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This looks of interest to me what do you think about this type of bass horn? I might try to build one simlar.Might need to build in 2 -3 parts to fit through a standard doorway, anyone know of a simlar cabinet design or any links etc that would be of interest or help.
Follow Ups:
nt
Hi Kloss, this type of bass horn was used by Ampex and Westrex in their big theatre systems of the 1950s. There were both the two and four driver versions. These systems were equipped with JBL speaker components, or similar units built under license. The system in your picture was built recently; I seem to remember seeing a picture of it in a hi fi or CES show report.
We found out that this basic design dates back to 1935, as a similar horn was evidently built as a prototype by the engineers of the MGM Shearer Two Way Horn System. I started a thread about this and another unusual bass horn on the Lansing Heritage discussion forums, link below.
It's missing the silver flecks from the screen touch-up paint.
Not the original woofers there.
Hi,
The Klangfilm Bionor is a similar type horn. It is open backed, the size of the baffles is crucial to good extension, according to the documentation. I suspect it has excellent midbass and may need some EQ for low bass in a theater-size room. Roomgain in a living room would change that, but you know your room better than I do.
The big Altec dual-driver horns are also similar.
Ivo
Those basically sounded like crap, considering the cost/rarity/hype/size/etc. Overly shouty, bad (non-existent) imaging, just really nothing to recommend them, IMNSHO. Yeah, cool looking and uncommon, but really, not worth bothering with.
-Ed
the bass cab design could be of some use I never got a chance to hear.But with diferant woofers.More modern comp mid and a t500amk2 tweeter sure sound quality would be very diferant.I dont think I will copy these I have better cab plans.
I would start with something like the Edgarhorn 80hz cab with a nice 15" in there. Maybe an altec 416A or 515-8G. That's what I use, it will get down to 40hz in room response, maybe lower (depending on room). between 95-105db/1wm depending on driver. You can also add mouth-extensions if need be.
FWIW
-Ed
Thanks Ivo, I already have bionor pictures down loaded just hard to get design right unless I can measure loudspeakers or get a basic cab plan.Klangfilm has some cool stuff booked marked this site many years ago.
In the '70s Steve Hall in Minneapolis designed a cabinet for Mike Justin called the "Cruncher", both for it's sound and what it could do to your foot. Horn looked something like most of the pictures shown in this post. The horn was 48" wide, 36" tall, and 29" deep, was attatched to the compression chamber with turnbuckles, so the horn would go through a standard door.
The throat was 7.5" wide. The horn arc was the radius of a 48" circle connected at the throat and mouth. Compression chamber was about 9 cubic feet for 2 15" cones. Rather large variations of those parameters had little sonic difference, as long as everything was well braced.
They sounded great, but to get them flat to 40 HZ would require a large boost, which they would handle with cone excursion far less than I was used to seeing in ported cabinets. Used them up to 800HZ, or even 1K when we used 1" drivers. With a pair per side you could definitely feel your pants legs fluttering in a big ballroom. I never did listen to them much in small rooms, but they would be impressive if you don't mind using a "loudness contour" to flatten them out. The rising response tends to work well for the peak power demands in most stuff originally mixed for vinyl, but could be viewed as anemic if you are used to flat to 30HZ.
Everything is a compromise, these types of cabs are not real bottom feeders, but they are hard to beat for impact when using sealed compression chambers. After listening to these, it seemed the huge ported RCA Ubangis,and Altec A2s sounded floppy, and folded horns sounded muddy.
Later, I built a bunch of dampened fiberglass units similar in appearance to scaled down versions of the Grey quad units, only they were for 2 15" and had nice phasing plugs between the cones. They were 45"x 45" x 30" deep, I had expected more bass out of them considering the almost 25% larger mouth size, but there was very little difference. The phasing plug and the non-parralel top and bottom cleaned up the sound 300HZ and above somewhat, although not a hell of a lot considering all the work. That was also a moot point, as I crossed them at 200 HZ into a 2x12" horn at that point anyway.
By the way, on some country gigs where space, time, and energy was limited, I used the 2x12" a 24" deep 22.5" x 45"horn,for bottom, and with 2 per side was able to get plenty of oomph down to 60HZ outdoors.
This is the famous Volkman theater horn developed by RCA to be found in Olson's "Acoustical Engineering" p 235.
It was used with an acoustic lens when made by Westrex.
It is also a maximum sensitivity horn study- another RCA project to be found on page 231 . It is almost 80% efficient.
By using a large throat, with a large radiating area, and a large rear chamber, it is possible to achieve a very high efficiency from 50Hz to 600Hz.
The shortish front horn was used as a pattern control device from 100Hz and up. It also increased the load on the front of the four woofers, yielding higher output than a big bass reflex. ( for example, an Altec A7 is around 105dB at 60Hz, due to the short horn and big rear chamber)
There are no horizontal time delay issues with this horn.
Later RCA employed a better version, a radial basshorn, wich with two woofers instead of four, would disperse to a higher cutoff.
I am sure Steve Schell, Master of all things RCA can correct me, and fill in the blanks!
Best Bill
Hi Bill,
Not sure how I could correct the master; I am the RCA-fan fan.
So the four driver straight horn is a Volkmann design? I didn't know this. I only have the earlier version of Olson's book, Elements of Acoustical Engineering.
Olson invented the W bin style folded bass horn and recommended its use to the Shearer team. RCA also used these bins from 1936 to the early 1950s, along with many other manufacturers. A persistent rumor from the old days was that RCA had made an arrangement with a casket manufacturer to build them during their slow times.
The new RCA radial horn systems replaced the Shearer style W bins and multicellular horns beginning in about 1952. The full size bass bin (in your picture) was the MI-9462, which was a combination enclosure featuring a 90 degree radial front horn loading the two 15" drivers and a large volume bass reflex box. It sat horizontally and its pattern was an excellent match for the MI-9595 90 degree midrange horn.
Hello Bill Thank you for the helpful post, any info on the radial rca bass horn? Iam trying to find a front loaded mid bass design to cover 50hz-500hz 110db 4-8ohms perfer 8ohm + this seemed a start I wouldnt stone copy of course just getting ideas.Would ne nice to cover such with 1 driver per horn but what? beside a comp. I can afford wood and drivers but bass comps are out of my reach$$. My main listening room is designed to corner load bass horns, room becomes part of the horn this design will fit.
.
much
I am busy with RMAF just now, but if you e-mail me at acoustichorn.com
I will see what I have on the more recent RCA radial basshorn, when I get back
bill
Hi Kloss,
I THINK RCA Fan is referring to what some people slang-call RCA " Ubangies", a bass horn which djk is also familiar with. Alan Sides, owner of Oceanway Recording Studios, etc., and of microphone fame uses these since the very early 70s.
I have used one pair of these, until recently, and have had friends who run 'em stacked, four 15s per side !!
Steve Schell will know the bass horn's RCA-MI number off the top of his head !! They are able to fit through a 31 1/2 inch door as I recall Kloss, and so, only sometimes do you need to remove a door frame's moulding.
I owned six at one time up until five years ago. "Interpleader" of eBay, on the North East Coast has 4 of mine, and David Gordon, of Josephson Microphone, has 2 of mine up in Northern California.
A true EXPERT on RCA Ubangies is vintage speaker Don Davis, of Texas. He used them for maybe 30 years, and mods them very intelligently. Don has also designed an improved bass horn - that should boogie. Hes THE man! when it comes to speakers and common sense.
Hope this helps. Will you be at RMAF?? Visit with me at the Serious Stereo room.
Jeff Medwin
As I searched about last night I found that out.I do thank you guys for your help.Wish I could show some off my work see hear others but my sons not ready for me to leave.Maybe in 2 years I will attend and if so I will bring many loudspeakers some giants so I will need a big costly room.
nt
Hi
might be ok for 150-85 traffic.. but i always found more coherence in
a single driver carrying 150-800 (or 150-500). i suspect that 4 woofers
would be overkill in most domestic living rooms. of course woould definitely be great
for a ballroom or disco. just my 2 cent of pure
speculation.
by the way, does anyone know of any horns that are pure front
horn for single 15" woofers that can go from 800-80. Edgerhorn Titans dont do that well from 400-800. just want an a bigger version of the horn portion of an A5 to go down to 80. thanks in advance.
munna
hello Munna...
you will likely have to DIY... but I have done this with a field coil 12 in a straight horn... the key is to find a woofer with low mass roll-off.. a good rule of thumb is 2*Fs/Qes... a very early 515 should do it.. but other than that, you will likely have to look into 12's, 10's, and maybe even 8's...
I keep saying I am going to try my B&C 8pe21's on a horn... perhaps I will just hold it up to Ming's big 60 Hz horns and see how it sounds.. :^)
Peace,
Me
is mass-load rolloff a key? - can it be "offset"? (groundplane response might look more extended)on central axis outdoors System 100 horn with 2220H and K43 type woofer
FH1 stock PV woofer groundplane vs 30 degrees off central axis
?
Under the mid horn sure might not be sub-sonic but sure looks like a bass horn to me.
"looks like a bass horn to me"
Not to me. Even a woofer good to only 40 Hz needs a minimum 7 foot path, that box looks to be half that size. An absurdly large mid-bass horn would be a better description.
Iam sure in room bass would be low enofe for what I need.I want to match a comp mid and dont want to biamp.If I feel the need for any deeper bass I can add it later.Not long ago I had a 15in woofer mounted in oris 150 horn cut for it mounted in a ob bass in room was good to 125hz horn hasent so deep, bell 31in.
I dont see any point at having four drivers in this box with that thing in a living room sitting a couple meters away unless you drive those things at concert levels outside then mabye it would be useful?
Isnt there some comb filter problems with this design?
"Isnt there some comb filter problems with this design?"No, but you're correct about the four drivers. A well designed horn would only use one, even for pro-sound applications. It looks impressive as all get out but that's about the only positive thing I can say about it. The throat is so large that the drivers aren't being loaded, so they're operating as direct radiators.
whats its goal and setting?
I'd like no speaker to be lifted by hand to weigh more than 70lb :^)
heres a sim of something
I would like 50hz in room. Maybe run up too 500hz or so thinking of useing 4 per 18in eminance sigmas.
And the volume of box those four 18" sigmas would require?
Or is this gonna be so heavily horn loaded it won't matter?For that matter, is the horn loading supposed to "outwoof"
the rear in some sort of open baffle? I can't see the back,
so I have no idea whats going on there...The minimum working length for bass horn is 1/4 wave???
I eyeball this horn about 1M long... Thats only 85Hz...
open back, drivers will be like a OB but with front horn loading.
4-sigma 2M length x2M square mouth - - can't do OB rear but gave 99999liter back chamberfor hell of it consider 4-8-10CF K's (4-6 sheets of wood) two side by side per channel feed them big cheap solid state watts put on some nice rap and have fun :^)
I think this could work well just hard to build to fit through my door.Would have to build in place or in parts.My end goal 3 way front horn t500amk2, tad 4001 and the eminance 4x18in front think 110db 4 ohm 50hz-35khz run on a nice SS or PP tube amp.Maybe build a large jenson imp or 2 for low end if needed.
OK, but below 85Hz, I think it may be an acoustic short circuit.
Seems silly to build all that, and then still need a subwoofer.
I'm not sain it won't sound great up close where the bass rushes
past on its way around the baffle.
Don't get me to lying. I have no real world experience that
would tell me this isn't gonna fill a huge room with bass.
Just the numbers don't seem to add up.
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