VTF-2 vs VTF-15H

[Skye]

There's a question after all of these relevant details, I promise. =]


My listening room has between 1,500 and 2,000 cubic feet of air. The room has a fantastic length vs width ratio for distributing the bass nodes evenly across the frequency spectrum. Also, the ceiling is vaulted, which further helps avoid consistent nodes. Because there isn't stacking of bass nodes in my room, as is common in most rooms, my room sounds very bass-shy with my ported bookshelf speakers and my pair of 10" Polk subwoofers (cheapest they make) compared to hearing the same speakers in other rooms. Someone less educated might say that my room sucks the bass out of the speakers, ruining the fun. (However, I believe this to be good, because after turning good subs up higher, the frequency response should be much flatter!)


Also, I am purchasing the materials to build significant bass trapping, including 4" thick absorption at all first reflection points and 33" hypotenuse super-chunk bass traps in the two front corners and against the rear-wall and ceiling corner. I am well aware that this does nothing to reduce the original sound-wave from the subs to the listener (which is good), but it does significantly reduce room reverberation in the low frequencies (which is also good, but does make the bass sound quieter at the same gain setting).


I like to listen at 90 dB or so, and I prefer fast, musical, slightly hyped bass (compared to a perfectly flat mastering studio, NOT hyped compared to a hip-hop studio). I want my bass to sound fantastic with deep organ music, for example. Frequency response is much more important to me than max output: in other words, I don't care about rattling door knobs with movie explosions, but I do care about the ultimate music experience. I'll take measurements after the bass traps are installed and use an equalizer to do what I can to flatten it further. I'm aware that boosting frequencies of bass nulls is very hard on an amplifier, and should be avoided or used conservatively.


I haven't yet decided on whether each subwoofer will sit on an isolation platform.



With all of this in mind, do you find that 2x VTF-2 mk4 will be perfectly sufficient for my needs, insufficient, or overkill? (Overkill is acceptable, since my next listening room may be bigger.) Do you think, with the details I gave above, that purchasing 2x VTF-15H would net me any improvements over 2x VTF-2 mk4?

Thanks!

[Skye]

Including shipping, a pair of VTF-15H costs 65% more than a pair of VTF-2 mk4.

Reasons to aim for the VTF-2:
- My room has a cubic volume of ~1700 feet. That's considered pretty small and well within the capabilities of a single VTF-2, by home theater standards
- Cheaper!

Reasons to aim for the VTF-15H:
- My room is extremely bass-shy due to its favorable dimensions
- I'll be bass trapping extensively, and although it does nothing to reduce the sound waves from the sub to the ear, it does lots to reduce the sound waves from the walls to the ear (which is perceived as a loss in volume, but an increase in precision)
- It goes slightly deeper, towards the ever-elusive 16 Hz note on the pipe organ
- Due to the increased cone size, cabinet size, and wattage, this sub simply has more power to create sound: although I don't need raw volume, that does give me more ability in boosting the frequencies in nulls and extreme lows (which is an enormous load for a subwoofer) while keeping the average volume at the preferred level. In summary, it gives me more headroom for boosting EQ.
- No temptation to upgrade
- My next room will most likely be larger than my current room


What do you think? Is it worth the 65% increase in cost?

[Ryan_Hsu]

Hi Skye,

I would recommend the VTF-15H, either single or dual, you can purchase a single one first and see if you like it, and if you order a second VTF-15H within 30 days we would honor the dual drive pricing.


For a smaller room, a pair of VTF-2 Mk4's won't have any problems giving you good output levels in mid bass, but for higher playback levels in the deep bass I would recommend the VTF-15H. A single VTF-15H will have more output than 2 X VTF-2 Mk4, especially in the deeper bass for organ music.

[Skye]

I suppose that would kill any upgraditis I might feel in a year or five.

Since we're looking at big budgets, should I consider the ULS-15? Wireless sounds like a bad idea, since there must be some latency, but it sounds like a solid performer, so it could be a good match for me wired.

I'm really set on dual subs for a flatter frequency response and stereo bass. But it seems silly to me to put two of the 15H subs in that smallish room, you know?

[SME]

Considering your preferences and the attention you are putting into your room treatments, I think you should get 2 ULS-15s. If they are too much money, then start with one and plan to add another later. The ULS-15 actually provides less output than the VTF-15H, but for temporal accuracy and low distortion, it can't be beat. Don't worry about the wireless feature since its use is optional.

That said, the VTF-15H is also an excellent sub, even for discerning ears. There's nothing silly about putting two of them in a small room.

Another thing to keep in mind is that your listening interests and preferences may expand as you learn what your system is capable of.

[Skye]

Even though the ULS has much less tuning features?

[shaolin95]

I have a VTF 15 in a large area (open basement) and it is fantastic. I have a old MFW15 I use next to it cause Bass just gets addictive but my goal is to add another VTF and sell the MWF or move it upstairs as my gaming/3d movies setup.
My vote goes tot he VTF for yuor case as well but hard to go wrong.

[SME]

Being a sealed design, the ULS-15 doesn't have the option of plugging ports. The EQ mode switch is not necessary because the sealed enclosure gives the sub a gradual roll-off at the low end rather than the sudden roll-off that is seen with ported designs. The ULS-15 still has the Q control (called ULF trim here) for adjusting the balance between mid and deep bass.

[Skye]

Originally Posted by SME

Being a sealed design, the ULS-15 doesn't have the option of plugging ports. The EQ mode switch is not necessary because the sealed enclosure gives the sub a gradual roll-off at the low end rather than the sudden roll-off that is seen with ported designs. The ULS-15 still has the Q control (called ULF trim here) for adjusting the balance between mid and deep bass.

Some people mentioned about the VTF-15H that even though they get better frequency response with the Q all the way in one direction, they thought it sounded tighter and more defined with the Q set somewhere else (sorry for the lack of specifics). Do you find this to be the case with the ULS-15?

Initially, I didn't like the idea of the ULS at all. It doesn't have ports to plug/unplug, it has less tuning options, the wireless receiver seems like a HT thing for non-dedicated rooms that very likely introduces latency, and since a large enclosure is good, why go small? The VTF-15H seemed to speak to me more.

However, I don't need raw power, just definition and precision. And it is starting to sound like the ULS-15 has the ultimate word in that department. I'm somewhat frustrated you mentioned the ULS should be an option for me, because now I'm reading owner's threads and reviews, and I think I am hooked. Haha.

Also, I wasn't considering the ULS for the price. But shipping is dramatically less than shipping the VTF-15H, so the dualdrive ULS isn't actually all that much more than the dualdrive VTF-15H.

This is getting expensive! Curses!

[SME]

To be honest I don't have a ULS-15, but with my ported subs, I have experienced what you describe in which bass sounds tighter with "lower Q" even though the response is no longer flat with my ported subs. I'm fairly certain that this effect is due to lagging response in the time domain with two significant contributors:

(1) It takes time for the resonance between the driver and the ports to establish itself. Similarly, the port continues to make noise for a time after the driver stops. The closer you get to the tuning frequency, the longer it takes for the resonance to set up and dissipate. For frequencies much higher than the tuning frequency, there is no resonance and the sub behaves like one with a sealed enclosure. As such, the deeper frequencies will tend to lag the upper ones which can make kick drums sound sloppy or even ill-timed.

With my VTF-15H and VTF3-MK4, I prefer to sacrifice a bit of headroom by running with one port plugged in order to lower the tuning frequency from 22.5 Hz to 16 Hz. The difference it makes is noticeable to me. Note that you can still run EQ2 with one port plugged and obtain the benefit I describe without giving up as much headroom. With the ULS-15, the enclosure is completely sealed, so this issue doesn't come into play at all.

(2) Reflections in the room interact to create standing waves or room resonances that also take time to set up and dissipate. Frequencies near those associated with room modes tend to be affected more, and lower frequencies are impacted more in general. For a broadband impulse like a kick drum, a "one note" sound may also be heard as the resonating frequencies dissipate much more slowly than the rest. It is my experience that room effects often harm temporal response much more than the port/driver interaction. This may not be the case with other brands of subs that may use higher tuning frequencies than the Hsus.

Room effects can be reduced (a) by placing subs closer to the listener, (b) by placing subs away from room modes (usually away from walls or corners), (c) by placing a pair of subs in regions of opposite polarity (for example, one on each side of the room), and (d) by using bass traps --- although keep in mind that most "bass traps", despite the terminology, are not very effective in the sub-bass range (< 80 Hz). Also note that sitting in a different location does little to mitigate temporal response issues due to room effects, even though it can help one to avoid frequency response nulls.

Room effects are as much of an issue with a ULS-15 as with a ported sub, as evidenced in this thread: http://forum.hsuresearch.com/showthread.php?t=95683. If you are able to configure your room and subs to avoid room effects, then the improved accuracy of the sealed box design will be apparent in the lower frequencies. Even if you don't, it is my understanding that the ULS-15 can deliver sound with less distortion (thanks to the linearity of its woofer) than the VTF-15H, provided that you aren't playing it beyond its capabilities. Lastly, the ULS-15 can provide lower extension than the VTF-15H, in case extension below 16 Hz matters to you.

Lastly, for anyone else reading this, my advice is directed at those willing to give up some output to achieve a more accurate sound. Except for placing the subs closer to the listener, most of what I suggest to mitigate room effects also reduces output to some extent. If you play your sub(s) so loud that they are overworked, then the distortion will overwhelm any improvement in accuracy you would be getting by avoiding room modes. As such, the usual advice on this forum is to place your sub(s) either very near to the listener or in the corner(s) to ensure you don't run them into distortion.

[Skye]

Haha, I'm the one who was suggesting the room was the issue in that thread. You're not allowed to cite me as an expert in a point you're trying to prove to me! Haha.

What you're suggesting is great news, because I don't need the last word in SPL. I'm not a bass-head, my room is comparatively small, and I tend to listen somewhat quiet, often around 85dB. And for the next 3-6 years, I'll likely intentionally keep the volume a bit lower than that since I currently live in a townhouse.

Bearing in mind that I don't need heaps of SPL, it sounds like the ULS really is the better product. And further, my plans are to build extensive bass trapping and purchase a calibrated measurement microphone to use with REW at the same time or before I order the subs. If it really does take a touch of laboratory precision and doggedness to build and position the treatment just so and to position and calibrate the sub just so, I'm dedicated enough to do it.

I'm toying with the idea of making the back-wall-to-ceiling bass trap simply massive, to allow it to absorb frequencies even deeper than the 24x24x33" corner traps in the front floor-to-ceiling corners.

What do you do for bass traps?, SME?

[Skye]

Well, I've read through 64 pages of the ULS Owner's Thread at AVSforum. Does that make me an addict?

If it comes down to 2x ULS-15 vs 2x VTF-15 for a small room with playback at moderate volume, are there any other opinions yet to be cast?

Thanks for the help.

[shadyJ]

For a small room at moderate playback, two ULSs would be ideal. I don't think there are any advantages at all to the VTF15hs in that scenario unless you really crank them.

[Skye]

Excellent! A working plan. And now to find out when the next sale is.

P.S. What size room would it have to be for that recommendation to change back to the VTF-15H?

[shadyJ]

Originally Posted by Skye

Excellent! A working plan. And now to find out when the next sale is.

P.S. What size room would it have to be for that recommendation to change back to the VTF-15H?

It's not just room size, its how loud you like it, and freedom of placement placement, and whether the room is sealed, etc. There are a lot of factors which would determine whether the extra loudness of the VTF15h is worth it to you.

[hometheatergeek]

Hello Skye, I see you are posting here too.

[Skye]

You caught me.

[jsbeesl]

Originally Posted by Skye

Excellent! A working plan. And now to find out when the next sale is.

P.S. What size room would it have to be for that recommendation to change back to the VTF-15H?

Dual ULS-15's offer a lot of power. A lot. Now I will say that for sheer fear-inducing output the VTF-15H can't be matched, but if your primary concern is accuracy, then I imagine you plan set your subs within a reasonable level of matched output to the rest of the system. Playing a pair of ULS-15's to the point that you "need" a VTF-15H under these conditions would be deafening, because the rest of your system would just be screaming. If you level match your subs to the rest of the system, I guarantee that you will give up before your subs.

[Skye]

Originally Posted by jsbeesl

Dual ULS-15's offer a lot of power. A lot. Now I will say that for sheer fear-inducing output the VTF-15H can't be matched, but if your primary concern is accuracy, then I imagine you plan set your subs within a reasonable level of matched output to the rest of the system. Playing a pair of ULS-15's to the point that you "need" a VTF-15H under these conditions would be deafening, because the rest of your system would just be screaming. If you level match your subs to the rest of the system, I guarantee that you will give up before your subs.

This is really helpful. As I may have indicated earlier, I have lower tolerances for SPL than most people. I really don't expect to be pushing 100dB, in fact, 90dB seems like plenty for me.

I like the bass a little hot, perhaps 2-3dB, but perhaps this is just a push towards equality since I don't listen super hot, and the Fletcher-Munson curves indicate that we're less sensitive to bass at lower levels.

From your simple contrast, the ULS has the accuracy and the 15H has the output. Do you have any more detail to add to that?

I suppose now it comes down to money. I think I'll continue saving for the ULS instead of purchasing 2x VTF-2 now. Hopefully there will be a sale soon to help.

[Kevin_Hsu]

Hi Skye,

I second a lot of what these wonderful folks are saying. If I was in your position, with the space you have and the preferences you have in regards to bass quality/musicality, I would definitely go with two ULS-15's. Our demo room is roughly about twice the size of your room, and two ULS-15s are more than enough to fill that area. The VTF-15H is definitely a musical subwoofer in its own right as well. However, it really doesn't reach the tightness that the ULS-15 can deliver, in my opinion. We do have a dualdrive ULS-15 package, which is basically two ULS-15's at a discounted price.

http://www.hsuresearch.com/products/uls-15Dual.html

Sincerely,
Kevin