Help with MTM woofer size selection

[nathan]

All,

I have an MTM design question to throw out there. I'm looking to build a floorstanding MTM set of front speakers. They are to be used for home theater and 2-channel music. I do have a sub to take care of the low stuff. I like the thin baffle width style so I'm looking to use either 5.25" woofers or 6.5" woofers. I've narrowed it down to a few choices. So here's what I've come up with for my two front-runners. I've run them through WinISD and they have pretty comparable low end responses. Putting two woofers into WInISD I get the following ported response:

Two 5.25" F3 = 38.5Hz in 1.238ft^3 tuned to 43.16
Two 6.5" F3 = 35.2Hz in 3.3ft^3 tuned to 40.28

Now I realize that two 5.25" woofers just don't have the radiating surface of two 6.5" woofers. But would the difference be huge? What sucks is I do not have frd or zma files for either of these woofers. Does anyone see any glaring reason to go with one woofer over the other? I'm not looking for big booming bass here; just punchy, accurate bass.

T/S for the drivers:

5.25":
Rdc = 5.9 ohms
Fs = 51 hz
Qes = .5643
Qms = 2.8167
Qts = .4701
Le = .43 mh
Vas = 9.68 Liters or .3420 cubic feet.
Zmax = 35.3 ohms
Sensitivity = 85.5@ 1Watt / 1Meter

6.5":
Rdc = 4.9ohms
Fs = 52Hz
Qes = .6509
Qms = 2.3624
Qts = .5103
Le = .4224 mH
Vas = 19.27 liters
Zmax = 22.8Ohms
Sensitivity = 88dB 1 watt / 1 meter

[rudyjakubin]

http://img.photobucket.com/albums/v641/rjakubin/driverlayout.gif


HT??? These drivers would get killed.
Well, maybe not in a small room.
If it's your living room you're going to need 'swept volume'...
Here's one I'm working on now using RS drivers no bigger than 8" and Pete Schumacher's 'Quads' using DA175's and a host of tweeters.
<A HREF="http://img.photobucket.com/albums/v641/rjakubin/RSMTMWW.jpg">http://img.photobucket.com/albums/v641/rjakubin/RSMTMWW.jpg</A>
DA175's;
<A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-335">http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-335</A>

[nathan]

Yea, they are both Peerless. The 5.25" is a CSC series and the 6.5" is a Classic series (I think). Explain how they would "get killed" Not sure if I'm following.

> HT??? These drivers would get killed.
> Well, maybe not in a small room.
> If it's your living room you're going to
> need 'swept volume'...
> Here's one I'm working on now using RS
> drivers no bigger than 8" and Pete
> Schumacher's 'Quads' using DA175's and a
> host of tweeters.
>
> <A HREF="http://img.photobucket.com/albums/v641/rjakubin/RSMTMWW.jpg">http://img.photobucket.com/albums/v641/rjakubin/RSMTMWW.jpg</A>
> DA175's;
>
> <A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-335">http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-335</A>

[cjd]

Pick up a more robust tweeter, go with the 6.5's, and cross low. Say, 1600Hz 4th order.

Which points you to something like the Seas TDFC or TBFC (H1212).

C

[rudyjakubin]

Explain how they
> would "get killed" Not sure if I'm
> following.

Just nit pickin'.. Every time I read that bedroom size drivers and HT in the same sentence irks me, but than if your starting out in a 5.1 system than your OK.
I'm in the "there's no replacement for displacement camp". It's the dynamics. Movies have a lot of quiet to really loud spl's from scene to scene and to hear a couple of tiny drivers try and reproduce that spoils it for me.
I'm spoiled!!!
There is also that problem of 'Who gets to sit in the sweet spot'????