What is being missed here is that it is the in-situ response that matters NOT some hypothetical free field response, which you will never get in-situ. In this situation the Q, f's, etc. hardly matter at all - the room dominates. And "yes" I have a flat LF response in-situ (flat being a relative term.) The in-situ mult-sub with EQ achieves this and is the only way that I know of to get to this ideal. I don't even read TS parameters on my subs, they are unimportant to me. Of course the woofers need to be high power with good excursion limits, low Le modulation, but Q? Don't care.
..."the only"? What about nearfield sub?
I mean eg.: Comparison of different near field and far field subwoofer configurations
Got it. Since the 4ohm and 8ohm versions have the same Le = .2mH, I assume your 16ohm version does also.
Since Le is already so low in the TD15M, I wonder what the real difference in sound would be. I also wonder if differences in sound of otherwise equivalent CD's are attributable to using the 16ohm vs the 8ohm version, both with the same Le. The data on my CD's doesn't list an Le.
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OK "only global." But, whenever LF EQ is used, a drivers Q doesn't matter; fs, hardly at all. It's debating over nothing.
Thats my main take away. You've already schooled me on the other aspects but mainly, in response to Scott L's position, a non dsp elitist no doubt...EQ... EQ is in the equation. Room EQ is simply EQ meant to fight against the rooms influence on the FR but plainly EQ non the less...MultiSub combined with EQ makes for a practical and effective solution. Could you get there without (room)EQ? I think the challenge would be cumbersome.
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I can tell you from my personal current set up (stereo 12" subs at 1 meter) that nearfield sub isn't the solution. It may lessen the blow but I still have a -10db dip at 100hz
The study posted is flawed...the woofers tested would need to remain in the same position for it to show some kind of relevance, moving the position changes the response regardless of approach (monopole, dipole, stereo vs single)
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Rooms ......shrooms...
Spend a zillion units of time, energy, and moolah on speakers, electronics, setup/tuning, and room construction & treatments.
Most often, stay confused by how much swapping things really helped.
Then switch rooms, or move to a new house, and do it all over again.
OR....try the best room in the house (that never changes all that much),
and listen to how much (waaay) better whatever gear is being used sounds.
That relatively unchanging, best room, defines achievable SQ imho....
OUTDOOR LISTENING !!!!
Spend a zillion units of time, energy, and moolah on speakers, electronics, setup/tuning, and room construction & treatments.
Most often, stay confused by how much swapping things really helped.
Then switch rooms, or move to a new house, and do it all over again.
OR....try the best room in the house (that never changes all that much),
and listen to how much (waaay) better whatever gear is being used sounds.
That relatively unchanging, best room, defines achievable SQ imho....
OUTDOOR LISTENING !!!!
OK, I'm starting to loose focus on how a Horn system is known as the most resolving of systems....I argued previously a good horn has tighter decay but as Rob shows here -> Is it possible to cover the whole spectrum, high spl, low distortion with a 2-way? I may have been too optimistic.
Directivity is a main topic....horns allow manipulation of dispersion, an aspect to which waveguides have narrowed in on leaving behind loading.... Loading lowers excursion, which lowers THD....I don't think 15" woofers have an issue of THD if we compare a horn to it within optimal spectrum for each scenario, due to its large radiating size as well, but maybe it does??...I've been focusing on a 350hz tractrix since this loading horn has the mouth of ~15" and thus a similar radiating area.
In the arena of tweeters....it seems that compression drivers without waveguide or horn are already at benefit due to a larger diaphragm, thus lower excursion.
I plead to a friend that its starting to seem that the larger horns are really where a horn starts to shine....creating larger radiation areas than we can successfully achieve with dynamic radiators (ie above 15")....it seems that possibly above 15" (or 18") mass starts to be "too high" and issues of rigidity. Break up modes happen in desired reproduction spectrum....
I think of sensitivity but see no readily measurable connection between sensitivity and SQ....forgetting watts/spl and heating issues I guess.
Am I talking crazy? I am completely letting go of dispersion for this argument, thinking of only the one person within the equilateral triangle....I can easily grasp why off axis is important....a properly treated baffle edge makes for a smooth off axis transition if I recall....similar to a tractrix horn...so theres that part.
I continue to look at the Altec 604 series and wonder how a horn competes with such a solution (above loading of the horn of course). In particular looking at the 350hz tractrix.....in the Altecs defense it is using a compression driver for the tweeter
Directivity is a main topic....horns allow manipulation of dispersion, an aspect to which waveguides have narrowed in on leaving behind loading.... Loading lowers excursion, which lowers THD....I don't think 15" woofers have an issue of THD if we compare a horn to it within optimal spectrum for each scenario, due to its large radiating size as well, but maybe it does??...I've been focusing on a 350hz tractrix since this loading horn has the mouth of ~15" and thus a similar radiating area.
In the arena of tweeters....it seems that compression drivers without waveguide or horn are already at benefit due to a larger diaphragm, thus lower excursion.
I plead to a friend that its starting to seem that the larger horns are really where a horn starts to shine....creating larger radiation areas than we can successfully achieve with dynamic radiators (ie above 15")....it seems that possibly above 15" (or 18") mass starts to be "too high" and issues of rigidity. Break up modes happen in desired reproduction spectrum....
I think of sensitivity but see no readily measurable connection between sensitivity and SQ....forgetting watts/spl and heating issues I guess.
Am I talking crazy? I am completely letting go of dispersion for this argument, thinking of only the one person within the equilateral triangle....I can easily grasp why off axis is important....a properly treated baffle edge makes for a smooth off axis transition if I recall....similar to a tractrix horn...so theres that part.
I continue to look at the Altec 604 series and wonder how a horn competes with such a solution (above loading of the horn of course). In particular looking at the 350hz tractrix.....in the Altecs defense it is using a compression driver for the tweeter
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I found my first mistake "Crossover is at 700Hz 15" woofer Waveguide 4" CD"....robs CSD isn't of a horn, its of a waveguide....but a waveguide generally has no loading and is much similar to a direct radiator at that point....
I am starting to recall points made last time I brought about similar discussion....points touching on dynamic ability allowing transient and magnitude information to not be distorted. I feel a lot of this is tied to excursion alleviation...Addressing such issue (dynamic compression) for dynamic woofer implies increasing sd (efficiency), and proper rigidity and BL. Isobaric increases rigidity and BL, yet no one (spoken) seems to be bothered or notice in terms of midbass-LF reproduction....increasing woofer count is widely accepted. Dual 15"s might reach a coupled sensitivity above 103db or so in the mid bass. If high sensitivity is so important then why are so many ok with waveguides?
I am starting to recall points made last time I brought about similar discussion....points touching on dynamic ability allowing transient and magnitude information to not be distorted. I feel a lot of this is tied to excursion alleviation...Addressing such issue (dynamic compression) for dynamic woofer implies increasing sd (efficiency), and proper rigidity and BL. Isobaric increases rigidity and BL, yet no one (spoken) seems to be bothered or notice in terms of midbass-LF reproduction....increasing woofer count is widely accepted. Dual 15"s might reach a coupled sensitivity above 103db or so in the mid bass. If high sensitivity is so important then why are so many ok with waveguides?
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A 6-10 increase in spl from the horn loading (where else would it come from?) results in a fraction of motion.
I agree about the first part of your answer (DRC mostly compensate loudspeakers) however to some extent you can compensate for some coupling anomaly of loudspeaker/room in the low end thanks to dsp approach.
I must confess i was reluctant to the principle until i understood what was done.
To used to the frequency domain limitation bias my brain!
Audiolense Digital Loudspeaker and Room Correction Software Walkthrough - CA Academy - Audiophile Style
About the second part, i'm sure i'm not the only one to read carefully what you have to say on subjects you write about ( like for a lot of other members i've identified over the years in there which members give interesting answers ( to my level of knowledge atm) and 'profile' being their bias, liking, etc,etc... which is always interesting to decrypt answers and put into my own questionning).
The nature of the internet fora make 'conflicting views' or reactions being over represented versus positive ones.
I agree it is sometimes tiresome/decouraging when you have good attention in answering someone. But that do not say it wasn't or will not be useful in the future to someone.
Thank you sharing your view Scott L, and please still do!
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A 6-10 increase in spl from the horn loading (where else would it come from?) results in a fraction of motion.
Waveguides do provide much gain (mostly from compression ratio,) and hence lower excursion, but my comment above was about differences in loading between different waveguides contours not waveguides as a whole. It's important to understand the context of a comment.
Sorry...
LT = Linkwitz Transform (not connected in any way to room correction..) and Fo is "resonance freq".
//
LOL - its all over the WEB
Linkwitz Transform
CFL Linkwitz Transform Designer with Monte Carlo Sensitivity Analysis
Put driver in a box. Estimate or calculate Qts and resonance freq.
Enter these parameters into the LT equation along with wanted Q for system along with the -3 dB point (fo)
Out comes a compensation in order to reach such a wanted system. Driver Qts needs to be lower than wanted system Q or you need to fix with active magic...
Example from CasmillaDSP filters (you get the whole compensation filter in one single IIR biquad):
CamillaDSP
LinkwitzTransform
A Linkwitz transform to change a speaker with resonance frequency freq_act and Q-value q_act, to a new resonance frequency freq_target and Q-value q_target.
//
Linkwitz Transform
CFL Linkwitz Transform Designer with Monte Carlo Sensitivity Analysis
Put driver in a box. Estimate or calculate Qts and resonance freq.
Enter these parameters into the LT equation along with wanted Q for system along with the -3 dB point (fo)
Out comes a compensation in order to reach such a wanted system. Driver Qts needs to be lower than wanted system Q or you need to fix with active magic...
Example from CasmillaDSP filters (you get the whole compensation filter in one single IIR biquad):
CamillaDSP
LinkwitzTransform
A Linkwitz transform to change a speaker with resonance frequency freq_act and Q-value q_act, to a new resonance frequency freq_target and Q-value q_target.
//
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Ok, I guess it didnt stick since last time I looked at it, being that its useless to me because ->Room Correction....ie I have a desired FR and room eq is going to execute that target as best possible, with no second thought or need of an "LT"
I thought we just discussed LF and qts were useless thoughts?
I thought we just discussed LF and qts were useless thoughts?
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Refreshing to see some kindness AND a high degree of knowledge !
Very kind of you, thank-you !
Yes, the attempt at manipulating the frequency domain messes up the time domain, but if high-tech can realize this, upon adjustments, it's a good thing.
But, it's not as simple as to choose either FIR, or IIR. Either can be a compromise of sorts. I have some research papers at home, I can re-visit on this. Right now though, [work] duty calls.
I agree about the first part of your answer (DRC mostly compensate loudspeakers) however to some extent you can compensate for some coupling anomaly of loudspeaker/room in the low end thanks to dsp approach.
I must confess i was reluctant to the principle until i understood what was done.
To used to the frequency domain limitation bias my brain!
Audiolense Digital Loudspeaker and Room Correction Software Walkthrough - CA Academy - Audiophile Style
About the second part, i'm sure i'm not the only one to read carefully what you have to say on subjects you write about ( like for a lot of other members i've identified over the years in there which members give interesting answers ( to my level of knowledge atm) and 'profile' being their bias, liking, etc,etc... which is always interesting to decrypt answers and put into my own questionning).
The nature of the internet fora make 'conflicting views' or reactions being over represented versus positive ones.
I agree it is sometimes tiresome/decouraging when you have good attention in answering someone. But that do not say it wasn't or will not be useful in the future to someone.
Thank you sharing your view Scott L, and please still do!
Very kind of you, thank-you !
Yes, the attempt at manipulating the frequency domain messes up the time domain, but if high-tech can realize this, upon adjustments, it's a good thing.
But, it's not as simple as to choose either FIR, or IIR. Either can be a compromise of sorts. I have some research papers at home, I can re-visit on this. Right now though, [work] duty calls.