I bought a pair of vintage FE103 sigma's with the intent if trying them in a wood mid horn in my 3 way setup. If it doesn't work, then they will reside as a bookshelf speaker.
These units peaked my interest because #1. I've never seen a this sigma model for sale before. It has a very flat response and its double magnet might mean its powerful enough for front horn loading.
#2. I've heard what a cone/horn can do with another project using JBL pro midranges, but felt it lacked the delicacy a lighter cone, with less power handling might have.
The horns I'm looking at building are either a bi-radial like a Yuichi a290 or a constant directivity horn.
Operating range will be the primary vocal range, limited to 300-600hz to about 2-3khz via a passive crossiver.
Altec 416 on the bottom, Altec 802 on top.
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These units peaked my interest because #1. I've never seen a this sigma model for sale before. It has a very flat response and its double magnet might mean its powerful enough for front horn loading.
#2. I've heard what a cone/horn can do with another project using JBL pro midranges, but felt it lacked the delicacy a lighter cone, with less power handling might have.
The horns I'm looking at building are either a bi-radial like a Yuichi a290 or a constant directivity horn.
Operating range will be the primary vocal range, limited to 300-600hz to about 2-3khz via a passive crossiver.
Altec 416 on the bottom, Altec 802 on top.
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I'm surprised only 4 db. Is it because of the type of horn ?
I had always thought that horns lift between 6 and 10db depending upon
the particular configuration.
I have for a long time, wished to experiment with putting a small Fostex driver (3 or 4 inch unit) on a huge round tractrix, just to see what it sounded like.
Andrew, thanks for that !
Had you considered using a back chamber ? I only ask because I have heard a few systems like that, with the rear wave splashing about, and it's just not my cup of tea.
Your horns are really really nice ! So, what driver have you found that you like the best ?
According to Hornresp, a compression chamber effects the front wave high freq extension greatly (not reflected sound, but loading of the driver). Maybe that is why it sounded so "laid back"?
My plan is to build an adapter and try both the Altec 288-8G compression driver and the fostex.
I think the biggest drawback will be efficiency compared to the rest of the system. The 416 Onken is around 100dB. So no chance of getting 10dB gain?
My plan is to build an adapter and try both the Altec 288-8G compression driver and the fostex.
I think the biggest drawback will be efficiency compared to the rest of the system. The 416 Onken is around 100dB. So no chance of getting 10dB gain?
Wide BW point source drivers designed for baffle or ~3-4 dB BLH loading usually can't tolerate any real compression loading beyond a 2:1 ratio throat and then only with conical [preferably parabolic] wave-guides, so little wonder Andrew's are 'laid back' as we would be too if our motions were always being pushed/pulled by a high pressure, wide frequency range wind 'tunnel' A/C pulse.
Bottom line for best overall performance, any [minor] BLH loading or FLH wave-guide baffling of such drivers should be limited to below its upper mass corner [2*Fs/Qts] to maintain its wide range output and due to driver design this holds true even in limited BW apps.
That said, there are [were?] some 'FR' drivers that are designed for modest compression loaded and are easily spotted due to having a prominent phase plug combined with a very strong motor [low Qes] and stiff suspension [abnormally low Vas], but even then best limited to a relatively large tractrix with a compression chamber.
If loaded with a 'weak' motor [higher Qes and/or coupled to a high output impedance], then use either a suitably large semi-aperiodic or sealed compression chamber; and for high Q drivers, 'gapping' them at the driver/horn junction to 'bleed off' some of its 'Q-ness' similar to a R-J BP alignment has worked well IME, especially if there's a filter to further damp it once the right 'vent' dimensions are found empirically. I wonder if AkAbak or similar can sim this.
GM
Bottom line for best overall performance, any [minor] BLH loading or FLH wave-guide baffling of such drivers should be limited to below its upper mass corner [2*Fs/Qts] to maintain its wide range output and due to driver design this holds true even in limited BW apps.
That said, there are [were?] some 'FR' drivers that are designed for modest compression loaded and are easily spotted due to having a prominent phase plug combined with a very strong motor [low Qes] and stiff suspension [abnormally low Vas], but even then best limited to a relatively large tractrix with a compression chamber.
If loaded with a 'weak' motor [higher Qes and/or coupled to a high output impedance], then use either a suitably large semi-aperiodic or sealed compression chamber; and for high Q drivers, 'gapping' them at the driver/horn junction to 'bleed off' some of its 'Q-ness' similar to a R-J BP alignment has worked well IME, especially if there's a filter to further damp it once the right 'vent' dimensions are found empirically. I wonder if AkAbak or similar can sim this.
GM
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At the moment, I'm using Faital Pro HF200, which works very well. I can run it veryow from 500hz if needed, but presently 800hz xover. No separate tweeter at this stage. Getting towards 17,000hz.
I would definitely encourage you to try this driver , I have been looking at sims for FF125Wk for a 180-200Hz hyperbolic myself in idle moments. I think there is a lack of practical info on low-Rms drivers used in low-mid horns . All compression driver have very low Rms as far as I can see.
You might want to try out a phase plug also, once you tried the horn initially. I found a phase plug for the B&C 8PE21 made a lot of difference to the tone when used on a 120Hz tractrix .
You might want to try out a phase plug also, once you tried the horn initially. I found a phase plug for the B&C 8PE21 made a lot of difference to the tone when used on a 120Hz tractrix .
I got decent boost - more than 4dB - from a simple (conical) Fostex front horn. I assume that would translate to your driver.
You might want to skim this thread, I just added some (nicer) FR plots to it:
[URL="http://www.diyaudio.com/forums/full-range/280220-fostex-ff105wk-conical-horn-2.html"]http://www.diyaudio.com/forums/full-range/280220-fostex-ff105wk-conical-horn-2.html[/URL]
You might want to skim this thread, I just added some (nicer) FR plots to it:
[URL="http://www.diyaudio.com/forums/full-range/280220-fostex-ff105wk-conical-horn-2.html"]http://www.diyaudio.com/forums/full-range/280220-fostex-ff105wk-conical-horn-2.html[/URL]
Just got the fe103 sigmas in the mail today. They were stuck in customs from Germany. The suspension is VERY stiff! Much stiffer than the fe126en I had. Almost pro audio stiff. Should I let the run in over night? Or is the stiffness good for horn loading. Initial REW sweep shows a strong rising response.
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Ideally you want a stiff suspension by design [low Vas, cms, Rms] along with a rigid diaphragm for compression horn loading to keep it from physically distorting its moving mass parts, so for some that have hardened with age, best to design based on its current specs, so that they will resist loosening up too much.
This will require a <1:1 compression ratio [CR], so a phase plug will be required for good HF output. Ditto a small rear chamber, limiting LF BW, so may not meet your response requirements.
GM
This will require a <1:1 compression ratio [CR], so a phase plug will be required for good HF output. Ditto a small rear chamber, limiting LF BW, so may not meet your response requirements.
GM
They are CNC machined by Artluthe Audio in Montreal. I bought them rough cut, and had to do the sanding and finishing. Great fun project. They sound very smooth. Vocals are very natural, but percussion isn't as real as the metal horns. They are 800hz bi radials xover at 1khz.
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