What to do with RS225-8?

[johngalt47]

I originally intended to build some Statements until I realized they were too big, too heavy and required space behind them for my purposes.

I'm thinking of something along the lines of the ZDT 3.5 but using the RS225 since I already have the RS52AN mid. But I also have some TB 1337's meant for the Statements and a couple of RS180's also in addition to several of the RS225's.

I also thought of extending Mark K's two way to make a 2.5 way with a 1.5 cu ft cabinet.

Any suggestions?

[LouC]

Good anchor for a three way with the TangBand for a mid. Not sure if I'd want to push those up to meet the RS52.

[johngalt47]

Lou, that was my concern in using the 52 with the 225. So probably I'll use the 52 with the 180 and the 1337 with the 225.

[Pete Schumacher ®]

I don't know why you wouldn't push the RS225 up to meet the RS52. Mark K has them running to meet the RS28 in his 2-way. Heck, even the RS270 has been successfully crossed to the RS52 in Tony Gee's Black Box project.

The RS225 is quite versatile, and more than capable of meeting the RS52 at 800Hz.

[aarond]

I originally intended to build some Statements until I realized they were too big, too heavy and required space behind them for my purposes.

I'm thinking of something along the lines of the ZDT 3.5 but using the RS225 since I already have the RS52AN mid. But I also have some TB 1337's meant for the Statements and a couple of RS180's also in addition to several of the RS225's.

I also thought of extending Mark K's two way to make a 2.5 way with a 1.5 cu ft cabinet.

Any suggestions?

I have plans for Mark K's 2-way but with a waveguide loaded RS28f. I'm building a 2nd enclosure on each side for an additional RS225 (either high output 2-way or 2.5 way). I was planning on going active for crossover but I'd be interested in possibly going passive but I got zero crossover design skills.

You might consider going ported if you go with the Mark K's design. The RS225 models pretty well in a 1 cf box w/ "standard" optimum volume port tuning. Problem is that I'm building 2 seperate boxes on ea side that need to be tuned pretty low so I ordered 4 PR's. If you were to put both woofers in a single 2cf box a true ported design might be a practical option.

You could build a smaller version of the full size statements and give up some low end but that won't solve the wall distance issue you mentioned.

[johngalt47]

Mark K's build uses a .75 cu ft sealed box. Using Paul C's measurements, I come up with a 1.64 cu ft sealed box.

Am I missing something?

The vented box is really attractive but results in a huge box...

[Pete Schumacher ®]

Mark K's build uses a .75 cu ft sealed box. Using Paul C's measurements, I come up with a 1.64 cu ft sealed box.

Am I missing something?

The vented box is really attractive but results in a huge box...

What are the parameters?

That 1.6 cubic feet number seems appropriate for a vented alignment from all the other RS225 setups I've seen.

[johngalt47]

http://techtalk.parts-express.com/attachment.php?attachmentid=14336&stc=1&d=1299204718

[aarond]

The alignment I suggested is a "trick" that was made known by Curt C.

First, model the driver in a textbook scenario to get the tuning frequency. You already did this I'm assuming.

Second, model the same driver in textbook (.707) sealed alignment to get a visual reference for the slope in step 3.

Third, using the same tuning freq from step 1, adjust the volume of the box (smaller) to get a slope similar to the one shown from step 2 (3's slope will look a lot like 2's slope but w/ more low end extension). This is what I did except I'm using passive radiators because a standard port would be impractical for a box this small and slot ports are hard to adjust.

With this driver the sweet spot is about 1 cf effectively. It's very easy to see/compare the models in WinISD. Some drivers take to this method better than others but it works well for this one considering the space it saves in my opinion. The box can be made considerably smaller w/ stuffing. I'm shooting for a finished volume of .8-.85cf probably and stuffing to get the desired result.

[Pete Schumacher ®]

http://techtalk.parts-express.com/attachment.php?attachmentid=14336&stc=1&d=1299204718

Do you have the shielded woofer?

[johngalt47]

yes

[aarond]

Do you have the shielded woofer?


yes

As do I, and all of my references in this post relate to such. Good point, I overlooked this after I posted. I'm not sure how or if the replacement would make a difference in my models but I'd wager they're close. One would definitely need to model to verify.

Luckily this oversight didn't cause much confusion and we are all on the same page now.

[johngalt47]

I'm pretty well set on using two woofers per side; it is just a matter of going sealed or ported and whether or not to make one of the woofers a .5 or not.

[aarond]

Hopefully this attachment works as intended. I had this saved on my laptop.

Standard sealed tuning (which is 1.15 not the .75 Mark K used),
standard ported tuning (28 HZ) 2.2cf
1cf ported tuned to (23 HZ) in the middle. I had thought I used the same port tune as the standard but it looks like the 1db hump caused by doing that was smoothed by dropping to 23 HZ, I doubt you'd be able to tell much difference though.

To get this tuning is 2cf (2 drivers) a single 3" port needs to be about 29" long. If that isn't practical then raising the tuning slightly shortens the port significantly and doesn't affect response much (all the way to 27 HZ).

[johngalt47]

Aaron, I can't read that pic. But anyway, are you saying I can get two drivers into a 2 cu ft vented enclosure with less than 30 hz tuning?

[aarond]

Aaron, I can't read that pic. But anyway, are you saying I can get two drivers into a 2 cu ft vented enclosure with less than 30 hz tuning?

John, the -3dB points are:

sealed / standard / 12dB roll off / 1.15cf: 52 Hz
sealed / .75cf Mark K design: 54 Hz
ported 28Hz / standard / 24 dB roll off /2.2cf: 25 HZ
ported 23HZ / 1.0cf / approximates 12 dB roll off: 43 Hz

[LouC]

I don't know why you wouldn't push the RS225 up to meet the RS52. Mark K has them running to meet the RS28 in his 2-way. Heck, even the RS270 has been successfully crossed to the RS52 in Tony Gee's Black Box project.

The RS225 is quite versatile, and more than capable of meeting the RS52 at 800Hz.

Can it be done, yes. Would I do it, no. I know I'm in the minority, but I'm just not sold on the RS-52 -- especially when pushed. If he's going active, it would be easier to have a bit more freedom as to where to cross.

[aarond]

Can it be done, yes. Would I do it, no. I know I'm in the minority, but I'm just not sold on the RS-52 -- especially when pushed. If he's going active, it would be easier to have a bit more freedom as to where to cross.

I don't have much experience w/ the RS52 but I do know there are a few people's who opinions that I respect that don't care for it. That being said and the fact that John has a pair of well regarded Tang Band 1337's that is definitly the direction I'd go on a 3-way.

[fjhuerta]

Good anchor for a three way with the TangBand for a mid. Not sure if I'd want to push those up to meet the RS52.

I've used the RS52 down to 800 Hz, LR2, without much trouble. I also used it 800 HZ, LR4. Pretty much the same. It'd be useable with an RS225, easy.

[johnnyrichards]

I gots me a quad of the non-shielded version, with a plan for a large 3-way. Was going to try and get it built in time for Iowa this fall, but now I am not sure.

Looking forward to seeing what you come up with.

FWIW, I was planning on doing the "small box/low tuning" approach as well. I have no desire to eat up four or five cubic feet of my living room :)

[aarond]

FWIW, I was planning on doing the "small box/low tuning" approach as well. I have no desire to eat up four or five cubic feet of my living room :)

Ha, I knew I was on the right track. Have you done any modeling yet Johnny? I'm not sure what you were going to do about ports/PR's but since I was planning on doing seberate cabs for the woofers I went w/ 4 PR's from a Definitive Technology parts seller on eBay. He gave me a decent break on those 4 and 2 8" PR's. They look good too (flat cone). They also make larger if you were interested in doing 2 woofs in a single cab w/ 1 PR. You can find them easily on eBay of search my user name for obvious keywords. I provided a driect link to the eBay auctions recently.

Care to share what you had in mind? Did you at least have a target volume?

[johnnyrichards]

~1.25 cubes per, probably a hidden slot port.