Originally Posted by Rick Craig
Actually one of the AE woofers is coming to me but I don't know when it will arrive. I've worked with John in the past and think he means well but the delivery problems have discouraged me from incorporating the woofers into my designs.
I never trust any Salk claims for bass extension because there are no nearfield or ground plane measurements to back them up. Having used some of the same drivers I can tell when the numbers look "optimistic".
Hello Rick. I have never posted here before, but you know me well by now. This thread was brought to my attention, and since I designed the bass alignments for the larger Salk speakers I thought I would comment and clarify.
A little history - when Jim and Dennis Murphy were first working on the HT3 Jim contacted me for woofer suggestions. They had originally looked at common commercial drivers and were leaning toward a Peerless driver. I suggested a custom woofer from TC Sounds. I already had a contact there, and connected Jim with them. Together we designed a 10" driver that met all of our requirements. We didn't need high sensitivity since it was being mated with the Seas Excel woofers, so we focused our parameter choices to trade off sensitivity for bass extension. When we were finished we had a 10" TC driver that was custom designed for Jim's application, and was not like hardly any other driver available on the market. This driver wasn't available to anyone else either, but anyone could have had Thilo make something like it if they bought in large runs like Jim did. This was the key. You can not buy drivers like these as one-off drivers.
This went well for a while but when TC Sounds ran into financial trouble and ultimately closed their doors, John at Acoustic Elegance agreed to duplicate the woofer for Salksound. Using identical motor parts in its construction, John made a woofer that matched our parameters and were confirmed with measurements. Incidentally, John's measurements and mine matched almost exactly. I can not say the same for most off the shelf drivers out there, even ones from SEAS and Scanspeak. These often measure quite a bit higher in Fs and Qes then advertised, but I digress.....
Between Dennis Murphy and myself response measurements have been taken on all of the Salk line of speakers, up to and including close-mic'ed nearfield measurements. These confirm that Thiele and Small were correct in their ability to predict the low end response. Seriously now, that's why we all use box modeling software - because it is well defined and accepted mathematics, and has proven itself time and time again. And having written a box model program of my own based on Theile, Small, and J.E. Benson's work I understand the math quite well. We do not post these as "proof", because we don't feel every measurement of a speaker needs to be posted and used as marketing gimmicks. Further, there is nothing to keep any company from posting anything they want, and none of that really proves anything. Jim's speakers are sold on the basis of how they sound and from the satisfaction of owners sharing their glee with others. But, suffice it to say, Jim is quite conservative in his claims. He is adamant that nothing be exaggerated in any claims on his speakers and Dennis, Paul Kittinger, and I back up all of our claims to him with proof beforehand. For example, with my Pharos design, even though we are using a 12" JBL woofer we state that is begins to roll-off at 44Hz and is -3dB at 40Hz. We are not exaggerating anything.
Moving on - the transmission line speakers were all designed for low end extension by Paul Kittinger using Martin King's Math Cad sheets. These are widely accepted as the most accurate transmission line modeling program extant, and our measurements of them confirm Martin's predicted extension as well.
Now, finally, to the new as-yet-to-be-name speaker, currently called the HT4. We are claiming a bass extension of 18Hz. I apologize if this ruffles feathers, but I stand by this claim, and put my reputation on it (whatever that may be worth). Jim called me and asked if it were possible to achieve this cut-off in a reasonably sized three-way speaker. I told him I would see what I could do. At this time a SEAS L26ROY driver sent for us to test. However, it just did not deliver the bass extension, or possessed the excursion we were looking for. Based on that, I decided that we needed to go in another direction. Given the fact that John J. at Acoustic Elegance could, once again, make us the woofer we needed based on our parameter selection, we arrived at a custom 12" driver for the job.
This speaker is not tiny; the bass bin is approximately 3 cubic feet+. It uses two 12" passive radiators each mass loaded with over one kilogram of weight and the Fb of the enclosure is tuned to 20.7Hz, as measured. Passive radiators were chosen because it allowed for us to use the equivalent of a vented alignment without having to deal with excessive port noise and restrictions. The 30mm Xmax capability of the two radiators can easily handle this job when combined with the high excursion woofer we are using. The predicted F3 for the speaker based on J.E. Benson's passive radiator model is 18Hz. Based on close-mic'ed measurements of the cone and the PR's in a complex summation we can confirm this cut-off. You are welcome to visit Dennis Murphy and listen for yourself if you like, he has one in his home. How's that for a friendly invite?
And finally, finally, John at Acoustic Elegance, in my opinion produces some of the finest drivers available in the world. His Lambda TD12H is the best 12" true woofer I have ever measured or worked with. The low distortion motors with the copper shorting sleeves are the real deal, and these measure with a very low Le for such large, high excursion drivers. His ability to customize drivers for us, if bought in quantity runs, adds to the advantage of using Acoustic Elegance. John has been excellent to work with, and his products are truly top notch.
Now, I do not believe anyone associated with Acoustic Elegance or Salksound has said anything negative or disparaging about Selah Audio or any of your designs, nor do we intend to. I am sure your designs are excellent as well. With that in mind, when you make a statement like you did about not believing Salk's claims you called into question the integrity of Jim Salk, Dennis Murphy, Paul Kittinger, John Janowitz, Martin King, and Jeff Bagby. So I decided to speak up and ask you to reconsider making such off-the-cuff comments. As a professional speaking about another professional's products you really should know better about being professional. Agreed?
Many blessings to you in 2010 with Selah,