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Cinema F-20 build thread


CECAA850

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Going from memory (again) yours may go a tad lower and his has a slightly flatter frequency response.

Whem I put the mike in the horn mouth, it was RULER flat from 20-60 Hz.

At my sweet spot, with room gain, it goes down to -6 db at 18 Hz. and -10 db at 15 Hz., which is still useable. Room has a peak at 25 Hz. and the response starts to rise at 70 Hz. but I cross at 80 Hz. via Audyssey setup

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Due to it's size and my room, I'm pretty limited in placement, but I'm hoping that it's size and output will make that a relative non-issue. it should compliment the rest of my system (noted below) and since I don't have any nearby neighbors i'll be able to air it out regularly. :)

OK, so have you tried a test tone CD..........say, from 10 Hz. to 100 Hz? BTW, this is a FULL 3 1/2 octaves below LaScala so-called bass.

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Due to it's size and my room, I'm pretty limited in placement, but I'm hoping that it's size and output will make that a relative non-issue. it should compliment the rest of my system (noted below) and since I don't have any nearby neighbors i'll be able to air it out regularly. :)

OK, so have you tried a test tone CD..........say, from 10 Hz. to 100 Hz? BTW, this is a FULL 3 1/2 octaves below LaScala so-called bass.

He's not going to get much if anything at 10 Hz. That's half an octave below the tuning frequency of the box. I also think he has a high pass filter set at 20Hz on his amp.

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Due to it's size and my room, I'm pretty limited in placement, but I'm hoping that it's size and output will make that a relative non-issue. it should compliment the rest of my system (noted below) and since I don't have any nearby neighbors i'll be able to air it out regularly. :)

OK, so have you tried a test tone CD..........say, from 10 Hz. to 100 Hz? BTW, this is a FULL 3 1/2 octaves below LaScala so-called bass.

He's not going to get much if anything at 10 Hz. That's half an octave below the tuning frequency of the box. I also think he has a high pass filter set at 20Hz on his amp.

that's correct; the box is tuned to 20hz and the driver itself isnt meant to go below aroynd 18hz and so i have it high passed at 20 hz. I know there's plenty of content below 20hz, but i cant say i'm missing much from an overall movie watching experience. no one that has indulged me with an audition has felt the need to chime in and comment on the lack of 10hz content in my setup. ;)

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I know there's plenty of content below 20hz, but i cant say i'm missing much from an overall movie watching experience. no one that has indulged me with an audition has felt the need to chime in and comment on the lack of 10hz content in my setup. ;)

Bingo. 10Hz is the wind..literally..it's a strong puff of air, like closing a door (at low volume) or a thunder clap (at high volume). I've had the opportunity to listen to a couple systems that could go that low, with the proper authority. Both systems were well into the 5-figure arena and custom engineered. One system played specially recorded content for the public, the other was a fine home theater system.

With that much acoustic power on-tap, the experience ended up one of two ways:

1. It was incredibly realistic. The real deal for all intensive purposes. Hair raising, if you will. [li][Y]

2. It was incredibly distracting. Almost comical how all the structure around me was getting the crap kicked out of it. Creeks, moans, and rattles galore[:S]

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Here is a good read about a sub a guy intends to build that will go 130db flat from 10-40 hz.

http://www.diyaudio.com/forums/subwoofers/63831-i-want-subwoofer-flat-10hz-40hz.html

Boy, that's an old one. I didn't notice the date till they started talking about Avalanche drivers.

Regardless, 130 db at 10 hz. is a pretty steep request. That guy from Italy that built 10 Hz. horns in concrete below his house, using 8 18's for drivers per channel, only uses a 6 Watt amp so he doesn't blow his house apart, not to mention his hearing.

I can see having super efficient speakers that can go 120 db plus with less than 100 Watts, I have those but it's NOT for SPL, it's for lower distortion and greater micro-detail clarity, a totally different goal using the same idea.

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  • 2 months later...

argh. was wondering when this would happen. between recovering from wife's unpaid maternity, out of town family visits, and rainy weekends I just haven't gotten it done. And since you're not coming up north next month, I'm no longer stressing about how it'll get done before then :P

Give me till the end of August and I'll have her painted and pictured. I've been doing what's most important - using it! Actually having a little star wars EP I, II, III marathon this saturday with some friends. I'm excited. :)

In the meantime, here's some much cuter photos.

addie-13.jpeg

addie-14.jpeg

addie-15.jpeg

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That finish was extremely easy to do. The pics are from a sub I just built for my son's car. It's 4' across, has a net volume of 7.5 ft, a 15" driver and interchangeable ports for different tuning frequencies. After the box was sanded and imperfections bondo'd (like your box is now) we rolled household primer on it with a long napped (rough) roller. After it dried, we gave it 2 coats of flat black with a similar rough roller. It actually looks better in person than in the pics.

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