Center channel decisions..

[poochieone]

Hi,
I'm facing a bit of a dilema regarding the build of a center channel for my HT system and would appreciate some advice.
The situation is as follows:
I'm nearing completion of a pair of Eros MKII towers for Left and Right duties run by an Adcom GFA5400. these will also double as mains for my musical
Hi-Fi (well as Hi-Fi as I can build) system.
The low end is taken care of a TC Sounds TC9 12" in a 1.5 cube enclosure run by a BASH500 amp.
I happen to have the following speakers which I would like to use to build the center channel and the rear surrounds:
2 x Vifa PL18's 7" mids (four ohm version of the mids in the Eros)
2 x Peerless 831882 5 1/4"mids
3 x Vifa XT35TG-30-04 tweeters
1 x Morel Mw114 4" midrange/Midbass
2 x LPG 25NA tweeters
My dilemmas are the following:
1) not having the know-how to properly match these drivers and design proper crossovers for them
2) while wanting to minimize the size of the CC i want the best possible sound and off axis response from it.
3) worried about possible timbre matching issues although some highly reliable sources (like j. Krute) say timbre matching is possibly very overrated.
to solve #1, I found this design : http://www.troelsgravesen.dk/peerless-center.htm which leaves dilemma #2 + #3 open.
the way to solve Dilemma #2 in my opinion is to build a WMTW with the vifa and morel mids plus one of the XT2 tweets which would give me great coverage, tremendous output and leave the peerless plus remaining 2 XT25's for rear surrounds and also takes care of possible timbre issues. but I'm thinking that would require an enclosure of at least 1.5 cubic feet which is rather large, and i do not have the knowledge to design such a crossover. Most well respected Xover designers i know of won't design a crossover without having the individual drivers at hand because they state without the drivers, you will need luck to really nail a well designed Xover.

At this point I'm not sure if I should just buy a commercial CC and sell some of my drivers, build the peerless design and hope it has good coverage, or pay someone local to design the WMTW (and i know no one that does that...).
Any advice out there?
thanks,
Marco

[Chris Roemer]

Re: Center channel decisions..

Hi,
I'm facing a bit of a dilema regarding the build of a center channel for my HT system and would appreciate some advice.
The situation is as follows:
I'm nearing completion of a pair of Eros MKII towers for Left and Right duties run by an Adcom GFA5400. these will also double as mains for my musical
Hi-Fi (well as Hi-Fi as I can build) system.
The low end is taken care of a TC Sounds TC9 12" in a 1.5 cube enclosure run by a BASH500 amp.
I happen to have the following speakers which I would like to use to build the center channel and the rear surrounds:
2 x Vifa PL18's 7" mids (four ohm version of the mids in the Eros)
2 x Peerless 831882 5 1/4"mids
3 x Vifa XT35TG-30-04 tweeters
1 x Morel Mw114 4" midrange/Midbass
2 x LPG 25NA tweeters
My dilemmas are the following:
1) not having the know-how to properly match these drivers and design proper crossovers for them
2) while wanting to minimize the size of the CC i want the best possible sound and off axis response from it.
3) worried about possible timbre matching issues although some highly reliable sources (like j. Krute) say timbre matching is possibly very overrated.
to solve #1, I found this design : http://www.troelsgravesen.dk/peerless-center.htm which leaves dilemma #2 + #3 open.
the way to solve Dilemma #2 in my opinion is to build a WMTW with the vifa and morel mids plus one of the XT2 tweets which would give me great coverage, tremendous output and leave the peerless plus remaining 2 XT25's for rear surrounds and also takes care of possible timbre issues. but I'm thinking that would require an enclosure of at least 1.5 cubic feet which is rather large, and i do not have the knowledge to design such a crossover. Most well respected Xover designers i know of won't design a crossover without having the individual drivers at hand because they state without the drivers, you will need luck to really nail a well designed Xover.

At this point I'm not sure if I should just buy a commercial CC and sell some of my drivers, build the peerless design and hope it has good coverage, or pay someone local to design the WMTW (and i know no one that does that...).
Any advice out there?
thanks,
Marco

I'd build that CC. I think it uses the most logical drivers (out of your stockpile) for a center.

So, all that's left is a design for your Vifa 2-way surrounds.

[Chris Roemer]

Re: and here you go . . .

I'd build that CC. I think it uses the most logical drivers (out of your stockpile) for a center.

So, all that's left is a design for your Vifa 2-way surrounds.

Using your Vifa XT25 tweeters and 4 ohm PL18s:
In a 0.20 cf sealed and stuffed box, should reach down to the upper 80's with a Q of 0.7. If you're looking for something lower (like the mid 40's), they model well in a 0.55 cf vented box with a 2"d x 7" long vent.

A good starting point for the XO follows, a high pass - 2nd order with an L-pad (picture the parts left to right - amp to drivers):
12uF series cap, a 0.40mH shunt coil (to gnd), for the L-pad use 2 ohm series and 4 ohm parallel resistors. Most likely hook up the tweeter with reverse polarity (listen to it both ways though, and use whatever sounds best).

Low pass - 2nd order w/Zobel:
1.2mH coil (0.4 ohms DCR), 6uF shunt cap (to gnd), a 4 ohm resistor and 8uF cap for the Zobel.

Chris

[robwest]

Re: Center channel decisions..

This thread should be in the main forum.