Compression Drivers - Why so heavy?
I am rather new at this horn thing. Today the compression driver I bought - a JBL 2445J - arrived. I have never seen one of these before. It's supposed to weigh 32lbs. but, my God, if feels as if it weighs 100! Why does it need to be heavier than a typical 18" woofer? There are lots of tweeters that can do the job that weigh so much less; why does a compresssion driver need to be so heavy? In other words, why does it need such a massive magnet? And how should this be supported? I certainly am not going to let it just hang there supported only by the bolts holding the horn.
Finally, how do you test a compression driver? Just attach an amplifier and let 'er rip? I asked in another post how hard was it to recone a woofer; how hard is it to replace a diaphram? It looks ok but there seems to be a few things around it that probably ought not to be there.
Bill Beer Hammonds and Leslies ( attention AUDITION )
Hi Audition.
I am a Hammond / Leslie enthusiast from Melbourne , Australia.
I have learned how to work on and modify Hammonds through the work that I have done on my 1962 C3 organ such as replacing the aged wax capacitors of the Tone Wheel Generator ( TG ) with new correct micro farad spec capacitors , recalibrating the whole TG to produce a louder and warmer sounding TG output curve and repairs and modifications to the AO28 preamp. I play my Hammond organ through a Leslie 122 that I have done some modifications to , including adding a JBL 2482 treble horn driver and I may put in a JBL-E140 8 ohms bass speaker.
I am currently repairing the gooey black foam related damage done to the manual resistance wires of my newly purchased 1965 C3.
I am quite interested in learning about the modifications that Bill Beer did to Hammonds and Leslies in order to get his customized fat sound.
Information about the Bill Beer organs and Leslies seems very hard to find and some stock Hammond/ aLeslie purists dont like the Bill Beer sound , but from examples that I have heard , I quite like the fat sound of the Bill Beer organs and the Bill Beer Leslies.
I have read that Bill Beer used to recalibrate the TG to produce a fatter sound than the Hammond factory stock TG calibration .
Do you know anything about the output levels specs of the Bill Beer TG recalibration ?
Where there particular areas of the TG frequency ranges that Bill Beer boosted or attenuated in order to get his particular sound ?
Bill Beer was quoted as having measured the TG output levels of six ''hot bitchin'' B3 organs and that he then used these as the basis of his TG recalibration specs and he said that he could recalibrate the TG to make it sound ''fat and ballsy''.
I know that the Hammond factory used to calibrate the TG's to have stronger outputs in the bass and the lower midrange region until 1956 when the factory TG output curve was changed to have slightly lessened bass and lower midrange levels and that this new TG output curve remained until the end of Hammond TG organ production in 1975.
Do you know anything about thes six ''hot bitchin'' B3's that Bill Beer used as the basis of his TG output curves , and what production years these B3's were from ?
As well as recalibrating the TG and replacing the aged wax capacitors of the TG notes 49 to 91 of the pre 1964 organs , do you know if Bill Beer also modified the TG note filters to produce a more pure sine wave quality and less background rumble or hum ?
Do you know anything about how the frequency response of the solid state Bill Beer organ preamps differed from that of a stock AO28 preamp ?
I have been told that the Bill Beer biamped solid state high power Leslie amplifiers had a three position tonality switch , and that this switch selected:
1) the straight flat response
2 ) boosted bass ( for organ)
3 ) boosted bass and treble ( for guitar ).
Do you know what the frequency range and the decibel level of the bass boost for organ was and what the frequency range for the boosted bass and treble for the guitar was ?
Although Bill Beer used the JBL E-140 or the K-140 bass speaker and the JBL 2482 treble driver , do you know if there are better JBL or other brand bass speakers that are more efficient and that produce a deeper bass response than the JBL E-140 or the JBL K-140 bass speakers ?
I have searched the JBL website for a frequency response curve chart but all that I could find was a brochure that described the E-140 series and the K-140 series speakers together with some other speakers , but there were no frequency response curve charts on that brochure.
Do you have a frequency response curve chart for the JBL E-10 or the K-140 speakers ?
I have been told that Gregg Rollie from the early Santana years used a Bill Beer modified organ or a Bill Beer Leslie on the early Santana albums but no one has yet verified this .
I know that Tom Coster and other subsequent Santana organists used a Bill Beer organ.
Apparently Dick Sims used a Bill Beer organ and Leslie on Eric Clapton's early 70' albums.
I have been told that Steve Walsh used a Bill Beer organ and Bill Beer Leslie on the 1976 album "Leftoverture". Do you know if this is correct ?
Are you able to say who the other big name organists / bands that used Bill Beer organs and Bill Beer Leslies were ?
Dop you know what year the modified Bill Beer organs and Leslies first started appearing ?
I am a big fan of the mid - late 60's / 70's era Rock music.
I am quite interested in finding out what I can about these things and Bill Beer's legacy in improving the tonality of the Hammonds and Leslies.
Thank you very much in advance for a reply and for your patience with my many questions.
All the best.
Kon
