La Scala upgrades

[railtycoon]

I am new to the forum and I would like to add my two cents to the the forum about La Scala upgrades. I am not new to audio electronics and have worked as an electronic technician for the last 35 years including HiFi and music stores.

A month ago I bought a used pair of La Scalas built in 1984 to use with my Harmon Kardon A50K tube amp. The previous owner had installed Bob Crites CT125 tweeters and Bob's A/4500Hz crossovers. I got the original crossovers and tweeters included in the deal. My first impressions were not very favorable. The speakers sounded great at low volume but when turned up a bit they were very bright and harsh. I corresponded with Al Klappenberger and got some very good advice. Al recommended tractrix mid range horns from Dave Harris at Fastlane Audio and new crossovers. Dave is building the new horns as I write this and I will give my opinion on them later. After a lot of research, I decided to rebuild the Bob Crites A/4500 crossovers to ALK Universal crossover specs with a couple of my own upgrades. I reused the 3654 auto transformers from the old crossovers and replaced everything else with parts from Madisound. I used Solen Fast Caps, a Solen Perfect Lay coil for the woofer and Goertz copper foil coils for the mid and tweeter circuits. I wanted a little flexibility to adjust the mid and tweeter output so added two switches to the design. The first of which contols the output for the tweeter. The tweeter switch has two positions, 0dB and -3dB. In the -3dB position, the switch inserts a fixed L pad circuit using a 2.2 ohm resistor in series with the tweeter and a 20 ohm resistor in parallel with the voice coil of the tweeter. The mid switch has two positions, -3dB and -6dB. The switch selects between the -3dB tap and the -6dB tap of the auto transformer and changes the swamping resistor across the input of the transformer from a 10 ohm resistor in the -3dB position to a 8 ohm resistor in the -6dB mode.

I installed the crossovers and began the test, listen and adjustment. I had a couple friends that I play guitar with give me their opinion as I adjusted the swiches. We all agreed that -6dB for the mid and -3dB for the tweeter sounded best. 0dB for the tweeter wasn't bad but -3dB eliminated the slight "sss" that the tweeters had on some recordings. The speakers retained excellent sound at low and moderate voulume levels. Loud volume was not tested as I am using a tube amp that may be able to muster about 30 watts per channel cleanly. My opinion went from "this needs fixing" to "WOW, WOW, damn WOW" and I wonder how the tractrix horns are going to make this any better. I am assured by folks that the horns will blow my mind.

When I worked at Sound World in the late 1970s and early 1980s I fell in love with JBL L-250 speakers. I could never afford them and have been looking for the type of soundstage they presented. My La Scalas now have that type of soundstage, maybe not quite the vertical height of the L-250s but certainly as much or more definition. The La Scalas disappear and I hear the music as if the musicians are performing in front of me.

I will give a report on Dave's horns and post a schematic of the crossovers as I built them in the near future. I would like to thank Al Klappenberger of ALK Engineering, Dave Harris of Fastlane Audio, Bob Crites of B&K Sound a.k.a Critesspeakers.com, Greg Roberts of Volti Audio, and The Klipsch Forum for help with schematics, designs, guidance and opinions. You guys ROCK![Y]

P.S. I share the opinion that the original Klipsch AL type crossovers suck! If you still use them, read all the great material about new crossovers, decide how you listen and what crossover might best fit your needs. For me, it is Al's Universals at -6dB for mid and -3dB for tweeters. You won't regret it!

[babadono]

railtycoon,

I think you will like Dave's horns. I know I sure do.

babadono

[Guest David H]

Your Horns should be delivered today. I think you may want to revert your crossover attenuation setting back to the original settings for use with the Fastracs.

Enjoy, Dave

[mustang guy]

In my large space, my horns tend to take over at high volume levels, and I am wondering if a -3 or 6db adjustment would help. I am using mostly AA networks, and a couple AL-3's. All the caps are in good shape or new. I suppose I coule put a microfiber towel in each and see if that tames the beast before I start buying electronics.

Any suggestions? My shop is 50' X 60' X 20' high, drywall walls, concrete floor, and no sound absobtion. I am getting plenty of bass from the La Scalas and the two THT's, but the horns just take over at a certain volume level. I mostly listen at -40 to -20 db, but I do put on the occasional AC/DC or Gun's & Roses LP.

[Quiet_Hollow]

Any suggestions?

Some of the aircraft hangars I used to work in had a chopped cellulose / mineral wool blend sprayed onto the I-beams and sheet metal. I don't have numbers, but you easily hear the difference in the RT-60's between a treated and non-treated hangar. Hanging a few absorber / diffusors above and out front of the speakers couldn't hurt. Given your space, a call to a consultant like Auralex might be worth your time and sound.

[BE36]

In my large space, my horns tend to take over at high volume levels, and I am wondering if a -3 or 6db adjustment would help. I am using mostly AA networks, and a couple AL-3's. All the caps are in good shape or new. I suppose I coule put a microfiber towel in each and see if that tames the beast before I start buying electronics.

Any suggestions? My shop is 50' X 60' X 20' high, drywall walls, concrete floor, and no sound absobtion. I am getting plenty of bass from the La Scalas and the two THT's, but the horns just take over at a certain volume level. I mostly listen at -40 to -20 db, but I do put on the occasional AC/DC or Gun's & Roses LP.

The mid horn rings on stock horns. Warm amps or Tractrix horns or both can solve the problem.

[BE36]

I am new to the forum and I would like to add my two cents to the the forum about La Scala upgrades. I am not new to audio electronics and have worked as an electronic technician for the last 35 years including HiFi and music stores.

A month ago I bought a used pair of La Scalas built in 1984 to use with my Harmon Kardon A50K tube amp. The previous owner had installed Bob Crites CT125 tweeters and Bob's A/4500Hz crossovers. I got the original crossovers and tweeters included in the deal. My first impressions were not very favorable. The speakers sounded great at low volume but when turned up a bit they were very bright and harsh. I corresponded with Al Klappenberger and got some very good advice. Al recommended tractrix mid range horns from Dave Harris at Fastlane Audio and new crossovers. Dave is building the new horns as I write this and I will give my opinion on them later. After a lot of research, I decided to rebuild the Bob Crites A/4500 crossovers to ALK Universal crossover specs with a couple of my own upgrades. I reused the 3654 auto transformers from the old crossovers and replaced everything else with parts from Madisound. I used Solen Fast Caps, a Solen Perfect Lay coil for the woofer and Goertz copper foil coils for the mid and tweeter circuits. I wanted a little flexibility to adjust the mid and tweeter output so added two switches to the design. The first of which contols the output for the tweeter. The tweeter switch has two positions, 0dB and -3dB. In the -3dB position, the switch inserts a fixed L pad circuit using a 2.2 ohm resistor in series with the tweeter and a 20 ohm resistor in parallel with the voice coil of the tweeter. The mid switch has two positions, -3dB and -6dB. The switch selects between the -3dB tap and the -6dB tap of the auto transformer and changes the swamping resistor across the input of the transformer from a 10 ohm resistor in the -3dB position to a 8 ohm resistor in the -6dB mode.

I installed the crossovers and began the test, listen and adjustment. I had a couple friends that I play guitar with give me their opinion as I adjusted the swiches. We all agreed that -6dB for the mid and -3dB for the tweeter sounded best. 0dB for the tweeter wasn't bad but -3dB eliminated the slight "sss" that the tweeters had on some recordings. The speakers retained excellent sound at low and moderate voulume levels. Loud volume was not tested as I am using a tube amp that may be able to muster about 30 watts per channel cleanly. My opinion went from "this needs fixing" to "WOW, WOW, *** WOW" and I wonder how the tractrix horns are going to make this any better. I am assured by folks that the horns will blow my mind.

When I worked at Sound World in the late 1970s and early 1980s I fell in love with JBL L-250 speakers. I could never afford them and have been looking for the type of soundstage they presented. My La Scalas now have that type of soundstage, maybe not quite the vertical height of the L-250s but certainly as much or more definition. The La Scalas disappear and I hear the music as if the musicians are performing in front of me.

I will give a report on Dave's horns and post a schematic of the crossovers as I built them in the near future. I would like to thank Al Klappenberger of ALK Engineering, Dave Harris of Fastlane Audio, Bob Crites of B&K Sound a.k.a Critesspeakers.com, Greg Roberts of Volti Audio, and The Klipsch Forum for help with schematics, designs, guidance and opinions. You guys ROCK!

P.S. I share the opinion that the original Klipsch AL type crossovers suck! If you still use them, read all the great material about new crossovers, decide how you listen and what crossover might best fit your needs. For me, it is Al's Universals at -6dB for mid and -3dB for tweeters. You won't regret it!

Mounting the mid horns on top of cabinet can solve vertical sound stage. Look at Indyfan's posts.