Ported La Scalas Photos and Review

[DizRotus]

This photo shows the network in place. I used the two terminal barrier strip that formerly provided the connection to the woofer through the sealed dog house to now provide the input connections on the outside of the newly covered back of the top section.

The new caps arrived from Bob Crites yesterday and are now in place. Honestly, in the garage setting with the H/K 430, I can't say that I noticed any difference between the 15 ohm swamping resistor and the lowered capacitance. With the squawker (+) moved from tap 4 to tap 3, in either case the squawker was attenuated enough to now blend smoothly with the lower in frequency, albeit lower in efficiency, bass output.

Cuts with which I'm familar now sound better than ever from these speakers. The acoustic bass and percussion on Take Five from Time Out are still fast and tight but now have more power down low. The drum solo in Devil May Care from Diana Krall's Live In Paris is still fast and tight.

Obviously, there is no free lunch. The increased bass output comes at the expense of some efficiency. Nevertheless, these are still very efficient. The 25 WPC available from the H/K 430 drives these to levels that would have summoned the police very quickly.

I would encourage La Scala owners to try this fully reversible modification.

 

EDIT: 12/20/2015

 

Photos deleted to free up server space.

 

Edited December 20, 2015 by DizRotus

[Marvel]

People have been dissin' Dennis for years about this mod, so I'm glad you did it and liked it. Perhaps I will do mine next year.

Since mine aren't beaters, I will be a bit more nervous about it, but I trust what Dennis has said in the past. Your results just confirm that.

Bruce

[DizRotus]

After more listening, I'm even more impressed. I substituted a mildly modified Dynaco SCA-35 tube integrated amp for the H/K 430. The Dynaco has a nominal 17 WPC (probably actually more like 10 WPC) but sounded very good; better than the H/K 430, for the most part.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

It's a cliché, but I truly was hearing things while listening to Kind of Blue that I did not notice before, such as a bowed, rather than plucked, acoustic bass. Of course, I've not been listening to that recording regularly on these, or any other, La Scalas so I can't swear that the bowed bass would not have been apparent without the modification. Nevertheless, piano, percussion, acoustic bass, electric bass, vocals and even the heartbeat from Dark Side of the Moon sound very good from these speakers. They are like Cornwalls with more snap rather than slam.

[Marvel]

They are like Cornwalls with more snap rather than slam.

Not sure the Cornwall lovers will like that comment. []

This makes me even more eager to try this mod. I wanted to try it long before I even got my LaScalas. Go figure. I have so many irons in the fire that I almost can't see the fire anymore. Still, once I get the crossovers done and give back John's, I'll get up the nerve to do this. My son wants me to just build the box underneath, but I like the height they are now. Maybe I slouch on the couch too much.

Neil, how much less efficient are they now that you have ported them?

Bruce

[DizRotus]

I have owned and love Cornwalls. That comment was not meant to disrespect Cornwalls, but whereas Cornwalls are often described as having "slam," these now have Cornwall-like bass, but with La Scala tightness. Don't forget that these have a 400hz squawker horn, where the Cornwalls have a 600hz squawker horn.

Without measuring equipment, it's impossible to quantify the reduction in efficiency. That said, with the stock Type AA network the modified speakers were too prominent in the mid-range. The switch from tap 4 to tap 3, combined with essentially halving the capacitor value, knocked the squawker down 3dB, which seems perfect. Naturally, it now takes more power to produce a given volume, but the low powered Dynaco and H/K 430 have no problems playing these way beyond a reasonable level. These appear to still be efficient enough to satisfy the SET crowd.

The success of this mod should not come as a surpise. Altec VOTs have used a front horn/reflex cabinet for decades.

[Marvel]

I knew you weren't knockin' the Corns. They're great. I'm just glad you have liked the outcome of this experiment. Let us know how they sound once they are back in place on the lockers.

Bruce

[colterphoto1]

"They are like Cornwalls with more snap rather than slam. "

That comment hurt.

A lot

[]

[DrWho]

lol mike, you're running lascalas (really perty I might add) for mains...why not bust out the LSI's and play with the reversable mod? It'd just make the tower of power that much taller []

Btw, nice work and glad it turned out! [Y]

[DizRotus]

Michael,

Of course, you know that I'm not saying that these are better than Cornwalls, just similar in some ways and different in some ways, not better or worse.

I will say that these are better suited to their duty in the band room. Corwalls would be wasted in that environment.

[DizRotus]

The speakers are back on top of the lockers. Unlike the earlier photo that showed a speaker resting flat of the locker, they are now raised ~3" in the back, so that they fire down into the area where the band sits, rather than over their heads. They're also angled toward the center.

Recognizing that a large empty band practice room with speakers > 6' off the floor is not ideal, they still sound very good. The improved low frequency response is still apparent. So, far the band director is pleased with the changes. The six people who helped get them back on top of the lockers were very impressed with the sound.

[Mrtie]

I just finished installing Bob's cast frame woofers and ported my la scala bassbins for my jubescalas this weekend, Sounds good to me so far.

[DizRotus]

Very interesting!

More information please. Crossover point(s), mid-driver, etc.

[Mrtie]

Very interesting!

More information please. Crossover point(s), mid-driver, etc.

Pretty standard jubscala, active with a Ev dx38, crossed at 470hz, quit a bit of eq as per Roy's information, trying by memory but a boost at 88hz, cut at 148 for cab resonance, boost at 380 I think, and -3db cut at near 40(currently trying 36hz), as per Dr.Who to not let woofer excursion get out of control after the porting. I cut a mirror of the woofer access into the top box, sealed the back with 3/4th ply and mounted spade connectors on the back for hook up. I then removes the motorboard and replaced with a piece of ply with 4" diameter 7" lenth PVC for the ports, I went this route because of posible phase issues with porting to the rear. My scala are beaters to begin with so I wasn't so Leary about surgery, I still plan to woodputty chips and repaint them black , but that's another weekend with warmer weather as far as drivers, a standard k69(p.audio bmd-750) and massive k402 horns from the jubilee. I had to grind tiny bit off each side of the crites woofers to get them in but they fit nice and tight. I lack the tools for accurate testing but using a frequency test track I now have alarge amount of sound starting around the mid 30hz range, which is fairly acceptable for me and better than they were before and certainly louder in that lower range. The most revealing thing is how shockingly forceful the bass bins are at loud volumes I now fear for my shutters:) I'm a fellow Michigander Diz I live in the thumb near Bay City currently but I'm house hunting in the Birch run/Frankenmuth area if you haven't had a chance to hear a Jubilee or Jubescala you should make the drive up one of these days, I obviously have the jubescalas but Bob in bay city has full pair of jubilee with k510 horns and Passover built by Roy I believe, I won't speaker for Bob but he was open to auditioning to me which led me down this crazy path, I'd be happy to audition the jubescalas and I could try and get you in contact with Bpb if interested as well. Oh jeez now I'm sounding like Coytee:) either way offers always on the table just shoot me a pm.

[DizRotus]

Have you started a thread dedicated to your Jubscalas? If so, what is it. If not, please do. This ancient thread won't reach the audience your project deserves.

PM sent

[DizRotus]

Bump.

[WTF]

Not to mention the wife appeal!

[NOSValves]

I'm pretty sure Mrtie sold off all of that Jubscala stuff late last year. I bought the Base Bins from him. I run them with Dave Harris Elitrac mid horn with BMS 4591-mid driver and a pair of Dave Harris ConTrac tweeter lens with B&C DE-10 driver. I use a Super AA passive crossover. The combination is pretty awesome.

[Daddy Dee]

Craig, that does sound like a good combo. would love to hear it

[DizRotus]

The djk bass reflex mod continues to impress. Try it. You'll like it.

Yesterday I returned to the high school band room to investigate a complaint about a "scratching" sound from the left La Scala. Turns out it is a problem with the vintage h/k 730 used to drive them. That unit was to be swapped with a DaleS refurbished unit last year, but it never happened. It will happen soon.

Naturally, the problem refused to manifest itself, so I was forced to listen to an excellent Ray Brown Trio performance of A Train. The tight bass was remarkable, especially given the large and far from ideal space and positioning high atop lockers. As I've said before. I would do this easily reversible mod to any La Scala.

Eventually, a problem appeared in the left channel. A quick swap of the speaker connectors left for right sent the problem to the right side, confirming the receiver as the culprit, not the speakers. Given the ease of the speaker switch due to the Neutrik Speakon connectors, it's surprising the band director hadn't tried that himself.

The director says he constantly gets compliments from students, parents and other band directors about the great sound produced by the La Scalas. He's glad he didn't follow the advice of the band parent who suggested a $4,500 Bose surround sound system.

 

EDIT: 12/20/2015

 

Photos deleted to free up server space.

Edited December 20, 2015 by DizRotus

[DizRotus]

Bump for Sancho

https://community.klipsch.com/index.php?/topic/108425-la-scala-bass-reflex-mod/