Guest David H Posted November 14, 2015 Share Posted November 14, 2015 Furthermore the B&C DCM-50 is an exceptional value. Yea but WHEN will I be able to buy a pair? Send ALK an email, he may be able to get some. Dave Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 14, 2015 Author Share Posted November 14, 2015 (edited) John have you done a cumulative spectral decay measurement of the driver and driver/horn? miketn First three plots are FFTs, no nets (BMS and B&C on the Selenium horn and a plot of both the BMS and Klipsch PD5VH on the K401). Also, a customer has asked me to mod the insert filter for his BMS drivers. He sent me a pair of 8 Ohm units and I've included them here. The BMS measures well but they all do a good job. The advantage of the BMS and the B&C is that they have 2" diameter throats. Edited November 14, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 14, 2015 Author Share Posted November 14, 2015 (edited) Next are Wavelets, insert is ideal Wavelet calculated from ideal impulse response. BMS has best response (far right). Edited November 14, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 14, 2015 Author Share Posted November 14, 2015 CSD plots Quote Link to comment Share on other sites More sharing options...
jorjen Posted November 14, 2015 Share Posted November 14, 2015 Furthermore the B&C DCM-50 is an exceptional value. Yea but WHEN will I be able to buy a pair? I believe USSPEAKER has them in stock for about 7 bills a pair. Quote Link to comment Share on other sites More sharing options...
Welborne Posted November 14, 2015 Share Posted November 14, 2015 The k55v / Atlas Pd-5vh measured very respectably Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 14, 2015 Author Share Posted November 14, 2015 (edited) Plot on right shows how the net alters the output of the B&C-Selenium horn assy. Plot on left is with the tweeter unit operating, the green response is the system response. Edited November 14, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 14, 2015 Author Share Posted November 14, 2015 (edited) Here's how the net alters the CSD of the B&C-Selenium horn assy. First plot is the horn assy without a network whilst the second is the assy on the net. Edited November 14, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 15, 2015 Author Share Posted November 15, 2015 (edited) This is a Be-diaphragm installed in the Radian 950 driver. Note the screwdrivers are Be-Cu (non-magnetic). If you have any intentions of replacing diaphragms on these high magnetic strength compression driver motors, I recommend you purchase non-magnetic tools. The magnetic fields on these drivers are very, very strong and will pull the screwdriver tips directly into the diaphragm. The first CSD plot is the driver without the network. The second CSD plot is with the net. Compare to the above. Edited November 15, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
Deang Posted November 15, 2015 Share Posted November 15, 2015 Nice work! Quote Link to comment Share on other sites More sharing options...
Welborne Posted November 15, 2015 Share Posted November 15, 2015 John: When you said above:"....The BMS measures well but they all do a good job. The advantage of the BMS and the B&C is that they have 2" diameter throats." What is the advantage of having a 2" throat (versus supposedly one of 1")? Quote Link to comment Share on other sites More sharing options...
Mancave Man Posted November 15, 2015 Share Posted November 15, 2015 Furthermore the B&C DCM-50 is an exceptional value. Yea but WHEN will I be able to buy a pair? I believe USSPEAKER has them in stock for about 7 bills a pair. Parts Express also has them at the same price with free shipping and free life-time tech support. Quote Link to comment Share on other sites More sharing options...
DrWho Posted November 16, 2015 Share Posted November 16, 2015 John: When you said above:"....The BMS measures well but they all do a good job. The advantage of the BMS and the B&C is that they have 2" diameter throats." What is the advantage of having a 2" throat (versus supposedly one of 1")? The advantage is lower distortion. The larger diaphragm doesn't need to move as much. Also, the horn throat distorts less - think of it like the air doesn't need to rush back and forth as fast. For the same volumetric displacement, the air velocity is less. Disadvantages typically include less performance at high frequencies due to heavier diaphragm (mass corner) and bell modes (the diaphragm bending resonances start at lower frequencies). Depending on the driver/horn design, you typically see beaming at ~6.8kHz with 2" throat versus 13kHz for a 1" throat. For a mid-range application, the 2" drivers tend to dominate....especially in PA applications. The tradeoffs typically end up outside the frequency range of the application. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted November 16, 2015 Share Posted November 16, 2015 (edited) I don't believe anyone has shown plots of frequency and phase of system output for any passive solution. Frankly, an FR measurement without an associated phase plot is incomplete. The fact is, nobody's passive solution is capable of correcting phase in a loudspeaker that is as far out of mechanical driver alignment as the Khorn. EQing to a flat FR without consideration of phase response can make the system sound worse. One simply cannot correct time domain issues in the frequency domain. Chris posted a plot of an active system with corrections applied showing both frequency and phase response. That sort of output is what you're looking for, and will likely be judged by most listeners to sound better than an unaligned system. However, this takes more amplification, a processor, and a lengthy alignment procedure - adjust, measure, and listen, over and over until you get it right. The passive solution is better for most folks because of cost and simplicity. John has produced an engineered package that replaced the stock Khorn tops that looks pretty good. It's another option for those seeking a passive upgrade. Edited November 16, 2015 by Don Richard Quote Link to comment Share on other sites More sharing options...
Welborne Posted November 16, 2015 Share Posted November 16, 2015 John: When you said above:"....The BMS measures well but they all do a good job. The advantage of the BMS and the B&C is that they have 2" diameter throats." What is the advantage of having a 2" throat (versus supposedly one of 1")? The advantage is lower distortion. The larger diaphragm doesn't need to move as much. Also, the horn throat distorts less - think of it like the air doesn't need to rush back and forth as fast. For the same volumetric displacement, the air velocity is less. Disadvantages typically include less performance at high frequencies due to heavier diaphragm (mass corner) and bell modes (the diaphragm bending resonances start at lower frequencies). Depending on the driver/horn design, you typically see beaming at ~6.8kHz with 2" throat versus 13kHz for a 1" throat. For a mid-range application, the 2" drivers tend to dominate....especially in PA applications. The tradeoffs typically end up outside the frequency range of the application. Thanks for explaining. So it's the similar argument that applies to cone speaker drivers. Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted November 16, 2015 Share Posted November 16, 2015 John..... Thanks for the time and effort to measure and post your findings. Many members that have never performed test like these have no idea how involved and time consuming the testing and posting can be. Very Interesting comparison data. Looks like the BMS would be a step up over the B&C and the Radian/Truextant Be an order of magnitude step versus the BMS or B&C. I'm especially impressed with the Radian/Truextent Be performance and would love to listen to it versus the TAD TD4002. I consider the TAD TD4002 as one of the best advancements to my system that I have made. For those interested here is a pdf of the Radian with stock Aluminum diaphragm versus the Truextent Be diaphragm. miketn TTB001_BeX_Vs_Radian.pdf 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted November 16, 2015 Share Posted November 16, 2015 Furthermore the B&C DCM-50 is an exceptional value. Yea but WHEN will I be able to buy a pair? I believe USSPEAKER has them in stock for about 7 bills a pair. Parts Express also has them at the same price with free shipping and free life-time tech support. Yea except they don't REALLY have them. And its OK cuz I'm in no rush, B and C will get their production back up I presume. Quote Link to comment Share on other sites More sharing options...
Mancave Man Posted November 17, 2015 Share Posted November 17, 2015 Furthermore the B&C DCM-50 is an exceptional value. Yea but WHEN will I be able to buy a pair? I believe USSPEAKER has them in stock for about 7 bills a pair. Parts Express also has them at the same price with free shipping and free life-time tech support. Yea except they don't REALLY have them. And its OK cuz I'm in no rush, B and C will get their production back up I presume. I got mine from ALK earlier this year. He is an authorized dealer. Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 19, 2015 Author Share Posted November 19, 2015 (edited) John: When you said above:"....The BMS measures well but they all do a good job. The advantage of the BMS and the B&C is that they have 2" diameter throats." What is the advantage of having a 2" throat (versus supposedly one of 1")? Air, at high pressure, begins to behave badly when one's trying to propagate waveforms thru it. In a nutshell, a larger throat will have lower air pressures than a smaller throat at the same acoustic output and from waveform distortion perspective that's a good thing. The disease we're trying to avoid is called "waveform steepening" and there's ton's of literature on it (attached). The Klipschorn mid is 0.7" diameter. Edited November 19, 2015 by John Warren Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted November 26, 2015 Share Posted November 26, 2015 (edited) I don't believe anyone has shown plots of frequency and phase of system output for any passive solution. Frankly, an FR measurement without an associated phase plot is incomplete. The fact is, nobody's passive solution is capable of correcting phase in a loudspeaker that is as far out of mechanical driver alignment as the Khorn. EQing to a flat FR without consideration of phase response can make the system sound worse. One simply cannot correct time domain issues in the frequency domain. Chris posted a plot of an active system with corrections applied showing both frequency and phase response. That sort of output is what you're looking for, and will likely be judged by most listeners to sound better than an unaligned system. However, this takes more amplification, a processor, and a lengthy alignment procedure - adjust, measure, and listen, over and over until you get it right. The passive solution is better for most folks because of cost and simplicity. John has produced an engineered package that replaced the stock Khorn tops that looks pretty good. It's another option for those seeking a passive upgrade. Finally, someone gets why I miniaturized my system with Danley SH-50's. Edited November 26, 2015 by ClaudeJ1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.