[music_man]

i have two very high end subs. the drivers barely move yet they put out prodigious amounts of bass. the volume is set very low or it is overwhelming. the cross over is set as it should be for the loudspeakers. i just thought that the drivers would have to really be pumping to move enough air to get that amount of bass. if i turn them off it is evident what they are providing so it is not the loudspeakers. i have had lower end subs that would have quite a bit of excursion to do their job. I can't see how they are moving enough air to shake the building without massive excursion. in fact barely any at all. how is this possible? thanks

 

[PaganDL]

Hi music_man,

A few questions first to satisfy curiosity first...

What subs do you have & how many drivers does each have, are they identical subs & also what size subs, also what power output, impedance?
What is the frequency response range on the subs & what are they set to?
Please define what you mean by crossover is set to be for loudspeakers?
What do you mean by volume is set very low as this can be subjective. On a sub, anything below the quarter mark is considered 'low volume', 'average volume' on a sub's volume control is halfway. Most subs don't need more than half though like all audio components, this is VERY SOURCE DEPENDANT...
Are both sub inputs controlled further by an external volume control (eg, amplifier, computer audio interface, etc)?

(A screenshot of the rear panel or wherever the connections are would help the second question)

As a general rule, subs have a lower frequency response range than speakers & being tuned for lower frequencies, (hence their purpose), the driver itself doesn't require much physical movement to produce deep bass especially if it's a big driver above 12 inch. Also, regardless of how many drivers & driver size, depending on how much output power & impedence each sub have makes A LOT of difference, much like high efficiency headphones & speakers, headphones more so as the easier it is for an audio signal to be driven on low impedance than high...

Also, in your opinion, define low end subs too, please

Hope this helps.

 

[voxie]

Stupid question time.... Passive or powered? 

 

[PaganDL]

Good point voxie...

Forgot to ask that one

 

[voxie]

No Probs PaganDL...

 

[music_man]

two jl gotham v2. i wanted the bass i just do not know how they can produce that much hardly moving. i imagine if you get on them they will tear down the building. the volume is quarter way. i have the controller on them. they are set at 40hz. i just thought they had to move a lot of air to get a lot of bass. i guess that is relative. some people may not think i have a lot of bass right now i suppose.  $800 little subs would move a lot in a large room. i imagine it has to do with the size and power. i would still think they need to move a lot of air.

 

[ProtegeManiac]

  i have two very high end subs. the drivers barely move yet they put out prodigious amounts of bass. the volume is set very low or it is overwhelming. the cross over is set as it should be for the loudspeakers. i just thought that the drivers would have to really be pumping to move enough air to get that amount of bass. if i turn them off it is evident what they are providing so it is not the loudspeakers. i have had lower end subs that would have quite a bit of excursion to do their job. I can't see how they are moving enough air to shake the building without massive excursion. in fact barely any at all. how is this possible? thanks

 

  two jl gotham v2. i wanted the bass i just do not know how they can produce that much hardly moving. i imagine if you get on them they will tear down the building. the volume is quarter way. i have the controller on them. they are set at 40hz. i just thought they had to move a lot of air to get a lot of bass. i guess that is relative. some people may not think i have a lot of bass right now i suppose.  $800 little subs would move a lot in a large room. i imagine it has to do with the size and power. i would still think they need to move a lot of air.

 
First off, you have two subs. Using two getting the same amount of power each gets you around 3dB louder, and that is a LOT.
 
Second, what are you basing the idea of "barely moving" on? If you're comparing it to a 5in PC subwoofer then obviously to get the same volume (much less the low end response) then that small sub will work harder. Kind of like how a Corvette V8 will produce enough power and torque to move the Vette around a race track at a comparable pace to a 1000cc BMW or Kawasaki, which has to work harder - 16,000rpm - to get less than half the horsepower of the Chevy small block (and yet still have less than 20% of its torque). 

 

At the same time it also depends on port tuning and amplifier damping factor. If you're forcing the sub response with the port and you're using a cheap amp - ie, a multimedia sub - then that sub isn't just visibly working harder, you'll see that along with it being a cheap diaphragm, it's already bent out of shape playing a test tone as it hits X-Max. Even a $100 (in brick and mortar stores, not online selling brands with no middle men dealers) subwoofer from a reputable brand will be visibly working a lot harder than those JLs.

 

If you're comparing it to 15in subwoofers in videos of people screwing around in parking lots with their trunks or SUV cargo area door open, you're not comparing apples to apples, and I'm not talking about build quality of the subs or the amps. I'm talking about how loud it is in what size environment. Those subs working hard in the Bass 305 idiot vidz can make coins dance on the roof of that car, and if they actually played that loud while driving around, they'd already get a ticket. If they closed the windows, they'd crack the windshields. When they compete in actual (ie, sanctioned and quantifiable) bass competitions they close all windows and hit Play on the receiver's remote from outside the car, and the display outside will display the decibels. 130dB is par for the course in the entry level, usually limited to 500watts. If you're comparing your system to that, note that the car is a smaller space, and even though it can hit 130dB in that small space, you can still hear it from 3 blocks away. Your house is a very different listening environment and likely just more efficient - you don't have all the noise of a parking lot so 85dB average for 35hz to 100hz seems really loud to you vs one of these cars (if you've actually even ran into one, rather than just YouTube vids from IASCA or EMMA events).

 

At the same time, what were you playing through them? If you're playing normal media then obviously it's not like the 35hz sine waves used by those people in parking lots who want to show how the bass moves the air on the scantily clad promo girls promoting their car audio shop or their brand of subwoofaz and amps. Play a 25hz sine wave and you'll probably start seeing those subs work harder than usual.

 

One other thing to consider - what's your crossover cut off? If it's too high then maybe the reason why it isn't visibly working hard and yet the overall sound is overwhelming everything else. Also check all the sub control settings. When you say "volume set very low" do you just mean the gain knob on the subwoofer amp? Check the receiver's sub output - for all you know its preamp is set to +6dB. Set that to 0 (not necessarily the same 0dB on the main volume knob, just that it's the same output level as the main knob). If that's not enough set it to -xxdB and if there's a manual frequency selector for the crossover, forget setting "Large," just set it to whatever the frequency lowest is. My car's sub is cut at 50hz just so it won't pull the image to the rear.

 

[music_man]

thank you protege. you explained it well. i was in fact comparing it on the one hand to like a klipsch sub and on the other those fosgate competition cars. i also forgot that non dance or pipe organ music rarely goes below 35 hz. i do have the xover set to high. i thought i liked that but put it down to 35 with the wilsons and it is better. i am using mono amps so no lfe or whatever it is called. the subs have a controller to integrate them in stereo. the volume is a couple of notches above 1/4. i left it there but setting the crossover lower made them integrate more seamlessly. i thought science dictated you must move x volume of air to get x decibels. apparently not. with it turned down just the subs are at 85ish db. i needed to get it even lower because with the speakers i was at almost 100db. i got the whole thing to 80 db. afaik good subs should not be like those cars but seamlessly integrate the lower octaves. they still don't move much, maybe less now. i guess the point to i was mistaken that they have to be pumping like crazy to provide adequate bass. this is apparently not true. to get a single 8" sub to do that in a 23x18 room with 14 foot ceiling it will be slapping i imagine. in the end, as usual i probably got much more than i needed. i could have honestly probably got one e-sub from them. it sounds very good now so i cannot complain. i think for ht you would want much more bass than for music. apparently these were really designed for music though. it is good now like what i expected because i can feel it but not hear it booming. with the xover lower. i was just confused as to why there is not a ton of excursion. you explained that with the corvette vs the 6 cylinder bmw. i am just making a lot more "torque" so i do not need to use all of it i suppose.at first, the bass i was hearing i expected it to be like those cars but now i understand this better after you have explained it. i always had much smaller subs and they had to work harder to achieve the same thing. i am not sure i wasted a lot of money because they must be much cleaner than small, inexpensive subs. now, with things properly set i feel it but otherwise do not know they are there. i listen to progressive jazz and easy listening, adult contemporary. there is not much below 35hz but enough information to feel. it worked out to my liking i would say. i guess another analogy is driving a 700hp car 40mph. it does not have to work very hard. whereas a prius would. mainly this is due to a lack of information in my genre of music below 35hz i suppose. if it was edm perhaps a different story. this problem has been solved! thank you

 

[PaganDL]

Once again, agree with ProtegeMusic, who always makes excellent points...

If I didn't say it before, two subs IS A LOT OF ridiculous power, not to mention 40 hz or below is almost ridiculously sensitive on the lower frequency scale even for just one sub, never mind two...
What a lot of people don't realise is the human body can tolerate a lot less over time certain low frequencies over time (60 hz & below though it tends to be 40 hz & below) than high or even mid range frequencies as your body 'feel' the low frequencies more which is why how big the space the subs are in are important too...

As ProtegeMusic says, the space and how big it is your subs are in makes a significant difference, especially at volume but even if whatever low frequency sound going through the sub is not so loud, it 'feels' & sounds louder than it should be...

As with crossover, if set too high, that's why it seems there is a delay in appearing to visibly work but actually pushing more than it should which isn't necessarily bad but it's not good either.
Also, the +6db setting ProegeMusic refers to is generally for room correction which isn't required in most cases.

Hope this helps.

 

[ProtegeManiac]

  i was in fact comparing it on the one hand to like a klipsch sub and on the other those fosgate competition cars.

 

If those are entry level they'd be visibly working harder, on top of which, the RF competition car will be pounding out as much bass as it can, except you're either sitting inside the car with the windows closed (and they can't pump up the levels) or you're outside the car, whether the windows are open and bass is dissipating into open air or the doors are closed and all you see is the display.

 

Use a dB meter in your room. I won't be surprised if what you perceive as too loud doesn't register over 95dB from your listening position.
 

  i also forgot that non dance or pipe organ music rarely goes below 35 hz.

 
Not just any dance music. You have to use crunk, like Usher's and Lil Jon's Yeah, for crawling deep bass. Or at least most dance electronic music I listen to just has loud, hard, upper bass hits.
 
At the same time even the pipe organ goes deep but isn't exactly meant to shake a building, not even that tune known for Dracula skits. Try the same kind of material that they play in car audio bass competitions - a 35hz test tone - and see how loud it goes before neighbours call the cops on you.
 
 

  i do have the xover set to high. i thought i liked that but put it down to 35 with the wilsons and it is better. i am using mono amps so no lfe or whatever it is called. the subs have a controller to integrate them in stereo. the volume is a couple of notches above 1/4. i left it there but setting the crossover lower made them integrate more seamlessly. 

 

You have to set a crossover to just "meet" where the mains trail off. Even then it's not a simple matter of looking at the stated specs. Standmounts rated for 55hz to 24,000hz have these two points as the point where they take a nose dive. Set the sub to 50hz low pass and there might be enough overlap between how much the sub's low pass filter is still letting through (ie this isn't exactly just "chopped off" at the stated crossover point) for the sound to be bloated, since you'll hear a lot more of the same frequencies of the same notes coming from two drivers.

 

On top of that you have to take into account time alignment (ie whether the sound from the subs and mains are reaching your ears at the same time) and gain structure, the latter getting even more critical the wider the range the sub has to play.
 

  i thought science dictated you must move x volume of air to get x decibels. apparently not. with it turned down just the subs are at 85ish db. i needed to get it even lower because with the speakers i was at almost 100db. i got the whole thing to 80 db. 

 
Where did you even get that equation? Because it's missing a heck of a lot.

 

1. How do you know how much air is being moved? That depends on the driver size and the max excursion, and whether you can provide that much power.

 

2. In what size room? A JL w6v3 in a transmission line enclosure getting 500watts will register differently in a car with the mic on the dash vs that car with its trunk open in a parking lot and the mic outside the car. Even if you put the mic right in front of the sub, you sitting in the car vs standing outside putting the moves on the scantily clad "paddock" (yeah, right) girls in a bass "race" would have you perceive the first situation as louder.

 

3. How loud is the noise floor? Your house is a lot quieter than a parking lot full of such cars each trying to impress the "paddock" girls or their friends. And that's before you hear sirens because the people living in the area just called the cops.
 

  afaik good subs should not be like those cars but seamlessly integrate the lower octaves. they still don't move much, maybe less now. i guess the point to i was mistaken that they have to be pumping like crazy to provide adequate bass. this is apparently not true. to get a single 8" sub to do that in a 23x18 room with 14 foot ceiling it will be slapping i imagine.

 
 
My car had a 10in Polk Audio and later JL subwoofer in a 0.75 cu ft sealed box getting 300watts from the amp, cut at 50hz, 24dB/octave, plus time aligment on the DSP delaying all other speakers' output so they all arrive at my head at the same time. When disabled there's barely any bite to ACDC bass drum thumps; once engaged bass drum hits are clear and deep. Sub barely moves even when playing dance music since I'm not out to crack my windshield, and yet, if I'm driving in a rather tight parking lot (ie anything that doesn't look like suburban USA), I'm still going to set off a few alarms. 
 

  in the end, as usual i probably got much more than i needed. i could have honestly probably got one e-sub from them.

 

The way I understood your set up you have two of the Gotham units, so four subwoofer drivers. I wouldn't get a smaller unit though as I usually prefer putting those on a platform and put them between the speakers but somewhat more to the rear. In any case, where is the sub/s relative to the speakers?

 

If you have just one Gotham unit, move it between the two speakers but farther to the back. If you're using CD/TT or an HDD server, move that closer to the wall and to the side if you need to see the display, and have the Gotham farther to the back without getting too close to the wall.

 

If you do have two of the Gothams, move them away from the walls (if they're almost at the walls) or away from your seat (but don't get them too close to the wall). See if that improves the excessive output. If not, switch off one, then play around with the positioning of just one sub, although if you keep the crossover cut off low it's less likely to pull the image of the bass drum to whatever side it's on (psychoacoustics are another matter, ie, if you can see just one sub to one side, it can affect your perception of where the bass is coming from).
 

  i think for ht you would want much more bass than for music. 

 

You want even more low bass for HT. With music as long as the response is wide enough down to 20hz the only problem is how flat the response is. With movies and video games you'd want the lowest bass frequencies you can pump out for the real movie experience. Explosions and natural calamities have a lot of really low bass, and some horror movies have very, very, very low freq infrasound in them. Your ears can't actually hear it as sound apart from the audible bass frequencies in the soundtrack but it will mess with your head and vision. It conjures up feelings of dread, and if it's at 19hz, it will start vibrating your eyes you'd think the ghosts are OH MY GOD SHE'S SITTING BESIDE YOU NOOOOOOOOOOO!!!!!
 

  apparently these were really designed for music though.

 

Short of a car audio bass competition where apart from the ultimate goal of more bass regardless of the quality you are also divided into separate classes (usually amp rated power;  sometimes how many subs of each size max, etc), any sub designed for music will do well with movies and such as long as it can get enough power to get as loud as the listener/viewer wants.

 

The box design particularly in car audio competitions extends response and overall the sub has a wider range and higher sensitivity in a transmission line box than one in a sealed box. That isn't even limited to subwoofers - look at Fostex fullrange drivers in TL enclosures running off 6wpc tube amps compared to, say, a B&W 900 series tower needing 100wpc.
 

  it is good now like what i expected because i can feel it but not hear it booming. with the xover lower.

 
Music generally won't have a lot of information at very low bass frequencies, which is why many can get away with just 2-way standmounts with 6in midwoofers. Setting the crossover higher will have the sub play what bass is abundant, and in your case, you have a lot of power and subwoofer diaphragm area.
 
On top of that it's playing low bass that forces such movement to happen, so if you're not playing those at all then you really won't see the sub work like the cars showing off in a parking lot playing Bass 305 or whatever groovy new song the girls are dancing to. Like the one below, which actually has a lot of pounding (snicker) bass.
 
Admittedly I watch it a heck of a lot more than I am listening to it, and those outfits aren't even what I'm into, but daaaaaaaaaaamn...

 

  i was just confused as to why there is not a ton of excursion. you explained that with the corvette vs the 6 cylinder bmw. i am just making a lot more "torque" so i do not need to use all of it i suppose.at first, the bass i was hearing i expected it to be like those cars but now i understand this better after you have explained it.

 
Actually what I said was "Kawasaki or BMW...16,000rpm," so I was not referring to the 7,800rpm M3 but for a bigger contrast to the Corvette.

This BMW S1000RR.

 

Second, the reason I mentioned the RPM was because a piston kind of works like a dynamic driver (except the cycles on a dynamic driver relate to the frequency being reproduced). Look at how differently the Corvette and S1000RR corner as far as the engine and transmission are concerned. With the V8 you ease into a corner and shift down mostly just one gear unless it's a hairpin or tighter (or coming from a really fast straight), then you just throttle steer on the way out, applying as little of it as possible so you don't go into oversteer. With the S1000RR not only is the engine working "harder" at a higher rpm, the rider has to work harder - shifting down more and blipping the throttle more to keep the revs high enough to be in the power band, not losing too much momentum by the time he's got the bike leaning, and then add how much the rider has to shift his weight around to lean the bike at high speed, all while trying to not lose the grip on two tyres with one drive wheel. The only way the bike isn't working harder is by its power to weight ratio (but then you have all that power in a single narrow drive wheel relative to the tyres on a sports car - too wide and you can't lean the bike for extreme cornering angles).

 

Even on the street it's the same thing. On a Corvette you barely shift, and you're sitting on a relatively comfortable seat. On the S1000RR (much less a Ducati 1299 or 959 in Panigale or Streetfighter body) your seat has a downward angle, your rear is higher up to the rear of the bike, left foot works the shifter, keeping your head up is stressing the lower back but you can't exactly ride with your face down to the instrument cluster for safety reasons (plus you have to raise your torso when shifting weight for a turn or under braking), your wrists are bearing the weight of your torso...

 

Basically, with all that torque at lower rpm due to the combined size of both subs in each Gotham unit and the quality of the amplifier driving them, plus their in-room response vs the trunk open, in-parking lot response of the RF subs, makes for stark differences in efficiency, whether amp power or how much the driver is visibly moving, to get to a given output level.

 

 

  it worked out to my liking i would say. i guess another analogy is driving a 700hp car 40mph. it does not have to work very hard. whereas a prius would. 

 

Depends on what high power car. If it's a torquey V8 or V12 no problem, but if it's a highly modified Japanese six cylinder with a large, very old design turbo, the engine and driver might end up working harder than the Prius - you have to stay at 40mph, but then the turbo which barely works below 3000rpm starts spooling up, so you shift...but whoops, barely enough air at 2000rpm, it stutters into the next gear. Think of the differences in driving the F40 around town vs a Corvette Z06 - and that's just the engine, not yet how you have to find some way to not scrape the undercarriage everywhere.

 

Think of it another way - Colossus and Professor X have awesome power under control. That's the Corvette, or the V12 S or 7, or the twin turbo S8. The F40 or S1000RR would be more like Cyclops needing his sunglasses, Jean Grey suppressing Phoenix, Bruce Banner trying to not get his heart rate up...

 

[music_man]

man, you know a lot about subs,cars and bikes! that was a great read. i think i have them setup okay now. they are behind each speaker and out of the corners. i just did not understand how they can produce plenty of output and not move much.
as far as cars i like the zo6 much better than the m3. the m3 is odd. it is like a deluxe sti. the z06 is just a sports car. you are going to get a lousy ride in the m3 so if you need 4 seats it is just a compromise. the z06 is not the most polished car either but i think it is more fun than the m3. i hate launch control anyways. go with all wheel drive. get the 4 seats and the rs7 lol. i think my sub question is answered. i did not have an issue really. they sound very nice. i just did not understand exactly how they work duh. thank you for taking the time to write all that. . the one thing though that is a contraindication to what you said is i found they work better with the crossover way higher than the speakers bottom. mine are like 30. i have the subs at 50 and it sounds better than going lower. i am not sure if that is a preference or if there is some reason behind it.i guess whatever sounds best to me. i think 50hz was noticeably better than say 30hz. of course i turned the volume down even more then. they are about 2 notches below a quarter. it is still shaking the room so i know it is working anyways, thank you for the detailed help. 

 

[music_man]

you will not believe this. if you do not already know i am a retired audio and electrical engineer. you would think i would know the answer to my original question. the thing is i always witnessed excursion because either commercial installations were played loud or the subs were sub par. the gotham v2's are really a marvel. i never had subs this good. now what i wanted to tell you. an old engineers trick is to adjust things with your eyes closed. it does something in the human brain but i am not a doctor. just know it is interesting to open your eyes and see just what you have done! so, i just did so with the subs. when i opened my eyes i was at 32hz and about 3/8 of the volume. so i just went in the opposite direction. since this trick was employed it is usually the correct setting because of what lack of sight causes the brain to do with the ears. the wilsons are beasts in their own right. going flat to about 20hz. i achieved what i wanted here. bass i can feel from the jl's and not just hear from the speakers. the speakers go low but do not have the kind of oomph the jl's provide. i knew this and was exactly why i got them. now, it should be setup right. i will not try placement of 300 pound woofers with my eyes closed though lol.
 
btw, if you are wondering about my typing and don't already know thinking this guy is not educated. i became very ill later in life and only one hand barely works but at least i still have both hands attached. i am not looking for sympathy, just telling you why i can rarely punctuate.as you know people type with both hands. i used to type 160wpm with 98% accuracy. honestly i am happy to be retired and pursue other ventures,. as in leisure haha.

 

[ProtegeManiac]

  you will not believe this. if you do not already know i am a retired audio and electrical engineer. you would think i would know the answer to my original question. the thing is i always witnessed excursion because either commercial installations were played loud or the subs were sub par. the gotham v2's are really a marvel. i never had subs this good. now what i wanted to tell you. an old engineers trick is to adjust things with your eyes closed. it does something in the human brain but i am not a doctor. just know it is interesting to open your eyes and see just what you have done! so, i just did so with the subs. when i opened my eyes i was at 32hz and about 3/8 of the volume. so i just went in the opposite direction. since this trick was employed it is usually the correct setting because of what lack of sight causes the brain to do with the ears. the wilsons are beasts in their own right. going flat to about 20hz. i achieved what i wanted here. bass i can feel from the jl's and not just hear from the speakers. the speakers go low but do not have the kind of oomph the jl's provide. i knew this and was exactly why i got them. now, it should be setup right. i will not try placement of 300 pound woofers with my eyes closed though lol.

 

One thing that I've noticed though is that using more power into a sub than is necessary - ie, replace one 150w amp with 300w, then set the gain to play a test tone at the same level - has a tendency to have the sub moving a heck of a lot less. or at least that was how it was when I got a new amp for my car and one other time a friend did and observed the same. It's possible that when an amp is taken to its limits it really is piling on distortion. Note that my weaker amp wasn't clipping and the sub wasn't hitting X-Max - the sub's movement was just a heck of a lot smoother.

 

It's a lot like going from a five year old entry level graphics card to a current flagship graphics card, and all video games start looking more and more like the real thing, no rough edges, frame rates are kept well above 32fps, etc.
 

 
btw, if you are wondering about my typing and don't already know thinking this guy is not educated. i became very ill later in life and only one hand barely works but at least i still have both hands attached. i am not looking for sympathy, just telling you why i can rarely punctuate.as you know people type with both hands. i used to type 160wpm with 98% accuracy. honestly i am happy to be retired and pursue other ventures,. as in leisure haha.

 
Actually I just thought English was your third language, and your first language isn't in Roman/Greek script.

 

[music_man]

yeah that makes sense. the graphics card is a good analogy. thank you for answering this dilemma. when i first noticed this is was thinking how is that possible. i imagine if i did push the two of those to the limit the building would collapse! i have enough bass for me with them hardly moving but it is certainly higher quality bass than much lower quality subs. so it was not a waste at all. plus my salesman knows he can get me to buy anything