Above TOP is the newest prototype of the Kennedy Alpha-II venue / custom 15 (soon also 18/21) inch woofer with 4 or 5-6 inch travel, the rare high amperage full range speaker in existence. Most zero to 100 hertz amplifiers, especially solid state, prefer voltage drive over current driven transistors because of the extra circuitry needed to buffer the voice coil reversal process and avoid transistor leakage and burnups. Another important reason is the heat dissipation or efficiency. Only class 'D' offers great watts per British Thermal Unit operation cost advantages. As a designer of Bi-Polar Transistor type (class H) bass instrument and playback woofer amplification, Mr. Kennedy has experience and knowledge beyond the obvious design improvements you see in photos of such transducer parts. These are pre-order or large volume unless you are able to pay an extra price. Thiel Small parameters just tested on 15 inch model are: Fs = 16.15 hertz free air resonance measured in JBL cabaret enclosure, ported. Qts (total Q) = 4.2 this is 4 to 8 times any other speaker in this size. Qes (electrical Q) = 5.15 called the ratio of stored energy to electrically used energy. Qms (mechanical Q or suspension) = 14.18 Most speakers average 5 with 10 the usual highest possible. The wattage is continuous with extra ventilation for 2 to 3 thousand watt rated amplifiers of all classes. This all means we have made a speaker with more punch, for bass drum and subsonics, but does not require class-D with expensive filtering for Class-D to get clarity if bass effects are used or smooth warm bass is wanted. It is also showing that it is more full range capable and also more sensitive (electrical Quality Q) R5.67 and LE 0.99H This spec on the 15 inch model is nowhere near the heavy duty large Alpha II not yet prototyped except for voice coils. This is just the junior version for large venue sound and stage where you need a few great speakers with high capability rather than many specialized designs.
Call me ONLY on this subject to discus orders at 920 area code and last for digits are zero and then same as area code. 850 prefix - John
Our web site is DIFFERENT from others. Almost anyone should consider buying a speaker or recone parts for vintage JBL speakers from our site. The older Ferrimagnet materials used by JBL are superior to today's speakers. Even with Neodymium, which has 30% more magnetic mass susceptability, but is often supplied in smaller mass sizes. Often buyers think a ferromagnet is the same thing as a ferrimagnet ceramic magnet. However, the magnetic eddy current that forms to prevent magnetic flux lines is much less in ferrimagnetic materials. Even ferromagnetic matericals are superior when they become hot, as they increase their magnetic property to convey the forces. This also means that they store very well over the years, immune from cold, more importantly, heat degradation.
When you compare costs, the vintage type speakers that we supply parts and customized components for are a much better value than current production for consumer electronic applications or extended play. Another example is the change from even (2nd) harmonic rich triode power tube amplifiers of the 1920's to beam tetrodes. A power triode such as a 6B5 amplifier works fundamentally opposite that of amplifiers produced after sound production capability was first offered to the general consumer public. Instead of turning power on from grid input signals, the newer thinking was to shut off power to the collector plate as the primary mode of operation. Changes or 'mods' that put a small capacitor back into tetrodes became very unpopular for good reasons. You just can not have flat response in guitar tone and use a small capacitor on a power tube to reverse the effect of a low music factor, low punch flat tone. Feedback for stringed amplified instruments that sit near the instrument and can cause standing wave loops and out of control microphonics was, at that time, impossible to compress, equalize out and limit or brickwall. Hearing damage as well as equipment failures, audience rejection and sound reinforcement with speaker reconing they considered as unknowable or too expensive. Another example is the anti-intuitive change of the long wanted and awaited bridge pickup of a Stratocaster to a Humbucker high output type in bridge position (treble). All the above changes introduce negative feedback as a method to achieve the lower overtone flat acoustically 'correct' sound stage profile. And then, as if not yet damped enough, hi-fi system tube amplifiers added ultralinear taps to the output transformer to further enhance both the sharp cutoff and remove any possible cathode follower dual preamp tubed differential signal modification possabilitys.
The plate size and plate material are also undergoing downgrading. When you compare power tubes, remember that the higher radiation capability of both larger plate sizes as well as Molybdenum coatings are no longer being produced or sold as a feature of the power tube itself. This is related to
the change to push pull pentodes and less Class-A full on full time systems as well as the cost advantage in smaller, yet on paper they look to the untrained eye to be just as capable a configuration of power tubes in amplification systems when you include speaker sensitivity, power/headroom capacity and, of course, thermal durability and duration service interval times. For one thing, lower impdeance speakers for the same output transformer increases the speaker sensitivity, assuming an 8 ohm tap is used on a 4 ohm speaker for instance. Heat compression is a major consideration in speaker designs. Mostly, constraints were imposed to allow more customers to buy at a $500 price point for a completed retail sale system. And that is what we are; really the most valued source on the internet for tone, punch, and tube sound. We are pushing away the old engineering values that say products should just barely meet the high demand needs. In the new Order Of Audio, there are few remaining such Theatines but God's little disgusted techno-devils. We also think that being able to offer such value at what historically would be very low investment levels is a feather in our dust caps.
The original design thinkers, now long lost both in documentation and like mindedness, did have an ingenious method of letting A/V users restructure the control system. On most vintage equipment, several taps on output transformers were used to allow lower or higher ratios of coil resistance to speaker resistance. A good starting place, if you have such options, is to determine if you want more treble peaks, or the effect of overlaid treble resonances either from wood instrument resonance or distortion pedals, power tube control couplings or interstage line matching devices. This applies to bass tones or higher midrange and above. If this 'presence' as it was called is desired, then for the same speaker impedance use a lower resistance output, which increases the impedance match ratio across the entire spectrum. The only disadvantage was that you then effect the entire spectrum, but equalization tone controls or bi-amping and other options can be added. In today's market, solid state interfaces use about a 20:1 match in just such a way to counterbalance the effects of higher solid state feedback controls that are internal and unchangeable by the users. In vintage design, a ratio of 4 or 5 to 1 was considered maximum allowable for power transfer reasons as well as transformer ringing effects. JBL used this to advantage by offering many speakers in 16 ohm versions, especially their higher frequency specialized voice coils. However, still today, a 16 ohm bass dual bass guitar speaker with flux concentration extended pole pieces or the shorting rings are still the single greatest example of why everyone has become an audio designer these days, for lack of better support and so much ongoing development in electronics. To take full advantage of our services and past experiences with what national bands have bought and liked, this is a recommended way to justify a buying decision. You don't have to be a national act to be doing this, but it just may help you to get your sound up to that level first and publish your work after that. Publishing is somewhat different than sound origination, mostly because both digital and analog signals use a topology of high impedance inputs and low impedance output - called bridging. The point there is to make all current constant, essentially almost steady state current with the signal carried on voltages only, helping to control phase artifacts from capacitors and inductors or digital byte sampling/recombinatory methods. The +4Dbu standard is 8 times more watts and uses a copy of the signal on each of two input wires as well. Such balanced use 2 milliwatts versus 1/4 to 1/3 milliwatt -10dbv unbalanced used in instruments and tube or mic inputs. Our advice is not to avoid it, but to understand why sounds from different designs are useful. We have a recording studio or DJ for 250+ person events. Some trial and error should be expected.
One service we are test marketing is the retrofitting of phase inverter tube FIRST stage tubes with a remote low pass filter instead of the much argued Miller capacitance versus Gain times Plate to Grid capacitance calculation. If you send us your preamplifier or guitar amp, we would refit it with a grid filter. It consists of a series resistor and capacitor. You get your old resistor (there is no cap in standard 12AU7 phase inverter grid nodes) back in case you don't like the sound. You pay shipping both ways and $35. Why do this? Because contrary to what you may have been told, tube amplification is much LESS linear than solid state is. Also because when the input impedance for a preamplifier's prior device is unknown, the designer is forced to allow 50 to 200 thousand hertz on the grid because the prior device may be high impedance as well, or bridging type interfaced. This is, perhaps, why 12Ax7 with more voltage gain and less transconductance tends to get too bright and loud when biased on the cathodes upwards and too dull and sibilant when voltage applied to cathode is too low. We also reduce blocking distortion. This happens because of 1) Overdrive 2) AC on the filaments 3) Too much ultrasonics because previous device is a too high impedance type. If you know the 1K hertz impedance of you pickup coil or pedal or previous device, let us know that.