Wanting to build LaScalas

[JohnA]

The bass to mid xover in a La Scala is at 400 Hz. I've never seen data showing the upper end of the basshorn's response, but that 400 Hz crossover limits the squawker drivers that will work. Bruce, you're correct that most squawkers want to be crossed at 800 Hz or so. That's one thing that has kept me from creating my own 2-way La Scalas. PWK first made 2-way K-horns and lately the experimental home Jubliee is a 2-way design (the Jubilee has a new basshorn that is said to go up to 1000 Hz or so. The xover is at 800 Hz). I think if Mr. Paul could have made a 2-way La Scala, he would have. In pro audio, a tweeter that has a long term power rating of 2 watts is one that is just waiting to be blown. The La Scala, in particular is not the speaker to have used that tweeter if there was a way around it.

John

[djk]

John Warren: I don't know what the specs are on the EV 18W-K .I do know that If you send them a frame they can still re-cone them. Bruce: There was a Motorola KSN1016 piezo mounted in the mouth of the EV SM120 midrange horn.The crossover was 6dB/oct at 400hz with a 6dB series pad.The pad was bypassed by a tank circuit tuned to 4Khz.This made the SM120 flat from 400~4Khz and also matched the level to the woofer.The KSN1016 was crossed at 18dB/oct at 4Khz and was flat to beyond 20Khz.This was fine in a big room but overpowering in a small room.Later I added a three position 20Khz roll-off switch.After making several dozen fiberglass horns that looked like the K400 I went to Atlas drivers.

[Marvel]

djk -- Shows you what I remember. They were, how should I say it, rather bright in a small room. I don't have a problem making them three-ways, so I'll probably go ahead and get the mid from Klipsch, unles someone knows of another mid horn driver that will work. For sure, most don't go down to 400Hz. This is more fun than stacking BBs is a corner.

Bruce

This message has been edited by Marvel on 08-27-2001 at 04:05 PM

[TBrennan]

Marvel--I've been told that the LS basshorn does respond to 500hz, it has one less fold than the Khorn. However I'm not sure. However adding reflectors to the back, such as in the very LaScalaish Peavey FH-1 (a basshorn that I know responds past 600hz with a K-33 installed) would probably help top end response. JBL and Altec 1" compression drivers will absolutely work very well crossed over at 500hz. I've even used the Altec 806 crossed at 500 1st order with no problems. However the JBL 2420 crossed 500hz, 1st order sufferd from diaphragm clacking, but 500hz 3rd order no problem. If you are going to use these as PA speakers once in a while note that JBL lowers the power rating for thier 1" drivers if crossed at 500 instead of 800. For more info on JBL compression drivers go to www.JBLpro.com, they have complete specs on all drivers even obsolete ones. Also note that Altec used the 802 compression driver very successfully for many years crossed at 500, 2nd order in professional speakers such as the A7-500. I suspect that PWK could have made the LaScala a 2-way but he was already geared up with a midrange-tweeter array that worked well and also a good aluminum diaphragm driver like a JBL or Altec would have cost more than the Atlas mid driver and EV tweeter combined, PWK was not one to use expensive top-shelf drivers if he could find a cheaper solution.

[Marvel]

A drawing forwarded to me by Gil (many thanks), for the LaScala bottom, has reflectors in the back corners. I don't know if this is a mod or not, but thought they made sense. There was a link to those on the site, but it no longer functions. Would it help the response to have all those coners rounded? Getting the high end bumped up a bit out of the bass cabinet would certainly make it easier to find a useable mid horn. Is the stock LaScala mid horn driver still made by Atlas? I would also assume that the price from Klipsch is still reasonable. Are the Selenium drivers worth looking at or should I stick with the Klipsch or JBL drivers? Perhaps I should just get the bottoms done and see what the response is coming out of them.

As far as PA use, most of it is strictly voice, speakers at conferences, or acoustic music. I think djk built his for some pretty hard core rock.

[TBrennan]

Marvel--Stock LSs don't have reflectors in the back corners. Ask about the high end response of the LS basshorn in the high-efficiency forum at www.audioasylum.com, many very astute hornys hangout there and I think one fella there has measured the LS bottom as responding past 500. If you can cross at 500 I don't think you should mess around with Selenium, Eminence, Beyma etc. The JBL and Altec drivers are tried and true, I'd rather use a used JBL or Altec than most new drivers. About 25 years ago my partner and I built LaScala bottoms and matched them with Altec 802s on 511B horns, if there was a hole in the response between 400 and 500 it wasn't obvious to us (we didn't measure the speakers). My partner's brother still uses these speakers in his hi-fi. They look real cool too, black LS bottoms with a black 511B on top look most impressive. :-) Note that some of what I say regarding this subject is based on supposition (the high end capability of the LS basshorn) and opinion (the superior sound of Altec and JBL compression drivers).

[Tony Reed]

Marvel:

That drawing you obtained from Gil had to be the one I did. (I had it posted here for some time) It's a mod that seemed to make sense to me, more so for a 2-way than a 3-way. I've built a pair of homemade LaScala's just for this mod, but I haven't had a chance to test it yet. One of the engineers at Klipsch said it looked like a good mod to him. He went on to say, they had thought of this before, but hadn't really explored it like they should have.

Tony

[Marvel]

Hi all,

Still working on this project, just have other projects in front of it for a while. I have two more questions for those who are far more knowledgeable than myself.

The LS horn flare isn't very smooth at all (I know, it was an industrial speaker first). After the initial flare (left and right) the horn stays the same as it comes toward the front (about 7 1/2 inches). Then it flares again, to the the mouth. I figured up the area for these three different sections, and figured out I could have the flare be more constant (or continuous at least) when I build them. As TBrennan says, he thinks they will go high enough to then cross at 500Hz anyway, but would this help out any? Someone had mentioned that adding the corner reflectors caused some funny output in the upper end, but this might be a better solution. Couldn't do what I have in mind on a stock LS, but these are starting from the ground up. Also figured I could make the cabinet just enough wider to make those side parts be 3 inches across instead of 2 3/4. Perhaps I will make these and run some tests, before I get the mid/hi horns.

The other is the wood I was going to use. What I had thought was birch that I had purchased before, turned out to be 'golden virola' a wood from South America. It has very clean grain, and has nine (count 'em: nine) plies. all the same wood. It is used for cabinet making and furniture, but wondered if anyone here has used it before. The birch here is running around $44 a sheet, while the virola is only $34 right now.

Thanks for the input,

Marvel

BTW, I got to hear John Albright's LaScalas a few weeks go. Sweet! Took over a David "Fathead" Newman CD of Duke Ellington songs. Sounded like they were playing in the room.

=================

After reading some of DJKs old posts on another forum, I realized the reason for the two different flare rates on the LS. Still wonder about the sides remaining constant.

This message has been edited by Marvel on 10-16-2001 at 07:49 AM