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Arkytype

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  1. Chris A wrote, One of the great missing links to the loudspeaker engineering repertoire (IMO) is a ranking of loudspeaker performance attributes by measurement type--not based on someone's opinion of what is important, but rather by subjective preference by listener groups on particular loudspeaker types (by listening group preferences), and then an analysis of how the most preferred loudspeakers actually performed, i.e., an approach that is reversed from the engineering literature on loudspeaker measurements. The person who is perhaps the most responsible for quantifying listener preferences in a loudspeaker is Floyd Toole. He has conducted hundreds (if not thousands) of blind listening tests at Canada's National Research Council with participants ranging from professional musicians to volunteers. I won't spoil the resulting findings. His latest book is well worth the investment. Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (Audio Engineering Society Presents) 3rd Edition He also is on several informative YouTube videos. Lee
  2. Where we are: Our power amplifiers (solid state & valve), preamplifiers (passive or active), CD players, DACs, turntables, integrated amplifiers & AV receivers all have one thing in common: Their “sound” is not affected by a room’s “acoustics” which include the dimensions, shape, dimensional ratios, reverberation time, standing waves, etc. That leaves the loudspeaker which, for the most part, is at the mercy of the above “acoustics” for its “sound” and whose measurements we often question. Where we’ll never be: In a perfect world, all reviewers in the audio magazine bidness would have identical listening rooms with the size (ratios, shapes) and acoustic treatment taken from the experience of notables such as Floyd Toole, Peter D’Antonio and the like. Then, maybe at least the objective measurements would be in closer agreement with the manufacturer’s specs. The subjective assessments would, however, be left to the whims, prejudices, and “golden ear wax” of the reviewers. Where we could be: If my memory serves me correctly, the factory listening room in Hope has four square corners but splayed side and end walls. I think it was constructed about the same time as the anechoic chamber. Shameless Aside: When the chamber was under construction (late 70s?), I visited the plant and found PWK spinning the revolving corner at maybe 40-60 RPM! I can still remember the whoosh of air as each partition went past. He quipped that he was testing the door’s bearings which were from a pair of truck axles. JRH probably was there as well as he drove a lot of the door’s unique, patented construction. https://patents.google.com/patent/US4387786?oq=klipsch WWCB (Cont’d) Anyhoo, I propose that Klipsch get a qualified acoustic consultant and outfit that listening room (Indy's as well) with the proper wall/ceiling/floor treatment that any manufacturer in the loudspeaker bidness should have to highlight their products. The present wall “treatment” at Hope is just sad. What we are striving for is an “ideal” acoustical space using proven solutions; not a few pieces of “acoustical” foam and wall-to-wall carpeting. https://community.klipsch.com/index.php?/topic/177136-klipschorn-new-build-introduced-to-pilgrimage-attendees/ Next, starting with each Heritage loudspeaker, measure every electrical and acoustical parameter known using state-of-the-art, calibrated gear, not a laboratory microphone adapted for entertainment use and the decades-old MLSSA testing software John Atkinson uses. Audio Precision not only manufacturers top-of-the-line measurement gear but also has some powerful, easy-to-use loudspeaker measurement suites. One can make more than a dozen accurate, repeatable acoustic measurements in a few seconds with a single mouse button click. https://www.ap.com/electro-acoustic-test/ Just think, you could start with a pair of Cornwall IIIs in the corners with the tweeter axis pointed at the microphone (at the listening position); take a slew of measurement; and then gradually move the CWIII toward the center all the while taking comparison measurements. Of course, these comprehensive measurements would trickle down the product line as warranted. As a “reference” each loudspeaker would be tested in the trihedral corner of the anechoic chamber to compare FR curves and those pesky sensitivity specs with those taken in the listening room. Finally: The end result of these measurements would be to, a) have a baseline for each loudspeaker model which could (should?) be used in product advertising, and b) could (should!!) be used to refute/dispute an audio magazine’s poor measurement results. In the case of the AK6 review, if Roy was privy to the poor measurement results prior to publication, he should have (at the least) moved heaven and earth to get those measurements re-done indoors or used the Manufacturer’s Comment section to strongly contest the AK6’s poor measurements. Lee
  3. Because of the Klipschorn AK6's bulk—each weighs 220 lb—I drove my test gear the 177 miles to Art's place and measured the speaker sitting on a furniture dolly in his driveway. So, rather than measure them in situ, Atkinson and Dudley manhandled an AK6 out of the house and onto the driveway? Surely the DRAA MLSSA could gate the room reflections.
  4. According to my architectural manuals a 17 foot room dimension is the worst for sound reproduction that you can use for any speaker system. JJK Say what?
  5. Deang wrote, I'm having a hard time believing that Roy didn't shoot for flatest response possibe. I'm inclined the blame the testing methodology. You have to give John Atkinson credit for making consistent, in-depth loudspeaker reviews. The measurement gear is reliable and gives repeatable results. He's made well over 1000 loudspeaker reviews and his in-depth methodology can be found within the Stereophile archives. Yeah, I'd like to see some I.M.D. tests as well as polars but while those tests would be welcome to fellow Klipsch forum members, I doubt they would be appreciated by most Stereophile readers. garyrc wrote, I wonder if Klipsch wrote anything in the Manufacturer's Comments section of Stereophile (conveinently buried toward the back of the magazine instead right with the component tested)? I'm curious to know what Roy Delgado would say about this review. Roy? @Chief bonehead. Perhaps he would contest some of their findings, or talk about important qualities they didn't mention. I would assume Roy was privy to Dudley's review and Atkinson's test data before he responded. His response did not address the review or test results directly but was a curious reiteration of PWK's "four sound principles in order of importance: High efficiency Low distortion Controlled directivity Controlled frequency response PWK actually had published his 1961 "Eight Cardinal Points in Loudspeakers for Sound Reproduction" which Gil posted back in 2004. https://community.klipsch.com/index.php?/topic/46835-article-eight-cardinal-points-by-pwk/ There is a huge disconnect between Roy's praise of the AK6's tweeter and the actual measurement results. I see Chris A posted the review link and an ugly on-axis frequency response. Maybe Roy would like to post some Klipschorn "dirty pictures" for us to see. Maybe it's time to rethink the politics of the inflated sensitivity specs, eight-foot bass horn BS and the Heritage "re-styling" decisions. Lee
  6. http://assets.klipsch.com/files/Dope_610220_v2n2.pdf http://assets.klipsch.com/files/Dope_720200_v12n1.pdf http://assets.klipsch.com/files/Dope_751205_v15n5.pdf
  7. The September 2019 edition of Stereophile has a long-awaited review of the AK6 Klipschorn. The only word that comes to my mind after reading both the Measurements section and the review by Art Dudley is----disappointment. First the measurements: Once again, a Klipsch loudspeaker does not meet its sensitivity specification. That's odd for a Klipschorn as I would assume its sensitivity was measured in the trihedral corner of the Hope anechoic chamber (see grainy image). You'd think there would be less of the "room gain fudge-factor" Klipsch uses than the 3.9 dB sensitivity shortfall John Atkinson measured. For logistical reasons, the AK6 was measured out of doors sitting on a driveway. The AK6 frequency response specification is 33 Hz--20kHz + or - 4 dB. For a premium-priced loudspeaker, that spec should be + or - 3 dB or better. Atkinson measured the AK6 frequency response using nearfield (bass horn) and farfield (squawker/tweeter) measurement techniques. The AK6 frequency response measured: 33 Hz -20kHz +8 dB minus 15 dB (my interpretation of the FR curves). The +8 dB peak at 10kHz is as disappointing as the overall tweeter level which appears to be 3 dB too hot relative to the midrange. I won't comment on the bass horn measurements only to say that even though the back is enclosed, corner placement is, IMHO, the only location to measure the bass response of a Klipschorn. Second, the listening test: It wasn't clear from Dudley's review how the Klipschorns were located in his 17' x 12' x 8' listening room. Were they on the long wall or short wall? Dudley writes, I began with the backs of the Klipschorn AK6s a short distance from the front wall--their front surfaces, measured at the centers of the cabinets, were a little more than 3' from that wall, and a little more than 8' apart from each other--and with the the speakers slightly toed-in toward the center listening seat. Really? Where's my horsewhip? Who in their right mind would listen to Klipschorns eight feet apart and three feet away from a wall? In 2006 Klipsch turned down Dudley's request to review the 60th anniversary Klipschorn because his (Dudley's) listening room at the time couldn't accommodate corner placement. Did the current Klipsch marketing department considered asking for dimensions and images of Dudley's current listening room? His current listening room would IMHO be marginal even locating the AK6s on the 17' wall. My listening room was designed around my Klipschorns/Belle and is 24' wide, with 11' high side walls and a 23' vaulted ceiling. The sound quality and imaging is magnificent and is a system not tolerant of poorly recorded pablum. Unfortunately, I cannot scan the AK6 review and post it----my trusty Epson scanner is refusing to power up. Stereophile will post it soon enough on their web site. Gosh, you'd think Klipsch would have posted the past two Stereophile Klipsch loudspeaker reviews on the web site by now. Lee
  8. HDBRbuilder wrote: The options for veneers available changed over the years....when yours were built, ebony and rosewood were still very much in the "availability zone" which changed over time as "the powers that were" decided to avoid offering veneers from "declining tropical rainforest" areas...a decision which never made sense to me, anyway...because if they are gonna cut those trees down to make more farmland, then how is not offering the veneers gonna make any difference, anyway? It was what it was! When I ordered my Rosewood Klipschorns and Belle in December of 1975, as a salesman for Custom Audio in Little Rock, I was allowed to go to the plant and pick out all my veneers (even the edge veneering!). My only choice was Honduran rosewood as Brazilian rosewood could (at that time) only be exported as a finished product. The cost? The Klipschorns were $937.00 each and the Belle was $780.00. The salesman's discount was 24%---far lower than say, McIntosh, Nakamichi or other high-end brands we sold. That 1975 list price of $2,654.00 is the equivalent of $12,635.75 in today's dollar. Lee
  9. windashine, you wrote: That's about all I have - this should be an interesting project, take your time.... I'll leave with the only picture of my next project... I'm still trying to figure it out lol That image of course is of the Libido Loudspeaker Company's Peyronie in distressed Hard Rock Maple. Libido aficionado's just call it The Woody. Lee
  10. Pats3of4, Except for the front panel which is 3/4" veneered lumber core plywood, my Klipschorn bass bins are constructed of 1/2" plywood. All the top housing is 3/4" veneered lumber core plywood. You wrote: Im not worried about cutting or the assembly. You'll probably wear out a planer shaving 1" plank oak to 1/2" thickness. Then if you can accurately cut the dozens of pieces (CNC router might work) , how do you know your construction plans are accurate? There are at least a half dozen "Klipschorn" plans on the internet and all differ either in the angles of some of the cuts or in the dimensions of the pieces. Here's some Klipschorn advertising copy from the October, 1965 Audio magazine (pg. 77) which describes the construction of the bass horn: The construction of this horn is beyond compare. Nearly 288 screws, plus other fastening devices, plus high -grade adhesives, are used to make the horn as rigid as possible. Also each bass horn is checked with a water manometer to ensure absolute air tightness of the rear air chamber. Guess you'll wear out a countersink bit or two. 😊 Please post images of your build. progress. Lee
  11. Gil. et al, I seriously doubt the height of the Klipschorn bass bin has been altered. The AK6 spec sheet says 53" high while the "regular" Klipschorn spec sheet says 50.75". For reference, my Style B (with the collar) Klipschorns are 52" high. Let's take the current non-AK6 Klipschorn first. From the spec sheet we see its height is listed as 50 3/4". Take a Style B (52") remove the 1" collar and the bottom 3/4" plate and you get a new height of 50 1/4". Add back the 1/2" unsightly air gap and you get the 50 3/4" spec. For the AK6, take that 50 3/4" and add the 2" riser and you get 52 3/4", not 53". Looks like there's a 1/4" discrepancy there. Whoever checks copy and continuity on the Klipsch web site is MIA. Note the "regular" Klipschorn's height of 50.75" is stated as the metric equivalent of 128.9.4 cm. Yep, there's an extra decimal point in there. 50.75" is equivalent to 128.905 cm. https://f072605def1c9a5ef179-a0bc3fbf1884fc0965506ae2b946e1cd.ssl.cf2.rackcdn.com/product-specsheets/Klipschorn-2018-Spec-Sheet-v02.pdf https://f072605def1c9a5ef179-a0bc3fbf1884fc0965506ae2b946e1cd.ssl.cf2.rackcdn.com/product-specsheets/Klipschorn-Spec-Sheet-v04.pdf Lee
  12. It was. https://www.thevintagenews.com/2019/04/09/playboy-braille/ The only problem was trying to finger out how to print a 3D centerfold!
  13. Looks like Stereophile posted the Forte III review on their web site. https://www.stereophile.com/content/klipsch-forte-iii-loudspeaker
  14. Sorry, pzannucci, it was ODS123 who wrote, Although the subjective comments about the speaker were positive, the measurements were a bit disappointing. I assumed he was referring to the on-axis frequency response curves and not some other deficiency. After all, that "...suckout centered on the 5.2 kHz upper crossover frequency, and a slight excess of energy in the top audio octave." somehow wasn't important enough to address somewhere along the Forte III development stages. Since John Atkinson uses "smoothing", I suspect the raw curve has a steeper notch indicating a possible driver polarity reversal. As for being a long-time subscriber to Stereophile, I just read it for the pictures. Lee
  15. Re August 2019 Stereophile review of Forte III: The slap in the face with a wet fish moment came when I read, The Klipsch Forte III didn't rise to the majestic peaks of the Volti Audio Rival.It lacked that speaker's ability to describe the richest, densest tonal complexities. Well, it turns out that Forte III reviewer Ken Micallef also reviewed the Volti Audio Rival in May of 2017. pzannucci, if you think the Forte III's frequency response is "disappointing", look at John Atkinson's measurements of the Rival here. https://www.stereophile.com/content/volti-audio-rival-loudspeaker-measurements. There was not one area in Greg Roberts' "design" of that turd that didn't reflect poorly in the test results. At the end of the Measurements section, Atkinson tries to downplay the poor performance by writing: Summing up the Volti Rival's measured performance is difficult: Its perceived balance will depend to a greater degree than usual on the listener's choice of music and the size and acoustics of the room.....I hate it when an audio writer says, "Listen for yourself"—but in the case of the Rival, that's all I can say.—John Atkinson As for the sensitivity rating, Atkinson's measurement of the Forte III shows a 3.8 dB lower output than Klipsch specifies. This discrepancy has been noted in several forums and blogs over the years, I found this exchange between Guest BobG and other forum members posted January 3-4, 2002 on the 2-Channel Home Audio forum: I have read from countless sources that the Klispch (sic) Reference series speakers are WAY over estimated reguarding (sic) senstivity (sic), sometimes up to 3-5 pts higher than what they really measure. On the other hand, most of the vintage Klipsch are very accurate in the stated sensitivity specs. As for the Chorus speakers, these probably have a better chance of being as stated although 101 does seem rather high. kh Guest BobG's reply in two posts are laughable: 1) Before we let the inaccuracy be taken as fact, I would like to mention that the sensitivity specs of Klipsch speakers are not overstated. We use legitemate (sic), repeatable measuring methods. There are many different methods of rating sensitivity, but we do not attempt to hide behind specs. 2) Klipsch measures sensitivity on home loudspeakers in the following manner: 1. We place the speaker to be tested in our anechoic chamber and do a free space measurement (no boundary gain or room gain) at a distance of 3 meters. This distance is chosen in order to be in the far field of the speaker. The test signal used is wide band pink noise. 2. Starting with this result in dB, we add 9 dB to obtain a one-meter equivalency, as the industry standard for expressing sensitivity is one meter. The 9 dB difference is all inverse-square gain. Move half as far away and gain 6 dB etc. (see note below) 3. To this we add 4 dB for room gain and boundary gain to translate the measurement to a typical listening environment. Speakers are not operated in free space in any normal application. An increase in sound pressure comes from proximity to nearby walls, floor and ceiling. Theoretically, a maximum of 18 dB increase is available through corner placement but that is rarely the position chosen for full range loudspeakers; and the increase is also frequency dependent, being prominent at low frequencies. Additional measurable increase comes from room gain wherein the room is pressurized by low frequency information. Again, this is frequency dependent impacting only the low end of the spectrum. We have verified the 4 dB figure we use in numerous empirical measurements and believe it to be quite accurate. (see note below) Our KPT-904 professional theater speaker was mentioned above. It should be noted that the KPT-904 is a model designed to be placed behind the screen at a movie theater and as such does not benefit from as much boundary reinforcement as in a typical home installation. The 4 dB room gain figure is not applied to the sensitivity measurement for such models. (emphasis Arkytype's) Now I don't know the identity of "Guest BobG" and/or whether he is/was a Klipsch employee. As for the claim he makes about a "4 dB" room/boundary gain, why doesn't that reflect in Stereophile's recent sensitivity measurements of the RP-600M and the Forte III? Curiously, the sensitivity of the Palladium P-39F (tested June 12, 2009) was within experimental error. The 9 dB difference is all inverse-square gain. Nope, sound pressure level falls/increases about 6 dB per doubling/halving of the distance from a source, not as the square of the distance. It's actually 9.54 dB, not 9 dB. http://www.sengpielaudio.com/calculator-distance.htm . We have verified the 4 dB figure we use in numerous empirical measurements and believe it to be quite accurate. Here's the problem with that statement. While their anechoic chamber yields accurate on-axis free-field sensitivity measurements, they cannot possibly pick a single number (in this case, 4 dB) increase in an owner's listening room; there are simply too many room sizes, H x L x W ratios, acoustic treatments, etc. to even begin to quantify that number. The SPL increase is certainly real but trying to arrive at a single number is folly. Instead, why not publish the anechoic sensitivity specification as follows: "The Klipsch Forte III loudspeaker measures 95 dB Sound Pressure Level (SPL) with a 2.83 volt band-limited pink noise at a distance of 1 meter in our anechoic chamber. At home (using the same test parameters), you can expect your Forte III to measure 2-4 dB higher depending upon location, room size and acoustic treatment." Enjoy pissing off your neighbors! Lee
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