Stig, how's this?
It's only 102dB @ 20hz, but average is 105dB.
This is all 4 subs together. It was a little exciting! But the poor little RSS265 subs are maxed out, although the Lab 12s seem to have a little more to give. (I calibrated SPL on the Umik using a decent SPL meter, so I think this is a real number.)
If I upgrade to the 12" subs, I I should be able to boost the 20-40hz by ~5dB.
What would you do?
It's only 102dB @ 20hz, but average is 105dB.
This is all 4 subs together. It was a little exciting! But the poor little RSS265 subs are maxed out, although the Lab 12s seem to have a little more to give. (I calibrated SPL on the Umik using a decent SPL meter, so I think this is a real number.)
If I upgrade to the 12" subs, I I should be able to boost the 20-40hz by ~5dB.
What would you do?
Your title asks about transient response. That’s a different wiki page, but I can see you meant transients.
If you consider what the transient is, it’s the start and stop of the speaker cone moving. If it can do it in 1 second, that’s very slow. If it can do it in 1 millisecond it’s much shorter.
So the faster a speaker is able to react to the transient - to start, stop, the faster it’s able to start/stop the opposite direction. Now that was one full wavelength. The faster a speaker can move and react to transients, the higher in frequency it can play and vice versa.
This is why transient response is directly tied to frequency response. In fact one specific kind of transient response, the impulse response, requires an infinite frequency response.
Yes... indeed. I noticed that the OP seems to be confusing transient response with dynamic range.
Dynamic range is the range from the loudest to the softest... it's measured in db.
Transient response is the delay between the signal being input into the driver and the driver following it... it's measured in seconds.
I'll give you a clear example. Owners of planar speakers know about dynamic range but with limited dynamic range. Maggies, for example, have "fast bass" and "bass slam" because the very light panel has very low mass and is driven by a big motor... hence there is very little time delay for the membrane to move and follow the signal. There is very little energy stored in the membrane. The bass sounds very good, but it is not all that deep, nor all that loud. But at 40Hz, they are champs!
IMHO, what the OP wants is dynamic range AND power (ie: acoustic energy). Meaning a driver(s) that can move a LOT of air, can play loud and has extended bass response. If it can also play "fast" then great... otherwise you get the dreaded sloppy "boom, boom" boominess.
Normally this is done with an array of multiple, smaller drivers.... or with few large -but very exotic- designs. For this, a real "Wall Of Sound" makes a lot of sense... forget 12 inchers.. just go with a bunch of 10 inchers.
Or, of course, you can do a quad set of El-Pipo's.
Dynamic range is the range from the loudest to the softest... it's measured in db.
Transient response is the delay between the signal being input into the driver and the driver following it... it's measured in seconds.
I'll give you a clear example. Owners of planar speakers know about dynamic range but with limited dynamic range. Maggies, for example, have "fast bass" and "bass slam" because the very light panel has very low mass and is driven by a big motor... hence there is very little time delay for the membrane to move and follow the signal. There is very little energy stored in the membrane. The bass sounds very good, but it is not all that deep, nor all that loud. But at 40Hz, they are champs!
IMHO, what the OP wants is dynamic range AND power (ie: acoustic energy). Meaning a driver(s) that can move a LOT of air, can play loud and has extended bass response. If it can also play "fast" then great... otherwise you get the dreaded sloppy "boom, boom" boominess.
Normally this is done with an array of multiple, smaller drivers.... or with few large -but very exotic- designs. For this, a real "Wall Of Sound" makes a lot of sense... forget 12 inchers.. just go with a bunch of 10 inchers.
Or, of course, you can do a quad set of El-Pipo's.
Really guys? If we're gonna be like that now, let me also give some insights into what you are saying.
Tony, your definition of "transient response" is wrong. You are actually describing is what engineers call "hysteresis". Also, your definition is completely different from bomber's.
Bomber, I don't see what you are objecting to. Your "transient response" is not something different from I'm asking about, except I skipped over the theory and went straight to the practical application! What you're talking about all cancels out, and in the end you're just left with power, frequency, and SPL.
You point out that it is theoretically possible for a driver to have "infinite frequency response", but that doesn't mean anything. To have infinite frequency response, the mass of the cone and the distance traveled would both be approaching zero, and the energy required would be approaching infinity. You can do it with math, but not with speakers. Transient response is just an engineering way of measure what a driver's frequency response is, but it is meaningless without factoring in SPL.
The question I was asking is about the ability of a specific driver to reproduce a transient sound in an audio signal, and that transient has a specific SPL.
If we know the SPL of that transient, we can calculate how far the speaker cone must move, given it's area, to produce a pressure wave with the specified amount of energy.
Then we can compare the required speaker cone travel to the driver's excursion. At the same time we need to make sure the motor force is strong enough to push the cone the required distance in the required time.
If the woofer doesn't have enough motor strength or excursion to reproduce the transient sound at the SPL determined from the audio signal, I think it is quite correct to say that the driver lacks the required transient response. This is correct to say, because the cone is unable to move the required distance in the specified time. Consequently the transient sound is not accurately reproduced.
Tony, your definition of "transient response" is wrong. You are actually describing is what engineers call "hysteresis". Also, your definition is completely different from bomber's.
Bomber, I don't see what you are objecting to. Your "transient response" is not something different from I'm asking about, except I skipped over the theory and went straight to the practical application! What you're talking about all cancels out, and in the end you're just left with power, frequency, and SPL.
You point out that it is theoretically possible for a driver to have "infinite frequency response", but that doesn't mean anything. To have infinite frequency response, the mass of the cone and the distance traveled would both be approaching zero, and the energy required would be approaching infinity. You can do it with math, but not with speakers. Transient response is just an engineering way of measure what a driver's frequency response is, but it is meaningless without factoring in SPL.
The question I was asking is about the ability of a specific driver to reproduce a transient sound in an audio signal, and that transient has a specific SPL.
If we know the SPL of that transient, we can calculate how far the speaker cone must move, given it's area, to produce a pressure wave with the specified amount of energy.
Then we can compare the required speaker cone travel to the driver's excursion. At the same time we need to make sure the motor force is strong enough to push the cone the required distance in the required time.
If the woofer doesn't have enough motor strength or excursion to reproduce the transient sound at the SPL determined from the audio signal, I think it is quite correct to say that the driver lacks the required transient response. This is correct to say, because the cone is unable to move the required distance in the specified time. Consequently the transient sound is not accurately reproduced.
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Dynamic range and transient response are (scientifically speaking) two very different terms describing, in our case, characteristics of audio reproduction. The first is measured in dB - a simple and dimensionless ratio of two levels - and the latter is a temporal event measured in seconds. To conflate or interchange the terms causes confusion amongst those who understand the difference, as evidenced in the comments above. (Whilst we could probably argue that a sudden increase in spl in the source signal is a transient event, the speed of the transient response proper is determined by the HF driver high frequency rolloff. Since the signal feeding subwoofers is heavily filtered it cannot play any part in a transient's leading edge slope/steepness).
As a very loose analogy, the confusion in terms here is akin to mixing up with how much a car's top speed can exceed the legal limit (say twice the limit) with its acceleration time to get there (seconds)!
tonyEE's allusion to the Fourier Transform is entirely valid and correct in relation to transient response as are looneybomber's comments , and others who have suggested 20-odd dB of headroom (I hope we can all agree on this term!) is also good real-world advice. A little driver like a ten inch should not really be considered a subwoofer if output is important and it is going to have to try really hard to produce clean bass at any significant level, so if you have space to try a decent 18" having proper power handling and Vd you will not look back!
As a general rule, nothing in forty plus years of building subs has shaken my mantra for good bass reproduction: 'Move a lot of Air - GENTLY!'
In the past decade or so I have added: 'Store as Little Energy as Possible'
As a very loose analogy, the confusion in terms here is akin to mixing up with how much a car's top speed can exceed the legal limit (say twice the limit) with its acceleration time to get there (seconds)!
tonyEE's allusion to the Fourier Transform is entirely valid and correct in relation to transient response as are looneybomber's comments , and others who have suggested 20-odd dB of headroom (I hope we can all agree on this term!) is also good real-world advice. A little driver like a ten inch should not really be considered a subwoofer if output is important and it is going to have to try really hard to produce clean bass at any significant level, so if you have space to try a decent 18" having proper power handling and Vd you will not look back!
As a general rule, nothing in forty plus years of building subs has shaken my mantra for good bass reproduction: 'Move a lot of Air - GENTLY!'
In the past decade or so I have added: 'Store as Little Energy as Possible'
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In the "Master Handbook of Acoustics", 7h edition, page92, (*) they describe ringing for a transient. This is what they describe as "transient response".
It is mostly (**) due to energy storage in the media and it is due to hysteresis as the speaker is storing energy and following the actual leading edge of the transient. Once the transient is removed, the stored energy is released.
Note that we also see this in diodes and why we have snubber circuits.
The best system is that one that minimizes energy storage because this is ultimately parasitic ( loss of efficiency ) and adds temporal distortion.
So, yes, perhaps I should have described my entire train of thought, but hysteresis is the reaction to energy storage in the driver/system. This energy storage is then released in the form of "transient response".. which causes ringing and non harmonic distortion ( time based ).
Anyhow, this is why I describe lightweight systems like the Maggies which have "fast" bass, meaning no energy storage and little ringing. Hence very good "transient response". They follow the signal with little hysteresis ( which is a time delay in the signal this case, as I described. ). Also, the large radiating panel moves very little, hence it moves lots of air "gently"...
Bottom line, systems that store little energy follow the signal with little delay ( no hysteresis ) and had little or no ringing after the transient is removed.
So, if you're gonna build a bass system that exhibits good "transient response" you want a low mass system or some exotic setup ( for example a servo system ).
(*) I got it opened by my left hand... because I wanted to find a more rigorous description of my sleigh of hand.
(**) I hate to make a blanket statement... I suppose there might be other factors but I believe they will be order(s) of magnitude less important.
It is mostly (**) due to energy storage in the media and it is due to hysteresis as the speaker is storing energy and following the actual leading edge of the transient. Once the transient is removed, the stored energy is released.
Note that we also see this in diodes and why we have snubber circuits.
The best system is that one that minimizes energy storage because this is ultimately parasitic ( loss of efficiency ) and adds temporal distortion.
So, yes, perhaps I should have described my entire train of thought, but hysteresis is the reaction to energy storage in the driver/system. This energy storage is then released in the form of "transient response".. which causes ringing and non harmonic distortion ( time based ).
Anyhow, this is why I describe lightweight systems like the Maggies which have "fast" bass, meaning no energy storage and little ringing. Hence very good "transient response". They follow the signal with little hysteresis ( which is a time delay in the signal this case, as I described. ). Also, the large radiating panel moves very little, hence it moves lots of air "gently"...
Bottom line, systems that store little energy follow the signal with little delay ( no hysteresis ) and had little or no ringing after the transient is removed.
So, if you're gonna build a bass system that exhibits good "transient response" you want a low mass system or some exotic setup ( for example a servo system ).
(*) I got it opened by my left hand... because I wanted to find a more rigorous description of my sleigh of hand.
(**) I hate to make a blanket statement... I suppose there might be other factors but I believe they will be order(s) of magnitude less important.
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Transient response refers to the time-domain response of a system to a transient input. Now, there are many types of test signals used for transient analysis, like impulse input, step input etc. However, all these responses (as GM already said in post #7), are directly related to the system bandwidth.
Maggies have "fast" bass because they have almost no bass.... which is also heavily distorted. I know all about that since I at some point owned eight pairs of maggies. I do love how they can sound ... above 500 Hz.
I agree with you that they don't "ring", since they have no defined resonance frequency like a traditional electrodynamic loudspeaker.
If your Maggies had no bass it's because your amps were wimpy.
I drove my 12s with a pair of clone Aleph 5s. ( 90w). They sounded quite good with reasonable mid bass. Then I changed the 12s to 1.7s. Hmm... so I went to a pair of clone Aleph 2s.
I tell you, from the very first 15 seconds I could hear that bass.
POWER, my man... Maggies have bass, but you have to give them lots of power. LOTS.
I drove my 12s with a pair of clone Aleph 5s. ( 90w). They sounded quite good with reasonable mid bass. Then I changed the 12s to 1.7s. Hmm... so I went to a pair of clone Aleph 2s.
I tell you, from the very first 15 seconds I could hear that bass.
POWER, my man... Maggies have bass, but you have to give them lots of power. LOTS.
Is 2 kW enough you think?
Anyway. Power will not change their frequency response or very limited dynamic range in the bass.
See my measurements of a 3.6 here :
Post in thread 'Magnepan 3.7i - Convert crossover to parallel'
https://www.diyaudio.com/community/...ert-crossover-to-parallel.383517/post-7187846
Anyway. Power will not change their frequency response or very limited dynamic range in the bass.
See my measurements of a 3.6 here :
Post in thread 'Magnepan 3.7i - Convert crossover to parallel'
https://www.diyaudio.com/community/...ert-crossover-to-parallel.383517/post-7187846
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It would be interesting to see distortion graphs at that SPL.
For home theatre, I think subwoofers should be able to at least 105 dB sustained ouput with distortion below 1%. At 20 Hz 1% distortion will be quite audible, because the ear is far less sensitive at 20 Hz that at the 2nd and 3rd harmonics.
That's because you are trying to play them LOUD and they lack the dynamic range. Period.
I've seen what you are trying to do with the crossovers and dynamic woofers and what not. And, your measurements are somewhat questionable... as measuring a large panel with the single microphone is yielding strange results... the comments in the thread are clear. The measurements do not clearly reflect how the panels are loading the room.
Maggies will play reasonably deep at lower levels -for music.
Feed them lots of power and keep the volume at 9 o'clock.
IMHO, stuff like Maggies do best in system with a low noise floor. The trick is to keep the system noise floor low ( room and audio system ) So, if the noise floor is at 45 dbA and the average loudest is 95dbA you've got dynamic range of 50db. Which is better than a well produced LP. With an 83db/w Maggie, that will require ~20wpc.... and for peaks, 200 wpc will give you something like 100 dbA.
This will be accross the entire bandwidth of the speaker.
If, OTOH, you are trying to drive the speaker louder, you will run into the situation where the frequency response becomes uneven, with big drop offs on the bass.
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During that test I measured from the main listening position, and the distortion measurement was pretty terrible...but there was so much rattling going on at the time that I'm pretty sure the distortion measurement is meaningless. I'd have to take it outside to get a meaningful measurement.
I can say that when playing a tone, I do not hear any harmonics or chuffing, which to me is more meaningful than a distortion measurement. This is because a 20hz tone is essentially inaudible, so any tone I hear when playing a 20hz tone is distortion. I can feel the 20hz in my eyeballs, but I don't really hear it that well...so if I hear any more audible frequencies, those would indicate distortion. I'm not getting those.
But I have experienced bad subwoofer distortion. If I played a sweep on my old subs, I could hear the tone jump up an octave when it got down to around 30hz. It was spec'd to play lower, but there was more distortion than there was the fundamental!
The wavelength of a 20 Hz audio signal is ~56 feet. Unless you're room is at least half that, ~28 feet, all you're going to hear are overtones.
My Entecs go quite low, the distance from the woofers to the kitchen (end to end of that part of the house) is about 50 feet. Interestingly. the bass is strong when the stereo is playing -loud enough, and you're standing in the kitchen. But in the middle, dining room den, you can barely hear the bass.
My Entecs go quite low, the distance from the woofers to the kitchen (end to end of that part of the house) is about 50 feet. Interestingly. the bass is strong when the stereo is playing -loud enough, and you're standing in the kitchen. But in the middle, dining room den, you can barely hear the bass.
It is a wise idea to dig into a problem with a theoretical approach. This way you understand what you do, what might work and what not.
On the other hand, in the end we are talking about a real room with a real speaker and existing amp.
After many years of interest in this theme, most have developed something like a gut feel, that guides them to the sollution of a given problem.
I just read this whole thread and my gut tells me you need something larger than a 12" or a few more of these, including very strong amps, but no 10" what ever.
The Lab 12 is a very capable driver, it may stick in a too small enclosure, have a too weak amp or both if two of them don't rock..
I don't know your real world room, but IMO 4 Lab 12 with a DSP and plenty of power (like 500W each) should get you close to your aim.
Someone mentioned servo subs.
This is a very differend beast. They can transform a bass weak, slow driver, into a wreaking ball. In my final installation the subs will be servo driven, no doubt. The only thing that matches such subs, are very large horn speaker, like a 2x18".
The usual idea of MFB, to turn small speaker into "large" sounding woofers is commercially interesting, but IMO stupid waste of resources.
Large 12" or 15" speaker, force feed by a large amp in not too small cabinets and a clever sensor will give you this jaw dropping experience you search. Compared to any alternative, at a ridiculous low price. Compare it to turbo charging engines. Nice on a small 4 banger, but incredible on a large, bi-turbo V8.
Anyway, the selection of the right chassis is critical, as it has to be mechanically strong, high excursion, high power, but with a not too heavy cone and medium strong magnet. To me it looks like some newer PA chassis are moving into this direction.
I'm pretty sure, those critical of this logical concept never heard such a sub, done right.
On the other hand, in the end we are talking about a real room with a real speaker and existing amp.
After many years of interest in this theme, most have developed something like a gut feel, that guides them to the sollution of a given problem.
I just read this whole thread and my gut tells me you need something larger than a 12" or a few more of these, including very strong amps, but no 10" what ever.
The Lab 12 is a very capable driver, it may stick in a too small enclosure, have a too weak amp or both if two of them don't rock..
I don't know your real world room, but IMO 4 Lab 12 with a DSP and plenty of power (like 500W each) should get you close to your aim.
Someone mentioned servo subs.
This is a very differend beast. They can transform a bass weak, slow driver, into a wreaking ball. In my final installation the subs will be servo driven, no doubt. The only thing that matches such subs, are very large horn speaker, like a 2x18".
The usual idea of MFB, to turn small speaker into "large" sounding woofers is commercially interesting, but IMO stupid waste of resources.
Large 12" or 15" speaker, force feed by a large amp in not too small cabinets and a clever sensor will give you this jaw dropping experience you search. Compared to any alternative, at a ridiculous low price. Compare it to turbo charging engines. Nice on a small 4 banger, but incredible on a large, bi-turbo V8.
Anyway, the selection of the right chassis is critical, as it has to be mechanically strong, high excursion, high power, but with a not too heavy cone and medium strong magnet. To me it looks like some newer PA chassis are moving into this direction.
I'm pretty sure, those critical of this logical concept never heard such a sub, done right.
Yeah, used a pair of Servodrive Contrabass for awhile thanks to Danley's long gone BASSLIST kit offering, truly awesome and way too much for my stick built/'floating' floor construction. 🙁
Larger than a 12" is out of the question. The cabinet I have is already as big as I'm willing to make it...meaning I was trying to shrink it as much as possible, and this is as small as I could make it!
The Lab 12 does rock. They will exceed 110dB in my room. But in my design they are in sealed enclosures and roll off around 45hz. Reinforcing the 20-50hz range is the goal. I thought of getting 2 more, but they would require a completely different cabinet. They would need a smaller cabinet with a higher port tuning...and then the SPL would be less than from the UM12-22 subs.
I'm about to pull the trigger on a pair of UM12-22s. They seem to be a perfect match for my cabinet. They seem to be optimized for 20-50hz.
Before committing to the 12" subs, I was investigating the amplifier part of the equation. My conclusion is that the Emotiva amp will be able to deliver the required wattage to drive the UM12-22s (wired as 4 ohm). Unless someone can explain why that is not the case? It was a little confusing because of the way they rate the amp. But now I'm pretty confident it has enough power to drive my entire system to above 110dB!
I think that's enough, right?
At home I drive a pair of Entec SW-5 servo woofers. They are big enough boxes with a single 9" woofer, heavy duty too... but they're very fast and match very well with stuff like Maggies and monitors like Acoustic Energy AE1s.
..
Check this:
https://www.pjbworld.com/cms/index.php/products-cabinets/
Phil Jones is the guy who came up with the Acoustic Energy AE1 and it's 5" "woofer". Eventually he came up with the notion of paralleing lots of 5 inch metal woofers.... that gives you the strong, high excursion per driver, cumulative strong magnet and reasonably light/small cabs. I don't think he's made one for home use, but looking at the specs I don't see why not.