Decided first project to be center channel

[tacomaboy]

I believe I want my first real DIY speaker project to be a center channel. This is the speaker I listen to most often, and it will offer the most learning experiences for me.

I have decided on a WMTW design, I have a fairly small amount of space to use, and a small budget as well. It will need to be shielded as well.

T TB 28-8485A Tweeter, 2nd or 3rd order at 4KHz
M TB W3-879S 3" 2nd or 3rd order bandpassed from 350Hz to 4Kz (is a bandpass advisable?)
2xW TB W5-876SA 5" 2nd order Low-Pass at 350Hz.

This should run abuot 75 for the drivers, and I would like to stay under 15 or so for the crossover. From what I have been learning, the impedence and freq response curves should work nicely at these crossover ferquencies, though I will use WINISD to verify this.

Thumbs up, or am I way off bass (pun intended) here?

BTW I intend on replacing the mains to match this setup later on down the road, they are currently low rate Pioneers...

[leadbelly]

Originally posted by tacomaboy
I have decided on a WMTW design

This should run abuot 75 for the drivers, and I would like to stay under 15 or so for the crossover

Good idea on the WMTW design, as lots of people feel putting voice smack on 1 driver works best for a CC.

But $15 for the crossover? You'll spend more that that on just the inductors.

[tacomaboy]

Yes you are right. I was just looking through the PE pre made Xovers and they run 40 bucks. Still, that would total 115 for a very nice center channel.

Previously I had been looking at a 300 dollar Inifinity CC and I dont think it would sound nearly as nice.

Plus I could later match these with a TW or TMW mains and TM surrounds...

[Zymrgy]

I am also very new to speaker building...and I would also like to build a CC. I have recently learned that my original thought of copying the popular MTM is not the way to go. I also was thinking of the WMTW configuration...when I thought of using a couple coaxial speakers instead....like what is seen in car audio.

I know that a speaker company (I think B&W) has done a simillar thing....

Any thoughts on this????

[darkm4n]

If this is you first DIY project .. be carefull .. be very carefull ...
www.spearkplans.com may help .

Be carefull to join all the board's corectly , to cut them good ... i recomand that someone else to cut them ...

Good luck !! Bye

[tacomaboy]

This will be my first Xover design, but cutting isnt an issue. I have built boxes before and they came out very nice.

I think for the 3 way X over I will do like so:

[edit I tried to ASCII art it, but forget it]

First order Mid/Woof Xover
C1 39.8uF //High pass 500Hz
L1 1.82uH //Low pass 350Hz

Second Order Mid/Tweet Xover
C2 3.517UF //2nd order HP 4KHz
L2 .45uH

C3 4.193uF //2nd order LP 3.5KHz
L3 .51uH

Parts should run about 30 bucks

Does this sound right?

Looking at the impedence graphs, it *should* average out to 8ohms across the board. What is a good software program to use ro add the freq response and inpedence response graphs?

By the way, I could save alot of money by replacing C1 with a cheap electrolytic cap. Would I notice the difference??

[leadbelly]

Originally posted by Zymrgy
I also was thinking of the WMTW configuration...when I thought of using a couple coaxial speakers instead....like what is seen in car audio.

If you like WTMW, the Audax CC looks good:

http://design3d.host.sk/Hi-Fi/Audax/ht_center.htm

If you like coax, Tony Gee's USB looks good:

http://home.hetnet.nl/~geenius/USB.html

[Timn8ter]

Looking at the impedence graphs, it *should* average out to 8ohms across the board

Impedance may be ok but what about sensitivity?

[tacomaboy]

Originally posted by Timn8ter

Impedance may be ok but what about sensitivity?

... meaning the sensitivity of the tweet as opposed to the midrange?

Well, I am still learning, so my guess (and I am asking for input here) that I would need a resister to pad the tweeter or an L-pad (and I have never used an L-pad). Whats the best way to determine resistance needed or what sort of L-pad I would need?

Also, I am not sure how to handle the Woofers in this case. They are going to be run parallel at 4ohms, and I know larger speakers are less efficient, so I would assume this would make up for that (having two in parallel). Oh, but then I would underload my amp.

Well, thats why I am here I guess. I plan on getting the LoudSpeaker CookBook before I begin of course.

Or, I could just buy the prebuild Dayton Crossover. Would that be the better way? I really would prefer to do it myself...

[tacomaboy]

Oh, you mean the frequecny response when you say sensitivity? To me it looks like it will flatten, but I will have to use software to be sure, right?