Originally Posted by shadyJ
Lol, that was with a 10 kW amplifier. Most people are going to give it 500 to 1500 watts. I would be interested in seeing what it can do with a more realistic amplifier.
Actually it's a 12Kw amplifier.
Originally Posted by N8DOGG
This is a pic of the cap driver It's made for JTR only by Eminence.
The driver is produced to JTR specs by the Fi build house, as are most heavy duty subs that are made in the US. Ascendant, Fi, SSA, PowerSound uses some, JTR uses some, SMD, etc...
Couple of things that you guys should be looking at when comparing tests other than the burst numbers alone. Forget the winisd simulations for direct comparisons of systems at the limit. They are nothing more than ballpark estimates at best. The UXL driver is a better driver and much more capable than the SI but it should be it weighs twice as much and is more than twice as expensive. It is about 3dB more sensitive, has less compression, greater maximum output, greater power handling, is more rugged and has lower distortion at the same output levels. This is not a dig at the SI driver which is truly impressive for the price point that they have hit.
If you dig a little deeper into the measurements you will see that while the CEA-2010 results for DIY subs are impressive the output numbers above roughly 40Hz should NOT be used as a basis for judging what they are capable of producing in your, or any other real world install. Firstly, no one except car audio SPL competitors are going to run 12kw of amp to one driver. You cannot apply an amplifier to the driver powerful enough to produce the outputs shown at 50Hz-125Hz in the CEA-2010 burst tests and have a dummy proof or “safe” system without truly advanced limiting and compressor circuit design. You know… The exact things that most DIY guys list as negatives about the ID or commercial subs. The test amplifier has enough power to melt the coils with a few seconds of constant signal and also to blow the driver apart or beat it to death in the deep bass. One gratuitous crank of the volume control with the wrong signal is all it takes. While the SI 18 may take the full burst output of the test amplifier for 1/10th of a second at 63Hz at 31.5Hz it runs out of mechanical clearance with only 95 volts applied. If you apply the full burst capability of the amp at 31.5Hz or below I will let you guess what happens. Since the voltages applied are now being listed for passive systems for both the long term output compression sweeps and the CEA-2010 bursts these should be used to get an educated estimate of what sort of power makes sense to safely and adequately power a particular system. You want to look at these 2 measurement sets and look at the power applied over the full bandwidth of 10-125Hz in order to determine what is likely to be an appropriate “safe” power level to extract maximum performance but avoid damaging the driver through one careless mistake as can happen with too much power on tap.
For example the SI driver in a 4 cubic foot sealed enclosure was able to survive a 118 volt sine sweep from 2-125Hz. However it was compressing by 3dB at this point and was distorting greatly and was clearly distressed. Clearly this is right at the limit. The CEA-2010 burst results in the deep bass, which is what you want to look at where the system is excursion limited, show that at 31.5Hz the system only handled a 95 volt input before running out of excursion. The distortion recording here is not high because it is near the system Fb, but I clearly remember that further increases in output caused the driver to emit a sharp mechanical “CLACK” sound. Now you may wonder how the system exhibited this at only 95 volts in the CEA-2010 test but survived 118 volts input during the sweeps? That is because the nature of the long term sweeps greatly heats the coil and motor of the driver causing impedance to rise, current through the driver to drop and thus actual applied power to drop also and sensitivity to decrease. The CEA-2010 tests apply power for a small fraction of a second so the driver is essentially cold and not experiencing anything like the heat build up encountered during the long term sweeps. Thus the impedance is lower, there is less compression and it is seeing greater current and power from the amplifier at the same voltage levels. Based on this information and assuming a similar sized sealed enclosure is used full bandwidth below 125Hz, I would put the SI 18’s practical rating at about 90-95 volts of amplifier maximum to avoid potential over excursion damage. This is still well past SI's 600w rating and about 1400w into the measured impedance minimum above 10Hz. What that means is that power level will keep the driver from damaging itself mechanically but you could still potentially cook the coil if you tried though I doubt many would have problems.
Comparing the SI to the UXL-18 and again this is a bit of a lop sided comparison due to the price differences, but comparing the maximum CEA-2010 burst output in the low bass where the limitations arise first the UXL-18 shows a 3.5dB average advantage from 10-50Hz. 3.5dB may not sound like much but I consider this quite substantial on a driver versus driver basis. You simply don’t have huge 6dB advantages between similar size bass drivers in most cases as it requires twice the linear displacement and power handling. When you are fighting against HIL at the ends of the spectrum every 1dB advantage in output potential becomes more and more difficult to achieve. Also compare the sensitivities of the two and the UXL shows a marked 2dB advantage in sensitivity with a 2 volt input. Again that may not sound like much but it is. Compare the maximum output levels recorded during the long term sweeps and you will see a similar trend to the CEA-2010 outputs with the UXL having 2-3dB greater broad band output potential while being driven with 93.1 volts versus 118 volts for the SI driver. The compression charts also show that the UXL was reaching just about 2dB in compression at the extremes of the 10-125Hz frequency range while the SI was compressing more heavily reaching 3dB over a broader bandwidth. Now consider that this extra compression was occurring at output levels about 2dB lower than the UXL. Yet another consideration is this…The UXL shows greater sensitivity and comparing the impedance curve of the two drivers in the same enclosure indicates that they are very close in shape and magnitude. Both are nominally 4 ohm systems. However the UXL exhibits a broader and larger impedance peak indicating a more powerful motor and higher efficiency in this area. The impedance minimum of the UXL is about 5.25 ohms as measured in the test enclosure while the SI is about 5.3 ohms at 10Hz but is 6.3 ohms or higher everywhere above 12Hz. Doing the calculations 118 volts into the SI systems 6.3 ohm impedance minimum would result in about 2200 watts from the amplifier. While the 93.1 volts applied to the UXL’s minimum impedance of 5.3 ohms results in a power of about 1650w. (Due to heating effects and the impedance shape, the actual applied power to either is quite a bit less.) The moral of the story is that the UXL is producing MORE output during its maximum sweep level with LESS power than applied to the SI.
The UXL does not require a more powerful amp than the SI necessarily since it is much more efficient.
Again I’m not ragging the SI driver here…Quite the opposite. It offers huge bang for the buck beyond what we could have reasonably expected from a $220 18”. I’m just trying to illustrate that there is quite a bit more to larger more expensive drivers like the UXL or LMS than a 3dB difference in some CEA-2010 burst numbers or the land of winisd simulation where everything has perfect behavior up to and past the limits.
Food for thought.Edited by Ricci - 8/7/13 at 9:59am