La Scala upgrading...

[Tab_cat]

My dad's got a pair of 1972 La Scala's, and I'm gonna give 'em a little extra kick, by replacing the K-33-E subs with something better. (I already blew up 1 of the subs... they're good, but they just don't handle the sort of power I need... they really don't like having any more than about 200W RMS continually pumped into them... the tweeter/squaker can handle it, but the subs won't.) What should I use? I chucked in a JBL sub that I got out of a J-bin, but it's horrible. It rattles and clacks because it relies on having an open enclosure, unlike the K-33-E. (Oh, and I know Klipsch rate the La Scalas as capable of a maximum of 124dB, but they can do more... even when you're not driving them to bursting point) I've considered other speakers, but the La Scala enclosure is the best IMO. Lowest distortion. Any ideas? (oh, and in case you're interested, here in Melbourne, Australia, La Scala's retail for $9000 aussie dollars, brand new, so they're pretty rare here.)

[WMcD]

My guess is that you're expecting too much.

The LaScala will give a good acoustic load to the woofer driver down to maybe 100 Hz and then starts rolling off. This means there is going to be more excursion of the diaphragm when driven hard in the bass. It bottoms out and creates the clack.

If you need horn loaded bass at the sound levels you're talking about, you're going to have to get a bigger horn or build it, rather than a more robust driver.

Gil

[TBrennan]

Tab-Cat--Klipsch used another woofer with double the power handling in the Pro LaScala, K-43 or something.

[Tab_cat]

hmm... wonder what sort? never heard of the Pro LaScala, I must admit... although it doesn't suprise me... the tweeter and midrange can already handle much more power than they are rated at. I'm considering a pair of JL Audio (no, there's no B in there, just JL) 600W RMS 15-inch subs. they seem to be able to do the trick.

as for building a bigger horn, well I probably couldn't. Can't even cut a piece of paper straight... Besides, I'm happy with the original La Scala enclosure. It's big enough for just about any 15-inch sub. The reason I need the sort of sound levels I'm talking about, is because I want to use the La Scala's for PA purposes, like medium-sized concerts. They perform better in the open over long distances than most other speakers. They don't lose clarity, like some JBL stuff I used a while ago.

[JohnA]

The K-43 woofer is what you want. It is designed to be used with the back air chamber volume and the slot size in the throat of the horn. It is sometimes said to have 2 or 3 dB more output than the K-33.

John

This message has been edited by John Albright on 12-07-2001 at 01:34 PM

[Tab_cat]

Got any other info on the K-43? I searched the web, and came up empty.

[Tab_cat]

Where can I find info on the K-43? I searched the web and found nothing.

[djk]

Cut and paste this into your browser http://www.audioasylum.com/forums/HUG/messages/4593.html Please read the entire thread.To use a pair of vintage LaScala for high power PA (over 100W) I would do the following: Replace the tweeter diaphragms.The old tweeter voice coils were self terminated, in other words the actual voice coil wire ran up to the terminal on the body of the tweeter.The newer voice coils use a flat BeCu leadout wire just like high power Altec and JBL compression drivers do.The old style will break.Change the zener diode protectors from the pair of 5.1V 10W to a single 8.2V 1500W bi-directional transient voltage suppressor, 1.5KE8.2CADICT-ND $.74 from DigiKey.This with the new tweeter VC will allow 3dB more maximum volume before protection sets in.Add 15~16 ohms 50W in parallel to the midrange driver and add ~13µF in parallel with the existing 13µF cap feeding the midrange.I use two 6.8µF caps in parallel to do this with two 30 or 33 ohm 25W resistors in parallel.Whatever is available.This keeps the 400hz crossover at the same point but smoothes it out considerably by presenting a more resistive load to the crossover near the horn cut-off.Change the woofer to either a K43 or JBL2226G.Down under the JBL will probably be a better buy and easier to find.The JBL will also handle 600W because of the 4" vented gap voice coil. The best way to get a 2226G is to buy a blown 2226H/J and have it reconed with a G kit.This will give new performance at a used price.The correct ports for the 2226G are two 4" dia by 7" long on the back board across the top of the mid-hi box.This gives an Fb=35hz and will handle 600W at Fb without exceeding x-max.Bi-wire inputs should be added with a 2A AGC fuse inline with the high frequency only.This fuse will only blow in the event of high frequency feedback.Ideally the amplifier should be high pass filtered at Fb=35hz with a two pole filter with a Q=1 to prevent damage from dropped mics, etc.