More sub questions...plenty vs. overkill?

[Scrappydue]

I believe it is almost always better to have equipment just loping along rather than all out and strained just to barely be good enough, at least with amplifiers and subwoofers.

Yes, but on the other end... and this is probably a misled and incorrect theory of mine, but I've always thought that subs were meant to actually flex, at least somewhat, and with that in mind, if you were going to listen to them at really low volumes, it would be better to have a smaller number of subs that flexed more rather than a larger number that are fed only a small fraction of what they are meant to handle. I guess I envision somewhat of a threshold that is required to get them to move right and therefore sound right. Not sure if this is true or not.

this would be completely untrue actually. The "flex" you refer to, the more there is the more distortion there is. If you had 30 18's in your room and they all only moved 2-3mm it would be the cleanest bass youve ever heard.

That would be loud as hell too, and they're still flexing somewhat. I'm talking about more quiet than that. Even with two subs at lower levels sometimes the bass is at a level that you actually have to feel the cones to realize that they are doing anything. I've always thought that maybe this doesn't exactly give the best response, that maybe a smaller number of subs flexing 2-3mm might provide more accurate feedback than several that wasn't hardly even moving, just kind of vibrating. I don't know if there is a threshold to get the things going properly at least after they are broken in. Before that there does seem to be.

your defector ion if flex is much different than most. 2-3mm is barely moving.

[Paducah Home Theater]

your defector ion if flex is much different than most. 2-3mm is barely moving.

Forget reference level home theater explosions at 15 hz for a minute and put your audiophile cap on. Let's listen to a low volume recording of Pachelbel's Canon in D with a cello or low key antique organ playing the bass line, at a quiet spot like at 1:55 below, with the output no louder than it would sound live. Is 30 18's still the best sounding solution if cost and size were no issue? I can't see it. Seems like the wattage would be spread so thin that the things wouldn't sound optimal, and if it wasn't then it would be too loud, but this may be wrong.

Edited February 18, 2015 by MetropolisLakeOutfitters

[Scrappydue]

I'll watch it when I get home tonight but I can't imagine thinking smaller woofers would ever be better than larger woofers. Just cause a woofer isn't moving doesn't mean it isn't doing anything. A 18 moving less will provide less distortion in bass than a 10 moving more.

[CECAA850]

A 18 moving less will provide less distortion in bass than a 10 moving more.

 

All things being equal that is correct.

 

The whole point of horn loading or using multiple drivers is to reduce cone movement which in turn reduces distortion for any given SPL.

[babadono]

 

A 18 moving less will provide less distortion in bass than a 10 moving more.

 

All things being equal that is correct.

 

The whole point of horn loading or using multiple drivers is to reduce cone movement which in turn reduces distortion for any given SPL.

 

Yes let's not forget who's Forum we're on

[Trentster5172]

How about Pete Belasco's Deeper? Great jazz song with deep musical bass. Done right it's musical bliss from my R-115SW's at high and low volume. With too much from my subs the brown note will cause you to Poo your pants and put your house foundation at risk. I'm telling you these R-115SW's bump.

[Paducah Home Theater]

All things being equal that is correct.

 

The whole point of horn loading or using multiple drivers is to reduce cone movement which in turn reduces distortion for any given SPL.

Disclaimer: I admit my theory probably has little or nothing to do with the real world and is solely me just being a nerd.

I guess I'm hung up on friction at very low levels. Are subs immune to friction? It's a basic law of physics, I'm not sure how they couldn't be. As an example, think about pushing a car by hand while it is in neutral with the engine not running. At first it is hard to get it going, you can push on it lightly and even moderately but it just doesn't move. Once it is rolling it is easier to keep it rolling. Is there nothing in the speaker world where such a phenomenon requires there to be an absolute minimum threshold that they need to actually work correctly, however tiny that may be? I mean, is it even possible to make 30 big 18's whisper at a quiet fan level of around 20 db... combined? I don't see how that would be possible but it may very well be. If it isn't, then there must be some absolute minimum power required to overcome internal friction. Seems like there's got to be anyway, but it may be so miniscule that it can't be heard or even measured effectively.

[derrickdj1]

Who wants 30 subs?  Larger subs have larger motors, not an issue at soft or loud listening levels.  Now there is intergal calculus where you are chasing infinity and never get there.    Four subs or  four areas of stacked subs will give the best room response.  Metro, if you are ever in Indiana, you have an open invite to hear my system.

[CECAA850]

 

All things being equal that is correct.

 

The whole point of horn loading or using multiple drivers is to reduce cone movement which in turn reduces distortion for any given SPL.

Disclaimer: I admit my theory probably has little or nothing to do with the real world and is solely me just being a nerd.

I guess I'm hung up on friction at very low levels. Are subs immune to friction? It's a basic law of physics, I'm not sure how they couldn't be. As an example, think about pushing a car by hand while it is in neutral with the engine not running. At first it is hard to get it going, you can push on it lightly and even moderately but it just doesn't move. Once it is rolling it is easier to keep it rolling. Is there nothing in the speaker world where such a phenomenon requires there to be an absolute minimum threshold that they need to actually work correctly, however tiny that may be? I mean, is it even possible to make 30 big 18's whisper at a quiet fan level of around 20 db... combined? I don't see how that would be possible but it may very well be. If it isn't, then there must be some absolute minimum power required to overcome internal friction. Seems like there's got to be anyway, but it may be so miniscule that it can't be heard or even measured effectively.

 

 

 

I guess I don't understand the friction concept that's hanging you up.  The face of the driver is pretty much suspended with the rubber surround and the spider.  The voice coil hangs off the back underneath the spider.  The driver moves when current passes through the voice coil and reacts with the magnets.  They'll play as quiet as you can regulate the current going to it.  I suppose there's a minimum amount of current required before they actually produce sound (or move) but it has to be awfully small.  I can turn a sub down so low that you can't hear it but yet you can still feel a slight vibration when you put your hand on the face of the driver.

[artto]

Having multiple subs will usually result in smoother overall deep bass response regardless of the (usable) listening/viewing location. The frequencies being produced have very long wavelengths, much longer than any dimension of your room. Consequently the reflections tend to build-up or cancel at various locations within the room, depending on where you are located, relative to the subwoofer(s).

 

The basic idea is that using multiple subwoofers will allow all the frequencies to be heard at more locations because you will more likely be hearing something from one or more of the subwoofers without cancellations regardless of where you sit, and it's less likely that all the subwoofers would sum together at any particular frequency or location.

 

In my listening room (about the size of your room) I use four 2x15 parallel drive subs (parallel drive substantially reduces cabinet/enclosure resonance/vibration). Each has it's built-in 600 watt RMS/1500w peak power amplifier. Two are located in the back corners. Two are used as pedestals for the L&R main speakers. They are about 6' from the front wall and about 2' from the side walls.

 

For *most* reproduction, yes, it's overkill. For music, most of the time, provided the low bass is on the recording, it adds just the right amount of "weight" to the sound. However, when called upon the output is both extremely prodigious and completely effortless.

 

Three to four subwoofers seem to be about optimum for most home systems. In most cases there's little if anything to be gained by adding more than that.

Edited February 18, 2015 by artto

[artto]

 

I believe it is almost always better to have equipment just loping along rather than all out and strained just to barely be good enough, at least with amplifiers and subwoofers.

 

Yes, but on the other end... and this is probably a misled and incorrect theory of mine, but I've always thought that subs were meant to actually flex, at least somewhat, and with that in mind, if you were going to listen to them at really low volumes, it would be better to have a smaller number of subs that flexed more rather than a larger number that are fed only a small fraction of what they are meant to handle.  I guess I envision somewhat of a threshold that is required to get them to move right and therefore sound right.  Not sure if this is true or not.  

 

Yes, that is a misled and incorrect theory.

 

All speakers (aka drivers) are meant to NOT "flex". Flex can create all kinds of distortion(s) including but not limited to frequency modulation, harmonic distortion, phase non-linearity, etc. On the other hand if your reference to "flex" means simply moving back & forth, which is referred to as displacement/excursion, then again, moving back & forth a shorter distance is better than larger excursion.

 

There is no "start-up voltage" per se' as you are imagining. All speakers, even the most sensitive and efficient require plenty more power to meet that threshold, if indeed there is one.

 

Remember, even at a low frequency of 20Hz, the driver is initally at rest, and must accelerate forward, then come to a complete stop, reverse direction, and come to a complete stop once again before it can reverse and accelerate in the other direction, and it must do this twenty times in one second. Is it easier or more difficult to do this having to move through a peak to peak excursion distance that is shorter, or longer? Shorter, is of course easier.

 

In my above mentioned system, if I play something with very formidable low-end sound, say the Telarc recording of Tchaikovsky's 1812 overture with the real canon shots, or something with deep loud synthesizer (Peter Gabriel's UP or Insane Clown Posse) or a recording of the Space Shuttle launch or a coal train, when played at much louder levels than I would ever listen to for sustained periods, those eight 15" subwoofers can barely be seen moving. 

Edited February 18, 2015 by artto

[DaveWJr]

Why not get a pair of R-115SWs? A pair would do quite well in that space.

 

http://www.klipsch.com/R-115SW

This. People can say what they want on this forum, but unless you've heard a pair of these in a large room (trust me when I say our listening rooms are quite sizable), you won't appreciate what they can deliver.

 

The notion of "too much sub" is also false. I tried to get this on our blog since people keep asking if a 115 will match with a set of RP 250Fs. Irrelevant. Even if you have 4, that doesn't mean you'd run them each at the same input voltage as if you had just 1.

 

Ideally, you should have 8 subs in a rectangular room: one in each corner which would negate the room mode effects. Reason being, no matter where you put a sub in a room, the corners are always loaded the most strongly. Hence, you instead load all corners as sources, and the net response is the smoothest possible. This might not be feasible for most.

[DaveWJr]

 

All things being equal that is correct.

 

The whole point of horn loading or using multiple drivers is to reduce cone movement which in turn reduces distortion for any given SPL.

Disclaimer: I admit my theory probably has little or nothing to do with the real world and is solely me just being a nerd.

I guess I'm hung up on friction at very low levels. Are subs immune to friction? It's a basic law of physics, I'm not sure how they couldn't be. As an example, think about pushing a car by hand while it is in neutral with the engine not running. At first it is hard to get it going, you can push on it lightly and even moderately but it just doesn't move. Once it is rolling it is easier to keep it rolling. Is there nothing in the speaker world where such a phenomenon requires there to be an absolute minimum threshold that they need to actually work correctly, however tiny that may be? I mean, is it even possible to make 30 big 18's whisper at a quiet fan level of around 20 db... combined? I don't see how that would be possible but it may very well be. If it isn't, then there must be some absolute minimum power required to overcome internal friction. Seems like there's got to be anyway, but it may be so miniscule that it can't be heard or even measured effectively.

 

What you are talking about is not actually friction, it's momentum. Momentum (as Newton would like us to know it) is p = m*v, where m is mass and v is velocity. Newton, not coincidentally, also said that F = ma. That means then that your momentum, is p = (F/a) * v. A little reduction shows that the net result is p = F*t, t being in time in seconds. For your car, this means that if you want to bring the car back to a standstill, you need to put in exactly as much effort as you did in the beginning, but if you want to stop it in less time (decelerate, or negative acceleration) aka more quickly than you brought it up to speed, you need to try harder (put in more force).

 

What this means for us speaker people is that accelerating a driver cone like you're accelerating a car from a standstill requires force. Once it is in motion, it does not require further force to keep it in motion (with zero losses, naturally ). Force in the speaker world is BL*i, with i being your input current. So, as long as you have some specific input current and a motor on the speaker (which of course you do), there is no reason why your 30 drivers can't move very little and produce exactly what you're asking. The large number of them just means you don't need a lot of force to create the same SPL. The summing of multiple sources takes care of that.

 

Long story short: there is no such thing as too many subs, and if you vary the input accordingly, they can do what your one sub can do. The opposite is not true.

Edited February 19, 2015 by DaveWJr

[mustang guy]

 

Why not get a pair of R-115SWs? A pair would do quite well in that space.

 

http://www.klipsch.com/R-115SW

This. People can say what they want on this forum, but unless you've heard a pair of these in a large room (trust me when I say our listening rooms are quite sizable), you won't appreciate what they can deliver.

 

The notion of "too much sub" is also false. I tried to get this on our blog since people keep asking if a 115 will match with a set of RP 250Fs. Irrelevant. Even if you have 4, that doesn't mean you'd run them each at the same input voltage as if you had just 1.

 

Ideally, you should have 8 subs in a rectangular room: one in each corner which would negate the room mode effects. Reason being, no matter where you put a sub in a room, the corners are always loaded the most strongly. Hence, you instead load all corners as sources, and the net response is the smoothest possible. This might not be feasible for most.

 

Four subs is easy enough, but 8? Klipsch should sell hangers for ceiling subs.  

 

A while back, Carl quoted a research that said 4 subs centered on opposing walls created the best overall listening experience. My question is this. If you have 4 subs, and speaking of room modes, are they better in the 4 floor corners, or centered on opposing walls?

[CECAA850]

4 corners would be slightly louder.  4 centered would give a slightly better response but they were close.  That's how I remember reading it anyways.

[dewthedru]

Who wants 30 subs? Larger subs have larger motors, not an issue at soft or loud listening levels. Now there is intergal calculus where you are chasing infinity and never get there. Four subs or four areas of stacked subs will give the best room response. Metro, if you are ever in Indiana, you have an open invite to hear my system.

I'm in Indiana. Just sayin'. ;-)

[DaveWJr]

 

 

Why not get a pair of R-115SWs? A pair would do quite well in that space.

 

http://www.klipsch.com/R-115SW

This. People can say what they want on this forum, but unless you've heard a pair of these in a large room (trust me when I say our listening rooms are quite sizable), you won't appreciate what they can deliver.

 

The notion of "too much sub" is also false. I tried to get this on our blog since people keep asking if a 115 will match with a set of RP 250Fs. Irrelevant. Even if you have 4, that doesn't mean you'd run them each at the same input voltage as if you had just 1.

 

Ideally, you should have 8 subs in a rectangular room: one in each corner which would negate the room mode effects. Reason being, no matter where you put a sub in a room, the corners are always loaded the most strongly. Hence, you instead load all corners as sources, and the net response is the smoothest possible. This might not be feasible for most.

 

Four subs is easy enough, but 8? Klipsch should sell hangers for ceiling subs.  

 

A while back, Carl quoted a research that said 4 subs centered on opposing walls created the best overall listening experience. My question is this. If you have 4 subs, and speaking of room modes, are they better in the 4 floor corners, or centered on opposing walls?

 

In this situation, I would definitely put them equally spaced in such a cross arrangement. That's likely the path to the smoothest in room response since the distance from source to boundary will always be minimized in the dimensions you have control over.

[DrWho]

Why not get a pair of R-115SWs? A pair would do quite well in that space.

 

http://www.klipsch.com/R-115SW

 

Ideally, you should have 8 subs in a rectangular room: one in each corner which would negate the room mode effects. Reason being, no matter where you put a sub in a room, the corners are always loaded the most strongly. Hence, you instead load all corners as sources, and the net response is the smoothest possible. This might not be feasible for most.

I think if you were to actually measure that, you'd find that your statement is false. There's a popular article about ideal subwoofer placement and the eight corners do not remove room modes. Maybe someone not on their phone can post it. The only solution I've seen is the dual zoned bass array.

[Bryant0086]

i moved from a place that had a fairly small basement where my trusty old HSU STF-3 never failed to move me. my current HT is much larger and i'm thinking i need to upgrade. i'm torn between DIY 18"s or getting 1 or 2 HSU VTF-15H's. i've actually toyed with the idea of just picking up another stf-3 but i can't find one anywhere. i've searched craigslist for the last year or so without any luck. 

my HT space is about 550 sq ft with 8.5' tall ceilings and carpeted concrete floors.  i've included the layout.

what do you think? would a single VTF-15 be plenty? i know more is always better but if it's totally overkill, i don't want to just throw money away. and i know some of you have already recommended building a couple of stonehendge 18"s but i don't want the bass to be ridiculous compared to the rest of my setup. (RF-35 fronts, RC-35 center, and RS-35 surrounds)

thoughts?

  Well since you said you would be interested in a DIY project, there are many out there you can google. They have everything from a small sealed 18 to a horn loaded one that isn't a difficult build, though it is QUITE large.

 

  Cinema F20

 

 

 

  Bryant

[DaveWJr]

 

 

 

Why not get a pair of R-115SWs? A pair would do quite well in that space.
 
http://www.klipsch.com/R-115SW

 
Ideally, you should have 8 subs in a rectangular room: one in each corner which would negate the room mode effects. Reason being, no matter where you put a sub in a room, the corners are always loaded the most strongly. Hence, you instead load all corners as sources, and the net response is the smoothest possible. This might not be feasible for most. 

I think if you were to actually measure that, you'd find that your statement is false. There's a popular article about ideal subwoofer placement and the eight corners do not remove room modes. Maybe someone not on their phone can post it. The only solution I've seen is the dual zoned bass array.

 

I bet I would as well. Acoustic theory states as such only, hence why I said ideally (and hence why someone actually tested it per your statement). That was not intended to be taken seriously.

Edited February 19, 2015 by DaveWJr