Originally Posted by basshead81
Lol it wins by a very slim margin that you would never hear. However I am glad you are happy with the results. Now head on over to my other thread and place your vote for the next sub to test.
So you've made multiple posts in this thread about the performance of the VTF15h, but hadn't looked at all of the data? Not sure what to think about that. And now you're still just looking at the CEA numbers. Ricci includes the other measurements for a reason. Look at the max output sweep, compression sweeps, THD graphs, etc. The VTF15h does have a larger advantage in some of those tests. Will that translate to an noticeable difference in real work use? I haven't heard either sub so I don't know for sure, but IMO it is a possibility. (Depending on the person, room, content, etc.)
Originally Posted by basshead81
I just wanted to post these graphs for those who dont read all the charts on data-bass.com. These are the In-Room numbers and you can see the VTF-15 has more output in 1 port on the low end but its filled with high order harmonic distortion...the kind thats clearly audible(4th-9th). 2 port mode has the cleanest output and will probably be what mode most folks run without sacrificing output. In 1 port the sub would need to be turned down a few db to produce clean output. Anything more than 10% thd from 4th - 9th order harmonics is audible. I am not posting this to further this debate, its to help some folks understand How to read these charts. When you carefully analyze this data its pretty clear the XV15 is even with the VTF-15 in 16-30hz, and has more output in the 40-80hz. So imo niether wins, its more a draw. Both have there pros and cons, its up to the end user to decide which is better for them.
I don't think you understand the full significance of the CEA tests either. First, what level of distortion is audible is largely dependent on the content being produced. Sure there is a threshold for sine waves or burst tests, but in real world use, that same level of distortion is not always audible. Many times it will be masked by other frequencies. Also, if you actually look at the CEA limits for each fundamental (http://www.audiomatica.com/wp/wp-content/uploads/2012/03/appnote_007.pdf
) you would know that the 4th and 5th harmonics are limited to 10%, 6th, 7th and 8th limited to 3.2% and the 9th and above are limited to 1%. So even though the VTF15H is limited at some frequencies by the 9th harmonic, that harmonic is still only 1%. The VTF15H has lower total THD at all frequencies for the in room CEA numbers but the THD harmonics of each sub are different, so which sub would "sound" worse at those levels? I'm not sure, but it is not as simple as your're saying. Second, you cannot use CEA numbers alone to determine the performance of a sub or what mode will work best. There was a recent discussion about how Ricci's CEA numbers at higher frequencies for DIY systems are not relevant for the average person. He is using an extremely powerful amp to achieve those numbers and the amount of voltage used at the higher frequencies would destroy the drivers at lower frequencies. So if you want a flat FR, the DIY systems are voltage limited at the lower frequencies and in real world use, the driver limits at the higher frequencies are never reached. A similar thing needs to be applied to commercial subs as well.
Look at the outdoor CEA numbers for the XV15. It has 14db more output at 50hz than 20hz. So as you keep pointing out, it has an advantage over a lot of other subs in its class around 50hz. Now look at the compression sweeps. There is very little compression at the 105db sweep, compression increases at 110db and the limiters are engaging at 115db. Its similar with the THD graphs. THD is below 20% for most of the range on the 105db sweep, increases significantly at 110db and would be off the charts at 115db. So, IMO you would want to keep the level below what produced the 110db sweep. For now, look at the 105db sweep. The output at 50hz is only 4.5db higher than 20hz. What happened to the 14db difference? To produce that higher output at 50hz in the CEA test, the sub had to be pushed to a level that would be past its limits at lower frequencies. So if you don't use manual EQ to put a hump in your response at 50hz, the output advantage around that frequency is not used in real world content. This is one of the reasons CEA averages can be misleading and why you need to look at more than just CEA numbers.
What about the VTF15h? In 1 port mode, the VTF15h has about 7db more output in the CEA tests at 50hz than at 20hz. Josh says that the 115db sweep produced audible artifacts showing the amp and driver were past their limits, so look at the 110db sweep. With that sweep, there is 6db more output at 20hz than 50hz. Almost the same as the CEA tests. This means that most of the burst output from the CEA tests is usable in real world content with a flat FR. At the 110db sweep it also has lower THD than the XV15 did at its 105db sweep, especially at higher frequencies.
Again I'm not saying all of these differences will definitely make an audible difference for everyone in real world use, but IMO, there are differences in the measurements that show the VTF15H is a better performer and could justify the higher cost over the XV15 for some people.