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  #1  
Old November 6th, 2008, 8:02 AM
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At last ULS-15 review!!!!

Good reviews as always...
Congrats to the guys at HSU Research!Keep it coming!
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  #2  
Old November 6th, 2008, 9:33 AM
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  #3  
Old November 6th, 2008, 9:44 AM
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Sorry....At secrets!

http://www.hometheaterhifi.com/speak...-speakers.html
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  #4  
Old November 6th, 2008, 11:35 AM
Pete_Hsu Pete_Hsu is offline
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I'd like to thank Ross Jones and Dr. John Johnson for the great review on the ULS-15 and HB-1 MK2/HC-1 MK2 http://www.avsforum.com/avs-vb/images/smilies/smile.gif

Some of you may be wondering why THD was 15% @ 20Hz @ 100db with mic 1 ft away from the cone. In Dr. Johnson's room, at the location where the ULS was placed, notice from the frequency response graph at 1 ft distance that there is a deep bass suckout where 20Hz is 6db down vs 60Hz. This inflates the 3rd order harmonic with a 20Hz test tone, which is what caused THD to be relatively high at that frequency. With outdoor measurements, the ULS would be no more than 1-2db down at 20Hz compared to 60Hz.

In our own demo room, where we don't have a deep bass suckout, THD @ 1ft from the ULS-15 was actually less than 5% @ 20Hz.

So the moral of the story is to use some caution when comparing results from one room to another or to outdoor measurements. In fact, even a small change in position within a given room will mean that data cannot be easily compared between one sub and another. For example, the ULS must be in a different location than the JL subs that Dr. Johnson measured, because there is not a prounced 45Hz suckout on the frequency response graph at 2m distance with the ULS.

P.S.: Even if not directly comparable due to potential differences in positioning, the THD measured from 25-50Hz @ 100db @ 1ft was even less on the ULS-15 compared to the F113 (note that 25-50Hz data is not shown in the review). Also, the frequency response is much more extended than the F113 too.
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  #5  
Old November 6th, 2008, 7:48 PM
tdekany tdekany is offline
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Pete, I don't think those numbers mean much either way, since the uls' competition is the pb ultra, and the $v$ fans over at avs put it down regardless. Now it is too small and it's numbers are weak.

http://www.avsforum.com/avs-vb/showthread.php?t=1082046
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  #6  
Old November 7th, 2008, 5:27 AM
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Quote:
Originally Posted by tdekany View Post
Pete, I don't think those numbers mean much either way, since the uls' competition is the pb ultra, and the $v$ fans over at avs put it down regardless. Now it is too small and it's numbers are weak.

http://www.avsforum.com/avs-vb/showthread.php?t=1082046
I know. I couldn't believe that when I saw it.
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  #7  
Old November 7th, 2008, 6:27 AM
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You just can't compare the Ultra to the ULS in SPL.
Different design goals...That is all.
Wait until HSU do something bigger and we'll talk about SPL...
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  #8  
Old November 7th, 2008, 11:04 AM
Pete_Hsu Pete_Hsu is offline
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I can honestly tell you that total harmonic distortion (THD) at 1 ft away from the cone at 100db should in most cases be very very low from a single ULS-15. Of course, if the subwoofer placement in-room results in a deep bass suckout that accentuates 2rd and/or 3rd order harmonics, then the THD can be high!

Due to these complications, one can never ever ever compare in-room measurement to outdoor measurement, or in-room measurement of one sub in one location and another sub in another location.

In fact, the ULS-15 measured at 1 ft away from the cone @ 100db outdoors would have much less than 10% THD @ 20Hz.
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  #9  
Old November 7th, 2008, 11:43 AM
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Quote:
Originally Posted by Pete_Hsu View Post
I can honestly tell you that total harmonic distortion (THD) at 1 ft away from the cone at 100db should in most cases be very very low from a single ULS-15. Of course, if the subwoofer placement in-room results in a deep bass suckout that accentuates 2rd and/or 3rd order harmonics, then the THD can be high!

Due to these complications, one can never ever ever compare in-room measurement to outdoor measurement, or in-room measurement of one sub in one location and another sub in another location.

In fact, the ULS-15 measured at 1 ft away from the cone @ 100db outdoors would have much less than 10% THD @ 20Hz.
That is why you have to publish numbers. Otherwise the $v$ boys eat you for lunch.

Reading their posts it looks like there is always a reason why the pb ultra is better, no matter what it is compared against.
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  #10  
Old November 7th, 2008, 11:49 AM
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Quote:
Originally Posted by cacihome View Post
Wait until HSU do something bigger and we'll talk about SPL...
By that time $v$ will have something even better.
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  #11  
Old November 7th, 2008, 11:59 AM
Pete_Hsu Pete_Hsu is offline
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The issue here is not max SPL at 20Hz, but distortion at a fairly modest SPL level with mic at only 1 ft away from the cone. Trust me, this is a room-related anomaly. Having a room-related suckout where 20Hz is 6db down vs 60Hz (even though anechoic response of the sub is flat from 60Hz to 20Hz) will cause the 3rd order harmonic to be dramatically inflated, simple as that. And note that this is just one frequency! The ULS has very low distortion and very high output capability at and above 25Hz under almost any circumstance (but again, in Dr. Johnson's room, the 2nd order harmonic with a 25Hz test tone is inflated due to the deep bass suckout at the location where the ULS was measured).
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  #12  
Old November 7th, 2008, 12:01 PM
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Exclamation

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Originally Posted by tdekany View Post
By that time $v$ will have something even better.

...
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  #13  
Old November 7th, 2008, 1:38 PM
Pete_Hsu Pete_Hsu is offline
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The most important thing is that people understand why a result would be unexpected. So I tried to give a good explanation of the results, and that's about the most one can do when discussing measurements in-room and in any particular subwoofer location.
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  #14  
Old November 7th, 2008, 2:17 PM
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If the data in the review is bad, are you going to have them edit it or put a note? I mean, a THD level like that in a review could affect a buyer's purchasing decision. And most won't see your post over here which explains it....
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  #15  
Old November 7th, 2008, 3:14 PM
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If the data in the review is bad, are you going to have them edit it or put a note? I mean, a THD level like that in a review could affect a buyer's purchasing decision. And most won't see your post over here which explains it....
exactly
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  #16  
Old November 7th, 2008, 11:54 PM
Pete_Hsu Pete_Hsu is offline
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The data from that review is valid in that room and in that particular subwoofer position, but the data is not comparable to outdoor measurements or to other in-room measurements due to the deep bass suckout.

I suppose I can ask Dr. Hsu about the possibility of adding a manufacturer's note at the end of the review, good idea!
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  #17  
Old November 8th, 2008, 2:01 PM
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or ground plane tests would help!
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  #18  
Old November 8th, 2008, 11:17 PM
Pete_Hsu Pete_Hsu is offline
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True, true. Whenever the new website is ready, we'll have lots and lots of outdoor measurements on all the subs.
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Old November 9th, 2008, 4:31 AM
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Pete, do you know of any more upcoming reviews?
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  #20  
Old November 9th, 2008, 6:09 AM
JonnyOzero3 JonnyOzero3 is offline
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Quote:
Originally Posted by Pete_Hsu View Post
True, true. Whenever the new website is ready, we'll have lots and lots of outdoor measurements on all the subs.
Sweet
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  #21  
Old November 9th, 2008, 6:14 AM
JonnyOzero3 JonnyOzero3 is offline
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Quote:
Originally Posted by Pete_Hsu View Post
The data from that review is valid in that room and in that particular subwoofer position, but the data is not comparable to outdoor measurements or to other in-room measurements due to the deep bass suckout.

I suppose I can ask Dr. Hsu about the possibility of adding a manufacturer's note at the end of the review, good idea!
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  #22  
Old November 10th, 2008, 8:37 AM
Ddavidson Ddavidson is offline
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Smile

Quote:
Originally Posted by Pete_Hsu View Post
True, true. Whenever the new website is ready, we'll have lots and lots of outdoor measurements on all the subs.
Good move and this will help those who live, breathe and die by a performance graph.

Great review well done Dr Hsu.

Ddavidson
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