Al Klappenberger Posted May 25, 2003 Share Posted May 25, 2003 Some time ago I was persuaded by an anonymous acoustics engineer friend to write a technical article about the extreme slope crossover networks that I developed for my personal audio system speakers (see "My stereo stuff" below). He believes that the research I have done tends to disprove a few of the long-standing beliefs associated with loudspeaker design, particularly the widespread misuse of the terms "group delay" and "time delay", the unwarranted fear of ringing in higher order filters and the need for "time alignment" of drivers. The article was written, submitted to and accepted for publication in AudioXpress magazine. AudioXpress magazine informed me only AFTER they had taken it upon themselves, without my permission, to rewrite many portions of my article, that they will publish only text written in "active voice". The editor was quite insistent and inflexible on this point. Technical merit was a secondary consideration. This is why the articles in that magazine read as they do! For example, I wrote: "It is known that any complex waveform can be analyzed in terms of the phase and amplitude of..." AudioXpress rewrote it like this: "It is know that you can analyze any complex waveform in terms of the phase and amplitude of..." I say: "you can", well can you? It certainly "can be" however! Since I consider their rewriting every authors text to make him or her sound like some "good ol' boy" to be offensive and as I have no monetary stake in having the article published, I denied them the authorization to publish the article and will simply post the article on my web site for anyone who might be interested in it. The article is about 4.3 Meg in size in "pdf" format and can be downloaded from http://www.alkeng.com/klipsch. You will find it at the bottom of the page below my tribute to Paul W. Klipsch. I give permission to anyone here who are members of other forums and who believe that this article may be of interest to post links to it there as well. I understand that my conclusions are quite controversial and I fully expect and encourage opposing viewpoints. Al K. Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Share Posted May 25, 2003 Hear, hear -- hats off to you Al! I can hardly wait for the headache I'm going to get trying to decipher the paper. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted May 25, 2003 Author Share Posted May 25, 2003 Dean, Have no fear, I left out the math! Al K. Quote Link to comment Share on other sites More sharing options...
Randy Bey Posted May 25, 2003 Share Posted May 25, 2003 Great job Al! Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted May 25, 2003 Author Share Posted May 25, 2003 Thanks Randy.. Al K. Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Share Posted May 25, 2003 "Have no fear, I left out the math!" LOL -- thank God. Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Share Posted May 25, 2003 I agree with that. Let's get real here -- after the first reflections it's poo-poo. Time alignment with the DQ-10 is especially suspect when one considers that between 8% and 12% of the total output reflects off of the back of the grill into the sound path. I know Dahlquist chose 1st order networks because of something related to phasing -- but I can't remember the details. I do know the crossover has some wierd things going on it that I've never been able to figure out. Everytime I build a board for a pair I spend a lot of time under the board soldering positives and negatives together. Something I thought of while reading the article was the issue of lower IM distortion by using the deep slopes. Even without the math, much of it was still too deep for me -- but still fun to pour through (several times in fact). I of course wonder if the RF-7 would benefit from something like this -- especially the use of the autoformer. However, I have neither the background nor patience for investigating it. Hell, I can't even figure out how to mod the crossover to allow for the use of higher gauge litz wire in the tweeter circuit. No, this is not a cry for help -- I want to listen more and work less! Something for you Engineers. Understanding Engineers - Take One <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> Two engineering students crossing the campus when one said, "Where did you get such a great bike?" The second engineer replied, "Well, I was walking along yesterday minding my own business when a beautiful woman rode up on this bike. She threw the bike to the ground, took off all her clothes and said, "Take what you want." "The second engineer nodded approvingly, "Good choice; the clothes probably wouldn't have fit." Understanding Engineers - Take Two To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be. Understanding Engineers - Take Three A pastor, a doctor and an engineer were waiting one morning for a particularly slow group of golfers. The engineer fumed, "What's with these guys? We must have been waiting for 15 minutes!" The doctor chimed in, "I don't know, but I've never seen such ineptitude!" The pastor said, "Hey, here comes the greens keeper. Let's have a word with him." "Hi George! Say, what's with that group ahead of us? They're rather slow, aren't they?" The greens keeper replied, "Oh, yes, that's a group of blind firefighters. They lost their sight saving our clubhouse from a fire last year, so we always let them play for free anytime." The group was silent for a moment. The pastor said," That's so sad. I think I will say a special prayer for them tonight." The doctor said, "Good idea. And I'm going to contact my ophthalmologist buddy and see if there's anything he can do for them." The engineer said, "Why can't these guys play at night?" Understanding Engineers - Take Four What is the difference between Mechanical Engineers and Civil Engineers? Mechanical Engineers build weapons and Civil Engineers build targets. Understanding Engineers - Take Five The graduate with a Science degree asks, "Why does it work?" The graduate with an Engineering degree asks, "How does it work?" The graduate with an Accounting degree asks, "How much will it cost?" The graduate with a Liberal Arts degree asks, "Do you want fries with that?" Understanding Engineers - Take Six Three engineering students were gathered together discussing the possible designers of the human body. One said, "It was a mechanical engineer. Just look at all the joints." Another said, "No, it was an electrical engineer. The nervous system has many thousands of electrical connections. " The last one said, "Actually it was a civil engineer. Who else would run a toxic waste pipeline through a recreational area?" Understanding Engineers - Take Seven "Normal people ... believe that if it ain't broke, don't fix it. Engineers believe that if it ain't broke, it doesn't have enough features yet." Understanding Engineers - Take Eight An architect, an artist and an engineer were discussing whether it was better to spend time with the wife or a mistress. The architect said he enjoyed time with his wife, building a solid foundation for an enduring relationship. The artist said he enjoyed time with his mistress, because the passion and mystery he found there. The engineer said, "I like both." "Both?" "Yeah. If you have a wife and a mistress, they will each assume you are spending time with the other woman, and you can go to the lab and get some work done." Understanding Engineers - Take Nine An engineer was crossing a road one day when a frog called out to him and said, "If you kiss me, I'll turn into a beautiful princess." He bent over, picked up the frog and put it in his pocket. The frog spoke up again and said, "If you kiss me and turn me back into a beautiful princess, I will stay with you for one week." The engineer took the frog out of his pocket, smiled at it and returned it to the pocket. The frog then cried out, "If you kiss me and turn me back into a princess, I'll stay with you and do ANYTHING you want." Again the engineer took the frog out, smiled at it and put it back into his pocket. Finally, the frog asked, "What is the matter? I've told you I'm a beautiful princess, and that I'll stay with you for a week and do anything you want. Why won't you kiss me?" The engineer said, "Look, I'm an engineer. I don't have time for a girlfriend, but a talking frog, now that's cool." Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 25, 2003 Share Posted May 25, 2003 Al, You should try to have it published by AES. Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 25, 2003 Share Posted May 25, 2003 What is the difference between Mechanical Engineers and Civil Engineers? Mechanical Engineers build weapons and Civil Engineers build targets. This one is actually true and the source of many jokes at work. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted May 25, 2003 Author Share Posted May 25, 2003 mdeneen I think your on the right track. For the top and bottom of a squaer wave to stay up (or down) is matter of how long it has to stay there! To stay there for ever requres response to DC. It really doesn't have to stay there since every half cycles it goes the other way! I think the trick is making the transition. That's where the high frequency components come into the picture. Rise-time and fall-time. If all these componets don't get to where they are going in phase with each other you have distortion. In a room, like was said, they are literly off the wall and the human brain is used to that and compensates for it. I think that is why time alignment is bull____ (as PWK would have sait). After all, humans evolved to know if when he hears is food, he is to come food for it, no matter if it's outside, with no echos, or in a cave! I think that's the real reason time alignment is a lot of bull.. That's my opinion anyhow. AL K. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted May 25, 2003 Share Posted May 25, 2003 Here's a direct link to Al's site. Scroll to the bottom or here's a link to the PDF. Be aware that the PDF took some time to DL on my broadband connection. It appears that it is only downloading the next page when you ask for it rather than downloading the entire doc. Another option would be to use the first link above, scroll down to the link to the PDF, right click on it and choose to "save link target as...." or whatever your browser calls that option. It came down very fast that way, I saved it in my Klipsch folder and can view it in Acrobat Reader. Tom Al, it appears that the text link in your first msg above needs an html added after the period. I got a 404 when I pasted it into a browser. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 25, 2003 Share Posted May 25, 2003 Instead of clicking the link simply right click and choose "save target as" and you will download the entire document rather then page by page ! Nice Job Al !!!!! Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted May 25, 2003 Author Share Posted May 25, 2003 Tom, Sorry, I didn't think to actually make it a link. I should have done that. Anyhow, the right-click procedure is the best way to download it. It will take a while to download becasue it is 4.3 Megabytes. It took me almost a half hour to upload it over my 56K dial-up connection. Al K. Quote Link to comment Share on other sites More sharing options...
jnorv Posted May 25, 2003 Share Posted May 25, 2003 A priest, a murderer and an engineer are set for the guillotine. The priest first up is offered face up or face down. He chooses face up so to view his maker at the last moment. The blade comes down but stops just short. A miracle and his live is spared. The murderer chooses the same option with the same result. The engineer also chooses the same face up option, and just as the blade is to be released he proclaims, I think I see your problem. Jim N, Engineer Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted May 26, 2003 Share Posted May 26, 2003 Al, Thanks for posting the article and also for leaving out the math, for me at least. I've got the article printed out for my engineer brother in law and another engineer buddy who are staying over the holiday weekend. Yesterday I had your web page material from the ALK crossover network awaiting their perusal at the breakfast table along with the crossovers themselves. They are impressed. We have been working on the La Scala buildup over the weekend, and are still finishing the cabs. They look really good, too. I'll post pics when finished. Hopefully we can get the horns installed before they go. Sorry to hear about the publishers snafu, but your posting is sincerely appreciated. Dee Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted May 27, 2003 Author Share Posted May 27, 2003 Dee, Post some pictures of your project when it's done. Leaving out the math is pretty easy for me to do. I just don't think that way! When the day comes that I see an equation on the screen of my oscilloscope instead of a waveform, I'll get serious about it! Al K. Quote Link to comment Share on other sites More sharing options...
Myhamish Posted May 27, 2003 Share Posted May 27, 2003 Thanks for sharing such valuable information, Al. One of the greatest advantages of this Forum is the access to such great tips and info from the likes of you and Scooterdog. I'm not an audio engineer, but over the years of tweaking, playing and listening to different systems, I've found that active xover, amp and subs add a lot to my setup, so the theory is appreciated. I've added your info to a file on Klipsch mods and ideas that I'm putting together. All the best. Hamish Quote Link to comment Share on other sites More sharing options...
Dflip Posted May 27, 2003 Share Posted May 27, 2003 Al: A very informative article. Thanks for sharing it with us. I noticed that you have an Altec 811 horn with your LaScallas. Could the 811's be used with a pair of Cornwalls? If so what would the advantages be and what changes would you have to make to the B network? I know a friend who might be willing to part with them. Do I need the crossovers that come with them, 800 Hz, or would I have to rebuild the existing network, new caps and inductors? Any other members please feel free to chip in with your thoughts. Don Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted May 28, 2003 Author Share Posted May 28, 2003 Don, I never though about putting an Altec 811 in a Cornwall, but I'm sure it would be an improvement. I don't see how you could make it look pretty though. It's going to stick out beyond the grill cloth. Anyhow, if you use the K55 squawker driver you shouldn't have to change the network. AL K. Quote Link to comment Share on other sites More sharing options...
Dflip Posted May 28, 2003 Share Posted May 28, 2003 Al: I was thinking about putting it on top of the Cornwalls, maybe later building a box around it. According to the Altec nonsite, it is 14" deep. It would not be a large WAF, but it might sound very good. Currently the 811 sits on top of a pair of Cerwin Vega big bass bins, vintage 1979. When you say I wouldn't have to change the network, you mean I could just disconnect the wires to the squawker and replace it with the Altec 811 and leave the "B network" alone? It is just a thought, no firm conclusion yet as to whether I would do it or not. Quote Link to comment Share on other sites More sharing options...
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