Al Klappenberger

Roberts, As usual, you missed the point. No problem though. I didn't write that for you. Al K.

Dean, You can fudge the Universal to work in a Cornscala, but you need to cut the tweeter back also. part of the problem with it is that there are so many Cornscala variations and each requires slightly different modifications. Not all of us are qualified to make those changes. Another reason the Universal is not a good match for the Cornwall or Cornscala is the fact that they are direct radiator woofers. The Universal is "universal" because its skirt slopes are so sloppy the frequency response of the horns determine the crossover frequency. The Cornwall and Cornscala don't have a horn loaded woofer! The woofer and squawker will have a huge driver interference window with a 1st order crossover. Klipsch moved to a 2nd order woofer filter in the B-3 network and so did I in the Cornwall networks you built. I suggest the AP12-600 and ES5800 now for Cornwell and CornScala users. That combination allows setting the squawker and tweeter to you taste. Jury rigging the Universal for use in those speakers is just a way to sell stuff you have on hand! It is not in the interest of the user. Al K.

Shawn, Nice to see you here again. It's been a while! Your suggestion about listening to white noise through the entire system is a good one. I have done that may times for myself and a few times for guests. I ask them to move around the room while it's playing. I believe it does demonstrate the smoothness of the sound distribution. I have definitely seen comb action using tone bursts that are long enough to overlap in time as seen on an oscilloscope when moving the mike around the room. Just move the mike a few inches and the overlap between a single burst will move from double it's original level to zip! It really happens. Al K.

Greg, Yep, Instrument measurement plots require some education to understand, but their meaning is definable. You will have to learn what a “dB” means since most plots are displayed in these units. Terns such as “crisp”, “bright”, “sweat”, “cool” and “lush” are universally understood and can easily be used to describe the sound of a tweeter, or the taste of an apple or even a chocolate bar that’s been in the refrigerator for a while. Now that we know that an apple is crisp and cool. Lets describe a beautiful sunset to a blind man. Lets call it “bright” and “lush”. If A equals B and B equals C, then A must equal C. It follows then that my apple must also sound “lush”. So my tweeter must also taste like a beautiful sunrise and look like a chocolate bar! Well,.. Err.. Maybe not! Al K.

psg, "The combfiltering is impressive to look at when the two source signals are of equal strength, but maybe less so when the second source is 6 dB down" EXACTLY! The next step is to quantify over what portion of the spectrum both sounds are equal enough to interact. This is what I call the "interference window" for the lack of any universally accepted term that I know of. I really have no science to specify what that level is. 6 dB is probably a good number. I have always assumed 10 dB just for comparison between filters, but what is important is that the steeper the filter slope the narrower that "window" becomes. It is the widest with a 1st order network. With a slope of 120 dB / octave, it is very narrow. The consensus of opinion of the people who have invested in networks having sharp slopes like this is that the stereo image comes nicely into focus. "on the other hand I love the sound of my two Klipschorns even when they are fed a mono signal." This is no surprise. A gentle slope network in each speaker would generate a pleasing ambiance with a mono program. I suppose extreme slope networks might make mono programs sound a bit dull. I never thought about that. Most people don't listen to much mono programs any more so I suppose it's a minor down-side. Al K.

Rudy, Don't let all the bells and whistles of that software bug you. Think of it as a big toolbox full of tools. You may use all of them someday, but you only use the ones you need at any given time. I only learned of that package a few days ago, so all I know of it is what you have posted. From that little glimpse, I am impressed! It's going to be your guide to learning about a lot of stuff you didn't know anything about before. Enjoy the process! Al K.

"The problem with you", Greg, is that you have no calibrated instruments, would not know how to use them if you did and therefor do not understand their value. This being the case, all you have left is your ear / brain combination and you try over and over to convince us that what YOU hear is the same as each of us hears also. It isn't true. That is why loudspeaker manufacturers use groups of people to evaluate how a speaker sounds, not just one. Stick to building speaker cabinets. Nobody, including me, questions your ability in that area. Al K.

This is good! This software is the first I have seen that gives you the simple impedance of a woofer as well as the polar phase component of the impedance. This is exactly how I measure a woofer to get the required impedance to design a crossover network. It's the same type display I get with my HP3563a analyzer and Z bridge. All you do is covert the Polar Zo and phase to rectangular R +-jX at the frequency where you want the crossover. The "R" component is the design impedance. That also becomes the resistor value of a a series R-C Zobel. The last step is to experiment with the cap value to get Zero phase around the crossover frequency. THEN you can use any of the many crossover calculator programs to design the crossover. The "R" component of R +-jX is used for the impedance. SUPER! Al K.

CJN, The really big bottleneck in the LaScala is the K400 midrange squawker horn. Replace it with an Altec 811b off eBay or, better yet, one of Dave Harris's FasTrac horns. The K55 is not a bad driver, but if you do replace it, the JBL 2426 is a good choice, but will also require that you change the network. The Klipsch stock networks DEPEND on the K55 to work correctly. I personally believe the tweeter is the last item on the upgrade list but I like the JBL if you can find a good one and especially if you already have a set! I don't think JBL makes them any more. You might need an attenuator on it though. The network is the second priority unless you have the "AL". I would get rid of that ASAP! BTW: Damping the outside of the K400 horn as 66hr suggested is a very good way to prove to yourself that the K400 needs to go. You WILL hear an improvement when you do that. I did it early-on as well. I used generic "Dynamat", a material you can get in auto supply stores, like Pep Boys, for sticking under floor mats. Al K

mark, Yes, Dean did build a few of my Cornwall networks, but only a few. Dean quickly found out how hard that design was to build and didn't want to do it any more! He also knew better than screw around with the design! They were correctly done and well built. Roberts, I didn't even bother to read your comments. I'm sure they will just make me mad! You are not qualified to design, modify or recommend other uses for my designs. All you may do is sell the remainder of the 10 sets of Universal networks I foolishly allowed you to build to support your 2-inch horn. NOTHING MORE! Al K.

Your experience with the various tweeters just illustrates the fallacy of listening tests by a single person. You got to start with good instruments and then do the listening. The human ear / brain combination is a very subjective instrument! Al K.

Mark, I didn't remember you had one of the few Cornwall networks I made. I think I only made about a dozen sets. Even it is now outmoded by the AP12-600 and AP15-6000 or ES5800 set that will work fine in the Cornwall or Cornscala. The Universal was NOT intended for that speaker or I would have made them for Cornwall owners too. My first prototype of the Cornwall network was 1st order like the Universal. It didn't sound right according to the guy who auditioned them (Allan Songer). That's why it went to 2nd order. The Cornwall woofer goes much higher then the horn loaded Khorn or LaScala woofer and a 1st order filter yields too much overlap. The tweeter needs to be cut back as well compared to the Khorn. At the time, I didn't want to use two transformers as I do now, so I taped a single one just as Klipsch did with their designs. It made the level setting fixed. Al K.

I am EXTREMELY sorry I ever allowed you to build my Universal networks! Stick to building cabinets. This is what you are qualified to do! "Playing around" with networks is not professional or wise. Changing the inductor from 1.3 to 1.8 mHy is insignificant and serves to upset the impedance unless the associated cap is also changed. you don't know what you are doing. To move the crossover frequency up you REDUCE the inductance value, not raise it! LEAVE MY DESIGNS ALONE! Al K.

Gram, I think your observations are correct. I think Bob Crites has compared them directly. He may know for sure. All I have seen directly is that the original K77 (round magnet) has the poorest low frequency range and the lowest sensitivity. The M version is better but still not reliable below 6 Khz. Al k.

" In fact I believe ALK refers to 2nd and third order networks as gentle slopes." Yes. There really isn't a bright line between gentle and extreme slopes. It's more a matter of what's in the middle! Most specification sheets for drivers want 12 or 18 dB / octave filters. That is what you see on most speakers. Active crossovers offer 24 dB / octave (N=4). To real filter people the entire concept of db / octave isn't even used. It refers to Butterworth response. Most flter people think Chebyshev which is much steeper than the same order Butterworth, especially at higher orders, like N=7, 9 or even 11. I have done as high as N=21. Next up is Elliptic function of orders 3, 5, 7 and 11 or even higher. N=11 is quite common. My ES networks are only roughly N=3 or 4! I simply look at the skirt from the crossover to the point where the attenuation starts to reduce (the arc top) and relate it to a Butterworth to get db / octave. It's only approximate. It turns out to be around 120 dB / octave. They are actually what filter people refer to as "zero placed". That's like elliptic function but not quite. Elliptic function filters have all equal arc tops between "notches" (zeros). A zero placed filter can put the notches anywhere. With only a single "notch" there is only a single acr top so it's had to call it elliptic even though N=3 and N=4 elliptic have only a single notch. Confusing, isn't it? "It is a real shame that ALK and Volti are not business partners" It actually started that way. Before the cat-fighting, there were quite a few Trachorns and ALK networks installed in Greg's speaker restorations. This is how Greg got license to build 10 of my Universal networks. I even made a prototype Es300 prototype crossover for his 2-inch horn. A dubious idea! That ended when I had the audacity to actually offer a 2-inch Trachorn! It was his idea to pull the plug. In the future I will be working with Dave Harris of the Fastrac horns instead. Al K.

Here's a couple random thoughts on all this. Again, I try not to say if something sounds good or bad to me.That's just my opinion and counts no more or no less than anyone eases. Anyhow, I did some listening tests on several tweeters (Beyma CP25 and the B&C, as I recall) to try to compare dispersion. I have not been able to do it in any repeatable way by instruments, so I tried rotating them around thier axis while listing to white noise. I was more struck by the difference in the sound of the noise between them. The example is when I evaluated Bob's CT125 a few years ago. I noted that the CT125 sounded like "FFFFFFF" while the K77 sounded more like "SSSSSSS". I realized that the difference was that the CT125 simply has a response that extends lower in frequency than the K77! After connecting an ES7500 network to both tweeter to limit the spectrum going to them, the Beyma and B&C sounded identical to my ear! To compare tweeters by ear with all of them in a big rack side-by-side is useless unless you have carefully equalized their sensitivity with L-pads using instruments and limited their frequency ranges with a network that cross over at the lower limit of the tweeter with the highest low cutoff or higher. Doing test like that, even if done correctly are just one person's opinion anyhow! At best in will allow you to choose what tweeter YOU like best with the network you happen to be using at the time. There is also the question of phase errors. I happen to have 5 (five) different signal generators here that will generate clean sine wave signals. A square wave is a frequency and all it's odd order harmonics (3,5,7 ...). I connect three signal generators up so they were set to 1000, 3000, and 5000 Hz and mixed them together in the correct proportions. I fed the combination to an amp, and oscilloscope and a set of headphones and listened. Since the three generators were not phase-locked to each other as the components of a square wave are, the phases become random and continuously changing. I set the generators for the most stable waveform I could on the scope.At best it looked like a worm squirming slowly around. I found that even by looking at the scope for clues while listening, the sound was a continuous unchanging raspy tone! In the case of a loudspeaker where separate drivers would be reproducing each tone (harmonic), the phase would be random but fixed at some given phase. The only conclusion is that my ears are totally deaf to phase errors between the components of a complex waveform. I just have to assume that my ear / brain combination is typical of all of us. In the case of music, the phase relationships are even more random than with a contrived waveform like the fake square wave I used. Your ear / brain can, however, perceive the phase relationship between a SINGLE sound as heard by TWO ears. This creates a stereo image. A steep slope filter generates faster phase shift with frequency shift (group delay) than a gentle slope one but that does not seem to be important so long as the shift is matched between the left and right speaker. A steep slope filter also has it's maximum group delay right near the crossover where the interaction between drivers is inevitable anyhow. BTW: Group delay and time delay are NOT the same thing and one can NOT be used to compensate for the other in any practical way. I know, I have done lots of group delay equalization in passive filters. .All-pass networks are very expensive at audio and generate lots of loss to a passband! Al K.

psg, I BEGAN by stating facts. The "person" simply presented his personal opinion on how something sounds to HIM. The question is the competence of a give "expert", not the "person". Certain people's opinions implicitly carry more weight than others because they are involved in somewhat related endeavors. A person who builds crossover networks, cabinets or houses is no more qualified to say how a stereo "sounds" than a man who operates heavy machinery for a living. The human ear needs a reference to judge the quality of music reproduction. You only get that my listening to live music on a regular basis. Only THAT qualifies a person as a judge of how something sounds! I don't, so I keep my mouth shut about how something "sounds"! If you want relevant debate, look at this web site: http://demonstrations.wolfram.com/WaveInterference/ The speed of sound in air is 13,560 inch / second so a wavelength at the 6000 Hz crossover is about 2.25 Inches. The path length difference between the squawker and the tweeter represents a different number of wavelengths as you move in either direction from the 6000 Hz crossover. The more gradual the slopes of the filter the wider the spectrum where this mess happens in your room. On the web page, each blue dot represents a single wavelength in distance. Run the animation and you will see just what kind of a MESS driver interference creates in your room. What it "sounds like" to each person is secondary to that fact that it is not correct. It is false ambiance. I compare it to singing in the shower. It sounds good, but it's not "correct"! A 1st order, 6 dB/octave crossover is the worst possible case for driver overlap spectrum width and a horn loaded speaker is the worst case of time misalignment. To avoid the mess of peaks and dips throughout the room a 1st order network must have perfect time alignment, which is NEVER totally possible, even in the best situation, a coaxial configuration. Look at the illustration below (from the web site I noted above). It shows about 5 wavelengths between sources. At a 6 Khz crossover, that represents about 11 inches. How does that compare to the path length difference between squawker and tweeter? Al K.

As I have said on may occasions, be very careful how you pick your experts. Al K.

Personally, I think 1st order (6 dB / octave) crossovers stink! They are so sloppy that you literally can't even specify where the crossover frequency is! You get major interference between drivers because of the huge overlap. This sounds nice at low levels because the multiple sources of the same sound tricks you brain into thinking it's "openness" or "ambiance". Turn the level up a bit and the tweeter starts to overload from the lows getting through the single capacitor isolating the tweeter from the woofer. [+o(] Oh yeah: The bumps and dips in the frequency range you mentioned are VERY often caused by the multiple sources adding together or nulling each other out at random spots all over the room as the two sounds go in and out of phase due to time misalignment. My advice is to get a cap replacement kit from Bob Crites and fix up your old AA if you don't want to spend the money to truly upgrade. Al K.

Simply put an adjustable "L-Pad" in the line to the tweeter. Al K.

Actually: I will be shipping the very last set of Martinelli horns in about a week. Martinelli has been making them for me but has moved on to doing other things and will no longer be making them. Dave Harris and I will be developing horns equivalent to the Trachorn 400 and 420. The Fastrac K for the Khorn is in the pipeline but Dave has hurt his hand and needs to let it heal before he does anything more. I never did offer one for the Cornwall. Al K.

Check out Dave Harris's Fastrac Cornwall. It's what you are looking for. Al K.

Try this company: http://www.wendellfabrics.com/ Al K.

Bob is right when he says most of the Cornscalas are built around the K400 horn. I have seen it may times right here on the forums and I cringe very time I see it! I suppose it's party because so may are available having been retired after upgrades. The Selenium horns pictured have GOT to sound better! When I built the "Heresy on steroids" speaker I use on my TV / home theater setup I used the K500 horns I removed from my Belles just to "store" them someplace. They didn't stay in there long! Al K.

" The biggest change by most was the loss of the K400." This is the most important factor not only in how it sounds but it the design of the crossover. There is simply no reason to cross a Cornscala over at 400 Hz when the woofer will go nearly to 1 Khz! A smaller horn will not load a driver down low enough to use a 400 Hz 1st order crossover. A K55 might survive under those conditions but it will have its proverbial tongue dragging the ground doing it! The lower efficiency of the direct radiator woofer requires totally different high section settings compared to a horn woofer. This is why the Universa; network is not appropriate for a Cornwall or Cornscala. Al K.