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  #1  
Old January 31st, 2012, 11:42 PM
TSAdmiral TSAdmiral is offline
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VTF-3 MK 4 vs. VTF-15H

I'm considering the possibility of upgrading my subwoofer. The two I'm looking at right now is the VTF-3 MK 4 and the VTF-15H.

On paper, these two seem to serve similar functional needs. Short of the woofer size, the specifications seem very similar. Both use similar amplifier power and similiar frequency ranges as well. Judging from the specs alone, it seems the VTF-3 MK 4 is driven by the same amplifer as and can go just as deep as the VTF-15H. What, exactly, is the advantage of the latter? I currently have the VTF-2 MK 3 and I can easily why either would be superior, but between these two, it doesn't seem as obvious.

I don't know if I'm a hardcore audiophile, but I do know I enjoy decent sound. I assume most subwoofer buyers look at two primary categories: quantity and quality. According to the Hsu Research website, both are appropriate for "huge" rooms. Again, with similar specs and the primary differentiator being woofer size, I would assume that the VTF-15H must produce more output than the VTF-3 MK 4, all else being equal. Would it be safe to say that if the VTF-3 MK 4 is suitable for "huge" rooms, then the VTF-15H is in its own category of "humongous" rooms? Or do both produce similar output, with the VTF-15H edging out in sound quality? Might the more expensive subwoofer produce tighter, cleaner bass at equal output levels?

Lastly, the VTF-3 MK 4 features ports nearly double the size of the VTF-2 MK 4. How do these compare to the triangular ports on the VTF-15H?

I ask all this because, from the specs alone, there seems to be little reason to opt for the pricier subwoofer. I assume there's a good reason the VTF-15H is more expensive aside from sheer size and weight.
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  #2  
Old February 1st, 2012, 5:32 AM
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cacihome cacihome is offline
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OK...
The VTf-15H vs the 3.4... it is just basically output difference, with the edge of course to the bigger woofer/box sub... The triangular ports which are made from MDF have less port noise at the same output levels vs the pvc round ports.

The 3.4 has more clean output than the 2.4 too(much less port noise at deeper freqs), with basically the same differences as the 3.4 vs the 15H...

Hope this helps,
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Old February 1st, 2012, 4:30 PM
Pete_Hsu Pete_Hsu is offline
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Hi TSAdmiral,

The VTF-3 MK4 and VTF-15H are both very good subwoofers. They both have the same feature set, but the latter has several dB higher max output capability, in addition to more linear frequency response and lower distortion for any given listening level. The port size on the 15H is just a tad bigger than the -3 MK4, and those triangular ports have less noise at moderate-to-high playback levels vs. the round ports. Finally, the build quality and industrial design is better on the 15H.

Sincerely,
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Old February 1st, 2012, 11:45 PM
TSAdmiral TSAdmiral is offline
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Forgive my ignorance, but can "port noise" be subjectively described to me? Is lack of distortion essentially the lack of port noise, or is it more than that?

I recently examined the graphs on the 15H page and managed to figure out what is meant by linearity. Unfortunately, I have no basis of comparison with the -3 MK 4 as no data is published for that particular subwoofer. How do both of these compare relatively to the -2 MK 3? Is there a big jump from my current sub to the -3 MK 4, and then a smaller one from that to the 15H?
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Old February 3rd, 2012, 10:49 AM
Pete_Hsu Pete_Hsu is offline
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Port noise is like a "chuffing" sound, and happens due to turbulence primarily related to lots of air rushing out of a port. So with relatively small and low tuned ports, there can be port noise and output compression too at the frequencies near the port tuning frequency.

The linearity of VTF-2 MK3/MK4, VTF-3 MK3/MK4, VTF-15H is all quite good, but the larger models tend to have less output compression and can maintain linearity at higher playback levels. There is a significant increase in max output capability when moving from VTF-2 MK4 to VTF-3 MK4, just as there is a significant increase in max output capability when moving from VTF-3 MK4 to VTF-15H.

Sincerely,
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Old February 4th, 2012, 9:41 PM
TSAdmiral TSAdmiral is offline
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Pete, I appreciate all the time you've spent addressing my questions. As the current owner of a -2 MK 3, the customization options of these newer subs intrigue me. I did a bit more research and am curious about a few more things.

What is max headroom mode? I understand max extension and output, but where does max headroom fit in? Pete, you've described this before as "overdamped," can you elaborate? According to the owner's guide for the 15H, this offers the deepest extension. Is it as deep as max extension, except with higher output? Secondly, the -3 MK 4 owner's guide warns against high-SPL operation in sealed max extension mode, but this does not appear in the 15H owner guide. Does this warning not apply to the 15H? Does the Q setting impact this?

Can the Q control be described in layman's terms? The owner's guides states that lower Q settings provide for higher mid-bass headroom. What, exactly, is "headroom?" I understand that higher Q settings mean less low bass headroom, sort of like running out of steam as the guide describes. What does this mean, considering that 0.7 seems to produce the most output in the graphs on the 15H page?

Thank you!
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Old February 5th, 2012, 12:07 AM
Stegen Stegen is offline
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I own a 15h and my theater is 16'long x 11'wide x 7.25' high. the sub presurizes the room quite nicely and is loud. thought it would be louder but i also have something wrong with my sub that i havent figured out yet.
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Old February 8th, 2012, 3:52 PM
Pete_Hsu Pete_Hsu is offline
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Hi TSAdmiral,

Ported Max Headroom mode is the same as what we used to informally call "overdamped" mode. This mode will have deeper bass extension than Ported Max Output mode, and will have higher mid-bass headroom than Ported Max Extension Mode. The Ported Max Output mode will have the highest max output, while Ported Max Extension mode will have the deepest bass extension. So the Ported Max Headroom mode falls somewhere in between. The reason we called it "overdamped" is that the frequency response starts to roll off gently a bit above the port tuning frequency.

The 15H driver has larger surface area and higher excursion than the -3 MK4 driver, so it will have less issues at high sound pressure levels in comparison, irrespective of Q control settings.

The Q control allows one to manipulate the deep bass response of the subwoofer. So if one wants a less deep bass heavy sound, one should use lower Q settings. And by having a more rolled off deep bass response, one will be able to push the unit harder in the mid-bass before it runs out of steam in the deep bass. So that is what we mean by higher headroom.

Sincerely,
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