I've built a sealed box - a little less than 5 cubic feet - for an Adire Audio Tempest (15"). It sounds good, but I can't help but think the bass could be tighter. I used 3/4 inch MDF for the box and it's fairly well braced. I'm going to add 1/4 inch High Density Fiberboard (material like clipboards are made of) to the outside to try to help.
Can anyone offer any other suggestions? Maybe a different driver? Should I try a 12"? Or a different 15"?
I'm using a Rythmik Audio 350 Watt amp, which replaced an Adire Audio 250 Watt amp. (They sounded similar in this regard.) The room is about 20' X 12' X 8'. I want to focus mainly on tight bass for music (jazz), but I actually USE it more for home theater, so 'extension' is on the priority list - below 'tight'.
Thank you,
Philip
Can anyone offer any other suggestions? Maybe a different driver? Should I try a 12"? Or a different 15"?
I'm using a Rythmik Audio 350 Watt amp, which replaced an Adire Audio 250 Watt amp. (They sounded similar in this regard.) The room is about 20' X 12' X 8'. I want to focus mainly on tight bass for music (jazz), but I actually USE it more for home theater, so 'extension' is on the priority list - below 'tight'.
Thank you,
Philip
There is no reason a sealed Tempest with a good 350W amp should sound flabby. I'm gonna guess that what you're hearing actually has more to do with the integration of the sub and your main speakers or with room modes. Are your main speakers ported or sealed? How are they crossed (i.e. mains running full and sub crossed with amp lowpass at xxHz, or mains running as small on receiver and sub playing wide open off LFE channel)? Also, what size is the room you have this in? Carpet or hard floor, etc?
Give us a couple more details and we can help some more.
Good luck.
Give us a couple more details and we can help some more.
Good luck.
More info
Sorry. I was trying to be thorough, but I guess I left some stuff out.
My mains are ported bookshelf-style speakers (the AR.com diy's) and their placement is far LESS than ideal. The room is about 20' X 12' X 8' but there are two double-door-sized opennings. The room has carpet. The crossover duties are being handled by a Harman Kardon AVR-7200 and I have the crossover point set to 60Hz. The sub is down-firing and is near only one wall (not in a corner).
I wouldn't say that the sound is flabby, just not quite as tight as I had imagined it would be.
Thank you!
Philip
Sorry. I was trying to be thorough, but I guess I left some stuff out.
My mains are ported bookshelf-style speakers (the AR.com diy's) and their placement is far LESS than ideal. The room is about 20' X 12' X 8' but there are two double-door-sized opennings. The room has carpet. The crossover duties are being handled by a Harman Kardon AVR-7200 and I have the crossover point set to 60Hz. The sub is down-firing and is near only one wall (not in a corner).
I wouldn't say that the sound is flabby, just not quite as tight as I had imagined it would be.
Thank you!
Philip
The bass will not get appreciably tighter. Assuming that you mean what I mean when you say tighter (you'd be amazed how many people say tight when they mean deep), you're pretty much stuck with the sound that you've got now. I'm not saying that it won't change at all, just that the "tightness" isn't going to get better just by stiffening the cabinet.
Timn8ter's suggestion will change the sound considerably, but if anything will make the bass more loose. As a general rule, you raise the Q if you want it to sound tighter.
Okay, now on to "extension." I've said it elsewhere, but people keep buying these drivers and ending up dissapointed, so I'll say it again: They ain't flat. Period. They have a broad peak in the 80-100Hz range and slope off at about 6dB/oct south of that. The end result is that your 20Hz response is a good 12-15dB lower than you think it is from the simulations. Don't argue with me...measure it. This is not some subtle, tweak, golden-ear thing, this is a real problem. Your only realistic option is to EQ the booger to get that bottom end up to a reasonable level. You'll burn valuable amp power getting there, but it can be done--trust me on this one, I've got twelve 12" Titanics (a similar driver). There are other options, but they get much more complicated.
Grey
Timn8ter's suggestion will change the sound considerably, but if anything will make the bass more loose. As a general rule, you raise the Q if you want it to sound tighter.
Okay, now on to "extension." I've said it elsewhere, but people keep buying these drivers and ending up dissapointed, so I'll say it again: They ain't flat. Period. They have a broad peak in the 80-100Hz range and slope off at about 6dB/oct south of that. The end result is that your 20Hz response is a good 12-15dB lower than you think it is from the simulations. Don't argue with me...measure it. This is not some subtle, tweak, golden-ear thing, this is a real problem. Your only realistic option is to EQ the booger to get that bottom end up to a reasonable level. You'll burn valuable amp power getting there, but it can be done--trust me on this one, I've got twelve 12" Titanics (a similar driver). There are other options, but they get much more complicated.
Grey
First, let's define tight. Most folks I know define tight as meaning that a drum has punch; a definite start and stop. Loose bass is wobbly or rubbery sounding, lacking in definition.
Now think of it in terms of what the driver's cone is doing. Once the cone starts moving--let's say it's a drum thwack--it will obey basic Newtonian physics and tend to keep moving. There are several braking forces at work, but one of the primary ones is the pressure or lack of it behind the cone. In an extreme case, let's say a 12" driver in a box of really small volume, like the size of a shoe box, as the cone moves forward it will create a substantial vacuum in the box, hence, a braking force. Likewise, if the cone moves backwards, it will compress the air, which will in turn resist the movement of the cone. Again, a braking force.
Large enclosures work oppositely.
Are we in agreement so far?
Okay, the only remaining thing is to posit that a woofer that's flying around uncontrolled produces loose, rubbery bass. It loses definition. One that starts and stops on a dime is tighter.
If Vandersteen defines tight and loose differently, all bets are off.
All things being equal, a smaller cabinet (higher Q) will produce a hump before the response rolls off. The rolloff comes much earlier than it would in a larger, low Q cabinet. Now, whether you call this "more energy" or not is in the eye of the beholder. That hump can get pretty noticeable. If your focus (like a lot of car stereo/rap peoples') is on the mid-bass, then, sure, it's 'more energy.' If, on the other hand, your goal is deep bass, you're going to say that it actually decreases the bass. The bass began a 12dB/oct rolloff at a much higher frequency. It's kaput by the time you get to 20Hz.
In the case of a driver in free air (I'm using free air here as a stand-in for a really large cabinet, i.e. one of infinite volume), the rolloff will be much more gradual, and will start somewhat lower. The slope will be closer to 6dB/oct leaving more capability at 20Hz compared to the higher Q cabinet--but less at higher frequencies.
So, which one is "more bass?"
Depends on your point of view. Me? I look for 20Hz. This car stereo boom-boom thing is for kids. Grown-ups know better. Or should, anyway.
By which you can assume that I disagree with Vandersteen's definition of tight. To me "more energy in the most audible bass range" is commercial-speak for "sells more speakers."
To put it another way, I've been using a paint recently that says something to the effect that "due to the extreme purity of the components in this paint, it will take more coats to get good coverage on your wall." Say what? Anyone who knows anything about paint will tell you that a good paint has sufficient pigment to cover in fewer coats, not more. Yet these guys are trying to make low quality sound like a desirable thing. Needless to say, had I realized just how poor this paint was before I bought it, I'd have picked something else. Now I'm stuck with trying to make a silk purse out of a sow's ear.
Oh, one other thing. The response of these drivers in a "properly sized" Thiele-Small enclosure already looks like that of a low-Q speaker. Increasing the cabinet size will only decrease the deep bass further. Granted, this isn't directly related to the tightness, but it's not going to help with extension at all. Now, you could decrease the size of the cabinet, which would bring up the bass somewhat. You'd have to cut and try, because the simulations have already failed miserably. The problem here is that the low end would be lumpy, then rolloff at a higher frequency. At a guess, I'd say you could achieve something approaching flat response if you were willing to accept a rolloff begining somewhere in the range of 45 to 60Hz. Your 20Hz response would still be way down. Bummer, eh?
Grey
Now think of it in terms of what the driver's cone is doing. Once the cone starts moving--let's say it's a drum thwack--it will obey basic Newtonian physics and tend to keep moving. There are several braking forces at work, but one of the primary ones is the pressure or lack of it behind the cone. In an extreme case, let's say a 12" driver in a box of really small volume, like the size of a shoe box, as the cone moves forward it will create a substantial vacuum in the box, hence, a braking force. Likewise, if the cone moves backwards, it will compress the air, which will in turn resist the movement of the cone. Again, a braking force.
Large enclosures work oppositely.
Are we in agreement so far?
Okay, the only remaining thing is to posit that a woofer that's flying around uncontrolled produces loose, rubbery bass. It loses definition. One that starts and stops on a dime is tighter.
If Vandersteen defines tight and loose differently, all bets are off.
All things being equal, a smaller cabinet (higher Q) will produce a hump before the response rolls off. The rolloff comes much earlier than it would in a larger, low Q cabinet. Now, whether you call this "more energy" or not is in the eye of the beholder. That hump can get pretty noticeable. If your focus (like a lot of car stereo/rap peoples') is on the mid-bass, then, sure, it's 'more energy.' If, on the other hand, your goal is deep bass, you're going to say that it actually decreases the bass. The bass began a 12dB/oct rolloff at a much higher frequency. It's kaput by the time you get to 20Hz.
In the case of a driver in free air (I'm using free air here as a stand-in for a really large cabinet, i.e. one of infinite volume), the rolloff will be much more gradual, and will start somewhat lower. The slope will be closer to 6dB/oct leaving more capability at 20Hz compared to the higher Q cabinet--but less at higher frequencies.
So, which one is "more bass?"
Depends on your point of view. Me? I look for 20Hz. This car stereo boom-boom thing is for kids. Grown-ups know better. Or should, anyway.
By which you can assume that I disagree with Vandersteen's definition of tight. To me "more energy in the most audible bass range" is commercial-speak for "sells more speakers."
To put it another way, I've been using a paint recently that says something to the effect that "due to the extreme purity of the components in this paint, it will take more coats to get good coverage on your wall." Say what? Anyone who knows anything about paint will tell you that a good paint has sufficient pigment to cover in fewer coats, not more. Yet these guys are trying to make low quality sound like a desirable thing. Needless to say, had I realized just how poor this paint was before I bought it, I'd have picked something else. Now I'm stuck with trying to make a silk purse out of a sow's ear.
Oh, one other thing. The response of these drivers in a "properly sized" Thiele-Small enclosure already looks like that of a low-Q speaker. Increasing the cabinet size will only decrease the deep bass further. Granted, this isn't directly related to the tightness, but it's not going to help with extension at all. Now, you could decrease the size of the cabinet, which would bring up the bass somewhat. You'd have to cut and try, because the simulations have already failed miserably. The problem here is that the low end would be lumpy, then rolloff at a higher frequency. At a guess, I'd say you could achieve something approaching flat response if you were willing to accept a rolloff begining somewhere in the range of 45 to 60Hz. Your 20Hz response would still be way down. Bummer, eh?
Grey
I'm running a mid-Q sealed tempest. What I found was that the sound changed quite considerably over the first 80hrs. After running it in for around that long and tuning in to my mains the sound was awesome.
You have everything there, just needs a little tuning and possibly experimentation with room placement and/or parametric eq.
You have everything there, just needs a little tuning and possibly experimentation with room placement and/or parametric eq.
Bass Perception
Philip,
I 've built several subs, and all I can tell you is deep(below 30 Hz), tight bass pressurizes the room like rolling thunder with no identifiable source. I use two subs for HT and I can't locate them as the source of the sound. If you can hear the box acting up, you have a resonance problem, and need to reinforce the enclosure.
A larger sealed box will lower the box "Q". It will also flatten the usual roll off curve on the low end, maybe robbing a dB or two from the upper bass region in the process. For example, with a "Q" of .8, if the output is 90 db at 100 Hz, but 75 dB at 30 Hz, the output might drop to, say, 87dB at 100 Hz, but rise to 78 dB at 30 Hz with a lower "Q" tuning (gross generalization). You really need to simulate the response in one of the box programs like WinISD or Bass Box Pro to accurately predict response vs Q, or just read the Adire tech stuff.
You might also want to get a inexpensive sound level meter from Radio Shack and run some test tones through the system. Chart the output to see if there are problems. It will also help you match levels between mains and sub.
Tim
Philip,
I 've built several subs, and all I can tell you is deep(below 30 Hz), tight bass pressurizes the room like rolling thunder with no identifiable source. I use two subs for HT and I can't locate them as the source of the sound. If you can hear the box acting up, you have a resonance problem, and need to reinforce the enclosure.
A larger sealed box will lower the box "Q". It will also flatten the usual roll off curve on the low end, maybe robbing a dB or two from the upper bass region in the process. For example, with a "Q" of .8, if the output is 90 db at 100 Hz, but 75 dB at 30 Hz, the output might drop to, say, 87dB at 100 Hz, but rise to 78 dB at 30 Hz with a lower "Q" tuning (gross generalization). You really need to simulate the response in one of the box programs like WinISD or Bass Box Pro to accurately predict response vs Q, or just read the Adire tech stuff.
You might also want to get a inexpensive sound level meter from Radio Shack and run some test tones through the system. Chart the output to see if there are problems. It will also help you match levels between mains and sub.
Tim
I have a ported Tempest. For a while I only had one coil connected, and when I connected the other, in parallel, the lower-midbass became meaty and better defined, and all of the subs output had better pace. At this point I was quite happy with my sub.johninCR said:
You also could do with a good source, amp, etc. and the best phase setting on the sub.
As is often said here, there's arguably no such thing as 'deep *and* tight' bass - perception of the two comes largely from frequency response and integration with the main speakers.
I have a baffle step correction circuit that I recently removed - this cuts the upper midrange and above by about 6db. In place, the bass often sounds over-rich and lacking in pace and definition.
Now, without any baffle step correction, I have fast-paced bass, and my sub seems to track the most difficult, deep speed garage bass lines with absolute ease! This comes at the expense of mid-range warmth and natural tone.
What I'm saying is you can't really have it all - you must decide where your priorities lie.
BTW, when I first got my Tempest, I tried it in a 100L sealed box, and the midbass was exciting and fun, but there was no appreciable deep bass. If you want to be put into a strange state of being by mind-bendingly low bass you really need a large, ported box.
If you just want tighter bass, turn the sub down
"tight"
I just want to add some comments here:
I think that the lower the Q, the tighter the bass will be. I know that Grollins said the opposite and here is the point I wnat to correct:
Well, this is partially true. It is true that air that is compressed (or "depressed") act as a braking force for the cone, but air is also a spring, so the air will then push against the cone to regain it's initial pressure. It is a resonant system. That's why when the volume of air is reduced, you get a higher resonant frequency of the system, as the "spring gets stiffer".
I think it goes like this: a system Q of 0.707 is said to be "critically damped", because the oscillation of the cone will be the quickest to return to it's rest position after an impulse. above Q>0.707 is "underdamped" because there will be some oscillation after the impulse and below is "overdamped" because damping is so great that it tend to stop the cone to return quickly to it's neutral position.
F
I just want to add some comments here:
I think that the lower the Q, the tighter the bass will be. I know that Grollins said the opposite and here is the point I wnat to correct:
Well, this is partially true. It is true that air that is compressed (or "depressed") act as a braking force for the cone, but air is also a spring, so the air will then push against the cone to regain it's initial pressure. It is a resonant system. That's why when the volume of air is reduced, you get a higher resonant frequency of the system, as the "spring gets stiffer".
I think it goes like this: a system Q of 0.707 is said to be "critically damped", because the oscillation of the cone will be the quickest to return to it's rest position after an impulse. above Q>0.707 is "underdamped" because there will be some oscillation after the impulse and below is "overdamped" because damping is so great that it tend to stop the cone to return quickly to it's neutral position.
F
GRollins said:
No
The compressed air acts a spring against the speaker, and as you rightly point out the smaller the airspace the stiffer it is. However, this stiffened spring force acting upon the speaker means that the damping inherent in the speaker is now less effective than when it was in a larger box, hence it is less well damped.
This is borne out by the fact that a closed-box speaker is a 2nd-order system, and all such systems exhibit increased damping with lowered Q. In the case of closed-box speakers, lowering Q means increasing box size.
To address the original posters problem, it is actually possible to overdamp a speaker and get an unlively sound that manifests itself as not being tight sounding. This occurs because the speaker is unable to respond to an impulse without 'rounding it off', hence lack of definition. This is pretty much a non-problem with the spectrum of sounds that are replayed by a sub though.
In your case I suspect room interaction or poor integration with main speakers or just poor main speakers/placement to be the root of the problem.
Good Bass
I agree with SimontY about perception of bass involving the integration with the mids. That is why the crossover to the mains is so important. The high frequency content from a complex signal must be reproduced by both the sub and mains faithfully and at the same time. If you just listen to the sub only, without any main output, the lower you go, the slower everything sounds, as if the longer wavelength must unravel to be heard.
Though many may disagree from their experience, the reflex enclosure has longer group delay at reproducing deep bass than a sealed box. So, if well executed, a sealed box can work very well in bass reproduction. It just takes more output to match the efficiency of the ported enclosure. Using two sealed boxes to get the output up, with your mains on top, and you really have the best of both worlds. For really big output, then ported twin subs would be the ticket.
When NHT released their 3.3 system years ago, Stereophile and other reviews raved. Here was a large well integrated 3-way with a new 12" woofer doing bass duties in a sealed enclosure of about 2.7 ft^3 (75 l). Good to perhaps 30 Hz or deeper. If you simulate the NHT 1259 woofer's performance, still available at Madisound and others, it has some of the best roll off characteristics of any sealed box sub woofer you'll find. Problem is, it will only generate about 105 dB output before things start getting dicey in terms of excursion, distortion, etc. Bass freaks consider this the place where things just start to get interesting. Everybody wanted more...
BTW, if you simulate that enclosure with the NHT 1259, you get mid "Q" tuning of about .89 which includes a small but broad 1dB peak from about 45 to 90 Hz. Very pleasant, though.
Tim
I agree with SimontY about perception of bass involving the integration with the mids. That is why the crossover to the mains is so important. The high frequency content from a complex signal must be reproduced by both the sub and mains faithfully and at the same time. If you just listen to the sub only, without any main output, the lower you go, the slower everything sounds, as if the longer wavelength must unravel to be heard.
Though many may disagree from their experience, the reflex enclosure has longer group delay at reproducing deep bass than a sealed box. So, if well executed, a sealed box can work very well in bass reproduction. It just takes more output to match the efficiency of the ported enclosure. Using two sealed boxes to get the output up, with your mains on top, and you really have the best of both worlds. For really big output, then ported twin subs would be the ticket.
When NHT released their 3.3 system years ago, Stereophile and other reviews raved. Here was a large well integrated 3-way with a new 12" woofer doing bass duties in a sealed enclosure of about 2.7 ft^3 (75 l). Good to perhaps 30 Hz or deeper. If you simulate the NHT 1259 woofer's performance, still available at Madisound and others, it has some of the best roll off characteristics of any sealed box sub woofer you'll find. Problem is, it will only generate about 105 dB output before things start getting dicey in terms of excursion, distortion, etc. Bass freaks consider this the place where things just start to get interesting. Everybody wanted more...
BTW, if you simulate that enclosure with the NHT 1259, you get mid "Q" tuning of about .89 which includes a small but broad 1dB peak from about 45 to 90 Hz. Very pleasant, though.
Tim
gary f said:
Dipoles and IB have the ideal transient response as they are not influenced by the spring added by the air inside a sealed box. I suspect that this would in fact mean "tighter" bass. If this is true, then lower Q is better, since as you increase the volume of the box and lower the Q you get closer to IB.
This is not to say that tightness and transient response are exactly the same thing. I suspect that the very subjective "tightness" relates to a number of things. What is often considered "tight bass" may well be early roll off.
---------
Back to the original issue ...
I think the most likely cause of the problem is room modes. A room of that size is probably going to have a nasty deep dip induced by room modes. Suppose you have a dip at 50 Hz, quite common in a medium sized room and you turn it up too high to try to compensate for the lack of midbass punch. What you have is exaggerated low end where room gain kicks in. This or a number of other room issues could make an otherwise tight sub sound bloated, unnatural. Just a guess but I suspect it is most likely a problem with your room rather than your sub.
So what to do about it?
A combination of placement, bass traps and eq would work best - BFD or Ultracurve.
You might also experiment with placement. Try putting the sub up close to where you sit. This lessens the impact of the room significantly. Set the level as required - you may have to turn it down. Try other locations if you haven't already - even if they aren't feasible - do it as an exercise.
One possible location could be behind your couch.
You may wish to have a play with the Room Reflection Response Calculator on the FRD consortium. This will give you an idea of the sort of impact you can expect the room to have on the bass response. When you see how bad your room can be, you will realise you should address this first before doing the fine tuning.
If you think your box isn't rigid enough, see if it vibrates a lot. If you want to make it more inert, then use liquid nails and build a box around your existing box. This is called "constrained layer damping." Attaching a thin layer wont do much. You want 3/4" MDF with flexible adhesive inbetween as a damping layer to decouple the layers. This will probably be a very subtle change compared to what I have suggested.
I agree with Simon on this. I started a thread about a problem I had when I swapped out the cap in my crossover of my KLS10 speakers. I hadnt done any critical listening for a while, but this Highly aclaimedin Siemans MKV sounded worse some ways. Problem was that I had taken the port tube out of the KLS10 satelite sub and was booming slightly which really killed the midrange. Was then I realised just how critical good crossover design is in bringing the best out of speakers. I think (and I have no experience with this ) that intergrating a sub well with speakers needs alot of tweaking to get a flat response.
I often wonder if a passive radiator would give a nice tight bass, I think some day I would like to try peerless XLS and passive radiator.
jbandpc, Perhaps you just have too much bass? Turn it down and play with the frequency crossover point,?
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