Which config of a centre speaker?

[HiFiNutNut]

I have completed 80% of the redesign of my WWMTMWW tower speaker with Dynaudio Esotar T330D tweeter and the rest drivers being Peerless HDS series drivers. The speaker's XO is a hybrid of passive and active. The XO for the MTM is passive (serial), and between the MTM and the WWs is active.

I now want to design a centre speaker so that I can play SACD, DVD-A and HT. The goal is to create a musical centre speaker that will work well with my WWMTMWW speaker on both music and movies.

I have a mid/large size rear projection TV and I think the top of the TV may be too high for the centre speaker and an alternative location would be on the floor immediately in front of the TV (which would be close to the firing gun of the TV) with a specially made stand to tilt it 20 degree up facing the listeners. Either position is still under consideration. My listening area is relatively large so space is not a big problem.

I have already had 4 shielded 5" Peerless HDS mid / woofer (89dB) on hand and intend to use 2 or all of them in a ported box in a 2-way. I have the following questions:

1. What tweeter? T330D (92dB) is not available any more. It would be too expensive anyway.

XT25SC-30-40? (91.5dB) shielded
D2905-9500? (90dB) there is no shielded version
D2905-9700? (89.5dB) there is no shielded version
TC25CF-002 over priced in Australia
or anything else?

I am not sure if a shielded tweeter is necessary when it is placed in front of the rear projection TV.


2. What configuration?

a)

M
T
M.

With MTM, if the speaker is placed on the floor, I can put the MTM upright to avoid lobbing problem and have a wide horizontal dispersion. So MTM is not an issue, and I have good experience with MTM. but -

b)

T
M
M

In this case the tweeter is placed higher, more closer in line with the tower speaker's tweeters and the ears. It will be better than MTM in that regard. However, I am not sure if TMM will work fine.

c)

nbsp;T
Mnbsp;M

This is just an alternative to b.

c)

nbsp;M
MTM
nbsp;M

I know that with the addition 2 Ms there is no sensitivity gain (I don't need any) if connected in series then parallel but the advantage is to reduce the cone movement to half therefore to improve distortion. Note that I have already had 4 drivers on hand (they will be wasted if not used) and the Ms will take care of all frequencies below about 2.5kHz. The WWMTMWW can play very loud. 4 Ms may make the centre speaker have an easier job. I don't know if such a configuration will work or not. I don't have enough accoustic knowledge to analyse / calculate it at the moment.


3. Will a notch filter on the woofer necessary? I intend to use a passive series XO. I have successfully designed the passive series XO for my WWMTMWW speaker but that one has an active XO between the mid ranges and the woofers therefore a notch filter has not been used.


Please shed some lights.

Thanks in advance.

Regards,
Bill

[HiFiNutNut]

I am sorry that the spaces I put in disppeared in the text in my post. I hope it looks better this way, please ignore the _:

a)

M
T
M


b)

T
M
M


c)

_T
M_M


d)

_M
MTM
_M


Regards,
Bill

[David Gatti]

Take a look at the Morel MDT22 - rear chamber, small face, and shielded. Cost maybe $A50.
I'd be more inclined to use the TM layout, for better horizontal dispersion (I'm really not a fan of MTM centres) but I guess that depends on your bass/mids & power handling requirements.