View Full Version : Center w/155h, L5-2, L25 to match L100

12-04-2007, 02:52 PM
Now I have drivers!

I have received some kind advice here in my previous post and scored two 115 h (Aquaplas) 6 1/2" woofers to go with an L5 and L25 to build a center channel to voice match my L100 mains.

Not being very electronically inclined but rather mechanically inclined, I would think that a small cabinet sized for the 115 h plus an L5 and an L25 with the L100 crossover would be the best match for what I want to do.

I see most of the systems that use the 115 are 2 ways, but the L5 and L25 "should" voice match the 100's and since the crossovers leave the woofer wide open, I really wouldn't have to change it (I recently rebuilt my L100 crossovers, so i know how to do them.) I had originally considered just using an L5 + L25 or MTM with 2 L5ís.

After the center channel, I plan on using the same components and building 2 surrounds.

Also this is what I have gleaned from reading posts here:

Cabinet volume is the important thing rather than proportions meaning that I can make the cabinet long and short and increase the depth keeping the target volume in mind.

What I am not exactly clear on is how to take into consideration the size of the drivers themselves and the space they take up. The L25 doesnít take up much space, and the L5 is in its own sealed space. I could take a 115 and put it in a plastic bag and sink it in water and measure the displacement to arrive at that then add these volumes to the target volume and build the cabinet accordingly.

I would appreciate any guidance afforded to me. Thanks in advance!

Original post for reference:

Help me design a center channel
My current home theater 5.1 setup consists of 2 JBL Century L100Aís with fresh crossovers with clarity caps and new pots.( Thanks to Zilch) They sound better than they have for years and I donít mind the bump in bass.

I am currently using a center channel with 3 Fostex FE 103 full range drivers and my rear channels are single Fostex FE103 units. I also am running a sub woofer that gets down below 20 hz. The center does fine, but when I try balance the levels with white noise, they do sound different.

I had a plan to get some LE5ís and LE25ís to put in some small cabinets to pass the wife factor for center and rear, but as I am learning here, they wonít go very low (My reasoning was that with a sub, I didnít need to go too low) I am a mortgage banker, not an audio expert, but have a lot of woodworking experience and built a Heath kit as a kid. At present I have 3 good LE25-2ís and one good LE25-4ís and one marginal (wrinkled cone) LE25.

Size is my second main concern for the center and rear channels. I would like to build a good 2-way or even a small 3-way out of vintage JBL drivers. I am not sure what drivers will voice match the mains. (I have jet engine hearing loss at 4500 hz and I say huh a lot, so I canít be an audiophile).

So what drivers should I look for etc.


12-06-2007, 04:17 PM
I'd be inclined to add a lowpass on the 115Hs.

The reason an L100 works without a lowpass on the 123a's, is that the woofer naturally rolls off, around 2500 Hz or so. In contrast, the 115Hs probably are relatively flat, to 5000-6000 Hz or so.

You might have to experiment with some slightly different lowpass filters (I'd suggest 12dB/oct. at around 2000-2500 Hz... but a 6dB/oct. might work as well) to see what blended with the LE5 and LE25, best...


12-10-2007, 09:47 AM
Thanks Gordon!

I will study up on this and experiment with that.

BTW Nice web site>