AudioNervosa
Systemic Development => Speakers => Topic started by: Werd on December 26, 2014, 03:00:13 PM
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What is the best method for picking a sub, do you look at the size of the woofer vs the main speakers drivers? Or is it the room and placement that dictates the type of sub woofer size and choice?
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What is the best method for picking a sub, do you look at the size of the woofer vs the main speakers drivers? Or is it the room and placement that dictates the type of sub woofer size and choice?
Budget is the primary driver of sub choice.
Generally:
Sealed is lower distortion than ported.
Bigger woofer is lower distortion than smaller.
Bigger sounds better and more relaxed than smaller woofers.
Stereo subs are better than single.
Ported is good for HT, but expensive ported can be good enough for music.
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Infinite Baffle, if you'e got the space. Obviously, the determining factors there are space and a desire to feel your pant legs, kidneys, and the hair on your head resonate.
Open baffle for the clarity and non "muddy, boomy" sometimes heard with other designs.
Both can create the tactile, visceral punch in the chest if the content requires it.
Bob
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I just got a sub for my Nola Boxers. I spoke with Carl Marchisotto from Nola and his only advise was to get a sub with as small a driver as possible because the boxer has a 6.5" woofer and if I got something with a 12' driver it would have a hard time keeping up with the speed of the Nolas.
Well I ended up getting a Sunfire True Subwoofer Super Jr, which has a 7.5" driver and it integrates very well with the Nolas. As a matter of fact last night we were listening to the system and my son said "I know the bass is better because I know what this recording sounded like before, but I'll be damned if I can hear the woofer. It just blends right in and doesn't call any attention to itself."
So like anything else in this hobby synergy plays a huge role in what works well in a particular system and in picking a sub I think one of the first thing one must do is evaluate the bass characteristics of your present speakers and figure out what type of sub will mate well with them so as to enhance the sound of the system as a whole.
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That's interesting. you got a woofer smaller than your mains.
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Hi, all.
This is timely for me as I am seriously considering buying the new Rythmik Double 8" sealed sub. I actually want two but financial constraints prevent my buying the second for now. :( Eventually I'll have two - one per monitor in my system.
If I had the room for them I'd consider OB, but room limitations and WAF don't allow this.
Michael
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For myself, the biggest factor is if it has the capability to keep up with my mains. I think sonically matching a sub to the mains is critical (if primarily for 2-channel listening). A sub for me has to be very fast. I prefer using high effeciency woofers for a sub. I would give up a few low end Hz before sound quality.
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I wonder if Tmazz's strategy is correct on the size of the sub woofer for maximum integration? Or is it just the quality of that sub? hmm
This could be a possible leveling plateau here. I never once considered using a smaller woofer sub. I see the logic in it. Bigger subs tend to draw attention to them selves. (Well with the speakers i use anyways). While a smaller sub allows the mains to still play boss. I don't see any speaker type not benefiting from this. Maybe panels might not react the same or matter.
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Depends on the content you're feeding it too. Smaller isn't necessarily better because it's faster. The old adage, "there's no replacement for displacement", still holds true. Especially if you're listening habits dictate it to be the case.
Bob
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I wonder if Tmazz's strategy is correct on the size of the sub woofer for maximum integration? Or is it just the quality of that sub? hmm
This could be a possible leveling plateau here. I never once considered using a smaller woofer sub. I see the logic in it. Bigger subs tend to draw attention to them selves. (Well with the speakers i use anyways). While a smaller sub allows the mains to still play boss. I don't see any speaker type not benefiting from this. Maybe panels might not react the same or matter.
Bigger is better because bigger means higher acoustic impedance which means playing lower, louder and less distortion with less power. There are lots of tricks engineers can apply to make small drivers play low, loud and clean, but never as clean as a large driver. And never as satisfying at low volumes, because a small cone can never have as high acoustic impedance as large cone.
The sense of speed in bass is a misnomer. All bass is slow. The illusion of fast bass comes from the midrange detail that is added to the bass frequencies. When midrange and bass bands are not in sync it sounds like slow bass. The misaligned phase of different frequencies is also called group delay. Good phase integration causes the illusion of fast bass.
Reflex ports have very high phase distortion, very high group delay.
The reflex ports on the main speakers have to be sealed to eliminate their phase distortion, to allow good phase integration with a separate subwoofer. Only the lowest playing speaker should be ported, if necessary. A sealed speaker has much less phase distortion that a port.
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Depends on the content you're feeding it too. Smaller isn't necessarily better because it's faster. The old adage, "there's no replacement for displacement", still holds true. Especially if you're listening habits dictate it to be the case.
Bob
But what if the main objective is sweet spot imaging? More bass weight due to powered extension.
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I wonder if Tmazz's strategy is correct on the size of the sub woofer for maximum integration? Or is it just the quality of that sub? hmm
This could be a possible leveling plateau here. I never once considered using a smaller woofer sub. I see the logic in it. Bigger subs tend to draw attention to them selves. (Well with the speakers i use anyways). While a smaller sub allows the mains to still play boss. I don't see any speaker type not benefiting from this. Maybe panels might not react the same or matter.
Bigger is better because bigger means higher acoustic impedance which means playing lower, louder and less distortion with less power. There are lots of tricks engineers can apply to make small drivers play low, loud and clean, but never as clean as a large driver. And never as satisfying at low volumes, because a small cone can never have as high acoustic impedance as large cone.
The sense of speed in bass is a misnomer. All bass is slow. The illusion of fast bass comes from the midrange detail that is added to the bass frequencies. When midrange and bass bands are not in sync it sounds like slow bass. The misaligned phase of different frequencies is also called group delay. Good phase integration causes the illusion of fast bass.
Reflex ports have very high phase distortion, very high group delay.
The reflex ports on the main speakers have to be sealed to eliminate their phase distortion, to allow good phase integration with a separate subwoofer. Only the lowest playing speaker should be ported, if necessary. A sealed speaker has much less phase distortion that a port.
You know what i mean though? A single sub tends to draw focus to the sub. It just with a generic set up. Never tried with a nice xover with good phase like a Bryston pro xover.
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Imaging on a subwoofer?
Maybe I'm missing something. That's a new one to me.
Mine start in the fiftyish range. Somewhere around there, there isn't any imagining.
Clarify?
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That's interesting. you got a woofer smaller than your mains.
No, it's bigger, but not by much. The Nola Woofers are 6.5" and the sub is 7.5 x2 (one active driver and one passive radiator.)
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I wonder if Tmazz's strategy is correct on the size of the sub woofer for maximum integration? Or is it just the quality of that sub? hmm
This could be a possible leveling plateau here. I never once considered using a smaller woofer sub. I see the logic in it. Bigger subs tend to draw attention to them selves. (Well with the speakers i use anyways). While a smaller sub allows the mains to still play boss. I don't see any speaker type not benefiting from this. Maybe panels might not react the same or matter.
IMO it has to be both. I don't think smaller is neccesarily better, but in my case it was a better match for my mains. I don't think that a bigger woofer, properly matched and set up will draw more attention to itself tan a smaller one. I think the key to a woofer not calling attention to itself is to pick one that has similar sonic characteristics to your mains so you are not starting out with a disconnect before you even try to set them up.
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Depends on the content you're feeding it too. Smaller isn't necessarily better because it's faster. The old adage, "there's no replacement for displacement", still holds true. Especially if you're listening habits dictate it to be the case.
Bob
Again Bob, the woofer you pick needs to blend with not only your system, but also your room and your your musical preferences (like everything else in your system) I went for smaller drivers because I am running a smaller monitor speaker in a relatively small listening space. Had I not moved and was still in my basement mancave, there is now way this sub would have done the job (heck, if I was still in that room I would be using the Thiel CS-^s and wouldn't need a sub at all.) Looking at the specs on the Sunfire Jr it definitely does not go as low nor play as loud as other Sunfire models, But it fits my needs right now. Anything much louder than it plays now would just end up overloading the room acoustically and be a waste anyway.
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Imaging on a subwoofer?
Maybe I'm missing something. That's a new one to me.
Mine start in the fiftyish range. Somewhere around there, there isn't any imagining.
Clarify?
I was refering to imaging on the mains, while improving bass response that doesn't amplify nodes all around the room. Basically trying to improve the mains bottom end weight with out sounding like there is a sub in play. I am talking bass guitar, bass drum resolution that appears in the sweet spot. I sit pretty close to my speakers in a pretty big room. Moving air with slam isn't a priority at all actually.
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I wonder if Tmazz's strategy is correct on the size of the sub woofer for maximum integration? Or is it just the quality of that sub? hmm
This could be a possible leveling plateau here. I never once considered using a smaller woofer sub. I see the logic in it. Bigger subs tend to draw attention to them selves. (Well with the speakers i use anyways). While a smaller sub allows the mains to still play boss. I don't see any speaker type not benefiting from this. Maybe panels might not react the same or matter.
Bigger is better because bigger means higher acoustic impedance which means playing lower, louder and less distortion with less power. There are lots of tricks engineers can apply to make small drivers play low, loud and clean, but never as clean as a large driver. And never as satisfying at low volumes, because a small cone can never have as high acoustic impedance as large cone.
The sense of speed in bass is a misnomer. All bass is slow. The illusion of fast bass comes from the midrange detail that is added to the bass frequencies. When midrange and bass bands are not in sync it sounds like slow bass. The misaligned phase of different frequencies is also called group delay. Good phase integration causes the illusion of fast bass.
Reflex ports have very high phase distortion, very high group delay.
The reflex ports on the main speakers have to be sealed to eliminate their phase distortion, to allow good phase integration with a separate subwoofer. Only the lowest playing speaker should be ported, if necessary. A sealed speaker has much less phase distortion that a port.
Rich I think what most people are referring to as speed is really tightness. While I agree that bigger is better in theory, bigger also means in most cases heavier and heavier tends to lead to overshoot. (like everywhere else in our system, each design decision comes with its own set of tradeoffs.) A heavier driver gains more inertia when it is moving forward and when the polarity of the input signal changes a certain amount of that signal is required to slow down the driver to a stop before it change direction.The amount of time that the driver is slowing down but had not yet changed direction causes a loss of clarity in the bass and makes it sound rounded and tubby, I think that is what people are perceive as slow bass response. Many years ago I had an old Dahlquist Sub which had big heavy paper woofers. It would over shoot very badly and sounded very loose until I turned it around and put it only a few inched from a cement wall. The wall acted as a type of breaking mechanism as the build up in pressure between the front of the sub and the wall would put an external fore on the woofer that would help slow it down and reduce the overshoot, making it sound much tighter. Unfortunately I got this sub not long after I got married and moved into our first apartment. When I bought my first house I was very happy to gain a basement mancave, but the walls in that mancave were hollow and resonated terribly when I loaded to woofer onto them, so it was hello mancave, goodbye Dahlquist woofer. :roll:
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But what if the main objective is sweet spot imaging? More bass weight due to powered extension.
I know what you mean that deep bass can be distracting. It is especially a problem with ported bass. A sealed box rolls off at the same rate that the room supports the bass, making a net flat response. The size of the woofer being the adjustment variable. Ported extends farther, then rolls off at 24dB/octave. So you get a net bump in the FR when you add in room support. This is great for HT and dancing where you want big thump, but it can distract the attention and sound unnatural for music.
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That's interesting. you got a woofer smaller than your mains.
No, it's bigger, but not by much. The Nola Woofers are 6.5" and the sub is 7.5 x2 (one active driver and one passive radiator.)
Dam... Back to the drawing board. :rofl:
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You know what i mean though? A single sub tends to draw focus to the sub. It just with a generic set up. Never tried with a nice xover with good phase like a Bryston pro xover.
A bryston crossover will maintain coherent phase if you seal the main speaker's ports and turn off the subs built in crossover. Either set it to LFE (external control) or turn the crossover frequency as high as possible with steep as possible low pass filter.
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I can't remember where I read it but I remember an article that turned a lot of the conventional "small sub is faster" thinking upside down and made some sense to me.
Greatly oversimplifying here, but a 7.5" driver has a surface area of 56.25 sq in. A 15" driver has a surface area of 225 sq in, for a ratio of 4:1.
The 15" driver is most likely not going to weigh 4x as much as the 7.5". Therefore to move X amount of air, the 7.5" has to travel 4 times farther than the 15". Now which driver do you think will be able to displace this air faster? Which driver has to achieve a faster maximum velocity and therefore needs the greatest acceleration (greatest demands on fast, accurate start/stop) in order to accomplish this?
The article's position was that the 15" will be the faster and tighter woofer because it's just so much easier for it to do the job that's being asked of it.
I've been subwoofer shopping myself to augment my Revel F206s (run full range) and I think each owner really needs to assess their individual needs vs. the features offered by each sub.
For example, the much heralded and surely fabulous SVS SB-2000 has a minimum low pass cut-off of 50 hz which will be too high for my speakers. (I know, those frequencies on the dial are sometimes not very accurate) while the B&W ASW610XP minimum low pass is at 25 hz. One reviewer said that a 25 hz cutoff is useless (he must have been speaking home theater-wise) when it is the exact feature that is important to me.
I've been focusing on brands I can get from family members who own shops (B&W, DefTech, Martin Logan etc.) but will probably pick up a used Aperion Audio Bravus II 12D my brother tok on trade that will cost me $300. I don't think I can do better than that for the $$.
Anyway, good hunting Werd.
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........ I think each owner really needs to assess their individual needs vs. the features offered by each sub.
Mike I think this statement hits the nail right on the head. Al the technical stuff you were talking about makes sense from a theoretical basis, (although we must also remember that the driver size itself ids only one of many choices made in a subwoofer design, each one of them influences the final sound), but all I can say is that I spoke with the designer of my speaker who said it would mate best with a small driver sub, and the combo seems to work for me. (in my room, with my system.) Granted it does not produce thunderous amounts of low bass, but I was never really looked to do that in the first place. It just fills in the lower octaves that the small size of the Boxers preclude it from producing, while still keeping the same overall character of the original speaker.
The small sub did what I was looking to do with my system. People who have other objectives would probably be best off looking at other designs that would better match their needs and equipment, which I guess was the point of my first post in this thread. Synergy, synergy, synergy........
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High acoustic impedance (https://en.wikipedia.org/wiki/Acoustic_impedance) is what big drivers have that makes them better suited to playing LF than small area drivers.
Bigger drivers grip the air better, and that provides a lot of advantages. Air slippage of a small cone is distortion, lost efficiency and lost detail. Bass drivers will never have the kind of acoustic loading that tweeters do, in terms of a ratio of diaphragm area to wavelength created, so we will never get that level of detail from bass drivers.
The advantage of a big driver over a small bass driver is similar to rowing with oar facing the water load, compared to cutting through it with the oar edge. The flat oar moves the water particles, creates a LF pressure wave whose opposite reaction moves the boat. An edge-slicing oar moving at the same speed simply allows the water molecules to slip by. But if you move the oar edge quickly enough through the water, the impedance at the edge would increase enough to move the boat. Same as a tweeter only needs a small dome, because it is moving faster.
A small woofer moves too slow to launch a wave efficiently. The air just spills out of the cone rather than explode forward. A big driver spills some air over the side, but some still remains in the center unable to escape and this trapped air causes the wave launch. The bigger the driver, the more air is trapped on the surface, cruched against the cone to create pressure, then released as the driver reverses to launch the wave.
When the small driver plays louder it is moving at faster velocity even though it is the same low freq. This is why small speakers need more volume to wake up and sound good. This is also why big speakers sound so satisfying at very low volume level, they grip the air and make clear undistorted bass even when they are moving very slowly on low notes played very softly.
The only potential problem with large drivers is overpowering a room. A sealed driver falls off at 12dB/oct, which matches the rising response of the room supporting FR into low freqs. When the sealed driver is sized correctly, it's rolloff will match the rising response of the room to make flattish FR. If the woofer is too big, the perceived FR will increase into lower Freq. This is very easy to correct with a single cap to make a high pass filter to cancel the net gain of the driver over the room. The shittiest cap in the world would sound fine at 40hz. The added dynamic range and tonal detail that you would gain from the oversized cone would more than make up for the hassle of adding a cap. This is why people put twenty 15" IB subs into their walls. It's all about detail and dynamics. The level is still matched, it's not about the loudness. But they want their subs to sound as detailed and exciting as midrange horns. Bass horns are a good example of this. A horn is nothing more than an impedance transformer.
edit: Actually, unless the woofers are directly next to each other, they can't combine forces to lower the impedance. If there is space between them, like a swarm of subs around the room, there is no impedance advantage over a single sub, they won't pay lower, only louder (and better room modes.) But if multiples are adjacent like a line array then impedance can increase and the array can play lower than individual drivers alone.
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Here's a trick if you want your subwoofer to sound "faster"/"quicker".
1. Forget the setup instructions about putting the sub in a corner.
2. Put the sub somewhere near the middle between speakers, or maybe just off to one side, but only by one wall, not in a corner
3. Turn a down-firing sub upside down so the speaker now fires up.
4. Get a piece of wood or a large carving board and rest it on the upturned feet, then put something heavy on top.
5. If you have a front firing sub get it up off the ground by raising it on some concrete blocks or something similar.
6. Then adjust it, but make sure your crossover point on the sub adjustment is below the bottom end of your speakers. So if your speakers bottom end goes down to about 40Hz, set your sub up at about 30-35Hz. Then adjust the volume of the sub to integrate. And don;t forget sub polarity, use the one that sounds loudest.
Enjoy,
Bob
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Here's a trick if you want your subwoofer to sound "faster"/"quicker".
1. Forget the setup instructions about putting the sub in a corner.
2. Put the sub somewhere near the middle between speakers, or maybe just off to one side, but only by one wall, not in a corner
3. Turn a down-firing sub upside down so the speaker now fires up.
4. Get a piece of wood or a large carving board and rest it on the upturned feet, then put something heavy on top.
5. If you have a front firing sub get it up off the ground by raising it on some concrete blocks or something similar.
6. Then adjust it, but make sure your crossover point on the sub adjustment is below the bottom end of your speakers. So if your speakers bottom end goes down to about 40Hz, set your sub up at about 30-35Hz. Then adjust the volume of the sub to integrate. And don;t forget sub polarity, use the one that sounds loudest.
Enjoy,
Bob
Subs are a mystery to me. I've owned only one sub, a Paradigm 15 Servo. Bought it new in 1998. (A pile of shit actually) lousy cabinet rattles all to hell. Well its not that bad since i don't push it. It does use an outboard xover which is a big bonus but still a lousy cabinet.
When adjusting phase i do listen for loudest but is phase relevant to listening position only? So if i am getting the loudest where i am standing at the xover adjusting is it the same at the listening seat? Am I getting the same phase adjustment at my listening chair. Again subs are abit of a mystery to me, maybe more than a bit.
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When adjusting phase i do listen for loudest but is phase relevant to listening position only? So if i am getting the loudest where i am standing at the xover adjusting is it the same at the listening seat? Am I getting the same phase adjustment at my listening chair. Again subs are abit of a mystery to me, maybe more than a bit.
For practical purposes, yes, phase should sync at the listening position. This will account for any sub location, as long as it is closer to you than the mains. Farther away cannot be synced unless you delay the mains. If the sub was placed under the main speaker then it wouldn't matter where you were when you set the phase because the distance from both of them to you would always be the same.
Any easy way to set the phase is to set the phase switch to 0, or turn the phase knob to 0 and then place the center of the sub cone the same distance to your ears as is the main woofer.
http://www.theabsolutesound.com/articles/a-guide-to-better-bass-tas-197-1/
I think this is the article in which Harley describes his sub integration method, where he inverts the polarity of the sub, which makes a notch instead of a peak. He says a notch is easier to hear than a peak. Then play a sinewave of the crossover freq. Move the sub closer and farther, or turn the phase knob until it is quietest. The sub must be equal or lesser distance than the mains to your ears or you can't sync phase without a processor to delay the mains.
If you have a computer connected to the stereo, you can use WinISD Beta to generate a sinewave, also JRiver has prerecorded test tracks. If no computer is on the stereo, then Audacity DAW can create the signal, which you can burn to a CD.
Good advice Bob. Minimize reflective surfaces near the sub for more clarity.
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I've been focusing on brands I can get from family members who own shops (B&W, DefTech, Martin Logan etc.) but will probably pick up a used Aperion Audio Bravus II 12D my brother tok on trade that will cost me $300. I don't think I can do better than that for the $$.
Anyway, good hunting Werd.
Screw spending money if need not be.
And Thanks
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It is more than the sub or subs. The amplifier feeding the mains needs to be attenuated with a high pass filter to ease the load of the mains drivers. That in itself will improve the performance of the mains.
Using a plate amp with accurate crossover points like a Rhythmic allows one to dial in "by ear" the best integration of such.
Using a servo controlled sub in a sealed or Ob configuration will yield tighter and accurate bass.
Dual subs offer better imaging of the low frequencies and do not meld right and left like a stereo sub. There is information in both channels which are not equal.
Choosing a sub to match ones mains must start with efficiency of the drivers. Have 90 db speakers well a 90db sub would be a good choice.
room position is also key. dual subs require space. At least 4ft from walls and 4ft away from mains. So if the room does not allow for that look a speaker that does not need a sub.
charles
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All excellent stuff thanks everyone! The recent posts by Richidoo and
Rollo informative.