Originally Posted by MIkeDuke
Thanks for the explanation. That does make sense. The tests showed it to have an incredible amount of SPL capabilities, at least IMHO. But it also had a very high -3db point when measured outside(which was explained very well by the testers though) whereas many other, much smaller and less powerful subs had a lower -3db point when measured outside. But then I was told that the -3db point when listed outside was really meaningless because this sub will be put inside a room and will most likely have some sort of EQ attached to it to give you what ever curve you want.
As I said, I have heard this sub before and at a store and at one point I was watching a movie so loud that I was told it was shaking the 30,000 cf building I was in
. I think if you were to look at the graphs and charts of this sub people would probably dismiss it because of its distortion numbers. But it was one of the only subs that could handle a 115db sweep and hit a max of 118, outside, at around 65Hz. I can honestly say that it is still one of the best sounding subs I have experienced but again, if you look at only the charts, people might dismiss it. But again, thanks for the explanation.
Mike, as the person responsible for those measurements on AV;Talk, I would like to make a few points.
Firstly, we made a mistake. Had I known this was a ported sub, I would have had the guys turn it round 90 degrees so both port and driver were equidistant from the mic. If you have any idea of the logistics of one of these testing sessions, it is not easy to test half a dozen subs in an afternoon. It's a lot of work. There has to be a division of labour. In this case, I was sat 100m or so away from the sub operating the test rig while my colleagues were responsible for manhandling the various subs in and out of boxes. From that distance, there was no way for me to realise this was a ported sub. I had no prior notice of exactly which subs were going to turn up on the day. The UK sales manager from Focal-JM Lab was on hand and he never mentioned this was a ported sub and none of those doing the "humping" mentioned it. It was only when I went hunting for the manufacturer specs on the web to publish the results that I realised our mistake.
Yes, the wrong orientation would have made a small difference to the overall measurements. The port is effectively 24.9" further away from the mic than the driver. At a guess you might expect to get 2-3dB more output at the extreme low end of the frequency response with the sub turned sideways. But it's not an order of magnitude difference.
Part of me says, this is like looking a gift horse in the mouth and nit picking over measurements that no-one had paid any money for and therefore has no right to expect perfection. We do however take great pains to try and get things right but slipped up on this occasion. I'm sure if you look hard enough you will find slips in Ilkka's and Ricci's work.
In terms of the original point of this thread, it seems to me that an essential point is being missed here in terms of the perception of sound vs objective measurement. The ear and brain do not operate in the same way as a spectrum analyser. Psychoacoustic effects come into play and are important.
While a flat frequency response and zero distortion may represent the ideal situation for any reproduction system, no real-world subwoofer gets anywhere close.
The important issue is the way in which a particular design falls short of that ideal and the way that shortfall is perceived
by the listener vs another design.
Some people may think objective measurements like THD% provide useful guidance on what something sounds like, but in reality a particular THD% number doesn't correlate with perceived sound quality at all. Also, THD% as measured ground-plane will be rather different when measured in-room. We actually need a better objective metric for distortion than THD%.