Folded Horn Configurations?

[Thumpr]

A friend of mine still has a Randall cab with 2x12's, folded horn. He hasn't used it in quite a while but he still has it.

Was just going to say Randall. I may have had that same cab. Like 1985 era? 212 with speakers horizontal center mount. Heavy cab! I blew it up then replaced w jbl’s and still remember the nightmare of having to use a regular screwdriver to remove/replace the (seemed like a zillion) 2” wood screws in the back.

 

[kesslari]

I wish I could get my Cerwin-Vega B36MF back. An 18 in back and a 12 up front. Once the guys at New England Speaker added an aluminum dust cap to the CV 12, the thing rocked. Not that bad to lump around either.View attachment 3333125

I have fond memories of my B36MF too.

 

[nixdad]

I owned several folded horn cabs in the 80's. Besides the size & weight issue, my experience is that they were difficult to hear on stage in many rooms.

 

[Boundary Effect]

The Electro Voice Sentry IV was a double folded-horn. The dual 12" drivers fire forward from a sealed enclosure into the horn. In the day as a kid, I rather liked the sound of them; however they do not provide big bass. EV Eliminators of that era were folded horn with a 15" SRO, fore bearer of the EVM.

 

[agedhorse]

In fact there's no gain in moving air, the plus in compression ends at the horn's orifice.

This is not true. In the pro audio (and earlier cinema) world, there were quite a few multiple driver folded horns. There were plenty of conventional multi-driver horns as welll.

 

[2F/2F]

Overall, folded horns don’t get much love. Probably because of weight.

My favorite sounding cab that I ever played though (and I own one) is a 2x15 foldedhirn. It’s crazy heavy and large. It’s a 197x Ampeg V4B cabinet.

I would love a small version. Would it work with a 2x10?

I have two of those "mid-sized" '70's Ampeg cabs, that were sized in between a 4x12 and an SVT-sized cab like yours. One is a 2x15 (a B-25B cab), and the other is a guitar cab, which is the same size, but with a 4x12 baffle (Jupiter B-42X cab). Two of my favorite cabs!

 

[DukeLeJeune]

Check out Bill Fitzmaurice folded horns.

My understanding is that Bill uses a tuba-like flare, gradual for most of the way and then widening rapidly near the mouth, as a technique for shoehorning adequate length and mouth size into a smaller-than-normal-for-a-horn enclosure.

This is not true. In the pro audio (and earlier cinema) world, there were quite a few multiple driver folded horns. There were plenty of conventional multi-driver horns as welll.

I am under the impression that horn mouth areas can effectively add to one another, such that if you know in advance that you'll be stacking multiple horn enclosures, you can under-size the mouths of the individual horns, as once stacked the effective mouth dimensions will be correspondingly increased. Is this in the ballpark?

If so, it would seem to imply that large PA-system horn arrays are more likely to be practical trying to use a horn for a bass cab.

 

[Blaze Barlow]

The speaker you’re referring to is the Sentry IV, not an Eliminator. It was comprised of the dual 12 bass bin, a 90 x 40 horn with a phenolic MF driver and an ST-35 HF. Those were pretty good PA speakers back in the early 70s.

I had 2 of those cabinets..mine were labeled Electro Voice Sentry IV B..they were 3 way and did have an adjustable crossover included..I used them as a small PA in a deli that had a small stage for live entertainment..mostly for vocals as everyones personal gear carried the small room..I have played bass through them..with a bass amp in front..and they really sounded pretty good..the low end really punched through and highs were added at the amp..wish I have kept them instead of selling them..there were no handles on the cabinets which made them difficult to move..so a dolly always came in handy..the midrange horn was mounted on the top and was some sort of plastic..they needed an enclosure around them to protect from damaging the horn..the small hi horn was mounted in the upper front region of the bass bin..it was minimal but vocals sounded nice through those cabinets..I bought the cabs in 1979 and at that time they retailed for $1100 a pair..the construction of the boxes was excellant..they were heavy duty and solid..before I bought mine..I saw 4 of these cabs pushing a disco mix at a club..they were elevated off the floor and were really putting out some sound..electro voice was definately a superior product..back in the day..their SRO speaker cones were king of the bass cabs..

 

[jnewmark]

And then there is this :

 

[byrdzeye]

The V4B was a great cab. Had mine (loaded with Altec's) in the seventies NE club circuit, with an SVT head on top. This thing just ROARED! Used a PBass with DiMarzio's and Rotosounds...classic setup, great growl, classic sound. But at about 160 pounds, it just sucked moving this thing, especially up and down steep stairs. However, I didn't like playing it in echoey rooms, just too distant sounding. Would have used an SVT cabinet if I were to go back in time and repeat said adventures.

 

[BergerHead]

This is not true. In the pro audio (and earlier cinema) world, there were quite a few multiple driver folded horns. There were plenty of conventional multi-driver horns as welll.

You state that just the plenty of horns in the cinema can overcome physical limits? There's definitely not more energy at its opening (for sure there will be bitta more db with fewer wattage inside the horn, but ...); in the '70s these have become a hype on bass-stacks (and p.a. systems), so Acoustic, Hiwatt and other companies produced and sold them in rough amounts ... i did a lot of stage techs during this period, and in the end they disappeared as fast as they went up: +costs, +sized and +weight with no effect in the bass-frequency range; also parallel driven horns tend to unwanted obliteration in mid range frequencies. These horn-speakers are yesterday's tech and that's probably why they're off nowadays.

 

[funkinbottom]

In the early '70s, I built an EV Eliminator cab.(no tweet and x-over) I loved it. Powered it with an Ampeg V4B. It was actually pretty easy to load in and out. It just barely squeezed into the back seat of my VW bug. If any one has a wild hair up their backside to build one, PM me and I'll email pdf file to you.

 

[Thumpr]

This is not true. In the pro audio (and earlier cinema) world, there were quite a few multiple driver folded horns. There were plenty of conventional multi-driver horns as welll.

+1

When I was at Skywalker South in West LA from 89-92 I was working sound stages set up with Voice of Theatre cabs. I’ve had smaller apartments than those bad boys but man they were more than impressive. They actually started phasing them out for custom builds at the end but those big multi driver cabs killed it.

 

[BergerHead]

In the early '70s, I built an EV Eliminator cab.(no tweet and x-over) I loved it. Powered it with an Ampeg V4B. It was actually pretty easy to load in and out. It just barely squeezed into the back seat of my VW bug. If any one has a wild hair up their backside to build one, PM me and I'll email pdf file to you.

View attachment 3333742

In the '70s i had the same ones for the practice room (which were a bitta oversized to get any benefit), we now run active 12"+tweeter wedges ...

 

[agedhorse]

Multiple drivers were coupled to a single horn to increase power handling and thus maximum SPL. Drivers of that day were very limited in power handling.There are limitations to this due to throat compression effects.

Xmax values were quite low, the matching to the horn reduced the required displacement through the acoustic transformer principle.

 

[agedhorse]

My understanding is that Bill uses a tuba-like flare, gradual for most of the way and then widening rapidly near the mouth, as a technique for shoehorning adequate length and mouth size into a smaller-than-normal-for-a-horn enclosure.



I am under the impression that horn mouth areas can effectively add to one another, such that if you know in advance that you'll be stacking multiple horn enclosures, you can under-size the mouths of the individual horns, as once stacked the effective mouth dimensions will be correspondingly increased. Is this in the ballpark?

If so, it would seem to imply that large PA-system horn arrays are more likely to be practical trying to use a horn for a bass cab.

Correct, coupled horns could grow the effective mouth area to some extent.

 

[ThisBass]

And then there is this :View attachment 3333687

the bottom chambers demonstrate nicely that moved air volume on its own means nothing but moved air volume.

The loudspeakers push the moved air volume into a "reduced" horn opening. While the moved air volume must remain a steady number the particle velocity will be increased according to the smaller surface of the horn opening.
As SPL is the derivation of particle velocity rather than moved air volume the efficience (respectively SPL) will be improved accordingly (this happens although the moved air volume does not change a bit).

 

[BergerHead]

the bottom chambers demonstrate nicely that moved air volume on its own means nothing but moved air volume.

The loudspeakers push the moved air volume into a "reduced" horn opening. While the moved air volume must remain a steady number the particle velocity will be increased according to the smaller surface of the horn opening.
As SPL is the derivation of particle velocity rather than moved air volume the efficience (respectively SPL) will be improved (this happends although the moved air volume does not change a bit).

This is a pretty high charge in techs & physics viewing the energy the amp has to pump in to get a bitta db more. As mentioned, increase basses' loudness is technically disproportionately viewing amp's plus wattage needed to have effect. -For sure everyone has its own likes and convictions, no offense or bashing intended.

 

[Oatis]

V4-B cab, also one of my all time favorite cabs. I've only played through them twice that I can remember but what a sound, solid solid.

The first time I heard the Stones Bill used a couple of those and he had plenty of bass !

 

[ThisBass]

This is a pretty high charge in techs & physics viewing the energy the amp has to pump in to get a bitta db more. As mentioned, increase basses' loudness is technically disproportionately viewing amp's plus wattage needed to have effect. -For sure everyone has its own likes and convictions, no offense or bashing intended.

True.
My intention was to contribute a very principle thing to the task.
And I think that the laws of physics don't ask any questions about my personal "likes".

But as usual, it all depends, there is no free lunch but trade offs.