Question about XS30 vs Vtf-15h - Page 6 - AVS Forum
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post #151 of 162 Old 08-05-2013, 04:03 PM
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Originally Posted by ack_bk View Post

Umm.. Maybe not. Look at the Epik Empire.. Dual 15" dual opposed drivers 600W RMS amp and it give up almost 3db at 20hz to the Hsu VTF-15H and that is using the very conservative Audioholics measurements. If you use the Sound and Vision CEA-2010 numbers I believe that number is close to 5db at 20hz. I would not be surprised to find that the VTF-15H was either the equal or superior to the XS30 at 20hz. The XS30 will have the upper hand above 40hz I suspect where the dual opposed sealed design helps.

Again, you are talking a large ported design vs a sealed design. You don't seem to grasp the engineering behind the two designs. There are pros and cons to each, but don't just look at the number of drivers and amp. The port tuning in a bigger box is a huge advantage and the reason why the amp is lower rated is due to the ported design and most likely the sensitivity of the driver.

This is why I cant stress enough that Ricci's data-bass site needs to be the go to for comparing data. Sound and Vision measured 1m peak when the tested the vtf15h, not 2m rms which is a 9db difference. I know this a old thread that was just necro'd but I felt some things needed to be corrected.
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post #152 of 162 Old 08-05-2013, 04:42 PM
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Sorry for the necro :-) dang if you do dang if you don't. I tend to prefer to necro on an old topic vs. creating a new thread for an older discussion.

Consolidation and all...

I emailed Tom V. with my worries/concerns and he still felt comfortable recommending the XS30 so I am ordering that. Thanks for taking the time to respond to my question!

Thursday can't get here soon enough!

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post #153 of 162 Old 08-05-2013, 04:47 PM
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Sorry for the necro :-) dang if you do dang if you don't. I tend to prefer to necro on an old topic vs. creating a new thread for an older discussion.

Consolidation and all...

I emailed Tom V. with my worries/concerns and he still felt comfortable recommending the XS30 so I am ordering that. Thanks for taking the time to respond to my question!

Thursday can't get here soon enough!

No worries...I was actually going to respond to your question but had to step away from the computer for a bit. The xs30 is a lot of sub for 1149.00 shipped. I doubt it will disappoint smile.gif
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post #154 of 162 Old 08-05-2013, 05:06 PM
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Looking at data-bass basic response of the xv-15 I see 88db at 18 hz (its tune) and 66db at 10 hz, seems like 24 dB/oct. to me. It uses a dsp amp with limiter (which I am sure is well implemented by PSA for the subwoofer), so they could have made the graph flat to 10hz at 65 dB if they wanted to. A hemholtz resonator is a 2nd order filter exhibiting a 12 dB/oct. rolloff combined with the 12db/oct. rolloff from the driver resulting in 24db/oct. Just seen you post "XV15 has a shallow roll off of 12db per octave so it acts more like a sealed sub beyond its tuning point" a couple times and it reads like it doesn't follow the same physics as all ported enclosures. smile.gif ack_bk's post was legit.
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post #155 of 162 Old 08-05-2013, 05:18 PM
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Originally Posted by Luke Kamp View Post

Looking at data-bass basic response of the xv-15 I see 88db at 18 hz (its tune) and 66db at 10 hz, seems like 24 dB/oct. to me. It uses a dsp amp with limiter (which I am sure is well implemented by PSA for the subwoofer), so they could have made the graph flat to 10hz at 65 dB if they wanted to. A hemholtz resonator is a 2nd order filter exhibiting a 12 dB/oct. rolloff combined with the 12db/oct. rolloff from the driver resulting in 24db/oct. Just seen you post "XV15 has a shallow roll off of 12db per octave so it acts more like a sealed sub beyond its tuning point" a couple times and it reads like it doesn't follow the same physics as all ported enclosures. smile.gif ack_bk's post was legit.

I was going off of these numbers below its tuning point..however looking at PSA charts is does appear to 24db per octave not 12..my mistake. Still that is fairly shallow compare to some other ported subs that use a 48/60db per octave slope. I was not implying it does not follow ported enclosure physics, more so it employs a shallower roll off than some other ported subs.

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post #156 of 162 Old 08-05-2013, 06:23 PM
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Its no big deal, I get corrected from time to time as well. smile.gif It just means we are learning something. Just for future reference I wouldn't use in room measurements to show a subwoofers inherent roll-off. I also wouldn't use cea-max output results as driver and port compression, not passing b/c distortion limited... Different bass reflex designs utilize different filter's/limiting to protect the driver, and they can signal shape to the desired result. However basic response compared to compression sweeps and cea bursting can give some light into how and why they are implemented. Since in a ported enclosure the driver is basically acting as though it is out of the box below tune, they are not going to have much usable output very far below tune.
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post #157 of 162 Old 08-05-2013, 06:57 PM
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Originally Posted by Luke Kamp View Post

Its no big deal, I get corrected from time to time as well. smile.gif It just means we are learning something. Just for future reference I wouldn't use in room measurements to show a subwoofers inherent roll-off. I also wouldn't use cea-max output results as driver and port compression, not passing b/c distortion limited... Different bass reflex designs utilize different filter's/limiting to protect the driver, and they can signal shape to the desired result. However basic response compared to compression sweeps and cea bursting can give some light into how and why they are implemented. Since in a ported enclosure the driver is basically acting as though it is out of the box below tune, they are not going to have much usable output very far below tune.

Thanks for the correction smile.gif! I appreciate your input and have learned quite a bit from you over the last few months!!
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post #158 of 162 Old 08-05-2013, 07:31 PM
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Its rewarding to hear that as i feel enjoying our hobby, learning the science behind it, and passing the knowledge on is the goal. I have to say you have come a long way in 5 months on avs and are no doubt reaping the rewards with a proper multi sub setup! Noticed you recently added a third gain matched xv15, congrats. cool.gif
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post #159 of 162 Old 08-05-2013, 11:20 PM
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Well I feel like I just went through a drama flick, now I'm ready for bed!
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post #160 of 162 Old 08-06-2013, 12:12 AM
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^^^ I’m going to have to read this thread in full myself.. night

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post #161 of 162 Old 08-06-2013, 07:07 AM
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I Just went through the thread, I would say dominguez1 reduces my thoughts down the T.


Quote:
It is dependent on the design of the sub, particularly with ported, sealed, horn, etc

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post #162 of 162 Old 08-06-2013, 08:36 AM
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With the size of his room it's obvious ported or horn is the only way to go. This is all inexperienced opinion and really only a few are truly qualified to make an real experienced suggestion. So I will not pretend to know what I don't. But from what I have learned, and playing with my HSU VTF 15H, ported will give you what you are looking for. Forget infrasonic in a room like that unless you are planning on a popalock setup
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