My odd little WAW/FAST with CHR-70.3 build

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Thought I'd share my strange little fast build with you. I say strange because I know implementing a full range driver in an open tunnel/open baffle and a small woofer in a small volume enclosure, all stuffed into a standmount size speaker isn't really the normal path one would take. Surprisingly, they do sound quite good though! Really as good as I had hoped.

I had had the Chr-70.3 in a 9L BR which I was very pleased with, but I just can't resist the urge to play and as of late I have been becoming more and more intrigued with the FAST concept. Plus I had actually built the small BR for the chp-70.2 and they were sitting around homeless. The extended range of the chr's and the fact that they seemed to lose their composure a bit when pushed started me thinking of trying a fast with them.

I wanted to make it a medium sized standmount, because I already have too many floorstanders kicking around my house. This creates quite a problem because it's a little hard to make much bass from a standmount and even worse with a good chunk of the enclosure is being taken up by a full range driver instead of a small tweeter. My woofer options were limited because not many are going to do well, bass wise, in these conditions, plus I wanted to keep the cost pretty low because I wasn't at all sure that this would work. I finally settled on the sb13pfc25 5" because it modeled pretty well was cheap and had a bit better sensitivity than the MA.

So, to try to make this long story short, I have a sb13pfc25 in 8L and a Chr-70.3 in a open back tunnel mounted above it in a mid size bookshelf speaker. crossover is at 400hz with a damped 2nd order on the woofer and just a cap and l-pad on the full range. Oh, I also used a small inductor in series with the FR to shape the top end. I don't know why, but thing like cymbals were very forward. I really didn't have this problem when using this driver in a BR.

Evan
 
And... here are some pictures

Crap! for some reason I always have problems uploading photos here. So only a couple at a time.
 

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and...
 

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And finally, here is the last of them. They turned out pretty good in my opinion. Being able to paint over any construction flaws makes for a less stressful build than using Ply:D even though the prep work is a pain. They sound very good to me; really I achieved more or less exactly what I was trying to with these. Relieve the Chr from producing bass to clean-up the midrange even further, they are quite nice all by themselves. Also, maintain or improve upon the bass from the Chr in a BR cab, hard to say here, but they have very good bass with more impact/feel and seemingly the same extension. Unibox shows f3 of 52 hz and f10 or 35 hz well damped box tuned to about 49hz. I don't have measurement equipment except for impedance. Minimum impedance 5.6 ohm @ 150hz, otherwise it stays above 8 ohms.

Thanks for looking. Comments or suggestions are very welcome.

Evan
 

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Can I ask what are you referring to by 'damped'?

Thank you!

Sorry, something I heard from someone else on here, not sure if it's a technical term

It's a resistor in series with the woofer's parallel cap. I was getting an impedance dip to maybe 3.5 ohms at about 100-200 and a corresponding audible whomp sound in that region. The resistor brought it up more in line with the rest of the frequency.
 
I say go for it. I'd be inclined to use a little bigger enclosure for more extention. I had originally planned on 11L for the woofer, but after I setup the test box it was bigger than I wanted for this project. It's certainly very listenable as is though.

Of course I don't know what woofer you want to use:rolleyes:

Sounds like a plan; the A7 should sound even better.

Evan
 
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