Originally Posted by Aaron Clinton
The fundamental issue here is that this topic, and a couple others, are home audio people who are working on a home audio install that are focusing on or showing interest in drivers that are car audio optimized. Drivers that on average, have higher Fs, lower Qts, have to address cabin gain, lower sensitivity and greater displacement then drivers optimized for home audio. Then those car audio sub woofers are getting torn down because they don't exactly fit the home audio market's needs. In car audio, we have to be very aware of how people treat our products once installed, so there has to be a good bit of DAF in each driver design, where as that is not as really an issue in home audio.
I'm well aware of the fact that audio industry folk seem to have this penchant for segregating themselves into little groups. But, I really am just shaking my head at the "optimized for car" thing in a GB thread.
For the majority here, I know you know this, but please bear with me as I state the obvious. Fs, 1W/1M and Qts specs are largely irrelevant in this app. We've been through this process as a community quite thoroughly. It's on-going, as any real process toward a goal should be, but it's certainly beyond being told the driver we want to GB isn't suited to the application.
Let's look at a currently available trio of different 18" drivers, each with different combinations of these "suited for" parameters in a 120L box. The parameter differences are explained on the graph. Please note that the driver with the highest 1W/1M spec has the lowest sensitivity at 20 Hz. Conversely, the driver with the lowest 1W/1M spec has the highest sensitivity at 20 Hz.
There are different philosophies in play. Josh (and others) prefer to control box size with a lossy Qts. I prefer to control excursion with box size while taking advantage of the higher Qts drivers free lunch at resonance. Pro sounders prefer higher 1W/1M because they need extreme SPL and don't care about much below 40 Hz.
All 3 of them have been used in multi-driver systems for HT by happy end users.
I posted this before but it seems to have been overlooked. This is the SSD-15, naked, naked with a notch filter to lessen the Le roll off and finally with one specific L/T curve shaping the input signal. (these are actual measurements)
What's the final Q? Anything I want it to be. What's the final F3? Anything I want it to be. It doesn't matter what the 1W/1M, Qts or Fs of the driver is when the application is a multi-driver sealed L/T sub.
Yes, you can debate, and we have debated nuances, preferences and tradeoffs of the various combinations of parameters in this and every other alignment. In my case, I've just built the damned things, experimented with many signal shapes and amplifiers, measured the results in-room and listened to the results with the most demanding source material on earth. I get state of the art results. Others interested in duplicating my results without having to buy the LMS Ultra or wait forever for the latest "umunna" driver have pinged me and here we are.
For this app, all that's needed is a quality overhung 15" or 18" with 20-30 mm X-max from a supplier we think will still be in business next week. Josh, and others, prefer a higher crossover, so we'd like to know what the he!! the FR is with the shorting ring. "a little bit higher" is not a proper answer.
I'm struggling at this point to understand how a simple Fi GB thread turns into someone telling me what will happen if I use the driver I prefer in my HT, especially after I already have done it and posted the results above. I've also elsewhere posted the FR at the LP and speclab caps of movie scenes mic'd at the LP. I'm not showing interest, I'm showing the results.
BTW, If DAF means what I think it means, wow... just wow.
This thread is entitled "Ficar SSD-18 Group Buy Thread". Since the SSD doesn't have the heat ring option available, the Fi Q was quickly mentioned as well. Many people have also asked me about 15", so the dust quickly settled around the SSD and Q with heat ring option, in 15" and 18" sizes. I think off-the-shelf at a discount for quantity is what was proposed originally and I don't see a need to alter the driver in some insignificant way. Since I'm interested in 4-Q-15 with heat ring, I'd like to see the thread get back on track. Otherwise, someone throw in the towel and LMK so I can get on with my purchase and build.
If someone wants the Xcon or wishes to explore a commission of some custom driver instead, they should start a separate thread.