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In Reply to: RE: Hornresp 1st pass - comments/critiques welcome. 40hz "L" horn posted by Oldbean2 on December 30, 2023 at 14:12:05
I know you're looking at a bass horn, but it's difficult to get low bass without a long horn. My EdgarHorns drop like a rock at 80hz. Personally, I haven't liked folded horns as to me, they don't have the impact in the same way as a direct driver.
Another idea is doing a hybrid like the Altec VOTT A7 cabinet. It can get down as low as 40hz and easily around 50hz. It's also much smaller and can be more easily positioned in the room.
-Rod
Follow Ups:
Your right about length, that defines the lowest F it can have any gain over a direct radiator.
You posted a drawing of an old friend, the A-7. I wasn't sure i had the measurements but i found them.
In 2003 i rebuilt a pair of them for a good cause and he didn't care what i did.
If i have seen anything in my life, it is that driver properties and the ability to model things have actually made a pretty big and for me giant difference at work and worth considering drivers when building.
So here i have posted that Altec A-7 with the normal drivers and ones i picked.
For hf it's a bms 4550 an excellent driver and keeping it at least partly Lansing a JBL2226 which i had on hand and looked good at the time.
Notice the difference, on the low end and top end a very noticeable diffidence in raw bandwidth (there is no crossover involved here, these were measurements for figuring that out).
When done, this was a considerably wider bandwidth and flatter speaker than it started and sounded good.
I have several of the 2226 woofers, which, represent the best of the mud magnet woofers of the last millenium. California made by American Labor also means an almost $600 price for that driver new.
Most of the Chinese made units now sell for 1/3 to 1/4 that price with similar performance.
I fact, SKAR car Subwoofer drivers, at about $300 vs. about $900 for American ones with similar TSP's, make great Tapped Horns!
Of course, I don't mean to preach to the choir here. LOL.
Did you re-use the 800 or 500 Hz. horn with the new driver?
Hi
Yes i did, it was the 511. I did change a couple things other than to the 4550 and 2226 drivers.
There was a spot on the back side of the vertical flare in front of the flat flange that had "sensitive" spot i put some damping material on.
There was a spot mid point on the woofer flare that had a resonance where i glued a brace to the outer cabinet wall. The baffle at the bottom (bare plywood in the picture elsewhere) for the woofer port was added after measuring the box sealed (i didn't want to try and calculate the volume when i can measure it's effect).
When trying to work out a crossover, i found if i moved the horn back an inch and a half, could get a Synergy style crossover with very little or no XO phase shift.
This was a long time ago, i don't have a measurement file in the folder for it but i know i did once haha. Red scale is phase, + - 180 degrees scale. Crossover is about the center left to right
2226 vs stock raw response
hf raw response bms 4550 vs stock
Thanks for the curves, Tom. They pretty much tell the story!
Thanks. I like A7s but I would like to avoid the hybrid approach if possible.
What's your lower crossover for the Edgar's? A steep crossover right at 80, or do you cross higher?
Back for a bit again. Ignore me if you like.
Yes, the subs are set at 80hz and are connected directly from the preamp using a second output for the amps.
-Rod
Volvotreter has plans for a 77hz straight horn using an EVM-15B, but it looks smaller than Bruce's 80hz horn. His Hornresp simulation shows it starting to drop off at 90hz, and he crosses it at 100hz in his system.
I might fool around in Hornresp and see if I can increase length and mouth size a little and get it a bit lower. I presume Bruce never published the plans for his.
Back for a bit again. Ignore me if you like.
Reaching 40Hz with a folded horn isn't at all difficult. For one thing assuming it's going into a typical living room you can model in 1/8 space. In most cases you're going to be less than 1/2 wavelength out from the nearest room corner throughout most of the sub pass band, and in addition to the boundary reinforcement you're going to have cabin gain. The hard part lies in knowing how to fold it and design the actual cabinet. There's only one way to do that, and it's the same way that you get to Carnegie Hall: practice, man, practice.
I'm now thinking that a 40hz horn might simply be too big for the room, 14 wide by 24 feet long. Would have to sit too far back from the horn mouth - that's part of what I forgot. Thinking as a musician, 40hz is a logical place; maybe not so logical in practice.
An 80hz straight horn (conical) would be an MUCH easier build for a first attempt, would be about 4 feet out into the room; pull it out from the back wall a bit and the Allison effect frequency is below the horn.
I've worked up a 2 segment horn with a JBL 2220h that sims really flat. Could probably cross as low as 70 and maybe up to 500, though I don't think I'll need to.
I'll keep reading
Back for a bit again. Ignore me if you like.
If you must go with a straight horn (and there's no justification for it) stand it up on end on legs. Your sim is too flat. With perfectly acceptable ripple it could go much lower. As for sitting back from the horn mouth, my Table Tuba folded horn sub is less than a foot behind my listening position, while the L/C/R are twelve feet in front of me. You can't tell. Crossed where a sub should be, 80Hz, all of the directional information comes from the L/R/C. BTW, it measures 30x30x16 inches, F3 is 28Hz, and it's loaded with an eight inch driver. Direct radiators need large drivers, horns don't.
The Kappalite 3015LF seems like a possible candidate. I might fool around with some old fashioned graph paper and see what I can come up with
Back for a bit again. Ignore me if you like.
The 3015LF is a great subwoofer driver, for pro-sound folded horns. IMO and IME it makes no sense for use in the home.
which should be sufficient in a home setting
Looking at folding, I think I can make it a fairly easy, if somewhat space inefficient build. No folds over 90 degrees, roughly 36" wide 40" depth 74" height.
Still learning...
Back for a bit again. Ignore me if you like.
It is my understanding that at 125db you will suffer immediate permanent hearing loss.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"It is my understanding that at 125db you will suffer immediate permanent hearing loss."
It wouldn't be pleasant, and with extended exposure it would cause injury, but it wouldn't be immediate. One wouldn't listen at those levels anyway. If you think it seems like a good idea clearly you've never experienced it.
Walked out after a Foghat/J. Geils concert ended in the 70's. Festival seating, so we were right down front at the old Civic Arena in Pittsburgh.
Go out to the parking lot, and noticed my ears were ringing, and it sounded like cotton was stuffed in my ears. That was in my 20's, and I'm 72 now with tinnitus.
Like they say:
"Too soon old, and too late smart"
mg16
I've been in bands since 1965, worked the FOH at a major concert venue where 110dB was the average for three years. My hearing tests fine, with an upper limit of 12kHz, which is normal for my age. I spent a lot of time shooting too, back in '72, when no one wore protection. If anyone was going to join the Pete Townshend club it would be me, but somehow I've managed to avoid it.
115dB is sufficient in a home setting. As for folds over 90 degrees, it doesn't matter with a sub. Reflectors aren't even necessary so long as the bend to bend distance is less than 1/4 wavelength. For that matter you can use 180 degree bends up to 2kHz, but only with fully rounded bends.
I'll see if I can get a diagram together and will likely have a lot more questions
Back for a bit again. Ignore me if you like.
I don't know if anyone has the info on Bruce's 80hz horn. However, you might try emailing eso as he may have worked with him some of his horns. If you click on posts and then add Edgar to the search with eso as the Author, you might find out more.FYI: My bass bin dimensions are 20"W x 26"H x 32"D. The actual horn is what I got from Bruce and my brother and I built the cabinet around it and filled it with spray foam. The actual horn is 18"W x 24"H x 24"D. The driver is bolted onto the horn in a box that is not much bigger than the driver in the back.
PS: I found some old measurements with no sub using the Stereophile test CD and a Radio Shack meter adjusting for the inaccuracy of the RS meter. The crossover is 500hz.
HZ SPL
63 70
80 79
100 80
125 78
160 81
200 81
250 79
315 78
400 80
500 77
630 76
800 78
-Rod
Edits: 01/06/24
Everything I'm modeling in Hornresp is 8-12 inches longer for -3dB at 80hz. But it's not a bad start.
I'm sure his design has a lot more to it than he straight sided DIY horns I would build.
Back for a bit again. Ignore me if you like.
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