JohnA

Absolutely NOT! That Phase Linear would be a great pro audio amp if it didn't blow-up so easily. It will sound steely and harsh even on cones and domes. You need a high quality, high Class A biased SS amp around 50 to 100 watts with a large power supply and made with modern components. I'd look at an amp with MOSFETs if possible. A good alternative would be a 50 watt, or so, tube amp. You could even build a tube amp fron a kit. You will normally operate the amp at 1/100 of a watt, so the first watt is the most critical. It must be squeaky clean.

L-pads could be used, but that would be a more complicated mod than the second schematic. One of my Heresies are not on the floor (it's over the RPTV), but the others are. Placing a speaker on the floor or in a corner gives a boost below 200 Hz (mostly below 100 Hz). If you add 3 below 200 and 3+ above 700 or 800 you have a smile-shaped response curve. That's exactly what my rears sound like. I'm sure you get some HF reverberation in most rooms reinforcing the HF output, so saying in-room boost occurs only in the bass may not be accurate. The proper circuit will be a complete redesign, but I have to hear it first before I publish it. The schematic is for experimentation, anyway. You may not like it after all.

You've got to get another '84 Heresy. I used a KLF-C7 with La Scalas for 3 or 4 years. I just substituted a Heresy and the difference is pretty large. you won't match the timbre (sound) of the Heresies with anything else.

K-33-Es don't have a vent unless the 2002/2003 models have them.

O.K. Gil, The real test: Did you change the cam so that it loped at idle? I won't ever do that again! What a bear it became in traffic!

The K-horn's, and any horn's, low frequency output is controlled by the length of the horn and the size of the mouth. The driver has relatively little to do with it. That said, the K-33 has been optimised by Klipsch over the years until it is one of the best bass horn drivers available. Nothing else will work better in a K-horn bass horn, and very few will work as well. If you want deeper bass than it can produce, you need to get some very large subwoofers. Look at the VMPS Larger Subwoofer like I use. It's distortion is similar to the K-horn and 2 will keep pace with a pair of 'horns. Somebody else makes what is called a servobass that can produce the prodigious output you will have to have. The Klipsch RSW-15 can the match output of the k-horns, but I suspect, from hearing it, that the distortion will be higher.

Marvel, I was doing great until I installed "Tax Cut" and started my taxes! TurboTax has some weird sort of copy protection/spyware thing going on. The server geeks at work are saying stay away from it. The reviews on Amazon are about the same. It gets 1 star this year.

Those speakers have plastic horns that probably don't need extra damping. Listen to them for 6 months, or so, and then make changes to address problems you hear. You may find they need nothing at all.

Isophon is a web site that has published a set of La Scala plans in SI. They have some dimension errors.

I suppose you could use the Type E network, but the extensive changes you want makes it better to start over with a new network. I think you need 2 of those woofers, since you forst crossover is at 1k. Almost all of the sounds and music will be coming from the woofer. With one you will have trouble balancing the system. The K-77-? probably should not be operated below 5k. It will have better power handling and smoother response. It's long-term power rating is 2 or 5 watts from 4k to 20k. By raising the tweeter crossover, you will be able to use a simpler network design (2nd Order) and still protect the tweeter. The impedance of the K-77-? should be considered 8 ohms from 5k up.

aab3rd, What ever happened to Bolivar Speaker Works? I thought they were a nice alternative to the boom and fizz of Advents.

Anything less than $1000.

This is supposed to be off of a '79 Heresy.

I called Atlas a few years ago about the Klipsch modified phase plug and they had no idea what it was. It seemed they did not build the modified version for anybody else and had not built it since 1982, or 20 years ago. They may be building it now, though.

Al is correct. I wasn't thinking clearly. This was intended to be an easy mod and for a test, but the extra resistor should not be installed across the tweeter. I've uploaded a corrected version. We used to be able to delete files on the server. I can't figure out how, now.

The 1975 AlNiCo tweeter has a rating of 2 watts continuous, 20 watts music and 40 watts instantaneous paek. The Cornwall crossover would almost double that. You need to replace the tweeters with known good ones to test the crossover.

Sometimes Gil is surprising, but I never pictured him in a speed shop either. The circuit I uploaded this time is the quick and dirty version. With the mods the impedance in the midrange is still over 110 ohms and the tweeter is 32 ohms, while the woofer is 11 ohms. This is WAY too high. The next one will have a swamping resistor like Al's network has. He has provided invaluable assistance analyzing my ideas. The old "conversation" we had only addressed the tweeter, but the squawker is too loud as well. It stands out a lot compared to my La Scalas. That's what got me looking at the crossover network. After a little study, I noticed both horns are 3 to 4 dB hot.

I posted this one first because it is easy and reversible. The redesign is not.

We all hope you become inclined in the near future. Want some help?

Thinking about it early is good. Take enough time to find something you are passionate about. There is little worse than to be stuck in a profession you dislike (or worse) and cannot leave because of financial commitments (house, kids) or lack of education. Go to university and start out studying a wide range of topics and zero in later. A science teacher, marine biologist for a government, industry or aquarium could be as enjoyable as an MD. Environmental engineering relies on a thorough understanding of biology, chemistry and geology.

The attached file is a schematic of a Heresy Type E crossover with modifications (in red) to reduce the output of the squawker and tweeter. the woofer's output rating is a fraction below 95 dB/w/m, but the squawker is run at a nominal 98+ dB/w/m and the tweeter is run at a nominal 99dB/w/m. Moving the taps down one on the autoformer reduces the output 3 dB and adding the resistors preserves the impedance seen by the network so the caps and inductor don't need to change. The resistors can be connected to the screw terminals for the squawker and tweeter. You could unsolder the autoformer connections and use temporary jumpers to see if you like the mod. I just added a Heresy to my HT for a center channel. The difference in brightness between a Heresy and La Scala is obvious and this is why. Give it a try and tell me how you like it. After I build the redesigned circuit and listen to it a while. I'll publish it, too.

A Heresy woofer *might* provide louder, deeper bass in a larger cabinet, not twice as large! This is a recipe for garbage. What you should do is put the components in the nice cabinets and modify the crossover. I have 4 Heresies in my HT and have looked over the crossover. The squawker and tweeter are run 4 dB hotter than the woofer. I have a schematic I'll upload with simple mods to correct that. Similar mos have been discussed on the BBS before now. Look for the new thread. I have also designed a new circuit (with a LOT of help) that requires replacing most of the parts that will be a proper crossover. It will be more expensive, but should sound better. I'm waiting on parts.

Freezin', My brother would have use for a pair. My front 3 all have the solder terminal -Vs, now. If any of you buy the pair off of ebay with the K-700 horn, I'll give you $50 + S&H for the horns.

Greg, The K-77-M tweeters in your K-horns are not piezoelectrics. They are normal coil-driven compression drivers. Your stock crossover is a Type AA, a very nice crossover. I have a pair. You should try 3 tweaks. First disconnect one of the KLiP diodes to disable the tweeter protection. At 2 watts input, the diodes chop off the voltage to the tweeter; it is NOT subtle. Next, buy a set of "Z" brackets from Klipsch to flush mount the tweeters to the front of the motorboard. It will require enlarging the hole so the tweeter horn will slide through. This will audibly smooth the tweeter. Finally, spend the bucks to replace the tweeter caps with Hovlands, great improvement. E-V rates the tweeter at 105 dB/w/m, 5 watts continuous and 50 watts program, if you have the late model diaphragms with tinsel leads (2/20 if not). You should not have any trouble without the KLiP circuit if you behave and don't clip the amp. A properly executed L-pad can attenuate the tweeter 1 or 2 dB and help with the timbre, if you still think it is too hot. Flush mounting the the cap change will "sweeten" the tweeter. Some (most?) of the K-55-Vs have a 9 kHz "bounce" or return in the frequency response. Some people hear this and call it "harsh" I don't seem to have/hear it in mine. There is a "P-trap" addition to the crossover that will solve that. Search the BBS for a description. Ths K-55-Ms are said to die at 6k and don't have the bounce. Another solution is the ALK crossover. His bandpass on the squawker attenuates the bounce a fair amount and they sound great.

Other than output, the newest tweeter and squawker should sound identical the the K-55-V and K-77-M. I'll look for your drivers.