Absolutely! If we do compare the maths on displacement in our two systems:
My 4x 10 inch woofers each have an SD of 356 cm2 and a Xmax of 12.3mm.
So I have a total Sd of 1428cm2. That gives my set up a VD of 1756 cm3. Or nearly 4 times the VD of your speakers. This doesn't include the two 8 inch speakers I have in each of my front main three way speakers which also contribute to the bass output.
Good, distortion free bass does demand massive displacement. However, your two main speakers undoubtedly have better bass output than my main speakers alone, so there is nothing stopping you from further augmentation like I have done with distributed small sealed subs - only if you felt it was required of course - I am trying to fill a rather large room!
My 4x 10 inch woofers each have an SD of 356 cm2 and a Xmax of 12.3mm.
So I have a total Sd of 1428cm2. That gives my set up a VD of 1756 cm3. Or nearly 4 times the VD of your speakers. This doesn't include the two 8 inch speakers I have in each of my front main three way speakers which also contribute to the bass output.
Good, distortion free bass does demand massive displacement. However, your two main speakers undoubtedly have better bass output than my main speakers alone, so there is nothing stopping you from further augmentation like I have done with distributed small sealed subs - only if you felt it was required of course - I am trying to fill a rather large room!
But you did get the point that with enough drivers adding to the total Sd you can actually get them to play bass, didn't you? Even if they don't have huge Xmax...
I already knew what to expect:
http://www.stereophile.com/rmaf2006/102106ids/
I already knew what to expect:
http://www.stereophile.com/rmaf2006/102106ids/
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What size is that subwoofer? I have 50x 3.5" line arrays and hardly see the cones move yet it is flat (actually a bit bumped up) down to 20 Hz.
My xmax (not to be confused with xmech) is 2.55mm and 50 of them gives me an Sd of 1815 cm2. That would make my VD (Sd x Xmax) about 463 cm3.
It equals one 15" sub with ~ 5.7mm Xmax. Or a 12" with about 10mm Xmax.
Here's the FR + distortion:
(as measured in a live room with more ambient noise than I would have wanted)
may i know what drivers r u using?
vmps
Vifa TC9 FD18-08
Link to build thread: http://www.diyaudio.com/forums/full-range/242171-making-two-towers-25-driver-full-range-line-array.html
Edit: almost every person that comes in for a listen thinks the black stool next to the array is a sub.
Link to build thread: http://www.diyaudio.com/forums/full-range/242171-making-two-towers-25-driver-full-range-line-array.html
Edit: almost every person that comes in for a listen thinks the black stool next to the array is a sub.
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I believe those lines used TG9-FSD10/08.
(The S is for shielded, no longer available though)
And a good quality 15" has the capability of handling many times over what the tiny drivers can cope with.
There is no such thing as tight and sloppy bass in the traditional sense and a lot of small cones are no faster than a single large one if distortion across the board is low.
Nothing, you are exactly correct but it isn't just as simple as that, the 12" driver will undoubtedly have a lower system resonance than the 25 drivers and therefore have a significantly higher efficiency than the 25 drivers for a given bass frequency. The 25 drivers will no doubt have a greater efficiency at high frequencies, but no one really cares about these when discussing bass.
If we're talking about a sealed system then EQ can literally compensate for everything equally, that is providing you have enough power and the loudspeakers can handle the power too. However even when dramatically EQd the 25 drivers are much more likely to have very high distortion levels down low, where it counts like when you're trying to hit reference levels at 20Hz for HT.
If we're talking about a ported/OB system or similar, then there is no contest whatsoever, the 12" driver will trounce the 25 small drivers. The system f3 and tuning frequency, for the 25 small drivers, will be pretty high up, most likely around 80-100Hz. In this situation the small drivers will have literally zero chance at producing any deep bass with low distortion. The 12" driver, on the other hand, could have it's f3 around 20Hz with a similarly low tuning frequency and be able to put out copious amounts of low distortion bass.
They aren't, where bass is concerned, the bigger driver > smaller ones.
Thanks 5th element, I completely agree, hence my comments about people comparing SDs of multiple small drivers to a single large driver and thinking this implied equivalent bass capabilities, also my comments regarding HD below driver resonance.
This is why I have multiple dedicated subs.
I just feel people should be aware that the two are not comparable.
This is why I have multiple dedicated subs.
I just feel people should be aware that the two are not comparable.
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If I were building a subwoofer I wouldn't use 25 smaller drivers 
. But as a full range speaker they do more than even I had thought they would. Here's a graph that's a bit louder compared to the previous one I posted, about 5 dB difference yet the distortion did not change that much if at all.
(I think distortion is even lower on this one, meaning no traffic outside at that moment)
For two speakers they had a remarkable steady response in the bass frequencies, hence my comment about distributed bass. Here's a sweep across my listening area:
Want to try that with a single 15" in a room?
Both graphs scaled the same...
I have more difficulty getting a clean measurement because I have a busy street outside than I am worried about gross distortion in my bass output.
. But as a full range speaker they do more than even I had thought they would. Here's a graph that's a bit louder compared to the previous one I posted, about 5 dB difference yet the distortion did not change that much if at all.
(I think distortion is even lower on this one, meaning no traffic outside at that moment
)For two speakers they had a remarkable steady response in the bass frequencies, hence my comment about distributed bass. Here's a sweep across my listening area:
Want to try that with a single 15" in a room?
Both graphs scaled the same...
I have more difficulty getting a clean measurement because I have a busy street outside than I am worried about gross distortion in my bass output.
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Let me add this: these speakers are build and used for stereo reproduction. For a reference HT build I would add subs for the first or maybe 1.5 octave.
I only shared these graphs to show a 25x 3.5" line array can actually reproduce low frequencies. Relieve the lines of the bottom 1.5 - 2 octave and they go louder than I would ever want them to be while listening to them.
I only shared these graphs to show a 25x 3.5" line array can actually reproduce low frequencies. Relieve the lines of the bottom 1.5 - 2 octave and they go louder than I would ever want them to be while listening to them.
Well simulating with the TC9, in a sealed alignment, 24 of them will produce ~103dB at 50Hz at rated xmax.
One 12" Peerles SLS driver will give you ~108dB @ xmax @ 50Hz.
You will only get ~87dBs out of 24 TC9s at 20Hz, with the SLS giving ~93dB.
Clearly 24 TC9s are quite capable, but they aren't ridiculously so. You could over drive them, or push them into excessive distortion with the right kind of music without too much difficulty.
One 12" Peerles SLS driver will give you ~108dB @ xmax @ 50Hz.
You will only get ~87dBs out of 24 TC9s at 20Hz, with the SLS giving ~93dB.
Clearly 24 TC9s are quite capable, but they aren't ridiculously so. You could over drive them, or push them into excessive distortion with the right kind of music without too much difficulty.
Build one and you'll notice the ~ 10 dB in line gain you're getting with a floor to ceiling line array. Your simulation does not show that. Measuring them will let you see that effect. I know because I did do all those simulations a long while back. I'm boosting till 30 Hz, and back off below that. I know the limits and stay under that.
One of the lines is in a corner helping it's output. The other is still close to a wall as you can see in the picture.
I've been beyond the 87 dB at 30 Hz at the listening position (not 20) in regular measurements, not trying to hit it with 20 Hz as I'd like to keep them save. That's what I learned from the simulations I did before I started building them.
All the graphs posted are 3 meter away from the line arrays, playing in stereo (so that makes 50 of them) and SPL calibrated with full range signal in REW with a cheap radio shack SPL meter.
You don't have to believe me, I'll clip my amplifier before I hurt my speakers, and if I do clip my amp I'll probably hurt my speakers in the process.
I'm not suggesting these are a substitute for sub duties am I? We weren't talking about sub duties in the first place. My lines are as handicapped as one 15" sub would be with about 5.7 mm Xmax. Placed in a corner.
But they will be a bit louder once you move away from them. But even that has its limits as they do benefit from floor and ceiling reflection but aren't long enough by themselves to maintain full line behaviour I'm sure. They do surprise you though.
Listening at sane levels to music it is quite pleasing. I do have neighbours living under the same roof and do not plan to use them that loud.
So to answer the original question: you get a bit extra from the line effect so it's not entirely a simple Sd x Xmax story but it has it's limits. Add more drivers and you gain Sd.
If one is wealthy enough one could use the Audience A3 with 12mm Xmax!
Quick calc on that, Sd = 32 cm2 x 50 drivers = 1600. 12 mm Xmax gives you 1920 Vd. About the same as a 15" driver with 23.5 mm Xmax. Not bad but very expensive at $ 170,00 each! Haven't seen any distortion graphs on those either.
One of the lines is in a corner helping it's output. The other is still close to a wall as you can see in the picture.
I've been beyond the 87 dB at 30 Hz at the listening position (not 20) in regular measurements, not trying to hit it with 20 Hz as I'd like to keep them save. That's what I learned from the simulations I did before I started building them.
All the graphs posted are 3 meter away from the line arrays, playing in stereo (so that makes 50 of them) and SPL calibrated with full range signal in REW with a cheap radio shack SPL meter.
You don't have to believe me, I'll clip my amplifier before I hurt my speakers, and if I do clip my amp I'll probably hurt my speakers in the process.
I'm not suggesting these are a substitute for sub duties am I? We weren't talking about sub duties in the first place. My lines are as handicapped as one 15" sub would be with about 5.7 mm Xmax. Placed in a corner
.But they will be a bit louder once you move away from them. But even that has its limits as they do benefit from floor and ceiling reflection but aren't long enough by themselves to maintain full line behaviour I'm sure. They do surprise you though.
Listening at sane levels to music it is quite pleasing. I do have neighbours living under the same roof and do not plan to use them that loud.
So to answer the original question: you get a bit extra from the line effect so it's not entirely a simple Sd x Xmax story but it has it's limits. Add more drivers and you gain Sd.
If one is wealthy enough one could use the Audience A3 with 12mm Xmax!
Quick calc on that, Sd = 32 cm2 x 50 drivers = 1600. 12 mm Xmax gives you 1920 Vd. About the same as a 15" driver with 23.5 mm Xmax. Not bad but very expensive at $ 170,00 each! Haven't seen any distortion graphs on those either.
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One more example before I go to sleep (it's kinda late here)
Measurement of left (corner placed) array, no EQ applied:
Measurement at 3 meters away from the array. Ugly, I know.
Compare this to WinISD prediction, lets look at say 2 KHz as a base SPL, above this the lines will lose SPL due to comb filtering (not shown in WinISD) below will be line gain and room gain, each playing their part (also not shown in WinISD). Here's a WinISD prediction:
Again, take 2 KHz as a reference, look at the output at 30 Hz, it's off the chart, lower than -30 dB from 2 KHz. Now look at the measurement and see where that one is at 30 Hz. What's the difference? Room gain and line effect. That's why I used WinISD to see to where I could boost safely, based on Xmax and know I get 10+ dB for free due to room boundary reinforcement and line gain. Based on WinISD I do not boost below 30 Hz and know I'll be save to about 94 dB according to WinISD. In the real world that will be closer to 104 dB (or above) on the same power, taking it very save and conservative. Instead of needing 30 dB of boost at 30 Hz I only use 15 dB max. A 15 dB reserve compared to the predictions of winISD.
In my real world I have about ~ 100 clean watt available at 8 ohm. That would give me 89 dB at 30 Hz according to WinISD. Again, in the real world I'll probably get more. Hence: my amp will clip before I reach the max the speaker can take. At 20Hz the speaker can handle 240 watt according to WinISD. I have no plans to try that though. But once I learned that's how it actually worked I started building my line arrays.
Now throw in an equaliser and in my case FIR based filtering and enjoy a full range speaker with quite a bit more output than you would think it's capable of.
Measurement of left (corner placed) array, no EQ applied:
Measurement at 3 meters away from the array. Ugly, I know.
Compare this to WinISD prediction, lets look at say 2 KHz as a base SPL, above this the lines will lose SPL due to comb filtering (not shown in WinISD) below will be line gain and room gain, each playing their part (also not shown in WinISD). Here's a WinISD prediction:
Again, take 2 KHz as a reference, look at the output at 30 Hz, it's off the chart, lower than -30 dB from 2 KHz. Now look at the measurement and see where that one is at 30 Hz. What's the difference? Room gain and line effect. That's why I used WinISD to see to where I could boost safely, based on Xmax and know I get 10+ dB for free due to room boundary reinforcement and line gain. Based on WinISD I do not boost below 30 Hz and know I'll be save to about 94 dB according to WinISD. In the real world that will be closer to 104 dB (or above) on the same power, taking it very save and conservative. Instead of needing 30 dB of boost at 30 Hz I only use 15 dB max. A 15 dB reserve compared to the predictions of winISD.
In my real world I have about ~ 100 clean watt available at 8 ohm. That would give me 89 dB at 30 Hz according to WinISD. Again, in the real world I'll probably get more. Hence: my amp will clip before I reach the max the speaker can take. At 20Hz the speaker can handle 240 watt according to WinISD. I have no plans to try that though. But once I learned that's how it actually worked I started building my line arrays.
Now throw in an equaliser and in my case FIR based filtering and enjoy a full range speaker with quite a bit more output than you would think it's capable of.
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My apologies to the OP for hijacking his thread. I just wanted to make clear that with the right driver you can actually get impressive bass with those small coned drivers.
I didn't just jump in and build some arrays. The results might disappoint if you do.
My advise would be floor to ceiling array as short arrays have all kinds of other problems.
I wouldn't (and didn't) pick any driver to give it a go. Pick one you actually like to listen to as you'll get that one on steroids.
If you do decide to build shorter arrays look into power tapering and forget about making any kind of bass. You'd need a whole lot of 2" drivers to get a good Sd number plus the Xmax of the 2" probably disappoints too. The smaller driver could be a lot closer together though moving the comb filtering problems up in frequency.
I didn't just jump in and build some arrays. The results might disappoint if you do.
My advise would be floor to ceiling array as short arrays have all kinds of other problems.
I wouldn't (and didn't) pick any driver to give it a go. Pick one you actually like to listen to as you'll get that one on steroids.
If you do decide to build shorter arrays look into power tapering and forget about making any kind of bass. You'd need a whole lot of 2" drivers to get a good Sd number plus the Xmax of the 2" probably disappoints too. The smaller driver could be a lot closer together though moving the comb filtering problems up in frequency.
Line array theory dicates that if you double up on the total driver area (2 drivers) then you square the efficiency in the bass (4 times). This can have 2 effects that you have to deal with:
1. Assuming the single driver is designed for flat response you will have a gain in the bass response - of course this all depends on the cabinet alignment adjustment and baffle-step compensation. In theory you would need less of the latter but still have to consider if your BS curve is correct
2. Assuming you have dealt with 1 you will have considerably improved bass headroom before the drivers run out of excusion
Yes it is a very effective way of solving the bass limitation of full-rangers and you may well find yourself in subwoofer territory, although with much added coherence (a bass note is really defined by the upper harmonics)
1. Assuming the single driver is designed for flat response you will have a gain in the bass response - of course this all depends on the cabinet alignment adjustment and baffle-step compensation. In theory you would need less of the latter but still have to consider if your BS curve is correct
2. Assuming you have dealt with 1 you will have considerably improved bass headroom before the drivers run out of excusion
Yes it is a very effective way of solving the bass limitation of full-rangers and you may well find yourself in subwoofer territory, although with much added coherence (a bass note is really defined by the upper harmonics)
My apologies too to the OP for asking another question! -But I think this is definitely pertinent to small driver full range line arrays.
OK - I did say 'correct me if I am wrong' and asked 'what am I missing here?'.....
So wesayso and Kevin - are you saying that the line array effect makes the bass produced by line arrays much more efficient, than 'normal' multiple sub-woofers in a room?
If so, are you saying that for a given VD, the most efficient way to produce bass - i.e. say 20-50hz is with a line array? And therefore although I have 4 times the VD of your line arrays this is offset by the fact you have floor to ceiling arrays?
A few questions come to mind - why do we not see more sub-woofer line arrays, particularly with the madness some HT builders go to to produce prodigious bass? Should I be stacking my sub-woofers on top of each other, floor to ceiling, to get better, lower distortion bass reproduction?
I am genuinely asking these questions so please forgive my ignorance if they seem entirely stupid.
I always thought given the wavelengths with sub frequencies, that distributed bass sources - AKA geddes was the best way to pressurise a room with optimum modal distribution.
I thought, given the wavelengths we are talking about, (13 meters for a 25hz sound wave) that a line array would simply act like a single source at these frequencies as all the drivers are almost all within a 1/4 wavelength proximity to each other and therefore behave like a single, large driver. Hence my entire argument about comparing VD etc.
I apologise now if I have this wrong - I have not done a huge amount of reading on line array theory, but really want to understand.
OK - I did say 'correct me if I am wrong' and asked 'what am I missing here?'.....
So wesayso and Kevin - are you saying that the line array effect makes the bass produced by line arrays much more efficient, than 'normal' multiple sub-woofers in a room?
If so, are you saying that for a given VD, the most efficient way to produce bass - i.e. say 20-50hz is with a line array? And therefore although I have 4 times the VD of your line arrays this is offset by the fact you have floor to ceiling arrays?
A few questions come to mind - why do we not see more sub-woofer line arrays, particularly with the madness some HT builders go to to produce prodigious bass? Should I be stacking my sub-woofers on top of each other, floor to ceiling, to get better, lower distortion bass reproduction?
I am genuinely asking these questions so please forgive my ignorance if they seem entirely stupid.
I always thought given the wavelengths with sub frequencies, that distributed bass sources - AKA geddes was the best way to pressurise a room with optimum modal distribution.
I thought, given the wavelengths we are talking about, (13 meters for a 25hz sound wave) that a line array would simply act like a single source at these frequencies as all the drivers are almost all within a 1/4 wavelength proximity to each other and therefore behave like a single, large driver. Hence my entire argument about comparing VD etc.
I apologise now if I have this wrong - I have not done a huge amount of reading on line array theory, but really want to understand.
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