Implementation of Fostex FF85wk

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#22
planet10 said:
Have you tried with the woofers closer to the FF85?

dave
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Hi Dave,

That's a good question, and the main concern I had when I was building the system.

My design constraint was that I wanted to use those bass modules, which I have been using for >20 years as the "foundation" of various speaker projects, and I had no intention of building a new set of bass modules. The resultant center-to-center distance between the FF85wk and the upper woofer is around 27.5" (31.5" between the center of the FF85wk and the mid-point of the two woofers). This is of course a large distance.

I try to ameliorate the issue by doing two things. First, the crossover frequency is 200Hz. Second, I listen to the speakers from ~10-12 feet away. So far, I have not noticed a problem.

Kurt
 
#25
The large size has the advantage of pushing the 2π to 4π transition, it also makes centre-to-centre larger resulting in (ideally) pushing the XO down in frequency.

To be more specific, the first thing i would look to in that system is to flip the woofers around do they are closer to the FR, and i would trim the paper mâché down so that the woofer box can be imbedded into the sphere.

I would suspect centre-to-centre could be halved, allowing for halving of the XO point while still maintaining the magic quarterwave distance.

dave
 
#26
KCHANG said:
The resultant center-to-center distance between the FF85wk and the upper woofer is around 27.5" (31.5" between the center of the FF85wk and the mid-point of the two woofers). This is of course a large distance.
Click to expand...

You need to maesure to the middle of the bottom woofer.

Guess about 36”. Suggests an XO less than 100 Hz to mauintain the optimal spacing. If that could be halved, you XO point would be close to perfect.

dave
 
#28
Whether you offset the midTweeter from the woofer depends on box, aesthetics, more… if you can get the midTweeter \/woofer XO low enuff that the centre-to-centre are less than a quarter wavelength there is no offset needed as the drivers are essentially coincidental.

dave
 
#29
I'm currently crossing high, 3200hz, but may try low, 250hz or so, to see which sound I like best. Using external XO makes it easy. If I center the ff85wk will I get good response either direction I go with XO? My cabs will have edge treatment to help with diffraction. Thanks.
 
#31
Adding a LP to any satellite, FR or multiway, can significantly improve the midTop.

First experienced when we added woofers to LS3/5A

Tysen and Tysen V2 as well as the bigger WAWs explempkify this.

Dome well, a WAW can give most of the magic of a FR and as much bass as you want/have room/can spend money on. And the FR can be smaller typically leading to the possibiliites of even better midTop (The FF85 & A5.2/3 are superb here).

We have XOed FF85 from 180 Hz up to 450 Hz. 180 Hz is too low.

dave
 
#34
Thanks Norman!

What can I say? Guys just cannot resist showing off their balls. 🙂

Joking aside, after listening to those balls for several months, I still think that the balls provide the best sound I've been able to squeeze out of those Fostex FF85wk drivers.

Kurt
 
#35
What I'm getting at is, is it necessary to offset the ff85wk, regardless of where I cross it over?
My baffle is 8 1/2" wide and driver centers are 4 3/4" apart currently.
Currently crossing to SB13 at 3200hz but would like to try the 250hz or so XO point.
I'm enjoying the Fostex covering HF, not as spitty, sibilant as dome tweeters.
Thanks for any suggestions.
 
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