy fast, especially when a guy double layers! So at 80-100 lbs a sheet of MDF depending on quality, it does get heavy. This sub is going to be much lighter than anticipated with the 3/4 oak ply even though three walls will be double layered with the 1/2 oak ply. I still need to ad a little more bracing and outside layer, but regardless of driver weight and more to do to the enclosure, this is going to turn out to be a light sub imo. If I added the 20 pound SPA it would come in heavier alright, but still be manageable as subs go, especially since the size has been cut down with utilizing PR’s.




 
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