By The Power of Grayskull: Subwoofer Watts!

[Pirate]

I have a 15x20 cinema. Do I need 1200 watts that, say, a Velodyne would offer? Would the 250 watts in a good Hsu do it? I’m so confused. Why do you guys think more/less wattage is better?

And, remember, no SVS talk in here.

[Ruined]

Velodyne SPL-1200R is a great sub for that room, mine is about the same size and it is just about the perfect fit.

Watts are deceiving because the figure can be inflated based on how its measured. But assuming the same measurement across different manufacturers (usually not the case), more watts means more forceful peaks can be delivered that you can hear and even feel better.

[Pirate]

The Velo in my sights is the SC-12. But I'm also looking at an Hsu that has better frequency response, but less wattage. I've been told that the Velos use a lot of energy controlling their digital servos, which is why they offer so many watts. I wonder, in real world testing, how much more powerful the Velos really are.

[PunkMunkey]

Pirate, is the Velo you're looking at the one that has the outboard amp? The SC-12 and SC-1250 Sub + amp combo?

If so, keep in mind that the amp produces the rated 1250 watts into a 4ohm load...a single SC-12 sub is rated at 8 ohms. What this means for you is that if you only have the single SC-12 paired to the SC-1250 amp, it will only make half it's rated power or 625 watts. You'd need to pick up another SC-12 and wire it in parallel to that amp to make it see a 4 ohm load and produce the rated 1250 watts. Depending on your budget, there might be a better way to fulfill your sub needs.

[Pirate]

No, I didn't realize that about the SC-12. The Hsu I'm looking at pushes 250 watts with a maxiumum extension of 18Hz. Maybe I should just get two of them.

[Pirate]

Silly question, but numbers confuse my head. If you have two 500 watt subs running at the same time. Is it technically correct to say you’re running 1000 watts or would it be 500 watts x 2?

[PunkMunkey]

Originally Posted by Pirate

The Hsu I'm looking at pushes 250 watts with a maxiumum extension of 18Hz. Maybe I should just get two of them.

Are you contemplating a pair of the VTF-2Mk3?...If I were you I think I might just opt for a VTF-3 HO. You may get a bit more volume with the two subwoofers, but you'd have an easier time trying to integrate one sub into your room rather than trying to integrate two...you could co-locate two subs (usually accomplished by stacking them) but I don't know if that would work for you aesthetically. The single VTF-3 HO would also be a little less than the dual VTF-2Mk3s.

The VTF-3 HO should be enough sub for your room despite it being a single 12". I'm running an SVS PB-12+ ( gratuitous SVS mention!), which is pretty much the equivalent of the VTF-3 HO in terms of size and wattage, and it's performed well in my "open floorplan" system. You should have no problem reaching the levels you need in your dedicated room with the VTF-3 HO.

Originally Posted by Pirate

Silly question, but numbers confuse my head. If you have two 500 watt subs running at the same time. Is it technically correct to say you’re running 1000 watts or would it be 500 watts x 2?

I think thaat, because you actually have two subs, it's more correct to say 500 watts x 2. The reason being is that just by virtue of adding a second sub, you gain approximately 6dB in volume intensity.

Let me see if I can explain this correctly...

Let's say you have 1 12" sub powered with 1000 watts that can play to 100dB.

The same sub would play to 97dB with 500 watts...the doubling/halving of power to a transducer equates to a 3dB increase/decrease in volume intensity (respectively).

But it you take that single woofer that plays to 97dB with 500 watts and you add sonter exacly like it to the setup, you gain approximately 6dB which would amount to a total system volume of 103db for the two woofers powered at 500 watts each.

I hope that doesn't just confuse the issue even more.

[Pirate]

Originally Posted by PunkMunkey

Are you contemplating a pair of the VTF-2Mk3?...If I were you I think I might just opt for a VTF-3 HO. You may get a bit more volume with the two subwoofers, but you'd have an easier time trying to integrate one sub into your room rather than trying to integrate two...you could co-locate two subs (usually accomplished by stacking them) but I don't know if that would work for you aesthetically. The single VTF-3 HO would also be a little less than the dual VTF-2Mk3s.you need in your dedicated room with the VTF-3 HO.

I was under the impression that I could place the subs to the left and right (next to my fronts) and that would flatten out my overall reponse. Stacking wouldn't be an option.

Originally Posted by PunkMunkey

I hope that doesn't just confuse the issue even more.

I think I understand. Basically.

[Pirate]

Aesthetics are important to me and I do prefer the Velodyne's size. It's much smaller than the Hsu's. I remember when I got my SVS. That damn thing took up half the room.

[PunkMunkey]

[quote=Pirate;880637]I was under the impression that I could place the subs to the left and right (next to my fronts) and that would flatten out my overall reponse. Stacking wouldn't be an option.QUOTE]

That might be a good place to start. However, there are a lot of factors that affect sub response...distance to any walls, distance between main speakers and subs, distance between subs, distance to subs from seating area...you get the idea.

All those factors influnece the sub's response...when you think of sound as waves with peaks and valleys it gets easier to imagine the interferences that might occur between speakers...depending on placement, the sound from one sub may be "cresting" when it reaches the listening position while the sound form the other sub may be "waning"...the soundwaves from the subs would then effectively cancel each out giving you weak bass.

All this can be correctd with placement and by messing with subwoofer phase, but it's a bit trickier than working with just one sub.

You might be able to do the "sub crawl" twice to locate your subs and then dial them in precisely by using the phase adjustments on the subs themselves...this should yeild a good result.

In any case, you really can't just place the subs arbitrarily next to the front speakers and expect the best response...do the "sub crawl" and use an SPL meter to see, for sure, where to best locate them.

[firestorm]

Honestly, I think two subs would automatically be flatter around the room, or, IOW, would have less highs from room gain and nulls from cancellations. I wanted my sub up front, so I had to rearrange the room to get the least "high and low" spots. Two subs, with differing locals in the room would create waves that interact differently in the room. Cancellations might still be an issue, but I don't think that would be an issue as long as they're phased the same.

I still somewhat prefer a sealed sub. Besides being smaller, they don't fall flat on their faces at the frequency that the port is tuned too (i.e. 18Hz). Anything below that frequency can send the sub into uncontrolled frenzies that *could* result in bottoming out or distortion. Sealed subs roll off gradually, whereas a ported/vented sub is flat to the tuned freq., but servo subs like the Velos greatly get around that. I do hate that my non servo sealed sub rolls off as quickly as it does though.

And I'd agree that two subs on separate channels is 500W x 2. Two subs, connected in series (e.g. two 8ohm subs make a 4ohm load) would be one 1000W channel.

[Pirate]

The sub crawl is so degrading, though.

Ideally, I'd like to just have one sub placed where my current one is (under my center channel), but the ones I'm looking at are so big. That Velo SC-12 (even at 600w) would fit just about perfectly. But it only reaches 22Hz.


You guys can probably see the battle raging in my head between watts, frequency response and size.

[Iguana Man]

The reality of the 18hz vs 22hz is this: Would you rather have 18hz sound boomy or 22hz sound controlled/tight?

There is a big difference in just saying I go 4hz lower and actually having the 4hz in your room sound good. And as someone somewhere else said, to get that kind of response out of a sub you will need serious room treatments.

I think for you given where you want to place it, and that both are very good products, the built in EQ's are critical. Anyone know which EQ is most flexible between the HSU's and Velo? I'd look into that for sure.

[Pirate]

Originally Posted by Iguana Man

There is a big difference in just saying I go 4hz lower and actually having the 4hz in your room sound good. And as someone somewhere else said, to get that kind of response out of a sub you will need serious room treatments.

I'm not sure if that's actually the case, at least not with a controlled environment. I asked the question about treatments in a few other places, and most said that it wasn't necessary to achieve the 18Hz. What concerns me about above-18Hz subs is that so many DVDs and BDs seem to go so low. That thread I point you to at AVS has some films hitting 8Hz.

Can I really give people crap about buying fullscreen DVDs if I'm missing so much under 22Hz?

[Iguana Man]

Originally Posted by Pirate

I'm not sure if that's actually the case, at least not with a controlled environment. I asked the question about treatments in a few other places, and most said that it wasn't necessary to achieve the 18Hz. What concerns me about above-18Hz subs is that so many DVDs and BDs seem to go so low. That thread I point you to at AVS has some films hitting 8Hz.

Can I really give people crap about buying fullscreen DVDs if I'm missing so much under 22Hz?

I still stand on how that 4Hz difference sounds dude. I'd rather have a sub that can smack me tight and hard at 25Hz than one that falls apart (but can claim) 18Hz.

[PunkMunkey]

Originally Posted by Pirate

The sub crawl is so degrading, though.

Sometimes it's necessary to degrade onesself for the greater good.

Originally Posted by Pirate

Ideally, I'd like to just have one sub placed where my current one is (under my center channel), but the ones I'm looking at are so big. That Velo SC-12 (even at 600w) would fit just about perfectly. But it only reaches 22Hz.

The problem with that positioning is that it's smack dab in the middle of a wall...which, from what I've read, is one of the more problematic spots for locating a sub as it plays to certain room modes which may mess with bass response.

Originally Posted by Pirate

You guys can probably see the battle raging in my head between watts, frequency response and size.

Yeah...but if you're going to overanalyze something, at least subwoofers are a cool thing to overanalyze .

[Pirate]

Originally Posted by Iguana Man

I still stand on how that 4Hz difference sounds dude. I'd rather have a sub that can smack me tight and hard at 25Hz than one that falls apart (but can claim) 18Hz.

The fact of the matter is that I simply don’t know enough about these numbers and calculations to really disagree with you. It might be that the action under 25Hz makes up such a small amount of content that the extra money/effort is not worth it. If that were the case, I get that nice Hsu VTF-1 and call it a day.

I don't care about claims, or the brand name. I just want to make sure that when something explodes or a string is plucked on a bass guitar, it feels as close to accurate as possible (within my budget).

[PunkMunkey]

Originally Posted by Pirate

The fact of the matter is that I simply don’t know enough about these numbers and calculations to really disagree with you. It might be that the action under 25Hz makes up such a small amount of content that the extra money/effort is not worth it. If that were the case, I get that nice Hsu VTF-1 and call it a day.

I don't care about claims, or the brand name. I just want to make sure that when something explodes or a string is plucked on a bass guitar, it feels as close to accurate as possible (within my budget).

The feeling of 18Hz is an awesome thing . Definitely don't short-change yourself by settling for an under-spec'd sub.

I can understand your predicament...wanting to get the most for your money. In that respect, I'd say but the largest, most powerful sub that your budget and sense of aesthetics can afford then take the time to place it correctly in your room.

The Velodyne products are great performers...but they trade size for expense. Because of thier small size, they're more complex and employ more expensive mechanisms (servos and EQs) to reach the output and frequency response that they specify. The HSU are much bigger, but less complex since they're able to use a larger enclosure to achive their desired output level and response...ergo they're less expensive (realtively speakeing).

In the end, it'll pretty much be a wash...the placement of the sub in your room and the treatments in your room will probably have a greater effect assuming the subs you're looking at are comparable in specs.

[Pirate]

Originally Posted by PunkMunkey

The problem with that positioning is that it's smack dab in the middle of a wall...which, from what I've read, is one of the more problematic spots for locating a sub as it plays to certain room modes which may mess with bass response.

Here is a basic layout of my HT. The arrows indicate where the sub could go.



You see how I'm kinda limited with my placement options.

[PunkMunkey]

Originally Posted by Pirate

You see how I'm kinda limited with my placement options.

Yeah...I had the same problem. Next to the mains would definitely me a good place to start. If you could pull the mains out into the room a bit and place the sub behind the left or right main speaker that might help your response by corner loading the sub.

I still wouldn't locate it centered on the wall...it may be nice and symmetrical that way but it's probably not worth the frequency response issues that you'll likely have.

[Iguana Man]

Originally Posted by PunkMunkey

In that respect, I'd say but the largest, most powerful sub that your budget and sense of aesthetics can afford then take the time to place it correctly in your room.

The Velodyne products are great performers...but they trade size for expense. Because of thier small size, they're more complex and employ more expensive mechanisms (servos and EQs) to reach the output and frequency response that they specify. The HSU are much bigger, but less complex since they're able to use a larger enclosure to achive their desired output level and response...ergo they're less expensive (realtively speakeing).

I agree and keep in mind the SVS situation not long ago. Size doesn't matter in his case.

He's got 3 spots to place the thing by his own admission. Of those 3, what fits best? I say sealed, high output and good EQ.
He's anal like me I think and for the last time PH, I will send you my sub for a demo. PM me your address if you wish. No charge dude.

[Pirate]

I guess that lands me at the Hsu VTF-2.

HSU VTF-2 MK 3 Subwoofer

or I could try SVS again.

[Pirate]

Originally Posted by Iguana Man

He's anal like me I think and for the last time PH, I will send you my sub for a demo. PM me your address if you wish. No charge dude.

That's such a nice offer and it makes me sooooo nervous. What if something happens during shipping? So risky.

[PunkMunkey]

Originally Posted by Pirate

I guess that lands me at the Hsu VTF-2.

HSU VTF-2 MK 3 Subwoofer

or I could try SVS again.

I dunno...in this instance I'd give the edge to the HSU...it'll probabaly net you greater output at lower frequencies. I like the SVS, but for a dedicated theater like your own I'd go ported over sealed...just MHO.

Now pull the trigger before you overthink this any more!

[Pirate]

What is the difference between ported and sealed?