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SEOS-12 / DNA-360 / JBL 2226(J) build

post #1 of 235
Thread Starter 
Looking for some input on a new set of LCR that I'll be building, based on the SEOS-12, the DNA-360 CDs, and the JBL 2226J (yes, the 16 Ohm version - price was too good to pass up, and I'm willing to lose some sensitivity and pad down the CDs).

These will be for my dedicated HT, so 90% movies. I rarely get past -10 from reference, but you never know. My current LCR are Chase Home Theater, generally very happy with them, but I got the speaker building bug, and became fascinated by the SEOS DIY effort / group buy. Thanks Erich and all the other contributors!

I made a noob attempt with WinISD - I'd like to be able to have the option to cross at 60, so was planning on a ported design - here's what I came up with:

2.75 cu ft enclosure (I assume I'd need to compensate for the volume taken up by the waveguide/CD/driver back?); tuned to about 38; SPL shown with 75 watt input (would like to be able to drive them with my receiver - hence passive crossover).

Showing both vented and sealed for the same enclosure size, based on a suggestion in the SEOS thread of building a design that could be run ported or sealed (port plugged).

SEOS-WinISD.PNG

4pi is also tuned to 38, and a slightly larger enclosure (3.1?) - also based on a 2226(H).

Any thoughts?
post #2 of 235
Are these going to be placed near boundaries or out in a room? If near boundaries a shallow roll off will work best for a flat response, as you will get reinforcement. If these are going to be pulled out from walls you should consider tuning higher, like 50hz.
post #3 of 235
Thread Starter 
Near boundaries (behind a false wall / AT screen)
post #4 of 235
The 38hz tune should work well, and like you you said, you can always plug the port. What are you doing for a xover
post #5 of 235
Thread Starter 
Quote:
Originally Posted by Jay1 View Post

What are you doing for a xover

Hoping others start posting 2226 based SEOS designs / begging rolleyes.gif - and in the meantime, I guess I'll take a look at PCD.
post #6 of 235
Quote:
Originally Posted by Brad Horstkotte View Post

Showing both vented and sealed for the same enclosure size, based on a suggestion in the SEOS thread of building a design that could be run ported or sealed (port plugged).

One easy place to start for size and tuning is the JBL 4647a cab. At 5 ft^3 it might be bigger than what you want.

http://www.jblpro.com/pub/cinema/4647a.pdf

Somewhere on Audiokarma Zilch experimented with plugging the 4 ports on the 4647 (or similar) cab. Of course you get 5 different tunings depending on how many ports you plug. Kind of a neat way way to build in flexibility at minimal cost.
post #7 of 235
Do you have a measurement setup?
post #8 of 235
Thread Starter 
Quote:
Originally Posted by tuxedocivic View Post

Do you have a measurement setup?

For measuring driver parameters, no - for measuring output, yes (REW, ECM8000, UCA202, AudioBuddy, laptop).
post #9 of 235
Brad, would a larger horn such as the seos 15/18 be a better match with the jbl 2226?
post #10 of 235
Good enough. I'm sure the impedance file for the SEOS12/DNA360 combo can be had from BWaslo easy enough. And the impedance for the 2226J can probably be gotten. Even if it's just from the manufacture...

If you measure the speaker with REW or HolmImpulse, save the measurement file and I can whip something up for you. Take it all outside if it's quite. Get the speaker as high as you're comfortable (6ft). Put the mic 4 to 6ft. away from the speaker on axis with the SEOS. Make sure the mic won't move.

Take a woofer sweep.
Take a tweeter sweep.
Sweep them both in parallel.
Save the measurements.
Email them to me or any other designer who will help.

Helps to have off axis as well, but a basic idea of those are already known if that's more work than you want to do.

If you can't go outside, it gets tricky for such a large speaker and low cross over, but still doable.

I did this for someone else recently who wanted to learn cross over design. I then gave him all the files and walked him through it. He's now trying to duplicate my work. It's a good way to learn, if you're interested in something like that. We both had the same drivers though.
post #11 of 235
Thread Starter 
Thanks tuxedo, sounds like a plan, and very much appreciate your assistance/tutelage.

Questions re: measurements:

- would I do the measurements on the assembled speaker (mounted in the proposed box)? (I assume so, if measuring both woof+tweet)
- how do I measure the CD/waveguide combo, sans crossover, without blowing it up - have to high pass it somehow, or just run the sweeps in a range that won't kill it? (say 800 and up)
- I wonder if my little lepai 2020 amp would be sufficient to perform the sweeps via REW (tiny so easy to drag around to the test site - but not sure how flat it is), or if I should really use an AVR?
post #12 of 235
"would a larger horn such as the seos 15/18 be a better match with the jbl 2226?"

the benefit of a lower crossover point is that you can put more sound in the horn, which tends to perform better at the crossover frequency than the woofer.

however, if your compression driver runs out of performance, it doesn't matter how big the horn is, it will sound poor.

for a 1" c.d., the low point tends to be in the 900hz+/- ballpark.

if you want to go down to 650hz or so, then a good 1.5" c.d. is what you are looking at and you could take advantage of the lower pattern control of a larger diameter horn.

the crossover point is determined by the directivity match between the woofer and the c.d.

the seos holds its pattern well down to 750-800hz or so (different people would call it a little higher or lower), so the c.d. will be running out of performance before the horn is running out of performance. most 15" drivers are down 6db at 45 degrees off axis somewhere between about 900-1300hz depending on the shape of the cone, so if you want controlled directivity the seos12 is fine.

bottom line. if you want to use a 1" c.d. the benefit of a larger horn would be mostly wasted, mostly. yeah, the seos12 is a really good design.

edit: here is the 2226. page 2 shows the off axis response. it is down 6db at right around 1khz, so that would be a good starting point for a crossover to seos 12.
http://www.jblpro.com/pages/pub/components/2226.pdf
Edited by LTD02 - 7/27/12 at 5:22pm
post #13 of 235
Thread Starter 
One more question for you guys - how do you measure the volume of the components that reduce the box volume (woofer basket/magnet, horn body, CD), to get at the net volume? So I can determine what the box volume will need to be, from the net volume that I came up with using WinISD. Do you do it by hand (measure components by hand, approximate their volume), or use a tool (I ran across Boxnotes, not sure how close it gets)?
post #14 of 235
Quote:
Originally Posted by Brad Horstkotte View Post

Thanks tuxedo, sounds like a plan, and very much appreciate your assistance/tutelage.
Questions re: measurements:
- would I do the measurements on the assembled speaker (mounted in the proposed box)? (I assume so, if measuring both woof+tweet)
- how do I measure the CD/waveguide combo, sans crossover, without blowing it up - have to high pass it somehow, or just run the sweeps in a range that won't kill it? (say 800 and up)
- I wonder if my little lepai 2020 amp would be sufficient to perform the sweeps via REW (tiny so easy to drag around to the test site - but not sure how flat it is), or if I should really use an AVR?

On my phone so short.

Yes, in the box. Biwire binding posts are handy for this.

If you have a DMM, use the tone generator in REW and set it to 120hz. Hook up the woofer and correct the volume until you have between 1 and 2V. The CDwill be fine without a filter and full range. If you're really worried do 0.5V or put a big cap on it.

I've been tempted to use my Lepai but haven't for fear of inaccuracy. If you can use something better, I would.

The volume of the waveguide and woofer don't amount to much. Call it 0.25cu.ft. And you're probably safe. Others may know better though.
post #15 of 235
Thanks for the in depth response LT. I've got some 2226s so following along with the various design ideas.
post #16 of 235
you are not alone. lots of guys with various 2226 -j -h woofs and are looking for designs. i'd guess a few designs are in the works. :-) hang tight, you are on the right path.
post #17 of 235
Quote:
Originally Posted by Brad Horstkotte View Post

Looking for some input on a new set of LCR that I'll be building, based on the SEOS-12, the DNA-360 CDs, and the JBL 2226J (yes, the 16 Ohm version - price was too good to pass up, and I'm willing to lose some sensitivity and pad down the CDs).

These will be for my dedicated HT, so 90% movies. I rarely get past -10 from reference, but you never know. My current LCR are Chase Home Theater, generally very happy with them, but I got the speaker building bug, and became fascinated by the SEOS DIY effort / group buy. Thanks Erich and all the other contributors!

I made a noob attempt with WinISD - I'd like to be able to have the option to cross at 60, so was planning on a ported design - here's what I came up with:

2.75 cu ft enclosure (I assume I'd need to compensate for the volume taken up by the waveguide/CD/driver back?); tuned to about 38; SPL shown with 75 watt input (would like to be able to drive them with my receiver - hence passive crossover).

Showing both vented and sealed for the same enclosure size, based on a suggestion in the SEOS thread of building a design that could be run ported or sealed (port plugged).

SEOS-WinISD.PNG

4pi is also tuned to 38, and a slightly larger enclosure (3.1?) - also based on a 2226(H).

Any thoughts?

 

 

No mention of excursion, is it still under control in 2.75?

post #18 of 235
Thread Starter 
Quote:
Originally Posted by NicksHitachi View Post


No mention of excursion, is it still under control in 2.75?

I believe it was fine, but I'll double check when I'm front of WinISD again tonight - thinking that if a 4pi using the same driver is OK in a larger enclosure, it should be OK.
post #19 of 235
Thread Starter 
Checked on excursion, without a high pass filter, and 250 watts, I'll exceed xmax at 28 Hz and lower - so I guess I could incorporate a high pass filter around 30 Hz into the crossover (assuming I knew how to do that, which I don't tongue.gif) - takes care of it when modeled anyway. They'll always be used with a sub anyway, but still would be nice to deal with for peace of mind.

Anyone want to take a shot at explaining how much to be concerned about port velocity and 1st port resonance? In my case, I modeled a 15" x 1.25" slot port (I've read that too narrow might be a problem, but no idea how narrow is too narrow and why), and it shows 1st port resonance at 743.45 Hz, and port velocity is 31 ft/sec at 60 Hz, and goes nuts below that. Is that resonance too high? too low? Should I be concerned about that port velocity below 60 Hz if I plan on crossing to a sub at 60 or 80, and will likely never send them more than 100W?

Any larger port dimensions I try result in port lengths deeper than my desired box depth (would like them to be fairly shallow as they will be behind my screen wall - only 24" deep - and toed in aggressively).
post #20 of 235
I don't think you'll have to worry about them exceeding X-max at 250 watts. You probably won't give them that much power without your ears throwing in the towel anyway.
post #21 of 235
Thread Starter 
Thanks Erich - any thoughts on the questions re: porting?
post #22 of 235
Thread Starter 
Hmm, guess I'll wing it - wood needs cutting! If it doesn't work out, I call it a test box. wink.gif

A bit more fiddling with WinISD, I think I will go with:

3.5 cu ft (~3.25 net)
38 Hz tuning
13.125 x 1.75 slot port (1st port resonance 628 Hz, port velocity a little lower then when I modeled a 4pi, so I assume shouldn't be a problem)
interior dimensions: 26"H x 16"W x 14.5"D
exterior dimensions (double baffle): 27.5"H x 17.5"W x 16.75"D

Traced one out on MDF - these things are big. Expect I may need to rework my behind screen speaker shelf mounting to support them.
post #23 of 235
Port velocity will be fine. Have fun constructing them.
post #24 of 235
Thread Starter 
Thanks tux smile.gif

Not much progress, but a start - marked up and glued up the first baffle (need to buy materials, this was using MDF I had left over from a previous project). I put some temporary screws through areas that will be cut out, to help where clamps wouldn't reach.

photo.JPG
post #25 of 235
Brad,

Just subscribed, I'm looking forward to DIY speakers for a future challenge.
post #26 of 235
Thread Starter 
Hi Craig! smile.gif

Not much progress yesterday - decided it was too nice outside, so went for a four hour bike ride, and when I got back, wife wanted to go for a walk, so another two hours smile.gif

When I got back, I did create a template for the waveguide recess and slot port, and tested it out on a scrap of MDF, seems to work / fit OK. I did realize after creating the template using 1/8" plywood, that my router bushings extend about 3/16" - lol - when I tested it, I shimmed the back of the template up with 1/8" scraps, which worked fine - now that I think about it though, I can probably just add washers between the bushing and the router base.
post #27 of 235
Thread Starter 
Last night, picked up a sheet of MDF, had HD cut it into three pieces so I could fit it into the SUV, got home and cut pieces for the two remaining double thickness baffles, and glued them up so they'd be ready to go today.

Today, marked and routed the holes for the waveguides, woofers, and slot ports - lots of sawdust. Jasper jig for the woofers, template / bushing for the waveguides, and clamped on guide for the slot ports.

photo.JPG

Not CNC, but came out pretty well - will do cleanup and roundover of the slot ports, and the baffle edges once the baffles are attached to boxes. Oh that reminds me, I still need to do roundover on the back side of the woofer cutouts (and I guess waveguides for good measure) before assembly.

I left the cutouts for the body of the waveguides (back side) pretty sloppy, not sure if that matters.

I thought I'd be able to start on the boxes this weekend too - had a place all lined up that carries Baltic Birch plywood, went over there during lunch break yesterday, but the guy at the counter says "oh, if you need the sheets cut, you'll have to call ahead and pick them up the next day" (of course the next day is the weekend, and they're closed). So struck out on the BB - maybe I can call another place and pick up what I need before work one day this week. Stuff is like gold, $45-50 per 5x5 sheet, but what the heck, even crappy plywood is expensive here.
post #28 of 235
You might check if you have a Ganahl in your area: http://www.ganahllumber.com they carry BB, make cuts and are open on the weekends. There prices are usually much better than the big box stores as well.
post #29 of 235
Thread Starter 
Thanks mj, they'll be one I'll try next week - they are a bit far when I'm at home, but some locations are close on the way to work, and open early, so I can swing by and make a pickup.
post #30 of 235
Quote:
Originally Posted by Brad Horstkotte View Post

Last night, picked up a sheet of MDF, had HD cut it into three pieces so I could fit it into the SUV, got home and cut pieces for the two remaining double thickness baffles, and glued them up so they'd be ready to go today.

Today, marked and routed the holes for the waveguides, woofers, and slot ports - lots of sawdust. Jasper jig for the woofers, template / bushing for the waveguides, and clamped on guide for the slot ports.

photo.JPG

Not CNC, but came out pretty well - will do cleanup and roundover of the slot ports, and the baffle edges once the baffles are attached to boxes. Oh that reminds me, I still need to do roundover on the back side of the woofer cutouts (and I guess waveguides for good measure) before assembly.

I left the cutouts for the body of the waveguides (back side) pretty sloppy, not sure if that matters.

I thought I'd be able to start on the boxes this weekend too - had a place all lined up that carries Baltic Birch plywood, went over there during lunch break yesterday, but the guy at the counter says "oh, if you need the sheets cut, you'll have to call ahead and pick them up the next day" (of course the next day is the weekend, and they're closed). So struck out on the BB - maybe I can call another place and pick up what I need before work one day this week. Stuff is like gold, $45-50 per 5x5 sheet, but what the heck, even crappy plywood is expensive here.

Nice work Brad!

Who needs CNC!?
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