Arkytype

What he said. :>) Al's step-by-step tutorial is very useful. However, if you aren't blessed with test equipment as Al and I are, you might want to consider a program from Parts Express called WT3. It will measure a boatload of your driver's Thiele-Small parameters as well as accurately measure the inductors, resistors and capacitors in your network. They have a special that includes the WT3 software/hardware and a precision scale for 100 bucks. http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-803 Lee

Mike, Your "thought experiment" is merely a straw man argument used as an attempt to discredit and distort Al's remarks. A square wave pulse train is completely different than an "impulse" such as a tap dancer's toe or heel click and has nothing to do with the well-documented example he correctly quoted. From the article (link below) one reads: The most significant deficiency, in John Hilliard's mind, was the phase discrepencies between the WE555's and the other drivers. The 12' horn paths so delayed the midrange response that monitoring tests of a tap dance routine resulted in two taps being heard for every one recorded. http://www.audioheritage.org/html/profiles/lmco/shearer.htm What part of this "irrelevant material" did Al misquote? The problem with your premise is that musical content does not consist of single sine waves. Musical content does consist of a fundamental note plus the attendant harmonics which consist of an infinite number of sine and cosine harmonics. Thanks in part to Joseph Fourier, we are able to measure and visualize musical spectra. Lee

I've owned the same model radial arm saw since I purchased mine new in 1978. I've gone thru several tops and a half dozen blades but it keeps on working. For the past four years it's been sitting outside and has sawed (sawn?) many a board feet as we finish our new home. (OK, four years is a long time--but it will be paid for when we are finished. Of course, I keep it under a nice tarp when not in use. The manual is on line and you can still get parts for it. The alignment is important if you want right angle cuts and true miters. Go thru every step and take your time. I've tried both plywood tops and MDF. In our humid climate, MDF is not suitable (it warps). I'm using a couple of layers of marine-grade plywood glued and screwed together. Lee

djk wrote: As we see above, the Jubilee would be even better than the Klipschorn for the bass. I would aver (that based upon the curves) the Klipschorn has a slight advantage over the Jubilee. From 35 Hz--100 Hz, the Klipschorn's response (relative to a 95 dB SPL) is +/- 3.25 dB while the Jubilee is +/- 4.75 dB. From 100 Hz to 500 Hz, the Klipschorn and Jubilee are mouth and mouth (sorry) at +/- 2.5 dB and +/- 3 dB respectively. Granted that while the chamber at Hope can't produce reliable date below about 200 Hz, one can see the trends of the two designs in question track each other nicely down to 30 Hz or so. If I were a bettin' man, I'd say the Klipschorn was crossing over to the squawker closer to 550 Hz rather than the traditional 400 Hz. See also that the squawker and tweeter levels appear to be about 3 dB too low. Does anyone know the particulars of the test conditions? Input power/voltage, measurement distance,etc.? Lee

Gee Al, (to paraphrase another forum member), none of the information you provided helped me in any way choose a midrange combination that I might like best for my Khorns. :>) Are them stalactitic (or is it stalagmitic?)-looking pointy thangs on those graphs supposed to help me finger out what I need for my Klipschorns? That JBL driver graph has more spikes than a hedgehog in heat! Heck, I just want ol' Slim Whitman's yodeling to be pure as the driven yellow snow and if you say a one-inch driver and a Trachorn is the best bang for the buck, then so be it, partner. Lee

Greg, While I won't question the subjective conclusions you reached after listening to the five tweeters, I will question your choice of sound level meter (SLM) to measure the output level. The Tenma 72-945 SLM you own has IEC 61672-1 Type 2 screened on the front of the unit. This means that it should meet the requirements as set forth by the IEC, the governing body of these type devices. Well, ANSI also publishes (sometimes conflicting) SLM requirements, too. Unfortunately, the microphone capsule in your SLM is a poor choice for accurately measuring frequencies above 3 kHz or so. In fact, your SLM's frequency response could be measuring -9 dB @ 10 kHz compared to 1 kHz and still meet the Type 2 IEC requirement! I suspect you are measuring at best a one-half octave range from 6 kHz to 9 kHz with any kind of accuracy. BTW, what brand and model SLM calibrator did you use before and after making your measurements? Rather than rely on the "factory" calibration to be correct, you should use always use a SLM calibrator before and after each round of measurements. While you have chosen to question Al Klappenberger's objective tweeter testing articles by concluding, "....this left me questioning the accuracy of ANY of the testing that he did.", I too question the validity of ANY of the measurements you have presented. I will vouch for Al's ability to perform accurate and repeatable acoustic measurements.The disparity with his measurements was (as I remember it) that there was a possible calibration issue which has since been resolved. Lee

Mark, Looks like you and your gear has survived several worst case "spikes"! Looking at the Monster web site, they have pretty comprehensive circuitry that disconnects the power from your gear when triggered by a surge. It it has cycyled thru numerous hits, it probably is robust enough not to fail internally. Agreed---get a direct hit and all bets are off! Lee

I can second Al's choice. We have several where I work and they work well despite our abuse! Lee

Mark, As you may know, surge protectors work by either shunting excessive voltage to ground or by absorbing the voltage spike. Some types sacrifice themselves in the process of protecting your gear and will need to be replaced. Other types may safely shunt the overvoltage to ground but in the process suffer some damage thus limiting future protection of your gear. If you have one of the second types and have experienced a recent lighning surge, I'd replace it. If it is damaged, it may not protect from future spikes. I would purchase a device that has a guaranteed equipment replacement or repair warranty in the event your gear is damaged while connected. Tripp-Lite and Belkin both have $30,000.00 policies. I'd sure document your installation with photos so in the event you file a claim, you'll have some evidence. There is fine print in the warranty so be sure you are not using the surge protection strip with an extension cord and that the electrical grouonding system in your home is sound. As far a a "joule rating" goes, in theory the more joules the more protection you'll have. But how many joules is enough? There's no clear cut answer to that. One reason there is no "X-joules will afford you X-amount of protection" law is that there are a dozen ways to generate spikes, surges, etc.--- each with different rise times, duration and fall time. Then there's the direct lightning hit to your pole-mounted transformer. About the only protection for that is to anticipate the strike and turn off the main service entry breaker and hope the voltage won't jump the gap in the circuit breaker! If you live near an industrial park, with businesses and manufacturers who use three-phase power, chances are you are going to suffer more spikes, surges and brownouts due to the motors, welders and other high in-rush current equipment used (motors, welders, presses, etc.) As for coax surge protection, some will block the DC power from your satellite receiver to the LNB in the dish. If your Dish or DirecTV is working OK, your protector is obviously of a different type. There should be no reason for a coax surge protector to "distort the picture". Some coax protectors are designed with RF filters built-in and some VHS and or UHV OTA reception might be affected. Anytime you bring an outside coax indoors, especially from a tower-mounted antenna, proper grounding is a must. You want the pre-strike build up of static electricity to be safely shunted to ground thru multiple ground rods. If a lightning strike does hit the tower, you'll soon learn how good your grounding system is! All broadcast and communication towers (except AM towers which are insulated above ground) use a multiple ground rods buried around the perimeter and each is thermo welded to heavy bare copper wire connecting them all together. The tower legs are also thermo welded to one or more bare copper buses or wires which are in-turn connected to the perimeter ground. The most spectacular up close and personal lightning strike I have witnessed was seeing multiple strikes dancing between the tops of two 1000-foot broadcast towers! I was sitting in my truck nearby afraid to move until the storm passed.The equipment in the transmitter buildings wasn't affected in the least---a testimony to a good grounding system. Check with your local electric utility to see if they offer a replacement meter loop with built-in whole house surge protection. I wouldn't rely on a whole house protector as my sole spike insurance, but it might mitigate transients and spikes before they enter the breaker panel. Lee

If you have access to the late Richard C. Heyser's collection of papers entitled Time Delay Spectrometry published by the Audio Engineering Society, I think you will find not only some answers to your inquiries, but answers to questions you didn't know you needed to ask! The link is to the second part of a two-part article someone posted earlier on this forum. http://forums.klipsch.com/forums/storage/3/1027018/6904heyser.pdf He concludes this article by stating, in part, A loudspeaker, when considered as a transducer of electrical signals to acoustic pressure, has a transfer function which has a frequency-dependent amplitude and phase response. The effect of these amplitude and phase variations may be considered to be the introduction of a time delay distortion in the reproduced pressure response. To sum up Heyser's many articles on the subject (no mean feat!), an on-axis "frequency response" is virtually meaningless without the attendant phase response. This discovery was the impetus for his invention of Time Delay Spectrometry (TDS). Whether you are using a Mitey Mike or a Bruel & Kjaer microphone to measure your loudspeaker, neither instrument is capable of measuring more than air pressure modulations. They are "deaf" to complex impedance, time delay, etc.. To get back to your overarching theme, keep in mind that in addition to the crossover network's complex impedance vs. frequency, you have the individual driver's acoustic delay due to offset voice coils as well as their complex impedance characteristics. Don't forget to factor in the back EMF generated by the drivers. Heck, it's a wonder that any loudspeaker works! Lee

Radiogram, Loudspeaker sensitivity ratings are specified based on Power and (@ 1 Watt/meter) and not Voltage. This would imply that the SPL will increase with increased power into the speaker and decrease with decreased power into the speaker. While the International Electrotechnical Commission (IEC) sets the standards for loudspeaker measurements under part 60268-5, not all manuafacturers specify their products according to the "book". For example, a perusal of JBL spec sheets shows sensitivity ratings of both 2.83 V @ 1m and 1W @ 1m for their products. To be fair, they do state that the nominal impedance rating of the loudspeaker. One of the more detailed loudspeaker sensitivity rating will be found on the Eminence web site. http://www.eminence.com/proaudio_speaker_detail.asp?web_detail_link=KAPPAPRO-10A&speaker_size=10&SUB_CAT_ID=1 A related article by Charlie Hughes goes even further to clarify loudspeaker sensitivity ratings. His recommendation is to apply the same voltage to every loudspeaker. That way the acoustic output will vary depending upon the rated impedance of the loudspeaker. http://www.prosoundweb.com/article/print/loudspeaker_sensitivity_whats_a_watt_anyway This would mean that two different speakers with same SPL rating but different impedences will have the same SPL at different voltages across the speakers for the same wattage. Yep. All things being equal (they never are!), if loudspeaker A has a nominal impedance rating of 8 ohms and loudspeaker B is rated at 4 ohms and both output 98 dB SPL with 1 watt input, then the voltage read across the voice coils would be 2.83 and 4.0 volts respectively. So here is my confusion. If this is indeed the case then would not a speaker’s acoustic frequency response be the inverse of the impedence curve? Let us assume we a have high current solid state amplifier with high damping factor (voltage source) capable of supplying enough current at the lowest impedence and can maintain same voltage. Now, wherever the impedence is lower, the amplifier is going to supply enough current so as to maintain the same voltage. Thus, the lower the impedence more the power and if SPL is based on Watts then, consequently more SPL. This again would then imply an acoustic frequency response that cannot be flat but one that will track the inverse of the impedence curve. The problem with your premise is that the efficiency of a loudspeaker is not constant. As the complex electrical impedance of the loudspeaker increases or decreases, its acoustic efficiency increases or decreases. All things being equal, while the "constant voltage" amplifier will vary its output current to mirror the load, the acoustic output of the loudspeaker may remain constant. Nelson Pass has written an article extolling the virtues of a constant current amplifier when driving full-range high efficiency loudspeakers. He also shows how to convert your constant voltage amp to a constant current device. http://www.firstwatt.com/pdf/art_cs_amps.pdf Lee

Gil, Thanks for the info. I've sent the guy an e-mail asking for the inside dimensions of the cabinet cutout. The foamboard idea sounds good. I'm having a local machine shop cut out my panel using a waterjet so as not to damage the brushed anodized black panel. Lee

Hello all, After three years in storage, I'm getting my horns, Belle and McIntosh gear out of storage and into our new home. I plan to mount the C504 preamp and MC502 amplifier using the Panloc brackets that came with the units. Unfortunately I have lost the clear plastic template which one uses to trace the cutout lines on a vertical mounting panel. Does anyone on the forum have the above units mounted either in a McIntosh L50 cabinet or in a panel? If so, I sure could use the cutout dimensions. Thanks, Lee

Tim, I plead guilty as charged on the badges for the 2006 Pilgrimage. I've printed out our VIP passes so they are 4" X 3" which is the size of the hanging-style name badges the attendees will get. That way, you can have your name on one side and the pass on the other. I'll have all the badges at the HIE Thursday evening as well as Friday & Saturday at the official events. Lee

Amy has sent me a list of the forum members attending the Pilgrimage so I can make name badges for everyone. I haven't settled on a format yet, but the badge will include your forum moniker and your "real name". I'd like to have pre-printed badges for non-forum members (wives, S.O.s, friend, etc) who will be attending. So, if you are bringing someone who is not a forum member, please e-mail me with their name, city and state. I'll also have some blank badges for late arrivals. The lovely and gracious Paula and I will be driving down Thursday to help Trey, so please get your info to me by Wednesday the 9th at 4:30 pm. See you there! lclinton@uark.edu

Trey, We just got our black T-shirts. They are nice quality (Hanes) and the printing should survive many washes. Lee

Great idea! I'm in Rogers, Arkansas 72756. Lee

Maron, Al's use of linear and not logarithmic scales to display frequency and distortion is neither simplistic nor misleading as you imply. His background is RF engineering and filter design and the instrumentation best suited for that discipline is a spectrum analyzer which usually offers only linear scaled displays for frequency and distortion when observing individual distortion products. While his HP3563A can measure spectra in the "log" mode, the results if displayed on a log scale, would be misleading. It's far easier to read IMD and spectra on a linear scale than a log scale. The same holds true for distortion products. As a broadcast engineer cum audiophile, I am used to reading distortion products as so many dB below the fundamental. So for me, Al's plots are easy to read. With a little practice, anyone can look at his plots and quickly determine which tweeter is "best". Now, if you are plotting swept sine measurements (distortion or amplitude on the Y-axis and frequency response on the X-axis), a log display is easier to resolve than a linear scale because of the log display's higher resolution at low frequencies. I have three Beyma CP25 tweeters and will be testing them next week with an Audio Precision SYS-2722 coupled to my 1/2" & 1/4" Bruel & Kjaer mics to see if Al has a rogue CP25 with out-of-spec distortion. Maybe I'll post the data in both log and linear formats and let you decide which is simplistic or misleading :>). Lee

As a semi-reformed "hot patcher", I've found the Neutrik NF2C-B/2 RCA plugs hard to beat. The outer ground shell is spring loaded and it connects the ground before the hot when plugging it in and disconnects the hot before the ground when removing it. They come with two sizes of cable grips or chucks so you can use any cable size from .12" to .29". Here's a link to the Parts Express listing: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=092-114 Lee

A Classic Tweeter is Reborn is the title of an interesting article in the current issue of Voice coil, a trade magazine I receive. http://www.audioamateurinc.com/digital/vc/issue/410/ The article titled Loudspeaker Sensitivity: What's a Watt, Anyway? by Charles Hughes is well worth reading, too. Lee

Seti, I'd call it micing and mixing for sound reinforcement as opposed to the unfortunately more common practice of micing and mixing for a "public address" system. My first experiences with both occured in the mid '60s at the Arkansas State Fair. We had a 70-volt P.A. system in the swine and sheep barns and a sound reinforcement system at Barton Colosseum where the headliners performed during the week-long rodeo. The barn's public address system had to be loud but intelligible for announcements but the colosseum sound had to be mixed with a deft ear because the venue was itself a huge barn acoustic-wise. As an aside, in the colosseum, they had recently installed a huge (for the time) loudspeaker cluster built with a welded aluminum framework that was 10-12 feet on a side. It was hung with a stranded cable running several hundred feet thru several pulleys to a hand-cranked winch. There was also a thick safety cable attached to I-beams overhead. Problem was, if the winch failed or the main cable broke, the safety cable would do its duty and stop the cluster about three feet from the concrete floor. Of course if there was a performer on a stage standing beneath the 500+ pound cluster, he or she would be diced like a zucchini under a Slap Chop! Worst duty for an audio grip at a rodeo? Wiping the cow sh*t off the audio cables and cleaning the XLR connectors. Best duty? Getting to meet Roy Rogers! OK, one more story. In '65 or '66 after he was introduced, Roy rode around the arena, dismounted from Trigger, ran up on the stage, pulled out both six-shooters from their holsters and fired a dozen blanks on either side of a brand new Shure SM33 ribbon mike! The audio guy 'bout had a heart attack! Fortunately, the mike survived and in the processed dispelled the notion that ribbon mikes (at least that one) were fragile. BTW, the SM33 was the mike of choice for Johnny Carson. Lee Lee

While I cannot address your question directly, see the link below and find the Volume 16 Noumber 2 issue of Dope From Hope entitled VENTED BOX BASS SPEAKERS AND HORN TREBLE SYSTEMS. This DFH shows how PWK's "cut and try" work on the Cornwall in 1957 resulted in a vented cabinet within a few percentage points of the TS B-3 alignment which optimizes low distortion over frequency response. While the difference between a two port and three port Cornwall might be measureable, it probably isn't audible. http://community.klipsch.com/forums/storage/3/492626/Dope%20From%20Hope.pdf Lee

Gary, Over the past 30 years I've had my Klipschorns in four different homes and none had true 90 degree corners. You are certainly better off having a corner angle greater than 90 than one less than 90! Rather than use the less expensive closed cell foam pipe insulation, spend a little more and get the closed cell rubber pipe insulation. Both Home depot and Lowe's carry the rubber type which more easily conforms to the gap between the tailboard and the wall. Lee

Trey, et al, For those of us fortunate and privileged to meet PWK, we might on his birthday tell our "Meeting PWK for the first time" story. For me it was early 1966. I wrote PWK asking for plans so I could build my own Klipschorn. His written reply was, to paraphrase, "You'd be better off digging ditches for two bits and hour and saving up for a tried and tested product rather than try to build one yourself." Boy, did that deflate my self-esteem! Not to be deterred, I built a pair of Klipch Shorthorns from some plans in a loudspeaker book. It had Altec 511's with Altec squawker drivers. I don't remember if it had a tweeter. With a modified Stromberg-Carlson PA amp, a Dynaco preamp, AR XA turntable with some flavor of a Shure cartridge, I was in Hi-Fi heaven! BTW, according to PWK there is no such thing as "high-fidelity" only fidelity and infidelity. PWK and I corresponded over the ensuing years and I finally met him in Little Rock around 1974 where I worked for a Klipsch dealer. At 6'-3" or so, he was an imposing figure and I remember him striding up to me, grabbing my hand and saying, "I'm Paul Klipsch. I assume you know who you are." I'm sure I babbled something unintelligible until I recovered from that introduction! Lee

Toole's writings should be required reading for those who want to know the correct way to set up and conduct controlled listening tests. Subjective and objective measurement of loudspeaker performance: A collection of papers, now out of print, dispels many myths of what constitutes the "perfect" loudspeaker. It should come as no surprise to Klipsch loudspeaker owners that (to poorly sumarize this "Bible") a loudspeaker with the flatest, widest bandwidth is preferrred over loudspeakers that suffer in these performance areas. Lee