Scott,
Not being an expert in that particular Altec 15" I would say that the integration of that speaker with a sub would be better with the sealed enclosure rather than a ported box as the rolloff would be smoother with the seal implementation. On that upper limit I would also say that with any 15" that would work out well as you are staying in the pistonic range of the device so the dreaded cone breakup region would be avoided. I'm sure you will get other responses but this is my 2 cents worth.
Not being an expert in that particular Altec 15" I would say that the integration of that speaker with a sub would be better with the sealed enclosure rather than a ported box as the rolloff would be smoother with the seal implementation. On that upper limit I would also say that with any 15" that would work out well as you are staying in the pistonic range of the device so the dreaded cone breakup region would be avoided. I'm sure you will get other responses but this is my 2 cents worth.
Pure speculation on my part... They should do well for midbass at the range you desire. May not be a breakin issue as the Fs changed from year to year, version to version. Down low they are limited due to low excursion, but believe Lynn addressed this with floor loading gaining back most of those losses. Appears that one was not enough so used two to address that issue. Adding a sub for below 60 shouldn't be an issue as long as it is clean and fast enough to keep up.
Clean is pretty straightforward term. How would you define fast in a sub? The reason I ask is that most of my experience with "fast" bass, is bass that's overdamped- either shelved or rolled off early.
The "fast" can also be applied to low room involvement bass- distributed or horn loaded systems. In those cases, the reduced resonance in the room is what makes a "faster" bass sound, but playing with the highpass still tends to take people's description from "fast" (30-40Hz highpass) to "slower" (15-25hz HP).
Fast as in wide flat bandwidth, with little to no breakup as possible with a light weight well dampened cone capable of fairly high excursion. In another discussion where we were attempting to find the spec that appeared to define "fast" led to Rms being close to one or less the better. The old standby description of fast bass would be a driver with a very wide flat bandwidth, regardless of low crossover point, with 2kHz being very good and around 5k being excellent. The drivers I had spent so many weeks/months looking for, would do both of these and had a minimal peak in the breakup region of about 2dB at 4.8kHz. After purchase and listening sessions ran some tests and the Rms had a spec of about ~1.25. The result was very deep, clean and fast. By clean I mean the second harmonic was nulled out, reducing all other even order harmonics. Crossover point was then placed before the third harmonic eg < ~240Hz as design dictated for integration with the MTM section that was sealed.
Badman,
One of the things that I have noticed over time is that fast is very subjective but also something that can be measured in specific areas. I wouldn't call a polypropylene coned driver fast as they have a somewhat muddy decay and slow response time. Paper and most composite cones will be faster in my opinion. I think most people would call a high efficiency driver fast, but it usually comes along with a limited excursion. You really have to know what it is you are looking for in the final sound and what kind of output you need in spl. Typically lighter cones will accelerate faster than a heavy cone but it depends on the size of the cone and the lowest frequency that you are trying to produce. I have never heard of anyone calling an 18" or 24" speaker fast, but solid in the lower octave is something that they do very well and easily. Again just my opinion here and others may feel differently about this.
One of the things that I have noticed over time is that fast is very subjective but also something that can be measured in specific areas. I wouldn't call a polypropylene coned driver fast as they have a somewhat muddy decay and slow response time. Paper and most composite cones will be faster in my opinion. I think most people would call a high efficiency driver fast, but it usually comes along with a limited excursion. You really have to know what it is you are looking for in the final sound and what kind of output you need in spl. Typically lighter cones will accelerate faster than a heavy cone but it depends on the size of the cone and the lowest frequency that you are trying to produce. I have never heard of anyone calling an 18" or 24" speaker fast, but solid in the lower octave is something that they do very well and easily. Again just my opinion here and others may feel differently about this.
No matter how well designed a sub is, poor placement can make any sub sound boomy or "slow".
A sub with a 15-25hz HP can sound fine as long as there isn't an abrupt rise in FR at those frequencies. Careful sub design, measurement and placement are needed though as it's easy for those frequencies to overtake the room.
A sub with a 15-25hz HP can sound fine as long as there isn't an abrupt rise in FR at those frequencies. Careful sub design, measurement and placement are needed though as it's easy for those frequencies to overtake the room.
I pretty much agree with all the above statements.
The challenge, of course, is that light coned wide-bandwidth driver systems used as subs tend to require more box (since they're generally dramatically more efficient than "pure" subs) and drivers to accommodate their limited Xmax.
I wonder if this may be another case where we chase what "seems" the problem but are really dealing with a correlated issue. I've found that as the systems scale up, they sound "faster" and cleaner, even using low efficiency poly coned subs. Perhaps we're just hearing the effects of flux and inductance modulation? These would fit both with the wide bandwidth (low Le and high efficiency tend to track this) and lighter cone (again, high efficiency tracks this). The lower efficiency drivers with heavy cones tend to also have heavy coils, and thus high Le. Their lower sensitivity would make them much more prone to flux modulation, thermal misbehavior, and whatnot.
And of course, it matters tremendously how low you XO. Below 50hz there's not a lot of "fast" no matter how you slice it. It seems like IF the distortion artifacts/thermal artifacts are underlying causes that lighter coned, wide bandwidth drivers correct for, an array of lower sensitivity drivers could be wired to limit the individual power through each coil required, while adding some additional displacement headroom to the system.
Or maybe I'm just justifying the subs I've wound up with vs something like a JBL 2235h based up.
The Kaboominator Big bass in your place. Article By Jeff Poth
There is a pair of these, so 8 12"s in total, but only the surface area of four. I haven't heard anyone complain of slow, though most guests are not audiophiles. The mains are vented exceedingly well-behaved 15"s and they're the source of slam. The subs are meant to disappear and just add that extra foundation and spaciousness, which they do handily.
Beyond the Ariel Subs? Given that I believe Lynn owns his place, I'd think an array of infinite baffle push-pull manifolds would be superb. 2 drivers per, and the manifolds scattered around front and side walls (and carefully integrated electrically) to distribute modal behavior.
The challenge, of course, is that light coned wide-bandwidth driver systems used as subs tend to require more box (since they're generally dramatically more efficient than "pure" subs) and drivers to accommodate their limited Xmax.
I wonder if this may be another case where we chase what "seems" the problem but are really dealing with a correlated issue. I've found that as the systems scale up, they sound "faster" and cleaner, even using low efficiency poly coned subs. Perhaps we're just hearing the effects of flux and inductance modulation? These would fit both with the wide bandwidth (low Le and high efficiency tend to track this) and lighter cone (again, high efficiency tracks this). The lower efficiency drivers with heavy cones tend to also have heavy coils, and thus high Le. Their lower sensitivity would make them much more prone to flux modulation, thermal misbehavior, and whatnot.
And of course, it matters tremendously how low you XO. Below 50hz there's not a lot of "fast" no matter how you slice it. It seems like IF the distortion artifacts/thermal artifacts are underlying causes that lighter coned, wide bandwidth drivers correct for, an array of lower sensitivity drivers could be wired to limit the individual power through each coil required, while adding some additional displacement headroom to the system.
Or maybe I'm just justifying the subs I've wound up with vs something like a JBL 2235h based up.
The Kaboominator Big bass in your place. Article By Jeff Poth
There is a pair of these, so 8 12"s in total, but only the surface area of four. I haven't heard anyone complain of slow, though most guests are not audiophiles. The mains are vented exceedingly well-behaved 15"s and they're the source of slam. The subs are meant to disappear and just add that extra foundation and spaciousness, which they do handily.
Beyond the Ariel Subs? Given that I believe Lynn owns his place, I'd think an array of infinite baffle push-pull manifolds would be superb. 2 drivers per, and the manifolds scattered around front and side walls (and carefully integrated electrically) to distribute modal behavior.
Anyone been trying to match a subwoofer with speakers that are hornloaded all the way down to 120Hz, like an Avantgarde Trio? I will try it with my trio clone in a few weeks, and I fear a mismatch. Is there a way around making a giant 25Hz basshorn, or a Labhorn with limited extension (35Hz)?
I wouldn't worry overmuch about the extension- if you have a lower compression throat horn, you can always EQ for the last little bit. (if it's high compression you'll tear the driver apart). What you really want to focus on is having the horn load smoothly high enough for the XO.
I know I will get disagreement on this but I think that short horns with loading attempting to produce low frequencies is very problematic. I have designed many horn loaded systems and have enclosures that load two 18" drivers on a molded throat section with a 25% throat loading. It is very easy with a large mouth horn such as this to get down under 75hz but below this really requires multiple horns that are close coupled to truly work well. The problem as I see it is that with a short horn and slow flare rate the mouth size does not support the on axis response below a specific point dependent on mouth size. Yes you can produce very low frequencies but the disparity between the on-axis output and the off axis output causes real problems. The on-axis output will have a very sharp knee or drop-off that can not be corrected without causing problems with the integration with the on-axis and off axis combinations. If you bring up the on-axis output with eq the off axis output will be so great in the lower frequencies that the combined output is just not useable. I have never seen a real solution to this problem with bass horns that are not very large in size. Look at an Altec A7 without the bass ports and the problems become evident. Attempting to reach 25hz or even 50hz is a sure fire way to be dissatisfied with the result. If we are talking PA sized arrays it isn't a real problem, but in a home trying to produce the full bandwidth with just horns is not a practical solution.
Again this is my opinion and others may disagree.
Again this is my opinion and others may disagree.
I was planning to try to add some kind of waveguide to a sealed 12" sonotube subwoofer, to try to match the directivity, but when I tried my prototype I noticed that the effect of hornloading is so special that it would probably not fit. Then again, ears are not so sensitive below 100Hz anyway. I will consider this before rebuilding the house. I have a half-done one of these: http://inlowsound.weebly.com/folded-bass-horn.html , that I could try if I am dissatisfied with the sealed sub. It would require another driver, or many more drivers. If it is anything like the labhorn one would require 6 of them to get a good bass, I have read. But the people with experience with labhorns were probably talking PA, and not HT, so one might still be enough for me. I have considered the 80Hz horn but it seems too short, with too little extension. It seems to be a a strange creation.
Kindhorn, I'm with you on that one. My experience with horns has leads my to think that a real bass horn has to be huge. Now I do understand doing some horn loading of the woofer, front or rear, to boost part of the range, but it's not going to be very flat across its bandwidth.
But I don't understand a lot of the short horn loading and back horns, so maybe I'm missing something. I see a lot of horns with LF claims that just don't make sense (to me) according to their size.
But I don't understand a lot of the short horn loading and back horns, so maybe I'm missing something. I see a lot of horns with LF claims that just don't make sense (to me) according to their size.
Pano,
I agree and think that most of what people think is the horn loading of the front and back loaded horns is just room gain. I think if you took most of these designs and put them outside and made a correct measurement, even though it is not an anechoic measurement you would see that these claims just don't hold water. The tapped horns which to me are really transmission lines have a better chance of working but those have other issues. I just don't see why the fixation on low frequency horns in homes, the integration of the multiple horns is also a problem that seems to be overlooked in almost all instances. There is nothing wrong with combining a direct radiator for the bottom end with a horn system that starts at a reasonable point. As long as the bass section can integrate with the horn and can produce the necessary spl level to keep up that is the way I would go.
I agree and think that most of what people think is the horn loading of the front and back loaded horns is just room gain. I think if you took most of these designs and put them outside and made a correct measurement, even though it is not an anechoic measurement you would see that these claims just don't hold water. The tapped horns which to me are really transmission lines have a better chance of working but those have other issues. I just don't see why the fixation on low frequency horns in homes, the integration of the multiple horns is also a problem that seems to be overlooked in almost all instances. There is nothing wrong with combining a direct radiator for the bottom end with a horn system that starts at a reasonable point. As long as the bass section can integrate with the horn and can produce the necessary spl level to keep up that is the way I would go.
I suppose there is some advantage to this limited horn loading. I have it with my A7s, but it only goes down to about 200Hz with the 30" horn, as far as I can tell.
There seems to be some clever cheating going on (I don't mean that in a bad way) with bass horns. I really don't understand it. I do think that a big, direct radiator can work very well with horns above. The Onken W cabinet comes immediately to my mind. Lynn wants to do a novel double 15, and that seems like a good idea. Lynn and I had a telephone conversation about this about a month ago.
There seems to be some clever cheating going on (I don't mean that in a bad way) with bass horns. I really don't understand it. I do think that a big, direct radiator can work very well with horns above. The Onken W cabinet comes immediately to my mind. Lynn wants to do a novel double 15, and that seems like a good idea. Lynn and I had a telephone conversation about this about a month ago.
There are a few things I have done that can get "undersized" basshorns to perform extremely well, certainly subjectively beyond dual or quad 15" JBL, TAD and Altecs I've built. Look at the Edgar Monolith article for information how the floor and room boundaries influence performance, look a Keele, Klipsch and many others. Full size horns don't fit, so you simply build them that will.