Arkytype

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

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!

Looks like Stereophile posted the Forte III review on their web site. https://www.stereophile.com/content/klipsch-forte-iii-loudspeaker

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

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

The August issue of Stereophile features a review of the Forte III. Roy is quoted at length throughout the glowing review and goes into some detail on how his patented "Mumps" was developed. As a print subscriber, I don't follow the on-line Stereophile reviews enough to know when they are posted compared to the print edition. Unless there is an embargo on releasing the Stereophile review before a certain date, you'd think Klipsch would have it posted on the klipsch.com web site. The big news is that a (hopefully full) review of the Klipschorn AK6 is forthcoming later this year. Lee

Here's a copy of page one from the original 1986 November Audio with the text you cited. Wonder where Heyser got the "8 feet" information. PWK? Some forum member has published the complete Heyser review in the past but I could post what I have. Lee Review page 1 of 6.pdf

Circa 1988 Klipschorn: + or - 3 dB 35 Hz--17.5 kHz; Current? non-AK6: + or - 4 dB 33 Hz--17 kHz. AK6: + or - 4 dB 33 Hz--20 kHz. Did quite a bit of looking thru old audio-type magazines from the '50s to modern times including Wireless World, Audio Engineering, Radio & TV News, Radio Electronics, etc. Couldn't find any mention of the unfolded length of the Klipschorn. This site is a treasure trove of old technology and it's searchable. There are some good articles on horn loudspeakers, just search each magazine or the entire library. https://www.americanradiohistory.com/index.htm Lee Audio-1965-10-OCR-Page-0077.pdf

Tony Martin and his team of "industrial designers" (or who ever is responsible) should be horsewhipped for turning the Klipschorn's classic appearance into a bad joke. By removing the "B-style" collar separating the bass horn from the upper housing, the balance and beauty of PWK's visionary styling has been lost in favor of .......what exactly? According to Klipsch ad copy, they "....removed the inset collar or spacer...for a cleaner aesthetic appearance." Oh, to have been a fly on the wall at that fateful design meeting in Indy! Fade up to a conference room where Tony Martin and his design team wizards are reclining in their Aeron office chairs sipping kale smoothies from the Klipsch vending service. "Hey Tony," says one of the minions wiping off his green mustache. "I know how we can save $39.45 in manufacturing costs on the K-Horn----let's eliminate that tacky collar and re-invent the Style C model! I can get us a deal on rubber feet to separate the bass horn from the top section. And, say, while we're making improvements to the K-Horn's looks, let's make it even taller by adding a four-inch ----no, make that a two-inch riser. That'll add to the WAF fer sure. Now, if you've got a minute, I've got some ideas for the Cornwall............" Fade to black. No, what they did was revive the old Style C Klipschorn which did not have the collar. Then, rather than attaching the upper assembly flush with the bass cabinet, they are using what looks to be round rubber equipment feet as spacers. Next, they'll want to enclose the back so you can use the Klipschorn away from the corner. Oh yeah, they already did that. Hey Rogelio, er Chief bonehead; how about showing us some curves of an enclosed Klipschorn cabinet several feet away from a corner compared to the proper corner location? Lee

There was an audible gasp from my Rosewood Belle when she heard she might not be bifurcated. I had to play soothing music to assuage her fears. At least she's not an orphan! Lee verb /ˈbīfərˌkāt/ divide into two branches or forks. "just below Cairo the river bifurcates" adjective /bīˈfərkāt,bīˈfərkət/ forked; branched. "a bifurcate tree"

What the......? Previous post should read, in part, "...co-inventors PWK & Gary Gillum used not only a factor of 12 (instead of eight) for a Pi/2 loading..." Lee

Keep in mind that the Klipsch La Scala, Belle, Jubilee and Klipschorn bass cabinet acoustic paths are bifurcated. I don't think you can arbitrarily add the two internal path lengths together or double the length of the external wall extensions to gain a longer "effective" path. As Edgar states, the measurements don't support that. You can, however, supposedly take either of the "single" mouth areas and multiply that by a factor of 8 (assuming corner loading) to arrive at the total "effective" mouth area. Curiously, in the July 1, 1980 U.S. Patent 4,210,223, co-inventors PWK & Gary Gillum used not only a factor of 12 (instead of 😎 for a Pi/2 loading to determine the necessary mouth size, but they added both of the bifurcated mouth areas together! I'm still scratching my head over that one. Lee US4210223.pdf

I've now both physically measured the path length of one of my Klipschorn bass cabinets and, using the Impulse Response tool within ARTA, made many measurements of not only the bass horn's path length (varying sample rate, chirp length, etc. but also measured (and confirmed) the path length of known distances between a Beyma CP-25 tweeter diaphragm and my 1/2" Bruel & Kjaer 4133 microphone. Since ARTA allows one to enter the room temperature and humidity to change the default speed of sound (344 meters/second), measurements and calculations were made using 346 m/sec. Here's how to read the data block. The cursor located just before the positive-going peak is at 6.484 milliseconds after time zero. Since all AD->DA converters as well as FIR filtering has latency, we must count our starting time not from 0.00 milliseconds but (in the case of ARTA) at sample position 300. Note that the cursor is at sample position 1245. Sample position 300 represents a system latency of 1.557 msec + or -. The time (path length) we are interested in is the gate time which is simply the difference between the cursor location (6.484 msec) and sample position 300 (1.563 msec). A gate time of 4.927 msec converts to a path length of: (34.6 cm/1 msec) =(X cm/4.927 msec) ; X = 170.47 cm or 67.11 inches. So, where does that leave the issue of the claimed "8-foot folded horn low frequency cabinet."? Lee

What I wrote, "Hope Klipsch isn't resorting to deceptive advertising." was written partly in jest. Should I have attached a smiling emoji at the end? With all the puffery associated with most audio product advertising, I was very surprised to hear the voice over of the animated Klipschorn state, "The key to the Klipschorn's deep bass and high efficiency starts with its eight-foot folded horn low frequency cabinet." About the only thing on my Klipschorn that measures 8 feet is its circumference, not the length of its acoustic path. I'll be making some acoustical measurements later today that might clear up the matter. 😊😊😊😊😊😊😊😊😊 Lee

Both glens and Edgar make good points. The path (A to I) was chosen more from a measured midpoint at key points along the horn. Once you remove the tailboard and the woofer access door, you can measure just about any distance, dimension and angle. Well, you do have to remove the "bug screen". 'Bout the only thing I couldn't begin to calculate is the rear chamber volume. Obviously, there are longer and shorter paths from the throat to the mouth. Sorry to hear the Klipschorn loses control at point J . :>(. Maybe Chief bonehead can "horn in" re where he thinks the mouth is. Tomorrow, I'll set up ARTA and do some path length measurements. Ivo Mateljan (the author) has just released the latest version. There is a trial version you can download but a licensed copy is only 79 Euros. Great (newly revised) user manuals, too. Lee

sixspeed wrote: "The KHorn now has the rear panel sealed since the 70th editions. That is likely where the extra length of the horn is coming from." Nope, unless the enclosed Klipschorn is located in a corner (where it belongs), you will lose at least 12" of the final horn expansion. Chief bonehead wrote, "Actually it’s about 97.3765”......approximately." Attached are some drawings of one of my Klipschorn bass cabinets. I came up with a throat-to-mouth distance of 70.33333333".....approximately. Where's the extra 24+ inches?? Surely you aren't counting the path from H to I twice? Regards, Lee

Since we're talkin' Klipschorns here and Chief Bonehead's video is being discussed , I'm gonna copy and paste an earlier question posted about the Klipschorn description in the video you can scroll down to after Roy's. Hope Klipsch isn't resorting to deceptive advertising. "Kudos to Roy for a well-done video on the Klipschorn AK6. Has anyone seen the Klipschorn AK6 video? Here's a transcript of the opening narration: "The key to the Klipschorn's deep bass and high efficiency starts with its eight-foot folded horn low frequency cabinet." Say what? Has there has been a major design change to the Klipschorn's bass cabinet? My Klipschorns, which I've had new since 1979, have a bass horn mean path length of about 66"----not the "eight-foot" folded horn described in the video. Does anyone know what "eight-foot" the video refers to? " https://www.klipsch.com/products/klipschorn#product-specs Regards, Lee

Celestial_Sound wrote: So what your point on quoting only negative aspects? My point wasn't to single out "negative aspects" of the RP-600M measurements---I was responding to Pzannucci's interest in two particular performance areas. Had JA not found any untoward cabinet resonances or a more balanced treble output, I would have quoted those findings. Lee

Pzannucci wrote: "It will be interesting on what they say about cabinet resonances and the balance on the highs." From John Atkinson's "Measurement" of the Klipsch RP-600M: "I found on all panels a strong, high-Q mode at 316 Hz and a lower-level one at 422 Hz. These are .... high enough in level that I would have thought they would lead to some midrange congestion." As for the balance on the highs, Atkinson wrote, "Both drivers are relatively flat in their passbands, but....the tweeter is a couple of dB higher in level than the woofer." OK, granted these are $549/pair Chicom-manufactured loudspeakers. However, based upon the Stereophile measurement graphs, it appears the woofer's crossover frequency chosen is too low and the tweeter's response is elevated in an attempt to fill in the dip at the crossover point. He also noted that his estimate of the RP-600M's sensitivity was 6.5 dB lower (89.6 dB(B)/2.83V/m) than the RP-600M's advertised sensitivity of 96dB/2.83V/m. He concluded the review by writing, "Overall, and that lively enclosure aside, the Klipsch Reference Premiere RP-600M offers impressive measured performance, especially when its affordable price is taken into consideration." Lee

Kudos to Roy for a well-done video on the Klipschorn AK6. Has anyone seen the other Klipschorn AK6 video? Here's a transcript of the opening narration: "The key to the Klipschorn's deep bass and high efficiency starts with its eight-foot folded horn low frequency cabinet." Say what? Has there has been a major design change to the Klipschorn's bass cabinet? My Klipschorns, which I've had new since 1979, have a bass horn mean path length of about 66"----not the "eight-foot" folded horn described in the video. Oh, wait. Never mind. I just measured the outside circumference of one of my bass horns and it is almost exactly 96". Mystery solved!!?? Seriously, does anyone know what "eight-foot" the video refers to? https://www.klipsch.com/products/klipschorn#product-specs Regards, Lee

Give Blue Jeans Cable a try. I've used the "Ten White" and "Twelve White" for years. If you know your exact length, they can ultrasonically weld your connectors of choice. https://www.bluejeanscable.com/store/speaker/index.htm

FWIW, Here's a comparison of the stock K-33 and Bob's CW1526C in one of my 1978 Klipschorns. The measurements were normalized at 100 Hz. Both (left & right) Klipschorn measurements showed the same roughly 6-14 dB "improvement" from 23-25 Hz with the CW1526C woofers. I regret not making distortion measurements at the time but that could be done easily as I still have the original K-33 woofers. Measurement gear used: Bruel & Kjaer 4133 (omnidirectional) 1/2" mic capsule; Bruel & Kjaer 2669 preamplifier; Bruel & Kjaer Type 2636 Measuring Amplifier; licensed version of ARTA acoustic measurement software. For accurate bass frequency measurements, I'm a big fan of Don Keele's innovative nearfield pressure measurement technique. The B & K mic obviously couldn't be placed near the woofer cone (as the technique calls for) but was about 18" above the floor very close to one of the side grill panels. The link is to all his papers. Paper #6 is worth reading if you want to learn how to accurately assess your loudspeaker's low frequency performance. http://www.xlrtechs.com/dbkeele.com/papers.htm Lee