SEOS-12 + DNA 360 + Deltalite-II 2512 Build

So I'm finally getting started on a project I've been looking forward to for a while, which is building some new mains for my home theater. I'm looking at building something in the vein of the Econowaves/4Pi/SEOS designs, and I thought I'd start a thread to post my progress and hopefully get some help from you guys that have done something like this before.

I know there are plenty of proven designs out there, but for this project I'd like to design the crossover myself as a learning experience (and this can actually count for course credit at my school, but it probably wouldn't be approved if I just worked off another design).

I've done a little research so far to try to narrow down the drivers and waveguide I'd like to use. I was originally going to do something more similar to the Econowaves, using the Dayton 12" and the QSC waveguide like in the Econowave Sr, but after reading through the SEOS thread, and looking at Java's great build. I'm getting really excited about the SEOS and the relatively inexpensive CD's on the diysoundgroup site.

Anyway, here's where I'm at with the drivers/waveguides:

Waveguides
QSC PL-000446GP Replacement Waveguide Horn for HPR152i ($35)
SEOS ($30) ( http://www.diysoundgroup.com/waveguides/seos/plastic-seos-matte.html )
Dayton H6512 ($7)


Compression Drivers
B&C DE250 ($130)
Denovo DNA 360 ($75) ( http://www.diysoundgroup.com/drivers/tweeters/dna-360.html )
Denovo DNA 350 ($57) ( http://www.diysoundgroup.com/drivers/tweeters/dna-350.html )
Selenium D220Ti ($50)


Woofer
Eminence Deltalite-II 2512 ($150)
Eminence Delta Pro 12A ($135)
Eminence Delta 12LFA ($100)
Dayton Audio PA310-8 ($65)

I'm leaning heavily toward the SEOS + DNA360 + 2512 combo, but if anyone else could weigh in (especially with the woofers) it would be helpful. Like how much would I sacrifice going to the 12A? And why haven't I really seen any mention of the 12LFA?

Budget-wise I can make the SEOS + DNA360 + 2512 work, but spending less is always good, so I guess the main question is if I would notice a large difference of quality saving a few bucks on drivers.
Edited by Scott C. - 9/4/12 at 4:00pm

Thanks for the discussion, guys! Still not 100% decided, but it's looking like the 2512. Now I'm kind of looking between the DNA 350 and the 360. Could anyone point me to somewhere that I could see measurements of the 350?

Well, not wanting to feel like I missed out on anything over such a small amount (compared to the overall cost of the speakers), I went ahead and took the plunge on the DNA 360. I ordered 3 sets of the DNA 360 and the 12" matte SEOS. In a few days I'll probably hop online and grab some of the 2512, and hopefully before long I'll have some goodies in my mailbox!

I just got my 2512's in today, and I'm getting really excited for this project.

The drivers surprised me actually with how light they are (despite that they still feel rock solid). Not having any experience with pro woofers I guess I was expecting something more like a subwoofer. Anyway, I'll be measuring these soon using a couple different methods to come up with some parameters to use for box/crossover design.

I'll be sharing in more detail as I do them, but I'll be using a setup in the lab at school that will measure the impedance and output it into a txt file. From there I'll use either Matlab or Mathcad to get the parameters. I'll also try using REW and compare the results between the methods and to the published specs.

I just got in my CDs and man these things are impressive. I wouldn't be surprised if the waveguide+CD combo weighs more than the 2512!

I'm going into the lab tomorrow to measure the impedance, and to start figuring out how I should measure the frequency response for PCD. I was thinking of building a lilmike mic to do the measurements. Could anyone explain to me the best way to measure the frequency responses for use with PCD, or point me to a place that can?

In the meantime here are some pictures:

Another question for you guys. I'm planning on using 3/4" MDF to construct the cabinets, and I was wondering if having a single baffle will be enough. I'm planning on recessing the driver and waveguide maybe 1/3rd of an inch or so.

I think I might still have some of the cutouts from the 15" subs I built. If they're still around I might try making a ring from those. Are you suggesting the wood around the cutout as general support, or mostly just as something for the t-nuts to bite into?

Well I went and measured the impedance for the drivers on some equipment at school, and plopped the Eminence data into REW to get the parameters, and this is what came out:

TS Parameters file
Room EQ V5.01
Dated: Oct 3, 2012 8:29:47 PM
From measurement Eminence 2512 off box.

Zmin 5.41 ohm
fmin 213 Hz
f3 1036 Hz
Le(f3) 0.508 mH
Motional impedance parameters
RES 137.61 ohm
LCES 35.003 mH
CMES 373.5 uF
RAMS 137608.424 mohm
Blocked impedance parameters
RDC 4.50 ohm
dR 0.26 ohm
Re 4.76 ohm
Leb 131.0 uH
Le 2.001 mH
Rss 1503.6 ohm
Ke 0.0619 S-H
Thiele-Small parameters
fs 43.5 Hz
Qms 4.355
Qes 0.485
Qts 0.437
Fts 99.6
Mms 61.15 g
Cms 0.219 mm/N
Rms 3.836 kg/s
Vas 83.90 litres
Bl 12.796 Tm
Eta 1.39 %
Lp (1W/1m) 93.58 dB
Dd 25.72 cm
Sd 519.5 cm^2
Vb 28.317 litres
Secondary measurement: Eminence 2512 on box 1
Air temperature 20.0 C
Air pressure 1013.25 mB
Air density 1.2041 kg/m^3
Speed of sound 343.2 m/s

The data seemed quite different from the published specs (2512 Specs), but when I modeled it in WinISD, there wasn't a huge difference.


(Yellow is Eminence parameters, Blue is measured)

I'm curious about the difference in the parameters. Could this be a break-in issue? I don't know how much I buy into the whole driver break-in thing over time, but it seems reasonable that the suspension might be stiffer if the driver has never been used.

I'm going to remeasure after running some stuff through the driver. What would you recommend to break it in?

In any case, the two models aren't significantly different, so I'm moving forward with the 2cuft box, which I'll be starting this weekend.

Here comes a long post. I made a lot of progress this weekend, and have 1 box pretty much done for testing. All I need to do is add some binding posts and chase the hurricane nuts with a tap.

I woke up to get started cutting some wood for the speakers, and found a great surprise. My parents are celebrating my birthday early since I won't be home on the actual day, and when I walked into the garage I was greeted with this:



I haven't had a chance to use the orbital sander just yet, but table saw has already proven to be worth its weight in gold. When it come to making repeatable cuts, nothing beats a table saw, and this made short work of the cuts that I had to do. Thankfully when I went to Home Depot, a helpful employee cut a couple 15" panels out of the full 4'x8' piece on the panel saw, which also significantly cut down on my work.



Before making any cuts I did a few checks to make sure the saw was properly aligned. I measured from one of the teeth on the blade to the fence, then rotated the blade until the tooth was at the back of the blade and measured again.



Since the measurement was the same, the blade was well aligned with the fence, and I got started on making the cuts.



There was a small setback, since I found that I had misjudged the sizes of my material, and I'm currently short one 19 1/2" x 14 1/2" side pieces. I'll get some more MDF when I get the chance, and cut that last piece.

Once everything was cut out I clamped up the sides and the top and bottom for one cabinet, leaving a bit to hang over on the top and bottom so they could be trimmed flush with a router later.



While the glue was setting up, I got started making the template for cutting out the recess for the waveguide. I followed the instructions in this post on flush mounting irregularly shaped drivers and started by making the larger router base. In the picture below is the circle jig I made for my router, including the incorrectly measured hole for the cutout.



Without thinking, I measured to the far end of the bit, which resulted in an exactly 6 1/4" diameter hole, and a 1/2" smaller cutout, so I remeasured and finally cut out the 6 1/4" disk I would go on to use as the larger router base.



Once the larger router base was cut, I put the original base back on. Next I screwed the waveguide into the MDF (this time 1/4" thick) and traced around it with the router to make the template.



With the angle on the edge of the waveguide, the router base ended up tracing a little too close and made the template slightly too small, so I'm going to cut out a slightly smaller custom router base which will make the final cutout larger. Tomorrow I should be able to finish up the front baffle and hopefully close up one of the boxes.

The next day I started by making a new, slightly smaller router base since the waveguide cutouts I was getting from my template were too small. Once that was fixed, I made a jig to align the front baffles underneath the template. Since the template is much larger than the baffle, I needed something to hold it up as I traced it, and also a way to make sure it was properly aligned on the baffle. To do this I took some scrap MDF and made a slot that I could slide the baffle into under the template. This made sure the template was aligned consistently for every cut and that the baffle didn't move. I simply clamped down the open end, and the baffle stayed put as I went to work with the router.



Below is what the baffle looked like after the first pass with the router. I made the recess about 5/16" deep and made sure to do the outline first. Then I went back in and chipped away around the edges until there was enough left over to seat the waveguide.



Next I used a jigsaw to make the rough cutout for the waveguide. It doesn't have to look pretty since the waveguide will cover it, so I made quick, rough cuts.



Once the waveguide holes were made, I got started on making the woofer cutouts. Comparatively these were extremely easy. Since I was using a 1/4" router bit, I had to make three separate passes, each one just smaller than the other to get down to the size where I would make the cutout.



First pass



Third pass



Final cutout



After all the cutouts were made, I went ahead and cut some more rings for the inside of the baffle. Since I cut about 1/3" for the recess I wanted to make sure there was plenty of stuff for the blind nuts to bite into on the backside. I did the same for the waveguide, but just cut some triangles for the corner. I originally meant for there to be a two layer baffle of 1/2" and 3/4" MDF, and had cut out the 1/2" pieces, until I realized that my flush-trim router bit only has a 1" cutting surface. A bit of an oversight, but I think this solution works perfectly well, and keeps the weight down a little.



Next up, I cut out some spare Baltic Birch to make some braces. These are 3/4" x 1 1/2", and are enough for all three cabinets. There will be two side to side braces, two front to back, and one top to bottom for each cabinet. After the boxes are complete I'll use a chopsaw to cut them to length and glue them in.



For the rings, I applied some glue, and rather than waste clamping time, I just shot it through with a few screws to hold it down with the glue dried. The glue is more than enough to hold it, but I'll leave the screws in.



I used a drill press to drill the holes for the mounting screws since I don't trust myself to drill the holes straight with a handrill and there isn't much space to work with.



Once the holes were drilled, I tapped in the hurricane nuts with a mallet after applying some Gorilla Glue to them. The nuts are supposed to hold themselves in, but I've spun my fair share of them, and it's no fun trying to fix it, so the expanding Gorilla Glue should do the trick. I'll also make sure to chase each one with a tap before trying to mount the drivers.



A row of finished baffles! The front baffle always takes up about 90% of the build time. The waveguide cutouts have 8/32 hurricane nuts, and the woofers have 10/32 nuts.



A quick test fit of the driver and waveguide in the front baffle. Looking good so far!



Clamping up the front and back. It's always a pain to get things aligned correctly, so I made them slightly larger than needed, so I can just trim them up with the flush trim bit and be done with it.

Thanks! Yeah, it does stick out about 1/3", but I didn't want to recess it any more since I wanted the recess to be the same for the waveguide and the woofer. These woofers have a pretty thick mounting ring! Taking into account the gasket material on the front and back, it comes out to around 3/4". I would have liked it fully recessed, but I'm fine with it not quite sitting flush. I'm hoping the gasket on the back compresses a bit, but it seems fairly solid.

Speaking of the factory-installed gasket, I think I might have read in one of the other SEOS threads that it doesn't do that great a job. Should I remove it and use some other gasket material?