I'm just trying to show that what mark said isn't really right in all cases, and incorrect for a basic LT EQ. You can see in the LT graphs that the rate of roll off of the sealed box isn't changed, but by using a lower Q and Frequency it is pushed down to the point that it isn't easily seen. Those graphs show 1 to 10Hz in an expanded scale if the graph stopped at 10Hz you would hardly see the 12dB roll off at all for the equalized version.
You are of course right Mark, especially in the case of a PA approach.
Last week at the biggest dance event in the world, I once again experienced how good modern PA can sound (and how bad if outdated/poorly implemented solutions were used).
Hi fluid,
Taking the idealized case of a response that I posted, the equalization curve should (asymptotically) approach the modeled/measured response at higher frequencies, then raise to compensate the drop of the response and again (asymptotically) approach level. Such can be described, as, e.g., 1+(k^2-1)/(1+k(f/f_b)^2), wherein f_b is one-half of gain/loss.
I may be overlooking something, so can you give me an example of equalization that would result in increased GD and reason why would anyone employ it?
I do not wish to beat a dead horse, much less to deride mark100, but the issue is of interest to me. I had discussed with someone the idea to design an equalizer that would compensate the GD of a vented enclosure, thus "to have a cake and eat it too".
Kindest regards,
M
My simplistic mind cannot think of an example of an equalization that could make mark100's statement correct.
Taking the idealized case of a response that I posted, the equalization curve should (asymptotically) approach the modeled/measured response at higher frequencies, then raise to compensate the drop of the response and again (asymptotically) approach level. Such can be described, as, e.g., 1+(k^2-1)/(1+k(f/f_b)^2), wherein f_b is one-half of gain/loss.
I may be overlooking something, so can you give me an example of equalization that would result in increased GD and reason why would anyone employ it?
I do not wish to beat a dead horse, much less to deride mark100, but the issue is of interest to me. I had discussed with someone the idea to design an equalizer that would compensate the GD of a vented enclosure, thus "to have a cake and eat it too".
Kindest regards,
M
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I have no experience with your definition of "direct energy" so I can't comment. It sounds to me like a perceptual effect, i.e. felt by you personally. There are never answers to this kind of situation until you can measure it and control it in order to test it.
There is a lot of evidence that feeling sound and hearing it are tightly coupled such that it is hard to determine which is which.
Hi Ro808,
So, thank you very much for them.
Kindest regards,
M
Nope, I was not following upon the idea, as it has been met with some skepticism.
So, thank you very much for them.
Kindest regards,
M
The 2nd paper, or better: presentation, is particularly interesting because it includes practical experiences and comments on 'typical hi-fi preferences'.
I agree with the author that many hi-fi speakers exhibit an unnatural bass response.
On the other hand, usually the well-thought-out no-nonsense systems score high. These are (coincidentally?) often BR systems, including the aforementioned Living Voice Auditorium/OBX.
I agree with the author that many hi-fi speakers exhibit an unnatural bass response.
On the other hand, usually the well-thought-out no-nonsense systems score high. These are (coincidentally?) often BR systems, including the aforementioned Living Voice Auditorium/OBX.
Sure I do it myself. I set an extended sealed type of roll off down to 30Hz where I then drop the output more steeply to avoid over excursion. It is the steepness of the final slope that adds to the group delay. So if you make a sealed box roll off at 24dB/oct it will have the same sort of group delay as a vented box which is something mark said that I completely agree with. I also have my cake and eat it by using an FIR filter so no group delay increase overall for me.
Me too and I hope mark does not think that is my intention, I think it is more likely to be a communication breakdown.
All sound energy that is a direct path from the source.
Direct sound
- Sound waves arriving at the listening location directly from the source. Differing from reflected sound, which arrives at the listening location after bouncing off the surrounding surfaces.Direct energy = Direct Sound. Sound Energy
"Sound energy is the result when a force, either sound or pressure, makes an object or substance vibrate"
I must not be saying it in a way that is commonly said in the field.
Does increasing Radiation area, increase Direct Sound, to the listener??? For some reason I am under the impression the answer is yes.
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Hi Ro808,
I actually like the first paper for the reason that it provides an analysis of the different types of approaches and analysis of potential caveats.
Hi fluid,
Kindest regards,
M
I actually like the first paper for the reason that it provides an analysis of the different types of approaches and analysis of potential caveats.
Hi fluid,
I had been thinking about the over-excursion problem, and to avoid the additional high-pass filter, I have been contemplating to use two drivers with reasonable excursion capability, which lowers the power and excursion requirement. Considering average SPL of 75-80 dB and taking into account estimated 30 dB headroom, the required peak SPL is 105 - 110 dB. Further, very few classical pieces have much output under 40 Hz.
Judging by mark100's posts, he is not the type of a person that would take the discussion personally, but rather as educational experience.
Kindest regards,
M
Hi fluid, hi M,
Linkwitz analysis is small signal analysis, and yes there it holds true that the rate of roll-off can be held to 12 dB oct.
But that not's reality when it comes to driving a sub with large signal.
Large signal analysis must take excursion into account.
If a sealed sub is simply EQ'ed up with shelving as per the above diagram, it will run past xmax or at least into excessive excursion and distortion at the lower end, when trying to use the sub at its normally specified full SPL.
A way to control over excursion when using a Linkwitz transform or shelving EQ boost, is to use an additional electrical high pass (like is mandatory for vented designs).
Alternatively, parametric EQ's can be used for selective low freq boost, without over boosting very low in freq.
Both of those techniques create additional phase rotation and group delay...simply because they both net out to create a steeper acoustic high-pass response at the very bottom end.
So with sealed, i think there are 3 basic options:
*Stay within xmax for true sealed 12/oct rolloff....with its implied SPL and low frequency limitations. This at least keeps the 12 dB natural rolloff, and associated low phase rotation/group delay.
*Or put in an additional hpf, or use para EQ for boost....to gain safe excursion limited SPL. This acts more akin to vented's rolloff, phase, and group delay.
*Or go with more sealed displacement to achieve SPL desired at low corner. Bigger drivers with more xmax, or more of them. No boost at all. Shelve down excess response above low corner EQ.
The true gold standard imo !
edit: Ps...of course guys, nothing personal at all...just good discussion among friends. And always happy to be corrected too, when need be 🙂
This is what I thought, that what you said before isn't the whole story of what you actually meant. I know you wouldn't have a system that couldn't blow your underpants off at 100m but you can't view everything from your own lens without explaining it.
So ignoring all the other stuff that is down to properly choosing the system for the SPL required, the extra group delay only comes from increasing the slope of the HP response.
It would appear the answer to the thread title is "yes".
18Hz - 20kHz, 107dB: Klipsch Jubilee
$36k/pair
18Hz - 20kHz, 107dB: Klipsch Jubilee
$36k/pair
With a closed box you will need the same amount of displacement for a given SPL at a given frequency, whether it is reached "naturally" or by EQing. If you have the same Vd at hand it doesn't matter whether your cutoff is reached naturally or by EQ. Closed box speakers have a natural resilience against LF overexcursion if used reasonably. If you are not intending to make subsonic orgies but reducing group-delay distortion further up in frequency EQing of closed-box speakers is a possible solution.
I can immediately see that, since the psycho-acoustic effect there is extremely strong.
Since all those active filters will follow the same rules, as long as the response of the filter is the same, the group delay will also be the same. So no matter what filter we use, LT, param EQ or an highpass with an higher Qts for boosting.
That being said in practice a LT plus a carefully chosen first order HP will give adequate protection against higher cone excursions, with very minimal penalty for additional group delay.
In this case the work flow is as following;
Design a LT with a desired frequency with a Q of 0.707.
Add an additional 2nd order HP at the same freq as well at a Q of 0.707.
This creates a nice Linkwitz-Riley roll-off with a Q of 0.5, meaning a very steady group delay.
Substitute the 2nd order HP with a first order HP.
In this case you have to fiddle a little with the Linkwitz Transform Q-factor as well as frequency.
As well as the frequency of the first order HP filter.
In theory textbook wise, this won't give exactly the same results.
But the deviation will be below -24dB or so, so nothing we have to worry about in practice.
Especially when one takes the low-pass filter also into consideration. 🙂
I can show some graphs if people find that easier to follow.
One important fyi, this DOES NOT work with the latest WinISD, since it has a major bug with Linkwitz Transform filters!!!
edit: Btw, we will have an increase in group delay anyway because of the lowpass filters.
But using a LT or a BR without any kind of HP (even first order) is not a good idea.
This is true for basically any kind of boosting actually.
I personally think there is WAY to much anxiety about group delay (as well as distortion) in general.
There is no or extremely little literature (meaning in extreme cases) that back this anxiety up.
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Yes, exactly ! All the highpass poles should be as low in frequency as possible if they are only used for blocking DC in order to not unnecessarily increase group-delay distortion. Only the highpass-poles that are there to systematically achieve a desired frequency response may be higher up.