need help on var. on a theme of frodaddy's custom center and the original statements

[tchaik]

ok, i think i have found a workable solution to bringing down the profile of my center channel somewhat and still keep a similar tonal character/balance to match my sealed statements. jed's re-work of the statements with the sealed mids and singular change to the tweeter xover could work in my set-up but in order to reduce cabinet size i would like to change out the 8" daytons with the 7" dayton rs180s-8. i have a few of these lying around that have not been used and employing these could put my cabinet size at about an 9" by 28" front profile. depth is flexible. i would keep the triangular arrangement of the tweeter and mids as per frodaddy's setup but obviously downsize the cabinet volume for the different woofers.

here are my questions.....

1. i assume the woofers would need a different xover and that is something i am unable to figure so i would need help on that....

2. since the center sits up about 5 feet high and tilts down slightly, would i go back to the original tweeter xover design of the original statements or still keep the singular change introduced by jed to accommodate the new design changes.

3. as far as cabinet volume, since the woofers are also sealed, do i have some flexibility as to the required volume for them.

i took a look at specs on the 8" vs 7" and there is only a .5 db difference in spl between the two drivers. i hope that small of a change is not consequential.

can anybody give me a hand?

tchaik................

all of this is of course to make my wife happy with what replaces the cynosure which sits on top of the entertainment cabinet for now.

and curt, i know you have weighed in on a few of my questions before as i have wrestled with this issue, and i did read one of your more recent posts explaining the limitations of the statement mid/tweeter setup when it comes to lowering the profile, so i hope this is my final solution to a perrenial problem.

[Jed]

If you are going with the old RS180s, change the inductor value to 4mh and the cap to 80uf (from my schematic) in the woofer section of the crossover (LP). That should get you close to where you need to be. These modifications you are proposing obviously will compromise the original design quite a bit (poorer off axis response and unpredictable diffraction artifacts), but since it does seem that you are willing to experiment- that's my suggestion for the crossover modification. For a sealed box RS180s application, you're looking at an F3 around 75hz or so. Download Unibox (google it) and you can plan out how various box sizes will impact the response.

[FroDaddy]

I defer to Jed for the crossover/lobe questions, but perhaps I can offer some advice on other matters. My Mini Statements have a modified cabinet with about 31L airspace for the dual sealed RS180's. With the T/S params I used their -F3 is about 71Hz, -F10 is about 41Hz. Have you considered a ported enclosure? You could use the same volume and tune as the Mini Statement Center. With my T/S pararms I show a -F3 of 51Hz and -F10 of 31Hz. Or maybe something else after I go on a tangent...

When comparing the RS180 and RS225 on paper and in models, there doesn't appear to be much of a trade off.

<Opinion disclaimer (tread carefully in the proceeding sentences)>
In reality the RS180 should be advertised as a 6.25" speaker, 6.5" at the most, but not a 7". The cone diameter for RS225's are 5_7/8", while the RS180's are 4_5/8". What this means is if you take the proportion of advertised diameter/cone area of the RS225, use the RS180 cone area calculate what the advertised diameter should be, you get 6.29" or graciously rounding up to a 6.5" speaker. This proportion was instantly obvious to me when I saw the RS225 and RS180 in person.

In the real world the two drivers sound significantly different at all SPL levels. When modeling the two they are deceivingly close, but in fact the difference is profound. Don't get me wrong, the RS180 is a great speaker and is a nice performer, but to say they are not giving up much in comparison to their RS225 big brother is grossly inaccurate in my experience.
</Opinion disclaimer>

So also consider making a large ported cabinet for the RS180's. I have heard RS180's in a large ported cabinet and they sounded much better than my sealed Mini's do. Again the fact is the cone area is small in proportion to their big brother RS225, while my opinionated ears hear distortion much earlier at a given SPL.

In a center channel I tried the Mini Statement Center, and then called upon Jed for the 2rCC. If you'd be happy with RS180's, I don't know. There are vastly more Mini Statement Centers out there than 2rCC's, and there are an overwhelming majority of Mini Statement Center owners that are happy.

HTH

[tchaik]

thanks jed and frodaddy for your input. i appreciate your suggestions and am willing to seriously consider all given. some points:

1. the drivers i have are the older version rs180s that jed spoke of.

2. i like the idea of the dual mids and singular tweeter because the triangle setup still gives a lower profile than the mini-statemsnt center can.

3. i also like what both of you did with the 2rcc mid-sealed set-up because my center has to sit 5 inches from a back wall because of where it has to sit atop my tv cabinet. this mitigates against open mids.

4. as far as an f3 in the 70's or even 80's because of sealed woofers, i do not consider that a problem. since my pre-pro directs all bass energy to the r/l not covered in my center i am not concerned. voices are my biggest issue.

5. my seated position is about 10 feet from the center channel and my room is about 12 by 16 although my rear surrounds sit another 8 ft behind me in the open foyer. i do not play volume levels that are excruciatingly loud and i would never push my center even close to what you did in your test of the statement/2rcc hybrid. so....using the smaller woofers doesn't bother me at all. i tend to listen at just a cruising level most of the time.

5. ultimately my goal is to retain as much of the driver compliment/tonal character and balance found in my sealed statements. if this variation an a theme can do that i will be very happy.

6. oh yeah..... keeping the height to 9" or less and width to 26" or less with the depth being 13-15" will keep my wife happy.

7. poorer off axis response and diffraction issues will be a challenge but when i finally decide on box size and xover choice etc.... i hope you and others will chime in as to your opinions and suggestions.

thanks much gentlemen. if you have any other thoughts let me know.

tchaik....................................

[Jed]

You should draw up your proposal and post it here. It'll help us give feedback.

[AdelaaR]

Interesting.
I will first be building the statements themselves but for a center channel I am contemplating on the 2RCC or something similar but smaller and less high.
I hope something like this could see the light one day.

[Jed]

A lower profile CC with dual tangband mids and RS180s has been developed. Only it doesn't use the Fountek ribbon. My suggestion for the LP of the RS180-8 conversion is based on that "research."

Jed

[AdelaaR]

Hey tchaik, any progress on this mini 2rcc (that should be it's name right?) project of yours?

Thanks for your suggestions about the crossover Jed

[AdelaaR]

I downloaded unibox and fired it up ...
... and I was completely baffled by the sheer amount of parameters and the immense complexity.
I'll need to do a lot of learning to get to understand these things

[tchaik]

Hey tchaik, any progress on this mini 2rcc (that should be it's name right?) project of yours?

Thanks for your suggestions about the crossover Jed

at the moment i am in the middle of winter semester. just finished conducting the community orchestra and i have a 2 piano recital to give in april. when these events come so close together everything else stops. i will start working on my idea during the spring break in the middle of march and i will let you know how it goes then. sorry i don't have any further news at the moment. it is obvious though that jed is a wealth of useful knowledge and may be able to get you started on this project long before i can.

tchaik..................