Ok, so I've had a chance to look over
's data and graphs. When I started using VS, the goals were twofold. First, to use to test all the various aspect of a subwoofer system and all the elements that sum to make up the tactile response. The room, the driver, the cab, the seating, the floor/riser construction, the placement and proximity and all the other aspects. While there are many variables, the biggest one being the actual model of accelerometer being used, with detailed testing and documentation of each test run, we can use the data to better understand and correct our playback systems to represent the source. Up until now, subwoofer systems and accompanying rooms descriptions have been subjective at best. "My room hits hard" really tells me nothing. All of our rooms do this to a certain degree, otherwise, we wouldn't be here talking about it, right? Having a signal chain capable of Low ULF is the first thing. Then having a mic-based measurement platform is second, going from 2D graphing like REW and Omnimic to 3D graphs like Speclab and others. When these graphs are displayed here, and we know how to read them
, we have a much better idea of what all our fellow LF/ULF nuts are talking about and describing wrt their systems. This, however, is far from a complete picture of system capability. 2D is good but 3D gives us a complete picture of what a system is capable of seated at the MLP. You can have flat frequency response and terrible tactile response and vice versa. That leads me to the second goal, flat system response to the best of our systems ability. You can only do so much if the signal chain doesn't cooperate. With a considerable effort and by using all the above mentioned measurement gear, I've got about as close to a flat response as my system is capable of. It makes for the best total subwoofer experience that I've experienced to date.
One thing I want to mention
is that the relationship between Vibration and the PSD's, while close, are not always the same. Much like two different 600hp engines can have different torque curves. Thats why I liken the Vibration(horsepower) and PSD(torque) too. For now here's a couple graphs demonstrating my point.
First is the EOT digital source graph.
My latest VS. Notice the difference between this and the above graph of mine posted by Dom.
Its not surprising with his size room and placement to have rolloff of TR(notice I didn't say FR)at 15hz and 10hz. Of more importance is his reasonable accurate TR at 20 and above. Some of you may only get the 30hz and 25hz before TR rolloff but atleast you will know what to work on and tactile transducers, which hasn't been covered much yet with VS testing, may be the solution. So that should be everyones goal, flat and extended source, sound pressure and tactile response.