That or there aren't any differences.
Pray tell what are these missing variables? And please don't say "phase" or "group delay" - which are clearly not audible in small rooms at low frequencies (for the situations that we are discussing).
That's called high frequency response and if it too is EQ'd to be the same then the "start and stop performance" will be the same. You need to get the physics right.
Since you don't post any response curves of what sounds "better", and you find a "flat to 31hz" ported (phase inversion) speaker to sound better than a sealed speaker that has a peaked response, I still think the major difference you are hearing in the different cabinets is the frequency response.
Comparing the L26Roy 10" in a 1 cubic foot box (factory spec sheet) to the TC LMSR 12" in a two cubic foot box (Josh Ricci Data Bass test) we see the TC LMSR 12 is -3 dB at 30 compared to 100 Hz, but is +3 dB at 45 Hz, while the L26Roy has no peak below 100 Hz, and is -7 dB at 30 Hz.
The two would sound quite different to anyone paying attention, the L26Roy would sound subjectively "tight" or "fast", the LMSR would sound "slow" or "boomy", it's response is similar to what people have complained about regarding other enclosure types.
Equalize them to the same response and I would bet you will find them to sound quite similar, other than the heavy cone mass of the LMSR does not behave well above 200 Hz.
Using a 24 dB per octave crossover that difference won't be very audible (if the out of band peaks are addressed), but with a 12 dB crossover with no EQ the L26Roy would "win".
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So you don't buy the time/frequency equivalency?
A waterfall plot shows you can have a flat frequency response with varying time stored energy. That's why we have waterfall plots; because the two are independently measured. Flat frequency response doesn't imply a clean waterfall plot.
I have 31 bands of EQ in my truck. I use a 1/3 octave analyzer to flatten the response. The head unit is an Alpine 9887 and its associated DSP unit that has some rediculous number of EQ bands and time correction. The sub amp is a RF TD4000.1bd. All of my subs were flat in truck. Using software models a sealed 1.7 cu ft TC 12" at -3db at 47hz and a 1.3 cu ft L26ROY at -3db at 32hz. Scan Speak specifies the bass data on their supplied sheet is not accurate. Run the numbers yourself in winisd.
I hear a difference in quality in the 3 sealed boxes for the same TC driver. Its decidedly not EQ. You cant EQ a .7Q sub to sound exactly like a .57Q sub or the industry would all use the same size sub box and EQ everything to death. Further if all subs in all boxes sound the same after EQ, then what a simple world it must be. Its all about getting that cone to stop making sound after you stop applying a signal. Varying the air spring does more than reduce the amplitude of a peak in the response. It vary the time it takes for the cone to stop moving. The weight of the cone also affects its ability to stop unless Newton had it wrong.
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OK so a bass driver in one box with eq shows that all sub box sizes sound the same with eq?
I'd like to point out that this debate started because it was said that the same driver can be EQ'd to sound the same in any alignment box.....ported....sealed.....forded horn. My position was that the phase and delay of a port/vent cant be corrected with eq nor can the weight of a cone be corrected to react as fast as a lighter cone on a speaker with a better power to weight ratio. Some alignments can better suit a driver. In my case....no way a TC LMSr12 can be made to sound as good in a ported box as a sealed box of .57Qtc with eq. The scan speak sub sounded better than the TC sub because its a lighter cone with a lower distortion motor and a better power to weight ratio.
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"My position was that the phase and delay of a port/vent cant be corrected with eq nor can the weight of a cone be corrected to react as fast as a lighter cone on a speaker with a better power to weight ratio. "
Fast?
The mass corner of the driver describes how fast a driver is. I have heard vented 18s that sounded faster than sealed 10s, it's all in the design and execution.
"OK so a bass driver in one box with eq shows that all sub box sizes sound the same with eq?"
Again, it has to be done properly, KEF is a brand with several speaker systems. When I sold them the KUBE were specific for the models. It was fascinating to listen to the way the sound of the bass changed as you adjusted the Q control. I really liked the small 103.2 model with its KUBE.
Fast?
The mass corner of the driver describes how fast a driver is. I have heard vented 18s that sounded faster than sealed 10s, it's all in the design and execution.
"OK so a bass driver in one box with eq shows that all sub box sizes sound the same with eq?"
Again, it has to be done properly, KEF is a brand with several speaker systems. When I sold them the KUBE were specific for the models. It was fascinating to listen to the way the sound of the bass changed as you adjusted the Q control. I really liked the small 103.2 model with its KUBE.
A waterfall plot shows you can have a flat frequency response with varying time stored energy. That's why we have waterfall plots; because the two are independently measured. Flat frequency response doesn't imply a clean waterfall plot.
Since both the frequency response and waterfalls come from the impulse response, if the system is minimum phase then if the frequency responses of two systems are the same then the waterfalls also have to be the same. The situation that you described with different Q's of the drivers was necessarily minimum phase.
If the system is not minimum phase in some frequency range, say due to multipaths, etc. then the waterfall can differ from the frequency response due to different times of arrival of the energy in those frequency ranges.
For the most part all low frequency systems are minimum phase, except for some small effects in the upper range. But at the lower cutoff, they will all be minimum phase - Hence EQ this range to be the same and the waterfall will also be the same.
[force factor driver A: MMS Driver A] vs [force factor driver B: MMS driver B]
You stop the electrical signal to the driver and one comes to a stand still first while the other keeps moving for some time longer, regardless of how insignificant it may seem. An object in motion tends to...
Having listen to a large variety of subwoofers, and with a basic understanding of the physics I can tell you this...
Horns are easily the best. They are more efficient, and efficiency means less distortion. In the real world this is because the driver has to exert less for the same spl. This also means lower wattage in, meaning less heat, meaning lower power compression and a greater dyanmic range.
Every other design is a compromise for space at the cost of audio. That simple. Horns can be and are often made with similar compromises, but they do not preclude hi-fi by their design.
Until you've heard a proper basshorn system, you haven't really heard bass.
IMO the most all other designs can do is a kind of deep rumble, not a dynamic 'alive' bass.
Horns are easily the best. They are more efficient, and efficiency means less distortion. In the real world this is because the driver has to exert less for the same spl. This also means lower wattage in, meaning less heat, meaning lower power compression and a greater dyanmic range.
Every other design is a compromise for space at the cost of audio. That simple. Horns can be and are often made with similar compromises, but they do not preclude hi-fi by their design.
Until you've heard a proper basshorn system, you haven't really heard bass.
IMO the most all other designs can do is a kind of deep rumble, not a dynamic 'alive' bass.
You referenced a post that was specifically talking about our paper. What else was I supposed to assume?
I'm told in this thread that if you play that horn and that same driver from the horn in a sealed box (or any driver in any box) and EQ them, you can't tell them apart. In my case that's a Seas L26ROY in a ported box vs. a TC LMS-R 12" in a sealed box. I felt the detail and ability to pick out individual notes was from a better power to weight ratio of a cone with 1/3 the MMS and motor that was more than 1/3 the strength of the TC. Earl states that damping is damping and cone mass is irrelevant.
I'm told the subjective differences either don't exist (in my head) or are from insufficient EQ if they do exist, IE better high freq range of one. I'm using DSP EQ.
I would love to just adjust some EQ and hear the detail of that 10" but I'm unable to figure this one out. If you're new here, Earl Geddes background and education are in this field of study and his products are held in high regard so I just figured it was something I'm not catching as far as understanding my complete model. Can two different drivers be the exact same flat response in the exact same frequency range and one be able to react faster to its input signal that the other (stop making noise when the signal is stopped). In the tweeter world, a ribbon tweeter and dome can be EQ'd flat and they would be readily distinguishable. Zaph says its distortion.
I would say the SEAS having all that copper in the motor would have less distortion in low level measurements but then at higher SPL's the motor would distort far sooner than the LMS-R 12" which is a tank that can handle 8X its power. After some time I thought the motors' strengths vs the cones' weights would make the difference but I'm told Newton's laws of motion have no influence here and that they both start and stop at the exact same time because damping is damping regardless of type.
There is alot of psychology to this diy bass stuff, even if you think "i know that there is psychology involved so it wont affect me". I for instance have build some medium sized tapped horns for my woofers, which were in closed boxes before. On a abstract level, i know i should not be able to hear a difference, since i EQ'ed everything perfectly and both systems have the same response. However, i still have more fun with them, especially at loud levels. Perception is clouded by expectations to a great degree.
I have the drivers I talk about here. I realize some people want a certain outcome to justify what they bought, but if that was the case, I'd be trying to justify buying the $370 12". If EQ had matched performance of two systems, I'd have to be insane to then build 4 more enclosures to try to get the 12" to sound like the 10". I changed because I was told that sealed sounded better than ported thus the 12" sealed should sound better than the 10" ported; I couldn't wait to hear what I was missing but it proved to not sound better.
I can, in fact, pick out which sub is playing 100 out of 100 times so I'm at a loss to figure out where I went wrong with performing a simple function of EQ.
I thought it was the power to weight ratios of the cones and that the 12" cone is 3 times the weight of the 10" cone but its motor isn't 3 times as strong. Geddes states cone weight is irrelevant and even mass is apparently overcome by EQ differences. It makes sense that damping is damping. I guess I still have a damping difference between two systems. If any driver works equally well in any enclosure and alignment, then EQ must overcome all differences.
Why would anyone go through such extremes for size, cost, and complexity when an EQ can accomplish what a horn does. SPL? OK then the open baffle people must be crazy to state how superior OB is with all its draw backs just to get that natural sound they talk about. I guess I agree with you about psychology in this hobby. I think people talk themselves into liking something they spent more money on, if it doesn't sound better. What they don't do is admit they wasted $370 and then build a bunch of boxes to try to better the worse sound.
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