# CSS SDX 12" dual PR build



## steve nn

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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## Mike P.

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


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## steve nn

Mike P. said:


> 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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## fusseli

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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## steve nn

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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## fusseli

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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## 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.


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## steve nn

fusseli said:


> 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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## Mike P.

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.


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## steve nn

Mike P. said:


> 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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## steve nn

Mike P. said:


> 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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## Creative Sound

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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## steve nn

Creative Sound said:


> 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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## steve nn

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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## theJman

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


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## steve nn

theJman said:


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


: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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## steve nn

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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## steve nn

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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## steve nn

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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## Stinn

Looks great, can't wait to see how it turns out.


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## steve nn

Thanks Stinn!

Well I worked a few hours today. No hurry since the veneer wont be here until Wednesday. This is screw and glue do to all my clamps are at another location.


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## steve nn

I made a little headway today and thought I would post a few pics. I’m going to go lighter stain on the sides and darker on the front. Now I can go darker on top also or gloss black. Any recommendations? I think I would like it both ways and am kind of leaning with the gloss black top? I dunno, but need to decide soon.


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## Mike P.

The cabinet looks great!


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## steve nn

Mike P. said:


> The cabinet looks great!



Thanks Mike! I keep finding myself wanting to ad more bracing, but it passes the rap test so well I don’t see any need. That’s not me, it just doesn’t require it imo. Everything is basically within 12 X 12 tolerances or more.


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## Stinn

I think gloss black top would look really nice and really pop off the wood.


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## steve nn

Hey Stinn! I sort of thought it would too and decided to go for it. I origanly was going to go with some black paint mixed with stain and then decided not to even though I knew the possibility of the veneer lifting. Me being me I went for it and guess what? yeah I got bubbles lol. Ok so what do I do to save this build? I’m going to take a piece of 1/8 and redo it. Anyway so I get down to loading the driver, oh dear. Since I went narrower than suggested and the magnet flares like it does, the diver backs up against the PR’s. I thought I had things measured out too, but admitedly did not take the time that I should have. If this would have been one of my earlier builds this never would have happened. With out trying to come across as cocky or anything, familiarity got the best of me. Reduced down that means poor planning. Ok so now what do I do? Move the PR’s out to flush or the driver beyond flush? I decided on the driver. This is going to be a funny looking sub before it’s over. lol I have part C and D to the baffle drying now. I have a name for this sub, it’s called the (Little Rebel Rouser) although it keeps growing. :R































































:sweat: :rofl:


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## Mike P.

You are definitely making the best of the issue. I think it will look good when it's done.


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## steve nn

Mike P. said:


> You are definitely making the best of the issue. I think it will look good when it's done.


Yeah I had to stand there and scratch my head for a 1/2 hour or so thinking about it. I would have totally freaked out at another time. Anyway after thinking of the different options to fix this build, I went with the one that ads character.:heehee: Seriously though, ah! it might not be that bad. Different than I planned, but you know what they say about making plans. Thank you Mike


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## Mike P.

Will you be covering the driver and PR's with grills?


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## steve nn

Mike P. said:


> Will you be covering the driver and PR's with grills?


Actually the thought never came to mind.. I really like the looks of the PR’s countersunk, but now that the driver baffle had to be modded maybe I ought to? It would give me the uniformity I would of liked to have. I was out looking at it awhile ago and can see if I decided to put a little more time into the baffle seat there might be a little more to be gained. I could do a round to relieve the edge some, along with putting more time in on sanding. I should have set the belt up. I think I could get it pretty good with the wheel and putty then paint over again though. You know how it is with the edge of ply. Anyway I’ll pull a grill off of another rig and check it out tomorrow before I do anything further. Maybe some sort of grill on the front is the answer?


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## steve nn

For now I decided to go with this. I decided against rounding over the seat and went with the blocked look. The light plays a few tricks but all in all it should be just fine in the bedroom. I had a little bleed, a few bubbles on top and the baffle issue. All in all a pretty fun build and more confirmation on a few things a guy should and shouldn’t do. Oh! and always factor in 12” SDX magnet flare.:bigsmile: My 15” doesn’t have it. I wanted to push the size a little bit with opting for not incorporating the amp since it’s simed at a 1000w and it made the sub come in on the lighter side as our DIY subs go. With a 40lb driver it still has some heft to it though but much lighter considering no MDF and 22lb plate. 

Now lets see how this guy sounds and what spl capabilities it has along with extension. The SPA and tune will limit it, but if it will do good down to 15-17hz I’ll be very pleased. I’ll post some graphs at a latter date..


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## steve nn

The sub sounds absolutely awesome, everything I was hoping it would. I watched OBLIVION today with around 110dB peaks and no strain what so ever. It Keeps it’s composure on all material so far and the SQ is as good as I have ever heard, no exaggeration. I have the EP running it at this time with no dsp and I’m basically +-3.5 100dB from 14 to 80hz. I noticed after I took a break from the forums for a few years that guys were building subs out of all kinds of material so I decided to try something different myself along with a PR design. No problem, the sub is lighter, smaller, good extension coupled with great output and SQ. I expect even more after it breaks in but not that I will notice?? The 12” SDX is a real delight as it should be. No it’s not your typical bang for your buck driver, but then maybe it is depending how you look at it.. SQ dB for the $$. Anyway I’m very impressed! This is’nt my first DIY/B&M or ID sub, so I would like to think I know a little about good bass when I hear it. I hope to have a graph or two up pretty soon along with some more time with it. Flight of the Phoenix is next on the agenda, I know that movie good. I’m in a 25 X 12’ room with a 6’ ceiling that drifts down to 3’ and then straight down.. like a army tent. So the room comes in around 900 or so cu ft. Not large by any means. Because of the shape the size doesn’t work against me like a small square room would. Anyway this sub would do just fine in a much larger room as far as single subs go.. that’s not to say two or three wouldn’t be better to smooth things out if a guy is so inclined. Nice job CSS on another great driver the 12" SDX presents.


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## Creative Sound

So glad that you're pleased.

We continue to develop new kits and these will start to show up next month.

I also have some Quartet10 flat pack and unfinished cabinets available for free (plus shipping) if someone orders the appropriate kit. More details to follow.

Bob


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## steve nn

Thanks Bob! Always look forward to what you come up with next. Here is a graph that another member put together for me since he had pity on my graph making skills. Graph extraordinaire I’m not! Although this sub measures very flat, this room has to play it’s part in it. I never have had it so good freq response/plot period. I did do it at a little higher level than normal, but either than that this is what she wrote. On the graph the plot represents one Hz increments from 12-20hz, so that dip is vary narrow, I doubt even noticeable. A 3dB push with the SPA might fix it though?


12" SDX


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## theJman

Is that an actual measurement or a simulation? If it's the former, what level of smoothing did he use? If your graph represents a real measurement, with minimal/no smoothing, that would be astonishing! Measuring essentially flat to 14Hz is quite the accomplishment for a sub with a 15" driver, let alone one with a 12".


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## steve nn

theJman said:


> Is that an actual measurement or a simulation? If it's the former, what level of smoothing did he use? If your graph represents a real measurement, with minimal/no smoothing, that would be astonishing! Measuring essentially flat to 14Hz is quite the accomplishment for a sub with a 15" driver, let alone one with a 12".




Yeah that’s after correction Jim. I was just saying it came out so good that I didn’t want to post it. Much of it has to do with this room not being very big and the shape of the room like previously mentioned. I wouldn’t want to push things any farther in the lowest region of the graph but at that level I have the output I need. With the SPA I might realize a little different plot, but then maybe not with the 3dB bump that is suggested at 18hz. The EP has no limiter as you know except for power until 5hz unlike the SPA.. if this was a bigger room I very well might tune it a little higher for more headroom? all it takes is removing a few slugs/washers. The PR’s look a little funky having the option on the outside but their functionality can’t be beat! Just about as easy as removing a port bung.


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## steve nn

From the reading I have done Jeff B did his homework with having two PR’s with the same size and Xm that the 12”SDX has. Now I fudged a little with opting not to include the amp in the build, so I have the potential of damaging the PR’s if I push things to far. That being that, he simmed it with a 1000 watts. Being true world watts never match up, I elected to not build it any smaller or put a spacer in the enclosure. If I rip things apart? why I’ll blame it on Bob. :bigsmile:


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## theJman

Realistically, if there's any legitimate output below 20Hz you're in the bonus. It's rare for a 12" driver to provide something like that, especially in such a small enclosure. Either way, that's still a pretty remarkable amount of deep bass considering the cost.

Regarding the PR's; I agree, the external tuning weight setup is very functional but not all that aesthetically pleasing. Maybe a grill is in order...


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## steve nn

Hey Jim.. Yeah I would agree! I guess I would equate it to the driver, the design, and the room. Considering the cost and size not forgetting the SQ, I would agree, it’s very nice indeed!

So you think I ought to build a grill huh? Thankyou, Thankyouverymuch!  :T


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## caper26

I enjoyed reading your build thread! :clap:


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## steve nn

Thanks caper!


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## steve nn

Hey Mike, are you still out there? :wave:


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## Mike P.

Always! :wave:


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## steve nn

Hey cool! I’m wondering if I might have a little help. I’m wanting to build again (the 12” dual PR rig is great, no need for more in this room) but since I have the 15” on hand I am contemplating doing the dual 15” PR option to keep size down for one. I have the file showing it in a 24” cube tuned to 20ish. Can I get away with tuning it lower with more slugs at a 1000w, or should I change the enclosure? Will the PR’s stand up to a lower tune if I were to do so? Thanks for your help Mike.


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## Mike P.

Which amp do you have for the SDX15?


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## steve nn

I can go EP4000 or the SPA1000. I would like to use the SPA though.


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## Mike P.

The SPA has a 3rd order hi-pass filter at 18 hz, tuning lower than 20 hz isn't going to make any noticeable difference in output.


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## steve nn

It has the PEQ function though.


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## steve nn

This is with the SPA500 but the SPA1000 is the same except more power of course (as you know) and maybe not as much adjustability due to power in the 15" case? Any thoughts Mike? A PM would be fine if that works out better. Thanks!

http://creativesound.ca/pdf/Q12XC.pdf


Notes: 
The Quartet 12XC uses the DaytonSPA500 subwoofer amplifier with two APR 12 radiators. This is the most versatile of the all of the Quartet designs. The SPA500 has a highpass infrasonic filter set to
18 Hz with a Q of .7 which helps to tame over-excursions. Since the system can handle 500 Watts and since the SPA500 allows for so much adjustment, a very wide range of settings can be used.
Using all of the supplied washers on the APR12 radiators and adding 3dB of boost at 20Hz results in an F3 of 15 Hz and excursions are well controlled. By reducing the weights to 15 washers on each 
APR12 and removing the boost at 20 Hz results in an F3 of 19Hz but will higher overall output (as shown by the gray line). Many more individually fine-tuned options exist as well. The Quartet 12XC gives
the user a wide range of control over their subwoofer's performance.


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## Mike P.

I forget about the PEQ. In that case tune it to 18 hz with 18 washers per PR and add 3 db of boost at 18 hz with a Q of 1. Here's a comparison of a 20 hz tune against a 18 hz tune with the boost. The driver and PR's will be within their Xmax limits.


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## steve nn

That's great Mike! Much appreciated.


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## steve nn

You know Mike I have been giving this a lot of thought and letting it rest with time. As much as I like to build subs I have no reason to switch the 12” out for the 15”. In this size room with a nice lower tune I have all I need at 110dB. I don’t know how high I could take it (not going to find out) but it gives me all the headroom needed and considering it’s flat response down to 13-14hz. I would be better served leaving the 15” SDX in the LLT sono enclosure and use it for smoothing when I find myself in a larger room. I think what would be the better route is to pull the 12” driver and fix the front/baffle mistake and go from there. 

I also want thank you for your help with learning how to sim up different options myself although I haven't tried doing so with PR’s yet. So you might not be quite off the hook yet.:whistling: You’re definitely a big asset here at the HTF Mike. Your time has and is always appreciated. I dunno why I put it off so long??


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## TheLaw612

Hey Steve I just read through this thread and I am interested in this kit. However, I don't have the means to build a cabinet at the moment and was wondering if any of the flatpacks offered by PE and DIy Sound Group would fit this build? I'm guessing the dual PR's would cause a few problems... Thanks

- Brad


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## steve nn

Let me go take a look and I'll get back to you.


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## steve nn

From what I see it would be no problem except they’re built for 15” drivers. A guy could work around that by doing his own baffle face with a panel of MDF. You would need to address bracing to a degree depending if you’re incorporating a amp or not? and of course taking the PR’s into account. You also have the option of this FP http://www.parts-express.com/dayton-audio-swc3-vi-30-cu-ft-subwoofer-cabinet-black-vinyl--302-847 and going from there. I would highly recommend you customizing the bracing though. Nothing elaborate, just two splines and a cross. Something like a T with the bottom being like the top if that makes sense including bracing the back.


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## TheLaw612

Thanks Steve that does make sense. I forgot about those flat packs. I could even do dowel rod bracing to work around the PRs. I need to make a decision soon, my brother is buying my XV15 at the end of the month.


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## steve nn

The dowles are a great idea! Which kit are you thinking of? Oh! why are you selling your XV?


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## TheLaw612

I'm thinking about this same kit that you built. Just researching all my options right now. 

I'm selling the XV15 to him because his room is huuuuuge and I'd rather sell him mine at a discount than have him buy a sub at the same price. I love it but my wife wants me to downsize a bit lol.


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## steve nn

Uhh I see. Well it’s a great option/sub that I would highly suggest if indeed you decide to go that route. I originally had my EP-2500 running it and was flat.. well I’m sure you checked out the thread. 

Anyway happy shopping. If you do build the kit, post your project here if your inclined, I'm sure help would be at hand.


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