John Warren Posted November 12, 2015 Share Posted November 12, 2015 (edited) A member of this forum emailed this plot to me. It's a measured response of the B&C DCM50, a JBL and the K55M taken by a supplier that markets the B&C driver (the middle plot in the attached). The B&C DCM50 appears to exhibit a dip in the response consistent with what I measured in the units I have here. There are a few years of production separating the plot of the B&C below and the ones I have (about 6) indicating that this "anomaly" is, in fact, the actual response of the driver. Given the enormous popularity of this driver, it suggests that this response, as Shakespeare would say, is much ado about nothing.... So Kudos to DrWho. Edited November 12, 2015 by John Warren 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 12, 2015 Author Share Posted November 12, 2015 (edited) And here's the comparison of a driver manufactured 6 years later (+/-). Surprise! Edited November 12, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 12, 2015 Author Share Posted November 12, 2015 The bottom plot is the quasi-anechoic response (FFT of gated impulse derived from noise immune MLS). The shape is the same but the dip appears at a somewhat higher frequency than the early reverberant measurements. I'd like to see response plots of this driver on other horns...anyone have them to share? Quote Link to comment Share on other sites More sharing options...
jwc Posted November 12, 2015 Share Posted November 12, 2015 Long live the K55!! BTW, What model number JBL? Quote Link to comment Share on other sites More sharing options...
tigerwoodKhorns Posted November 12, 2015 Share Posted November 12, 2015 Question on the K55 plot. If you have a better tweeter than the k77, are you better off crossing the K55 at 5Khz? Quote Link to comment Share on other sites More sharing options...
vindeville Posted November 12, 2015 Share Posted November 12, 2015 Its a wonderful sounding driver in my opinion. I've had a few in my khorns and this one is about perfect to my ears. Looks like it may be the smoothest of the 3 compared regardless. Maybe that little dip in that area is a net positive for human consumption? Odd how the JBL is very closely inverse in response at that frequency. Bet the JBL is a bit more etched sounding. Just my 2 cents. This driver will likely never leave my system Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 12, 2015 Author Share Posted November 12, 2015 (edited) A comparison of the B&C response plot provided with the driver to a measurement of the raw driver response with the mic sniffing at the tip of the phase-plug. The diaphragm begins to deviate from true piston-like behavior above about 2kHz. The arrows identify where the sensitivity peaks at each node. The red plot is the driver with no network. (p.s. Beranek has a nice treatment on this behavior for cone drivers and (I think) there's a JBL white paper on this related to compression drivers. The Be diaphragms push these nodes out at higher frequencies). Edited November 12, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 12, 2015 Author Share Posted November 12, 2015 Its a wonderful sounding driver in my opinion. But it's "jelly-fishing" right where your hearing is most sensitivity! You are wrong, you do not like this driver, you cannot like this driver!!!! . Quote Link to comment Share on other sites More sharing options...
Schu Posted November 12, 2015 Share Posted November 12, 2015 I wonder if there are measurable differences between the V/M/X versions... Quote Link to comment Share on other sites More sharing options...
Chris A Posted November 12, 2015 Share Posted November 12, 2015 Question on the K55 plot. If you have a better tweeter than the k77, are you better off crossing the K55 at 5Khz? Chris, I see that your question hasn't been answered yet, and although it's a little diversion from John's original purpose for this thread, I believe that the following will answer your question. I've found that the K-55/K-500 crossed over to a Beyma CP25 at 2.5 kHz (with suitable active crossover PEQs and delays) sounded and measured much better. I tried many crossover frequencies and 2.5 kHz seemed like a much better crossover frequency in terms of correctable amplitude and phase/delay, and in terms of mismatch in the tweeter vs. midrange coverage: https://community.klipsch.com/index.php?/topic/123370-settings-for-tri-amping-an-82-belle-with-an-active-digital-crossover/?p=1762755 Chris A Quote Link to comment Share on other sites More sharing options...
vindeville Posted November 12, 2015 Share Posted November 12, 2015 (edited) Its a wonderful sounding driver in my opinion. But it's "jelly-fishing" right where your hearing is most sensitivity! You are wrong, you do not like this driver, you cannot like this driver!!!! . Damn it John, all the trust I've built with my ears and you gotta do this to me. some nice guy you are. for some added perspective I will say one of the more noticeable audible changes I ever made to my Khorns was going from cloth to leather furniture in my room. Not that its relevant to what you are looking at specifically John but overall its worth pondering the big scheme of things I think. Edited November 12, 2015 by vindeville Quote Link to comment Share on other sites More sharing options...
jwc Posted November 12, 2015 Share Posted November 12, 2015 JW. Tell us your favorite 2" or smaller compression driver you recommend for dedicated midrange only. Again, what JBL driver is the FR curve on. Quote Link to comment Share on other sites More sharing options...
Chris A Posted November 12, 2015 Share Posted November 12, 2015 (edited) The original figure that Al K. posted: https://community.klipsch.com/index.php?/topic/115305-the-bc-dcm50-can-it-replace-the-k55-driver/?p=1276701 ...and in the same thread, but earlier: https://community.klipsch.com/index.php?/topic/115305-the-bc-dcm50-can-it-replace-the-k55-driver/?p=1274647 The JBL 2426h is a 1-inch driver: http://www.music.mcgill.ca/caml/lib/exe/fetch.php?media=equipment:jbl2426.pdf The B&C DM50 driver cut sheet showing its raw FR (I suppose on-axis in a plane wave tube) and impedance. The dip that John is talking about is one of many shown. Edited November 12, 2015 by Chris A Quote Link to comment Share on other sites More sharing options...
Welborne Posted November 12, 2015 Share Posted November 12, 2015 Oh dear, when I am about to order a pair of DCM50 based on everything else I read good abput this driver, now I see this @@ Quote Link to comment Share on other sites More sharing options...
mark1101 Posted November 12, 2015 Share Posted November 12, 2015 I'll stick with my BMS. Quote Link to comment Share on other sites More sharing options...
Deang Posted November 12, 2015 Share Posted November 12, 2015 You get what you pay for - there's no free lunch. Quote Link to comment Share on other sites More sharing options...
Arkytype Posted November 12, 2015 Share Posted November 12, 2015 John, You wrote, “A member of this forum emailed this plot to me. It's a measured response of the B&C DCM50, a JBL and the K55M taken by a supplier that markets the B&C driver (the middle plot in the attached).” That “supplier” you knowingly failed to credit is Al Klappenberger who posted it on March 11, 2010. Now why on earth would you want to cite one of his measurements when you’ve recently said the following about (or to) him: October 19: In reply to one of his impassioned posts, you wrote, “No one cares.” October 21: “W Tee Eff, what can you do other than do what the ALK expects of you?” October 25: “Why should I waste my time with you (ALK) when you read (or comprehend) 1/2 of what's provided to you?” November 8: After dtel’s wife wrote, “one (ALK) has already been banned”, you wrote, “Mission accomplished.” I would call into question your double standard of behavior. On the one hand you damn Al and on the other you choose to use something he posted that might corroborate a point you are making. You wrote, “Given the enormous popularity of this driver, it suggests that this response, as Shakespeare would say, is much ado about nothing....” In reply, I’ll quote PWK who wrote in the February 1977 Dope From Hope, “The midrange is “where we live”; this is the frequency range where the ear is most sensitive to both tonal anomalies and to distortion.” (emphasis mine) The attached plot was made by me, not Al and shows an alternative to the DCM50+Selenium horn that you are offering. It’s a Faital HF200 mounted on Dave’s Eliptrac 400 horn. Now, what’s not to like about that on-axis response? Yeah, it’s a more expensive combination but worth saving the extra shekels for IMHO. You wrote, “A member of this forum emailed this plot to me.” If this is true, then you have admitted to violating Christy’s rule against posting emails and you should be given nine Warning Points. OK, Christy, did John cross the line here? Rules are rules. Here’s what she wrote on November 7th, “Posting by "proxy" is not allowed on this forum. I'm hoping members are not engaging in this type of activity. Posting of messages between parties, private emails etc. are also not allowed. There will be no more verbal/written warnings in this thread. Next step is nine warning points or being banned.” (emphasis mine) Lee Quote Link to comment Share on other sites More sharing options...
Deang Posted November 12, 2015 Share Posted November 12, 2015 Good grief. Blah, blah, blah. 1 Quote Link to comment Share on other sites More sharing options...
Chris A Posted November 12, 2015 Share Posted November 12, 2015 (edited) Lee, I believe that you're assuming that it was Al K. that emailed the plot to John. Since I've used that same plot in one of my own threads on tri-amping a Belle from almost 5 years ago, that may not be a valid assumption. Chris Edited November 12, 2015 by Chris A Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted November 12, 2015 Share Posted November 12, 2015 Good grief. Blah, blah, blah. +1 miketn Quote Link to comment Share on other sites More sharing options...
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