Little DIY back-load horn for FF85WK - diyAudio
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Old 3rd November 2012, 03:51 PM   #1
IG81 is offline IG81  Canada
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Default Little DIY back-load horn for FF85WK

Hi,

Despite not ideal specs as a horn driver, I wanted to try the FF85WK in a BLH, with the intent to make it sound "bigger" and to be used on its own. Here's what I came up with:

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They sound pretty good! The back-load horn does its job to fight-off baffle-step in order to keep sensitivity up. Bass is strong and fairly "flat" down to ~75-80Hz and it's useful down a bit below that, but the cutoff is steep under there though. They are roughly 4-5dB more sensitive than a Minimus 7 measured next to them and sound better by far. Tonal balance is good, leaning a bit on the bright side, but it's not a bad thing considering the FF85WK's good behavior up there.

They won't do stadium levels naturally, but are very good within their SPL range, which is enough for my small room. They can put out some fairly strong transients on sparse material. They have to be on the floor, or at least very close to help give some LF support. Sitting in a low-boy chair or just a mat on the floor enhances the bass and gets my ears closer to driver level. A bit of back-tilt helps for the latter otherwise.

IG

Last edited by IG81; 3rd November 2012 at 03:54 PM.
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Old 3rd November 2012, 04:15 PM   #2
zman01 is offline zman01  Bangladesh
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IG81,

Interesting challenge you took and cute BLH! You mentioned small room - I see some BIG speakers behind the horns....?
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Old 3rd November 2012, 04:22 PM   #3
IG81 is offline IG81  Canada
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Quote:
Originally Posted by zman01 View Post
IG81,

Interesting challenge you took and cute BLH! You mentioned small room - I see some BIG speakers behind the horns....?
I am a man of contradictions. The big ones are for early evening, the BLH for late-evening and the Sony MDR-7506 for night time. The TD15M is somewhat over-damped in the 5.0cf box tuned to 32Hz, so it works in the small room. I thought, why not go for a 3" after these 15" in the back? I like to DIY and want to try as wide a spectrum as I can too.

IG

Last edited by IG81; 3rd November 2012 at 04:25 PM.
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Old 3rd November 2012, 08:44 PM   #4
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How did you figure out what size to build the horn box? Also how did you know were to put the spacers inside the box to get the most out of this driver? jm
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Old 3rd November 2012, 08:52 PM   #5
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Excellent job on the back horns! I too enjoy a large and small system.

Large: 15" H-frames with a 12" wide range driver and helper tweeter.

Small: 4" Fostex 127e or 5" Dayton fullrange driver in BIBs (which barely take up any floorspace at all).

Totally different sound for different moods. Both systems sound GREAT!
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Old 4th November 2012, 01:42 AM   #6
IG81 is offline IG81  Canada
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Quote:
Originally Posted by natural sound View Post
How did you figure out what size to build the horn box? Also how did you know were to put the spacers inside the box to get the most out of this driver? jm
I used Hornresp to model it. I also left some provision to adjust things like the compression chamber volume and the throat area, measured and evaluated subjectively, what I preferred was not necessarily what simulated best.

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Originally Posted by Godzilla View Post
Excellent job on the back horns! I too enjoy a large and small system.

Large: 15" H-frames with a 12" wide range driver and helper tweeter.

Small: 4" Fostex 127e or 5" Dayton fullrange driver in BIBs (which barely take up any floorspace at all).

Totally different sound for different moods. Both systems sound GREAT!
Thanks! I like to enjoy as many aspects of audio as I can.

IG
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Old 4th November 2012, 01:56 AM   #7
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Old 4th November 2012, 01:29 AM   #8
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those just look too cute.
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Old 4th November 2012, 08:55 AM   #9
ODougbo is offline ODougbo  United States
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Yes very interesting! Looks bigger than a 83mm speaker, must be the tall cabinet.
Did you buy the drivers through P10? His "treatment" makes a huge difference; way better imaging and a "matched set" sound.
(Pic - Loner set of FF125WK drivers from P10)

It be great if somebody could design a BLH for the FF125WKs.
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File Type: jpg 125s P10.JPG (184.7 KB, 71 views)
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Old 4th November 2012, 12:02 PM   #10
IG81 is offline IG81  Canada
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I got the drivers from Solen, I don't live too far from them.

IG
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