High(er) efficiency LR and or surround project choices

[marc g]

I have built Dennis' RS Center channel monster (which may be heavier than the TV above it). I have a few of Bill Fitzmaurice's horn subs including the new Tuba HT. Now I'm looking for dedicated front L/R channels that don't necessarily have to go below 60-70 hz. I had planned to build the matching RS towers but they may be a little overkill. For ease of placement a smaller cabinet would be preferred. I looked over the thread and can't find any reference to sensitivity. I was looking for something that sacrificed low end (below 60-70) for greater sensitivity. The Zaph waveguide TMM caught my eye for front L/R in a sealed cab. I had also thought about 4 Natalie's in home made cabs to keep costs down.

Does anyone have any other suggestions for a sensitive L/R surround candidate ?

[cjd]

What kind of sensitivity are you looking for?

Nat P's are probably ~87dB. My MTM's are ~88 with ~half baffle step, ~90.5 with none...

The RS center you have should be ~90dB sensitivity.

And, I haven't seen one of those horns that's actually a sub yet...

C

[rumatt]

The RS center you have should be ~90dB sensitivity.

I assume the RS towers (3-ways) would be similar?

[cjd]

I assume the RS towers (3-ways) would be similar?

Yes. The final number depends on whose crossover you implemented. I know my CC variant in that thread was ~90.5dB or so (unpadded tweeter). I think I was the only one that did not pad the tweeter - how much variance, hard to say.

The WWMTM 3-ways are similar (no padding on the tweeter). The TMWW 3-ways are, again, up to the individual crossover implementation. I doubt any drop below 89dB.

C

[Mark Seaton]

If you can handle the minor crossover changes, swap to some different woofers in the RS-3 way project and/or much smaller box that isn't intended to get as low in frequency. Do all you can to maintain the TM compliment of your center.

[marc g]

Yes that is what I was thinking. A more efficient / smaller version of the D. Murphy TMWW tower. I'm currently using some old Pro JBL Control 10 monitors that are rated 94 db at 8 ohms and they are quite punchy but have pretty signifigant second order distortion below 200 hz. Somewhere from 90-94 would seem reasonable.

What changes would be needed to make the towers into stand mounted, near wall sealed boxes that would actively cross over at 60-80 hz ? If I kept the baffle dimensions and just shortened the cabinet and or made it shallower would I get a little bass hump ? would it requre severe crossover tweaks to get the relative levels back to flat ?

If I married the crossover of the tower mid and tweet to the CC woofer would I be "there" more or less... keeping the volume of the CC for the L/R mains ?

[cjd]

Stand mounted near wall sealed monitors to cross at 80Hz sounds awfully like my MTM's with 2 RS150's. The RS180 doesn't quite have the sensitivity but it's a slightly better option on power handling and well-rounded bass (Natalie P). So ~88dB or 87dB, give or take.

A 3-way to fit your desired dimensions would be a tough fit, unless we dropped to a TMW, but that hurts the sensitivity...

C

[Mark Seaton]

A 3-way to fit your desired dimensions would be a tough fit, unless we dropped to a TMW, but that hurts the sensitivity...

marc, What exactly are the dimensions you are trying to keep within? Personally I would look at a vertical orientation of the center similar to what Aerial Acoustics does with their LR3/CC3 or go with the TMWW design, but those would probably start at 26" tall or more, with the advanatage that depth could be kept reasonable.

[marc g]

Mark, yes, that is what I was getting at. A smaller cabinet with the same drivers like a center channel but with the vertical tower driver orientation.
I know that the crossovers are optimised for the differing layouts. I wondered about which one of Dennis's crossovers to use. The tower, the center or an hybrid of the two.
Now if mounting the speakers near the side and back wall will less baffle step be in order if I also crossover above 60 hz ? Just wondering if that would make a difference.

[Mark Seaton]

If you kept the same baffle width as the TMWW design mentioned earlier, you could certainly swap to different drivers, and in many cases just go to a smaller box and adjust the crossover, but it is certainly doable.

One often overlooked set of drivers for midbass are the Peerless SLS "subwoofers." They are reasonably efficent, and in smaller sealed boxes do nicely with reasonable Xmax for the dollar.