Curious_George

I agree. Voxx needs as many sales as possible.

I bought a pair of these recently for my eventual LaScala rebuild. I know these horns have come up before in various threads, but I don't recall seeing any frequency response graphs of a K55V (push-pin) on the 18 x 10 horn. Perhaps one is buried in a thread somewhere, but here is a measurement that I made this morning. Two items I wanted to know about the horn was the low-end response, which clearly goes down to 400Hz and how smooth the frequency response was across the midrange band. The 18 x 10 and K55V appear to be a great match. I'm not a horn expert, but the 18 x 10 looks to be an exponential horn. I have not listened to them yet, but will try and patch together at least one channel to see how they sound.

I tried 30Hz to 40Hz (with two 4" ports, 7" long) and 40Hz sounded the best to me. Nice tight punch. Less than 40Hz started to sound flabby and uncontrolled. For reference, my LaScala's are 1974 with the open back and dog house panel up top under the K400.

I don't understand the stigma that has been placed on the LaScala bass modification or so it seems. I believe the LS bass mod is similar to Claude's ported Heresy mod (you are taking a sealed enclosure and modifying it into a ported enclosure). I think all would agree the Heresy port mod is great and definitely worth persuing. Klipsch even moved the Heresy IV to a ported enclosure. I have not forgot that the original inspiration for the ported Heresy mod was for better midrange clarity and the bass extension was just a bonus. On the other hand, there are other designs out there worth persuing if you want bass extension, however, for someone who does not want to build an enclosure or just does not have the space, the ported LS mod is an option.

Just about any flavor of 2 channel audio op-amp will work. The circuit is very forgiving and layout is non-critical for the most part. I prefer bi-polar input types to FET, for audio.

Power supply can be a simple bi-polar unregulated type to fully regulated. +/-9VDC to +/-15VDC is acceptable. I’ll leave the power supply type up to the end user.

Another forum member PM'd me and asked if I would help them build the high pass filter circuit for the LaScala mod. I put together a BOM from Jameco so the parts could be sourced easily from one location. Of course there are many places to get the parts from, but Jameco has good prices and has everything in stock. I have no affiliation with Jameco. 18dB High Pass Filter EQ_LaScala Part BOM_102121.pdf

Yes, still experimenting with different tweeters & crossovers.

When I first bought my used LaScala's, I thought they sounded great. I had read many threads here on the forum about the K400 (metal) horn not being the best, but I could not hear the "harshness" that was discussed. After many hours of listening, especially at high(er) listening levels, I began to hear the harshness. Now even at lower levels, I can clearly detect the sound of the K400 (metal) horn. It's not totally unlistenable, but it does have a forward character to it. My LaScala's were DJ speakers and fairly beat up, but the original drivers were in good shape. When I get around to refurbishing the cabinets, I am going to change the K400 and tweeter out. If you want to experiment, I would go with a different horn, not driver. If you go with a different driver you will more than likely have to change or modify the crossover.

Here is a quick & dirty REW curve. I can't find the other measurement from many moons ago. I say quick & dirty because my basement has yet to be straightened out and set-up after moving. To clarify - Blue line is with port mod, purple line is with port mod & EQ.

Great Series. I bought all of them back when.

They do look pretty. I’d buy some if they were $10 each. That’s about what they are worth.

I stocked up on 6SN7, 12SN7, 7F7 and 14F7 long ago anticipating inflation. Now the only issue is is finding a good Loctal type socket. Those cheap ceramic Chinese ones suck.

I have measured it. Let me find the file or remeasure with REW again. If I remember correctly, with the EQ and room gain, it will extend the low end down to 35Hz.

Unfortunately, it looks like the Exodus 6.5" woofer is no longer available or hard to find at best. Here are the TS specs if you want to substitute another woofer for the project.

That looks like a great sub project, no doubt. I've not heard one yet.

I'm not sure. I'd have to do some research. The problem with a regular EQ is the bandwidth or Q of the circuit. It would probably be too wide and affect to many frequencies on either side of the 40Hz boost region. In addition, the high pass filter EQ has a built-in "infrasonic" slope to attenuate the lower frequencies from unloading the woofer at 1/2 the port tuning frequency.

Au revoir as Pepe Le Pew would say...

The below circuit is an example of what you would need to realize the high pass EQ filter electronically. This is only the high pass EQ filter circuit, no power supply is shown. This circuit could be inserted into your preamp's tape loop function (in/out). On some preamps, there is a specific "EQ" loop for external processors, such as this high pass filter. If you need a power supply circuit let me know.

It is hard to refute facts, data and experience, but I don't recall doing any of those three. I made an observation that a lot of opinions on this forum are "half-baked" to use your descriptive words. NOW THAT is up for debate.

6SN's and 12SN's are the same except for filament voltage. Again, there may be sonic differences, but I can't hear them.

The coin base is not as attractive or Art Deco as a "GT", but they should "behave" the same. I use the word "behave" because of the way some people describe the way they sound. I don't believe that a vacuum or slightly different metal choices (cathode, filament, plate) can change the sound of a tube, but I don't want to take anything away from someone's music.

Everything in life is a compromise. Did we really have to debate an audio topic in order for me to make that statement for you to realize?

Exactly. Thank you. This is all I was alluding to. Claude, you need to make up your mind. One minute you state the above, which I agree with, other times, you say the opposite like "half-baked". It can't be both in reality. If you want to flounder, then that is your prerogative.