Sealed Mini Statements with RS225's ?

[Cort]

First I would like to thank everybody on this forum for sharing so much knowledge etc..I didn't have any questions till yesterday.

I am building a set of mini statements and was just about to cut the holes in the front baffle when I read the previous thread on the sealed statements. The cabinets I ve built have net volume of 54 liters so it seems like a little crossover modification and I could use the rs225's intstead of the 180's and gain some low end? What do guys think
BTW these speakers are for music.
Cort

[snmhanson]

I'm no expert but it could take more than a little modification. Looking at the crossover diagrams, the Minis and Statements have significant differences throughout the three crossover circuits. I am presuming it would not work to simply swap out the woofer circuit from the Statement to the Minis without making changes to the rest of the crossover as well. Not sure if that's what you were thinking but if it is, I would hold out for a comment from Jim or Curt, or at least a more knowledgeable member than me.

Another issue would probably be the difference in width between the two designs. If you built them to spec your speakers should be 10" wide, while the Statements are 11-1/2" wide. I was told that I can change the height and even the depth a bit but to never change the width for a given design.

Matt

[Jim Holtz]

First I would like to thank everybody on this forum for sharing so much knowledge etc..I didn't have any questions till yesterday.

I am building a set of mini statements and was just about to cut the holes in the front baffle when I read the previous thread on the sealed statements. The cabinets I ve built have net volume of 54 liters so it seems like a little crossover modification and I could use the rs225's intstead of the 180's and gain some low end? What do guys think
BTW these speakers are for music.
Cort

Curt is the expert but it looks to me like you're proposing a crossover redesign which is highly doubtful. The only subjective difference between RS180's and RS225's is a slightly lower f/3 and more impact from the larger drivers which move a "little" more air.

Sorry!

Jim

[Cort]

so this is what I've built so far. It's 9.5" w x 10.75 d x 35.5, internal, their are no notes in this cabinet. I was planning to spike each piece to solid oak solid oak floor and prot out the back. All the parts are here for the mini's. playing with the on-box plots looks like I would get a 3 dB increase at 31 Hz with the rs 225, sealed vs ported Rs180. Each piece will be spiked to an oak floor, and I am thinking about finding petrified wood for the the top.

[Jim Holtz]

so this is what I've built so far. It's 9.5" w x 10.75 d x 35.5, internal, their are no notes in this cabinet. I was planning to spike each piece to solid oak solid oak floor and prot out the back. All the parts are here for the mini's. playing with the on-box plots looks like I would get a 3 dB increase at 31 Hz with the rs 225, sealed vs ported Rs180. Each piece will be spiked to an oak floor, and I am thinking about finding petrified wood for the the top.

Cort,

The new sealed RS225's have a F/3 of 56 Hz. If you go ported in a cabinet with a net for the RS225's of about 80 liters, the F/3 is around 31 Hz.

The cabinet size with the new RS drivers is only about 20% smaller.

Jim

[Cort]

I will build an 80 liter someday but for now i am learning on something i can move by myself. Initially i had a vision of a pair of speakers that i had made from hollowed out logs. So this is a prototype project. the crossover goes in the bottom of the speaker so i can tweek and listen for room optimization.
Sorry those pics are rotated. The plots for the rs180 ported and the 225 sealed are tight until 40hz then the 225 are + 3.5 db by 30. the f3's are essentially same for both set ups. thought that is a nice step up with the same cabinet.

My day job is physics so everything is an experiment.
My idea for the cabinet is that it is a musical instrument all it's own. so i have attempted to design a box that will have a flat frequency response and transfer it to my oak floor. Which is why they are built from scaffold planks and will have stone tops that add an additional 30 lbs or so to each speaker. I chose the minis as a base, because i thought they were beautiful in many ways.

[Jim Holtz]

The plots for the rs180 ported and the 225 sealed are tight until 40hz then the 225 are + 3.5 db by 30. the f3's are essentially same for both set ups. thought that is a nice step up with the same cabinet.

What software are you using to determine F/3?

Jim

[Cort]

I am using

http://www.ajdesigner.com/fl_subwoofer/subwoofer.php

So if I understand correctly? The ported cabinet is a couple db louder than a sealed one. The rs 225 is ~1 db less in sensitivity, Therefore a ported cab with Rs 180s will have a higher spl down to 31 hz?
Thanks
Cort

[Jim Holtz]

I am using

http://www.ajdesigner.com/fl_subwoofer/subwoofer.php

So if I understand correctly? The ported cabinet is a couple db louder than a sealed one. The rs 225 is ~1 db less in sensitivity, Therefore a ported cab with Rs 180s will have a higher spl down to 31 hz?
Thanks
Cort

I think that's the disconnect. The RS180 and RS225's are mid woofers, not subs. HERE is the free software that I use and many recommend. Unibox has proven to be extremely accurate in predicting F/3 and driver roll off.

Jim

[Cort]

Thanks Jim, After playing for a couple of hours with unibox, it looks like the ported rs180's are the way to go. Do I recall correctly that the minis port is tuned to 35 hz?

[Jim Holtz]

Thanks Jim, After playing for a couple of hours with unibox, it looks like the ported rs180's are the way to go. Do I recall correctly that the minis port is tuned to 35 hz?

Hi Cort,

That's a Curt question but if I remember correctly, you are very close. The Mini's have excellent bass. Depending on the music you listen to, the Mini's usually don't require a sub. Home theater, pipe organ or techno will benefit from the addition of a sub to get the "big" bass most folks like.

Jim

[cjd]

RS180's definitely do bass nicely when ported. I tuned to ~37Hz I believe.

[snmhanson]

Hopefully I am not being rude by asking this question here, as it was this thread that started me on this exercise. I plugged the RS180-4 and RS225-8 into WinISD to see how they compare. Approximating a box size based on this and other threads and running two drivers per box, the results indicate that the RS180-4s are quite close to the RS225-8s in almost all regards, and in some cases outperform their bigger brothers. Particularly in a vented enclosure, the 180s seem to have higher output by ~3dB and initial roll of is slightly slower than the 225s as well (the 180s start taking a dive once it gets down in the -5 to -6 dB range). The -3dB frequency for the 180s comes out at ~33.40 Hz while I get ~35.62 Hz for the 225s. I am using enclosure sizes of 65 liters for the 180s and 75 liters for the 225s.

I am a bit confused here. If this is accurate, why would any vented enclosure utilize the 225s when they could get higher output and lower frequency response in a smaller cabinet with the 180-4s? I figure that I must be making a mistake or missing something, but where? One area that I am not too sure on is in the system input power numbers. Per WinISD instructions I divided the power output of my amp (130 WPC) by the RE of the speakers to get the power input. So, I guess that could change the SPLs of the 180-4s but they still would be able to go lower than the 225s. Also, the 180-4s obviously have a lower impedance so maybe that is where the difference comes from.

Can someone straighten me out here?

Matt

[cbark]

snmhanson,

The impedance value mis-match is going to throw you off for sure, and possibly other things, as I am not sure what your power response curves look like. Try plugging in the RS180-8 vs the RS225-8. That way you do not have the power issues at play. This will allow you to get a better apples to (slightly larger) apples comparison of the two drivers.

In any case, the 180s or the 225s (x2) in any enclosure is a lot of driver. They both will be capable of very good performance, but all things being equal, the 225s will be able to play a little deeper and a little louder.

[Jim Holtz]

There's no replacement for displacement. RS225's simply move more air.

Jim

[Curt C]

Matt,

Paralleling two RS180-4’s will result in a 2 ohm impedance. –Something most amplifiers aren’t too happy with. I suspect that may be why they look so good in WinISD compared to the RS180-8’s.

As Jim so succinctly stated, there is something to be said about the from the additional surface area of the larger drivers. In the Statements this results in more visceral impact compared to the MiniStatements.

C

[Cort]

Plus you can tune a port to the 80 litre cabinet of the 225's to the low 20's. Which gets you comfortably past the b-string on a 5 string bass. The sealed cabinet now just seems wrong, although I have never done a side by side coparison

Got my crossovers built today, I am happy with the layout, room left over for in room tweaks etc... with the exception of the 68 uf cap that erse now tells me they no longer stock (I thought it was back ordered until I emailed them). ordered a jansten from PE.

Going rock hunting tomorow for the top.

[Cort]

Finished the minis yesterday about noon. They sound fabulous!!!! after just a few hours they seemed to settle right in. everything from Black Sabbath to Alison Krauss. Although my old HK avr500 drops out at -0db so I had to order a emo upa 5 to compliment the new speaks. even though at -5db it seemed to have no issues. Wow

Thanks to Jim and Curt for such a beautiful design.

These were built completely from scrap wood I had laying around. I didn't know if I could get a good box from solid wood. but I took the time to tap and tweak as I put them together, like I was building an instrument. They sound beautiful.

[Sylvan]

Congrats! I like the "rustic" look.

[Jim Holtz]

Very nice! I'm glad you're enjoying them... :T

Jim