# Budget DIY 7.1



## Guest (Apr 16, 2007)

A while back a friend of mine asked me to help assist him in putting together a “budget” home theater speaker system to include 7 speakers and a sub. I spent some time reviewing his design goals and in the end we settled on smaller speakers to sit in his entertainment center and in-wall for the rears.

For the front left, right and center I built MTM speakers using the Creative Sound Solution’s WR125ST woofers http://www.creativesound.ca/details.php?model=WR125ST and Seas 27TFFNC/G tweeters http://www.seas.no/Prestige Diskanter PDF/27TFFNCH1396.pdf . The 4 rear speakers are all in-wall speakers using Parts Express in-wall kits http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-520 and FR125S (full range) drivers http://www.creativesound.ca/details.php?model=FR125S .

Due to the smaller enclosure requirement, I opted to build the LCR enclosures with aperiodic vents to avoid the bass boom. Believe it or not this rather small 4.5” driver really packs a punch. Past speaker experiments has taught me that this driver works best in large sealed enclosures, bass reflex designs, or in mass loaded transmission lines (in a MLTL expect bass to 40 Hz - not at great spl, but low bass nonetheless!).

This project was my first attempt at incorporating a aperiodic vents into a speaker design. While I was not able to perform actual impedance measurements, I feel confident that I am close and am happy with the finished speaker. Bass is a little more limited than a larger ported design, but it is still adequate and mates beautifully with a subwoofer crossed at 100 Hz or lower.

The crossover is second order LR at about 3500 Hz. Originally, I shot for a crossover point around 6000 Hz (the WR’s are almost full range capable) but felt the WR125’s beamed too much and so I lowered the crossover point. I had to pad the tweeter a little to mate with the woofers. I would say the speaker efficiency is around 88 db. As for the rear speakers these are currently running full range mounted in the PE in-wall grill kits.

Overall I am pleased with the turnout of our efforts. We stuck to the budget and my friend now has a nice 7.1 setup to match his new 65” TV.

Here are a couple of finished pictures of the speakers along with a couple of build pictures. As for the subwoofer I plan to report on this in another thread.


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## kano32 (Sep 14, 2006)

Great job. Thanks for the post.


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