For clarity I put my words in the quote area in blue
Originally Posted by basshead81
Not really because what you are comparing is compression on the low end...not the same thing as what Tom was saying. Also long term power should be taken with a grain of salt comparing to real world use. All that test is basically for is testing the subs protection circuits @ 100% DUT. No real world content comes even remotely close to long term power...actually the most demanding movie content is 1/4 DUT. In the past Ricci mentioned using those numbers for his diy testing to get a "real world" representation of what a end user might see by powering a UM-18 with a Inuke amp instead of a power soft k10 like JR uses...other then that, there should be no correlation made.
I guess we see things differently and interpret things we read differently. I looked into it more myself and found more info and from what I understand what I stated earlier is correct.
The PSAs tested by data-bass shows they have a minimal loss at Max Long Term Output, which matters if you are someone that pushes your system hard. It will not matter to you if you have a bunch of subs(more headroom) and/or run at a lower level so that you are not running into power compression. I would say the higher efficiency drivers that PSA uses is a big part in this as if you compare different drivers on data-bass the ones that suffer less loss in the Max Long Term Output are higher efficiency drivers from what I am seeing. For example, compare the JTR 1400 to the JTR 118 and look at Max Long Term Output the 118 has more output from around 45hz and the frequencies below that are within 4-5dB where in the Max Burst the 1400 shows it being ahead by 6dB+ most of the FR until around 60hz. I would guess the V1801 is closer in Max LTO to the 118 more so than the 1400.
This may explain why some people are finding the PSA v1801 is closer than most thought it would be in real world listening comparisons to the JTR1400. The Max Long Term Output is probably closer I am guessing even though Max Bursts wouldn't show that and that is what most people focus on mistakenly. Josh compared the Max Burst numbers to car audio SPL numbers I didn't quote him but you can find data-bass if you want.
Like I mentioned in an above post this matches my experience with different subs I have used in my room from the PSA XS30, Submersive, UM18 and some pro Audio drivers which most are listed in my signature(not that this is a large sample). I do listen to higher volumes with the bass frequencies right around reference on average and sometimes higher. The primary use of my system is for listening to music.
Here is what I found from further reading. I just took snippets but you click on the links I provided to read the rest of the conversation.
"For practical output comparisons of systems I prefer to use the maximum long term output sweep myself. These are much more representative of what can be actually realized with an appropriate "safe" amplifier capability.
Sounds like Josh doesn't agree with you here or can you explain
"Basically stated this is the maximum level attainable in a long term manner, at which point the subwoofer’s behavior in some part of the frequency range has become a limiting factor. The higher the maximum output attainable the better the dynamic tracking of the subwoofer and the more suitable it will be for high output duties
, or large, open spaces."
From diy speaker guy and data-bass
"It looks like you completely missed the part about power compression
"But for long term max spl it's power compression that we are more concerned about
The CEA testing is useful for certain things but it won't give any clue about long term max spl. The CEA burst is incredibly short. Even at 10 hz it's well under 1 second long so it won't give any information about power compression or the ability of the driver to handle that amount of power long term.
If you listen to music similar to the track I posted, the safe power level is very low. Much lower than data-bass test levels"
Sounds more like Max Long Term Output to me that you say no one hits. EMD type and "bass-head" music will be MUCH more demanding.
"The long term output compression test is meant to simulate the effects of high duty cycle use on the system but in a much more rapid manner
. The long duration sine wave sweeps at the highest power levels are brutal on the systems and are meant to simulate many hours of playback of typical material with a MUCH lower duty cycle.Sine waves are 100% duty cycle so the voice coil gets heated relentlessly and in fact this test type kills more drivers than any other. Heavily compressed electronic music is only 25% duty cycle at mostand typical music is far less than that so the average power is far less than that of the test signals used here.Therefore the voice coil and amplifier have some "downtime" to recharge and cool off a bit. Don't think of this measurement as output that can be sustained indefinitely...Think of it as a survival point...The sine wave test signals may generate an average power of 1500w from the amplifier into a system. Actual music or movie content that produces peak outputs of the same SPL levels might require the same amount of peak power but the average power seen over the same time period is more likely to be 200 watts than anywhere near the 1500 of the sine wave.
www.youtube.com/watch?v=UnQY3swM4tA Edit added link again for context to the quote below
In other words, stuff like most rock music is fine at the Max Long Term Spl level reported by data-bass
, but if you try to play something like this on repeat at that level it's going to be a costly event UNLESS you have an impedance peak at the bassline frequency."
Again this does NOT sound like Burst is what we should look at. It sounds to me more like we should be looking at Long Term Output if you want to listen to stuff even like rock music(at high levels) which most would not consider taxing.
"All the drivers tested at data-bass have Long Term Output Compression Magnitude information, this shows how much total compression was measured in that box size at that power level. This is very important info, and it seems some people might not be aware that these losses"
"Posts like this will go un-noticed or get buried and forgotten. Josh took the time to explain, in detail, the differences yet the latter will never be looked at or taken as true information on other forums"
I realize that Max Long Term Output is only a part of it but I believe it tells us more than the Burst numbers do for real world use and that was my point from the start.