Which alternatives do i have with Fostex FE208EZ as a midbass? Horn on top and 18 inch sub.
Range ca 100 to 800 Hz with 24 inch wide baffle (or maybe up to 140-1000 Hz with narrower baffle).
I need to play LOUD so the excursion must be at a minimum. I use active dsp crossover (Audiolense).
I think it will be to weak in a open baffle!
Back loaded horn is to big and not clean enough in the lower register!
Front loaded horn is way to long!
What about a closed enclosure? Or cardioide? Or closed enclosure with passive radiator?
Joseph Crowe has an idea here? Could it be adapted to FE208EZ as a midbass in a much larger enclosure?
Range ca 100 to 800 Hz with 24 inch wide baffle (or maybe up to 140-1000 Hz with narrower baffle).
I need to play LOUD so the excursion must be at a minimum. I use active dsp crossover (Audiolense).
I think it will be to weak in a open baffle!
Back loaded horn is to big and not clean enough in the lower register!
Front loaded horn is way to long!
What about a closed enclosure? Or cardioide? Or closed enclosure with passive radiator?
Joseph Crowe has an idea here? Could it be adapted to FE208EZ as a midbass in a much larger enclosure?
Last edited:
I dont have experience with passive radiator simulations but i give it a try here:
https://www.seas.no/index.php?optio...catid=54:prestige-passive-radiator&Itemid=465
Passive radiator in red. The parameter for fs and volume is the same as default vented simulation.
https://www.seas.no/index.php?optio...catid=54:prestige-passive-radiator&Itemid=465
Passive radiator in red. The parameter for fs and volume is the same as default vented simulation.
And how do i match the off axis response as god as possible at the upper crossover frequency? Could it be some kind of a short waveguide like Avantegarde Mezzo?
Last edited:
I was thinking about the dipole loss down in frequency. But i can test in a 32 inch wide baffle with JBL 2384 horn:
I can't see the polar pattern of an 8" midrange matching that of that big horn, and good off-axis matching is important. That big JBL horn and 1.5" CD are meant to be crossed directly to a large-ish woofer, though an 18 might be pushing it.
IMO high excursion / high SPL is not the Fostex's strong suit. Simulation in Basta says the Fostex is good for about 106dB at 300 Hz in a tiny 2 liter box, but I'm not sure how good it would sound at that level. How loud do you need?
If I wanted to use the Fostex I'd put in a small enclosure, cross to the woofer at 200 - 350 Hz (depending on how high the 18" woofer can play), and use a small (~8" wide) waveguide / horn tweeter crossed where match the polar pattern of the Fostex matches that of the horn. Something like a Faital STH100 + HF108 should work. Or mabat's ST260 design, though it might be bigger than optimal.
Personally if I already had that horn and a suitable driver, I'd save the Fostex for another use like the Black Dahlia Jchris linked above, or sell it off and get a good 15" woofer to match the horn.
Bill
IMO high excursion / high SPL is not the Fostex's strong suit. Simulation in Basta says the Fostex is good for about 106dB at 300 Hz in a tiny 2 liter box, but I'm not sure how good it would sound at that level. How loud do you need?
If I wanted to use the Fostex I'd put in a small enclosure, cross to the woofer at 200 - 350 Hz (depending on how high the 18" woofer can play), and use a small (~8" wide) waveguide / horn tweeter crossed where match the polar pattern of the Fostex matches that of the horn. Something like a Faital STH100 + HF108 should work. Or mabat's ST260 design, though it might be bigger than optimal.
Personally if I already had that horn and a suitable driver, I'd save the Fostex for another use like the Black Dahlia Jchris linked above, or sell it off and get a good 15" woofer to match the horn.
Bill
The FE208 would work great as a midbass in an Oris 150 crossed over to the 2384 horn. I have two pairs of Oris 150 and a pair of 2384 horns and was thinking of doing just that.
make an XKi - tune it as needed for midbass duty - the vent will not be as long as indicated. Apply some carpet felt on the inside of the aperture's "wings"
https://www.diyaudio.com/community/threads/karlson-approach-for-fe206en.365744/#post-6489561
https://www.diyaudio.com/community/threads/karlson-approach-for-fe206en.365744/#post-6489561
I have some Oris 200 and have contemplated their use as mid bass horns for a while…wasn’t sure how well they might work.
I’m only just now moving into a space where a multiway horn system I’ve fantasized about might be possible.
There will be a lot more to consider then how I just threw an 8” fullrange into the Oris previously and then figuring out some bass support.
I’d be trying to match up with some 350Hz Edgar horns I have and most likely using a super tweeter above that.
I still haven’t settled on the driver for the Edgars. I mounted Radian 760pb neo and ran some tests, but was disappointed. My other option on hand is some NOS Dynaudio D54 which are said to work well in the Edgars and have a similar sensitivity to a Fostex 8”…but I haven’t run tests yet.
Both horns would have a similar profile
I have a pair of the 208ez and a variety of other 8” widebands including a pair of 206esr I picked up that showed up with mold/mildew damage.
Since I got most of my money back on the 206esr, I was thinking of cleaning them up as best I could, coating them with some dark tinted modge podge and losing the whizzer and dustcap for a phase plug…essentially turning it into a big magnet light cone midbass…it’s a crap shoot not based on any science…but not much to lose.
Still need to figure out proper bass support below…probably just a Jamo sub I have to start.
To be honest, I thought something like the well documented B&C 8pe21 was the way to go for mid bass…I have some on hand…especially in a horn. It just presents a lot of issues in my situation with trying to use the Oris.
The Fostex FE208 has higher THD than the 8PE21, which performs better as a midbass in a horn. On a flat baffle, you'll be hard pressed to get any low end from the 8PE21 based on the TSP specs. I've used the 8PE21 in both direct radiating and horn loaded enclosures. It sounds far better in a FLH than a flat baffled sealed or ported enclosure.
Not to push off topic…
I tried the 8pe21 in the Oris 200 just for giggles at one point.
Did a sweep with my uMic and REW…not useable like that for me.
The large vented back chamber did it no favors.
Every application I’ve seen that’s successful with the 8pe21 has used a very small sealed back chamber and a pretty small throat presenting a bit of compression on the cone.
Still I did try reverse engineering the Oris 200 as a Tractix in Hornresp based on measurements I took off my horn and was able to model usable response from 200-800Hz by shrinking and sealing the back chamber.
I’m just thinking I may get a broader usable range with something like the Fostex 8” wide bands.
I tried the 8pe21 in the Oris 200 just for giggles at one point.
Did a sweep with my uMic and REW…not useable like that for me.
The large vented back chamber did it no favors.
Every application I’ve seen that’s successful with the 8pe21 has used a very small sealed back chamber and a pretty small throat presenting a bit of compression on the cone.
Still I did try reverse engineering the Oris 200 as a Tractix in Hornresp based on measurements I took off my horn and was able to model usable response from 200-800Hz by shrinking and sealing the back chamber.
I’m just thinking I may get a broader usable range with something like the Fostex 8” wide bands.
Not only mid bass. In general this new FE208 sigma has extremely clear/articulate bass and low bass if EQed to it.
Close to a corner or deep in a book shelf it began to work in a bass reflex box to sound well. In contrary to other loudspeakers it did not sound muddied due to close room boundaries but it worked only with this help right - beside being EQed. Closed box did not work at all. Even with applied EQ it did sound over damped.
So this driver needs at least some front horn alike setup.
In the highs I just EQed it to desired response and it sounded then very well.
A diy speciality I exercise is putting aluminum foil to the dust cap only for better highs.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443469
My box was only 8 liter box and 4cm reflex tuned to 50hz.
Close to a corner or deep in a book shelf it began to work in a bass reflex box to sound well. In contrary to other loudspeakers it did not sound muddied due to close room boundaries but it worked only with this help right - beside being EQed. Closed box did not work at all. Even with applied EQ it did sound over damped.
So this driver needs at least some front horn alike setup.
In the highs I just EQed it to desired response and it sounded then very well.
A diy speciality I exercise is putting aluminum foil to the dust cap only for better highs.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443469
My box was only 8 liter box and 4cm reflex tuned to 50hz.
Last edited:
Yeah, based on published specs its Fhm = 2*87/.2 = 870 Hz, so a wide horn loading BW tuned to sqrt(87*870) = ~275 Hz = tiny sealed chamber.
If I remember correctly, I tried adding a conical adapter to that Tractrix model to see what could be gained by extending the horn and having the throat taper down and present the 8pe21 with a throat area of about 25% its Sd.
I was Essentially trying to mimic some of the multi segment conical horns I had seen designed for the 8pe21.
In the end I felt like I only marginally extended the effective bandwidth. Maybe 150 to not quite 1000Hz? I haven’t looked at it in a while.
That leaves me wondering if a driver like an 8” Fostex that provides circa 96dB of sensitivity and is essentially using the Oris as a waveguide to bring up the bottom end and increase the overall response a bit with no real compression might sound better and could be used over a slightly broader bandwidth without running into beaming problems.
My goal would be to have enough overlap at the top end to hand off nicely to a Dynaaudio D54 in a 350Hz Edgar horn…assuming I’m happy with that combination once I do some tests.
The D54 is supposed to be capable down to 800Hz…whether it will sound good that low is another matter.
It may be that either 8” will do if all that is needed is some fill from 200-800Hz…but something tells me it won’t be that easy.
I was Essentially trying to mimic some of the multi segment conical horns I had seen designed for the 8pe21.
In the end I felt like I only marginally extended the effective bandwidth. Maybe 150 to not quite 1000Hz? I haven’t looked at it in a while.
That leaves me wondering if a driver like an 8” Fostex that provides circa 96dB of sensitivity and is essentially using the Oris as a waveguide to bring up the bottom end and increase the overall response a bit with no real compression might sound better and could be used over a slightly broader bandwidth without running into beaming problems.
My goal would be to have enough overlap at the top end to hand off nicely to a Dynaaudio D54 in a 350Hz Edgar horn…assuming I’m happy with that combination once I do some tests.
The D54 is supposed to be capable down to 800Hz…whether it will sound good that low is another matter.
It may be that either 8” will do if all that is needed is some fill from 200-800Hz…but something tells me it won’t be that easy.
This design from Inlow is very good and can do over 1k if the throat is shaped carefully to avoid reflections. You'll need a phase plug to push it a little higher, maybe 1.3 - 1.5k if you can get a tight gap in the throat to the cone. Just a square throat and no phase plug will end up with around 1k cutoff at best. It will usually sim at a lower cutoff than what you get in practice.
https://inlowsound.weebly.com/135-hz-mid-bass-horn.html
https://inlowsound.weebly.com/135-hz-mid-bass-horn.html
I have Inlow 100 Hz today. But it has a horn throat extender so i can use smaller (and faster) drivers.
Measured 50 cm from the front:
Yellow is EMS LB7 (seven inch)
Green is original B&C (twelwe inch)
EMS LB7 sounds better, more micro dynamics and faster transients, better response up to 1000 Hz (and even higher)
https://inlowsound.weebly.com/diy-100hz-midbass-horn.html
This was the horn I was looking at when I was trying to see what I could do to try and modify the Oris horns I have for mid bass use.
To be honest, part of it was because I already have them.
It seems like most people levitate towards hyperbolic or conical profiles when you spend time looking into low frequency horns online.
However, using the same tractrix profile (supposedly Oris is an “embellished” version) as the Edgar mid horns I have did seem like an attractive idea. Volvotreter did this first time around (but switched to conical).
Adding a conical throat extension didn’t seem like a bad idea either.
Using the Oris with a dedicated mid bass driver as opposed to a wide band (208ez?) shouldn’t really matter.
I was going to be limited by the length and profile of the horn either way.
When I reverse engineered the Oris in hornresp based on it’s dimensions it actually models with a lower cutoff frequency than the “200” designation.
However it definitely had limited bandwidth no matter how much I played with the model.
This coincides with what you were saying profi.
Your comment about adding a phase plug reminded me that I was looking at the Limmer 870 short mid bass horn at the time I was doing this.
https://www.limmerhorns.de/870/
I wondered about trying a phase plug with the Oris even without a throat extension to try and gain some HF extension so I would have more leeway to match up with a mid horn.
I am trying to avoid the beaming you get with the Oris horns regardless what driver I use in them once you approach 1-2K. Maybe the phase plug helps with that as well?