Folded Horn PA Subs for La Scala (or generally)

[gearfreak]

Howdy all, If this is better posted in 2ch audio or otherwise, let me know.

There seem to be numerous La Scala Subwoofer threads, but most discussing HT / amplified style subs.

I don't care about looks or size, so what is anyone's experience or opinion on using something like a folded horn sub-woofer?

e.g.

http://www.b-52pro.com/models/LX18V2.html

All of these ~1x18 variety seem to be of similar design. Freq. Response charts seem to be lacking in general.

Peavey seems to be (resurecting) the design, and I think you can still get the Cerwin (j-36?) 'earthquake' models used.

Should I expect comperable specs/performance from the design generally, or seek out a particular make/model?

Crossover probably would be active /to begin with.

thanks!

[Islander]

I may be wrong, but I think those PA-type "subs" don't go nearly as low in the bass as a regular home audio sub. Horn subwoofers that go really low are huge and usually pretty expensive. AvantGarde makes one that you could look up to see what I mean.

[darkside]

Islander is correct. Most pa speakers don't dig as low or go as high as home speakers/subs will do. A folded pa horn is good to maybe 30 hz in the more expensive ones (Cerwin Vega Afterburner comes to mind). The other thing about PA subs is that they're meant for long throw, high power handling, and high sensitivity to fill large rooms since they are almost all used for concerts. Look at the Klipsch cinema speakers though. The MCM 4-T-Grand will go deep for sure, but the horn sub is massive. At the same time, in a small environment, you will still get deep bass out of a PA sub, just not as much as with a home subwoofer since PA subs (the speaker itself) are usually low excursion (only 7-9 mm at most) and deep bass is dependent upon displacement of the driver cone itself. Hope this helps.

[darkside]

Not to say it won't work. If you're looking at that type of sub for music, and you get a good power amp to go with it, you'll never lack output for sure!

[colterphoto1]

30 Hz is NOT 'sub'.

PA cabinets are loud and very punchy, but surprisingly not really low for HT useage.

[djk]

Add 23dB for 1W/1M, CV 36 sub (30hz claimed).

[gearfreak]

Thanks all for all the good input.

Looks like avantguard is out of business (or out of distribution) in the US, but I will take a closer look via http://www.avantgarde-acoustic.de/index1.php?sprache=en.

I'll clarify, this is not for HT, so there is no overall goal of 20hz per se.

Maybe more practical would end up being another set of La Scala bins instead. (or do the ls bass mod). Will ruminate.

[darkside]

30 Hz is NOT 'sub'.

PA cabinets are loud and very punchy, but surprisingly not really low for HT useage.

If you want to get nitpicky and technical, sub isn't sub to begin with. Technically, it's infra...

[colterphoto1]

sorry, so this IS for PA- does it need to be portable? Is there a size restriction (truck or van?).

More LS bass bins will add more punch but you're looking for 30-100 to fill in. Klipsch made a 4000 bin that is sized to fit under the LS, but is a bit flatulent due to it's large passive radiator. KP682 is a dual 18" but it's a monster. A single of those might do for a lot of occasions.

[gearfreak]

Just experementation, 2ch stereo. The a dual 18 is probably overkill and untennable, unless there is a great deal on locally.

Not for a PA use at this time, though I would not be opposed to having the PA level-ish capability down the road.

The (advertised) efficiency of the horn 'subs' described seemed to match up in the range of the LS/LS Bin.

I see a lot of direct radiator 18's around cheap and was considering going for one of those, but then thought that for a little more investment up front I could do horn loaded and keep apples to apples.

[Cornwalled]

Hello Gearfreak,

I hope my (little) bit of experience can help. I used to work in the Pro Audio department of a Guitar Center store. Our speaker brands were JBL, Peavey, Yamaha and B-52. I might have forgot one. Anyway, those were the main ones. We didn't have enough room for any higher end JBL subs, but we DID have room for plenty of horns. Whoever stocked that room before I came in liked horn subs cause we had 4 of em, right across the front line. Arranged, left to right, CV, B-52, B-52, CV. (Don't ask me why they didn't buddy them up). We also had some 1x18 Peaveys, and maybe a yamaha or two as well to pair with the smaller speakers. So it was a pretty good rig in a not very large room. Definitely WAY smaller than they were meant to run.

It was setup such that both subs of any company ran at the same time. Let me tell you, by far the best sub, the clearest, deepest and punchiest was the Cerwin Vega EL-36B. I loved that sub. The only thing I had to do was patch in a 1/3 band EQ to correct for a room boost around 80 Hz that affected all subs. Of course, as mentioned, they certainly didn't mind if you brought up the bottom end around 40, and cut off below 25-30 or so. Maybe I have a PA ear, but I really thought it sounded great, and I got compliments from customers and the other employees on how much I cleaned up the sound in there. (It was a mess when I started, sounded like mud.) So while I didn't have a freq. response chart or measuring tool telling me what the sub was doing, I just knew that everything sounded right, and cd's that I played at home for years sounded good in there too. Of course the JBL 2x15 MRXs on top didn't hurt either! That's the only thing I miss about that job. Sure don't miss the pay.

Don't be afraid to check this out further. If I had the money, I'd have one at home too. It's been on my mind on and off for a long time. There's never any other company I considered. (No I'm not sponsored..lol)

-Jon

[djk]

As we can see from the CV L36 graph, it has no real bass (below 50hz).

Here is a series of simulations from Hornresp.

The LaScala with K33 (black) and K43 (grey):

A tapped horn design suitable for a sub for the LaScala (subtract 17dB to get the 1W/1M sensitivity):

The Hornresp input parameters:

Note that it is about 108dB/W/1M at 25hz, about -3dB at about 20hz, and looks like it should be crossed at about 90hz to the LaScala. The numbers are for 0.5Pi (corner loading), for 1Pi (along the wall), it is about 103dB/W/1M.