Pan said:
Look at this anyway you wish but I wasn't calling you a liar. You've seen measurement data, why not post it here to offer a real insight into performance instead of vague snippets that are difficult to provide any context to? You advocate for this tweeter/design based on some data you've seen, forgive me if I'm not privy to the same information as you but you can quite easily change that. If its as you've said then I'm happy to agree with you.
I'm only a sceptic looking for some validity to the claims made.
I agree, loudspeaker design is all about compromises. You've just picked up on one but there's an opposing argument to many choices as well. You've got to ask yourself what's the benefit of crossing at 1.5Khz vs. 3Khz and look more deeply into each to see where the audible benefits are. I can't hear the Guru's and I'm sceptical of the claims because I have no objective data and would like to see the magnitude of these compromises. We're on a forum discussing a loudspeaker so, for me, this really is the only worthwhile road of enquiry.
Can't really argue with subjective opinions. I like to keep things objective in these sorts of situations since claims can be quantified to some degree.
But since your being subjective and to provide a bit of balance then I'm sure their are as many SS owners who wouldn't swap to Guru.
I think we established that custom or otherwise isn't an indicator to performance and that's what I was really getting at.
No need to pack up and leave, I think you misunderstood my post, apologies if I offended.
Dave,
those measurements with the SE amp, did they swap absolute phase to check out any cancellation effects between the even order harmonics?
Also the SE amp most likely having a highish output impedance can reduce loudspeaker distortion from modulation of VC inductance. Thermal compression also can be decreased by this high impedance drive mechanism.
To what degree? No idea!
/Peter
those measurements with the SE amp, did they swap absolute phase to check out any cancellation effects between the even order harmonics?
Also the SE amp most likely having a highish output impedance can reduce loudspeaker distortion from modulation of VC inductance. Thermal compression also can be decreased by this high impedance drive mechanism.
To what degree? No idea!
/Peter
Pan said:
http://gboers.xs4all.nl/daisy/home/135.html
I take these results as an illustartion of how misleading single number THD results can be in the absence of all the factors, and that to further illustrate that in isolation charts like Shin's are meaningless as far as actual music playing goes. (not that there is anything wrong with Gerrit's results -- and in this case they are not presented without knowledge of the amp)
dave
Dave, sorry for stating the obvious but this is a forum. Please describe the sound of your speaker to me and I'll interpret that as best I can. Actually I'll have a better chance of understanding if you show me accurate measurements along with that and then at least we can chat about something quantifiable. You tell us that measurements are unrelated to performance although you over indulge in that just as much as I might do the opposite.
Do you get my point and see why I asked for measurements?
When debating and refuting claims relating to subjective writings, the best thing to do is listen to the design and decide for yourself. The next best thing is to look at this from an objective point of view because even if the measurements aren't telling the whole picture they're better than alternative.
Mathematics is the universal language 🙂
Instead of skirting around the tree's what do you suggest then? We all pack up and leave this thread and abandon such discussion. I think most are aware of the rough value of measurements, claims and prose. Enough of these in the right quantities and you can have a balanced argument. There's a deficit of one of those in this thread 😉
BTW I'm not saying there isn't a place for touchy feely words on here but when a thread goes down the road this one has, what else is their to do if you can't hear the design? I understand your saying to be wary of measurements as their accuracy is an unknown quantity and they don't reveal everything but to me they offer more accuracy than musings, at least in this situation.
That's a bit of a stretch for me to believe the amplifier would meaningfully throw the results of a test such as this. I think you could point the blame at a poorly designed amp output stage as much as a bad loudspeaker design in that case.
If I went out and did testing on a driver with two differing amps would the results be significantly different? What sort of error margin are we talking about here?
Do you get my point and see why I asked for measurements?
When debating and refuting claims relating to subjective writings, the best thing to do is listen to the design and decide for yourself. The next best thing is to look at this from an objective point of view because even if the measurements aren't telling the whole picture they're better than alternative.
Mathematics is the universal language 🙂
Instead of skirting around the tree's what do you suggest then? We all pack up and leave this thread and abandon such discussion. I think most are aware of the rough value of measurements, claims and prose. Enough of these in the right quantities and you can have a balanced argument. There's a deficit of one of those in this thread 😉
BTW I'm not saying there isn't a place for touchy feely words on here but when a thread goes down the road this one has, what else is their to do if you can't hear the design? I understand your saying to be wary of measurements as their accuracy is an unknown quantity and they don't reveal everything but to me they offer more accuracy than musings, at least in this situation.
That's a bit of a stretch for me to believe the amplifier would meaningfully throw the results of a test such as this. I think you could point the blame at a poorly designed amp output stage as much as a bad loudspeaker design in that case.
If I went out and did testing on a driver with two differing amps would the results be significantly different? What sort of error margin are we talking about here?
Hi,
This is interesting, the Guru-Ino stuff.
I'm within two ours of travel to Stockholm so I gladly take a trip for a listen to the "wonder speakers".
Those who know who to contact or if someone will contact me, I’ll be delightful for an audition.
This is interesting, the Guru-Ino stuff.
I'm within two ours of travel to Stockholm so I gladly take a trip for a listen to the "wonder speakers".
Those who know who to contact or if someone will contact me, I’ll be delightful for an audition.
ShinOBIWAN said:
I do know why, all i'm pointing out is that in the context presented the data you presented is meaningless and are proof of nothing except that these drivers can achieve those numbers with that amplifier. They do not tell anything but a tiny slice of information about the drivers and without the spectrum (properly a 3D chart) they tell absolutely nothing about how the driver sounds.
This actually reflects back to one of the points attributed to Ingvar -- that objective measurements can be as much a detriment to achieving the goal of fidelity as are the foibles of subjective testing (& the pshycoacoustics involved)
Indeed, in the end only each listener can say if a particular design allows them to get closer to the music. You do have to be very careful about interpretation of objective results.
In the specific case you presented as evidence you have collapsed a 3-dimensional measurement of an amplifier/speaker system into a 2-dimensional graph that removes sufficient information to remove any useful indication of the performance of the DUTs. And further presented as information on the loudspeaker when it is data on the amplifier/speaker system.
In uni we used mathematic technicques like this to create paradoxes just to illustrate things you could get away with and things you couldn't when collapsing multidimensional data into more human understandable datasets. In this specific case the data has been collapsed to the point where it becomes useless. In the context of a development situation where there is a lot more data & trials it might be useful, but still viewing this data before it is collapsed into 2 dimensions while perhaps harder to interpret would be really useful (but still only valid for amplifiers the same or similar to the one used in the test)
Still one has to keep in mind that it is still but a small subset of distortions that are present in any loudspeaker and that other distortions can alter the way that this distortion is perceived.
Not at all. I just pointed out that the measure you presented is not evidence in any sense. I then asked if you had the spectrum that came before the data you presented was collapsed. This necessarily means taking another slice of the data at a certain frequency to present as a 2D chart, but sliced that way it does have more meaning. Best (and i admit i've not seen many) would be a 3-d graph with axis of frequency, distortion amplitude, and spectrum. If it was rotatable it would be even more useful. Finding a way to add amplitude distortion, dispersion distortion, phase distortion, IM distortion. dynamic distortion, etc would push it towards a more complete dataset, but it is now beyond the capability of the human mind to comprehend as a single entity.
Specifically the measurement you presented is meaningless as presented and for those that latch onto it as something solid to hold onto will find that they are potentially being misled.
Of course the amplifier used can have a significant effect on the measurement. The amplifier & the speaker are a system.
Gerrit's data clearly shows that to be the case. And if you start saying things like "poorly designed amp output stage" that lead's to a line of reasoning that says Nelson Pass' F1 & F2 are poorly designed because they will have significant amplitude distortion when driving a speaker with typical XOs and BR woofer alignment. They aren't. Nelson has simply -- and IMO very intelligently -- designed the amplifier as part of an amplifier/speaker system and has specified those types of speakers that his design are intended to be paired with.
dave
planet10 said:
Dave I can't help but feel your taking this out of context. I agree with you on some points and specifically that measurements reveal only so much of the truth. Yet you seem to have missed the verbal 0.05% distortion claim on a tweeter earlier in the tread and instead pulled over a graph that shows infinitely more than that. Bit of perspective please.
Let me get this straight; Three dimensional distortion graphs? Are you talking about some kind of combined HD and IMD plot? If so what's wrong with a separate IMD and HD plots?
None of the software I use, and that includes ARTA and WinMLS, have capabilities to display data in that format or at least not that I know of.
Since these 3d graphs aren't widespread how are they useful for comparisons to other drivers? Sounds like you pulled me over on some idealistic view of how you think distortion should be shown. If it was more revelatory of driver performance why isn't its adoption widespread?
Personally I've never come across such a thing and given that the measurement I've shown is fairly standard format for the world over I feel comfortable using them within their limits - and that's a swept sine showing HD magnitude induced by a steady state stimulus intended for comparison to similar measurements. If others want to take them out of context I can't police that, although I'm trying to right now 😉
What? I think you over egg the importance of the context in which that measurement was posted as well as your own opinion. Despite offering to be the Shining Knight and undo some perceived evil I ask you to take a step back for a minute and realise why it was posted and just how many similar graphs are in existence. Perhaps a white paper to AES is in your future?
And you better write Zaph and tell him his hardwork is meaningless in case anyone else falls into his trap.Sorry I'm being an obnoxious **** now, I'll stop.
If I said the ATC mid is closed back and their was no filter for testing would it make a difference. Passive is a dirty word around here. 😀 Also the testing occurred in the benign region of the imp. curve. except for the low end.
Yeah I agree about my "poorly designed output stage" comment, I should have said "poorly designed output stage and/or a poor amp selection vastly unsuited to the load its driving".
I have done alot of measurements on different speakers and the lowest distortion does Ino speakers have (of the once I have measured)
I have had alot of SS element like the tweeters SS9000, SS9700 and 9900.
From Seas I have at the moment from the excel series: W15, Crescendo, Millenium and W22. I also have alot from the basic series but the only element there that have impressed me alittle is the CA18RCY, but it demands like 35l to be decent, which is alot foir such small speaker.
Since I am a friend of Ingvar I am biased you think, but Im not 🙂
I might share some data in the future of different things Ive measured.
The sad thing here is that it is alot of people bashing without even have anything to bash really. He creates great speakers end of story. 🙂
Ingvar is a high level engineer, don't fool yourself to think something else.
//Jonas
I have had alot of SS element like the tweeters SS9000, SS9700 and 9900.
From Seas I have at the moment from the excel series: W15, Crescendo, Millenium and W22. I also have alot from the basic series but the only element there that have impressed me alittle is the CA18RCY, but it demands like 35l to be decent, which is alot foir such small speaker.
Since I am a friend of Ingvar I am biased you think, but Im not 🙂
I might share some data in the future of different things Ive measured.
The sad thing here is that it is alot of people bashing without even have anything to bash really. He creates great speakers end of story. 🙂
Ingvar is a high level engineer, don't fool yourself to think something else.
//Jonas
ShinOBIWAN!
I also have the RME FF800 but I dont succeed to measure 24bit inSpectralab with it, I have to use PCI card for this, have you succeeded with that?
I also have the Earthworks M50 for measurements.
I also have the RME FF800 but I dont succeed to measure 24bit inSpectralab with it, I have to use PCI card for this, have you succeeded with that?
I also have the Earthworks M50 for measurements.
ShinOBIWAN said:
The magnitude is immaterial to the argument.
Any IMD distortion measurement is inherently 3 dimensional. Frequency, magnitude & order (spectrum). To get the plot you showed all the orders are added up and presented as a single number. The problem with that is that as the order goes up the distortion becomes more objectional to the ear/brain. Let's say we have a speaker that measures 5% 2nd order and 1% 3rd (any higher harmonics showing up in a loudspeaker are most likely from the amplifier/electronics) and one that has 1% 2nd and 5% 3rd. Your measurement will show both as having 6% distortion, but the 2nd one is going to be more audibly distorted than the 1st.
In amplifiers THD is even more of a problem since higher orders can be generated easily (usually by a feeback loop). A 5th order harmonic can be detected at an extremely low level even in the presence of 10s of times as much 2nd order. (i'm talking in generalities, i don't know what the real numbers are)
Second & third order distortions are present in nature, higher are not, so the unnaturalness of the higher orders stands out in stark relief (this is why the distortion argument that amplifiers are not as important as speakers falls on its face as it is easy to generate higher order components with electroincs and much harder with loudspeakers)
dave
Lazyworm said:
Hi,
No longer have the RME and I now use EMU 1820 which is PCI card with an external I/O dock. This happily allows 24bit precision with ARTA. ARTA does allow for 32bit precision but the WDM mode of the EMU driver won't support that and ARTA doesn't allow for ASIO which is supported by the driver.
Earthworks make very nice mics. I hired an M50 and Earthwork preamp from a local music hire shop and got some excellent impulse captures of my room for use with digital room correction. The ECM8000 is good value but a poor relative to the M50.
Apparently Sweden is full of people who know how to post on the internet.
Who know to measure loudspeakers.
But none who know how to post measurements of loudspeakers on the internet.
cheers,
AJ
Who know to measure loudspeakers.
But none who know how to post measurements of loudspeakers on the internet.
cheers,
AJ
planet10 said:
Erm Dave, I can't imagine you missed this so I might have read your reply wrong but just in case take a look at the graph again. It has a break down of the products from 2nd, 3rd and 4th+ orders of harmonic distortion. This allows you to see the distribution of the harmonics within the test conditions. With the ATC you can see a nice distribution of low order even harmonics with decreasing higher order odd harmonics - given the THD of around 0.1 to 0.2% its an indication of a low distortion and natural sounding driver. Subjectively that's borne out as well.
An externally hosted image should be here but it was not working when we last tested it.
What about going with an amp with low high order products and predominate 2nd as well as being capable of driving the load required? A couple of examples off the top of my head would be Greg Ball' GB series or Hugh Dean' AKSA.
Hello everyone!
I just want to say that there seem to be a lot of misunderstandings ventilated in this thread. I can not untangle all of them here, and the new questions that will follow makes me even less inclined to involve myself - but I will try to say a few words, regarding things I've seen so for far, here.
Let me first make clear that my English is of poor quality, and there is a risk of me choosing a less than optimal way of explaining things for that reason - but I will try to do my best. Please try to be tolerant back. I’ll be, if you are native English, and try to speak Swedish to me.
1. The problems with diffraction from a cabinet is a complex matter, and formulating the target performance of a loudspeaker makes the problem even more complex. Some diffraction is unwanted, some is unavoidable, and some is (or might be - depending the aim of the design) constructive and wanted! When possible, I'd like to use the middle, to create the latter.
Now before someone believes that the above said is a way of avoiding the critic by just claiming that the diffraction present in the QM40 (and the time smearing and interfering that it causes) is “a good thing” (without explaining why), before you give that thought any weight: Let me make clear, that the direct sound from a QM40 arriving listening position is VERY clean. The time domain problems that some people have indicated might be present due to the properties of the design, is simply not there!
To go in to the reason for it NOT being there, would be a sisyphus-accomplishment, but let me just say this:
The knowledge of physics (namely acoustics) among some of the more sceptical posters (people posting opinions and believes here), might be somewhat... factional, rather than complete enough to grasp the complex situation that is at hand. I can see that some "question risers" are not complete novices, they know some, but maybe not enough to understand their lack of knowledge - significant understanding and ability to grasp the whole and to se proportions, seems to be missing. And that’s all fine - everyone has to learn to crawl before learning how to walk. And stuff will break when falling over, trying to get there faster then the legs are ready to.
Or in short: It is difficult to explain WHY a problem is not there, when there is no physical reason to expect it to be there! (What there are is uninformed guesses, some of them very speculative and formed as accusations, from people perhaps having a lot to learn yet.)
Some of the misunderstandings regarding diffraction are (or seems to be) these:
A. Diffraction causing problem for the boomer driver: A big membrane is much less sensitive to a charp edge very close to the rim of the membrane itself, since a close distance will only cause comb-interferences starting at high frequencies - where the directivity from the membrane is quite high, and protects the wave to bend (diffract) and cause interferences due to reflections. Voila! 😎
B. Diffraction (or other shape-depending behaviours) causing problems for the tweeter driver: The surface beneath the tweeter is at a 90 degree angle from the tweeter baffle, creating a mirror image of the tweeter baffle just continuing on down. This mirror image does contain a tweeter too of coarse, but it is not acoustically seen from listening position, it isn't "seen" until being "viewed" from way up - far above listening position (more about that later...).
(The mirror image parallel is a simplification, but for now, it is accurate enough for the frequency range being analyzed.)
Here is a 0.2 ms sin^2-pulsrespons of the Guru QM40 (or rather the pi60, but they are very close to being identical in this aspect):
http://user.faktiskt.se/IngOehman/bilder/pi60-puls.JPG
And here I compare it to two normal 3-way system with 4:th order L-R crossovers:
http://user.faktiskt.se/IngOehman/bilder/pulssvar_a4-14_BW801.JPG
As you can see, even if the QM40 has the shape that it has (no use denying that!) and is not "perfect" (as viewed from the idea-target "no wave shape-distortion allowed!"), it does not show a lot of delayed energy due to diffraction and hence caused edge reflections...
In fact, I'd say that speakers performing BETTER than the QM40 regarding freedom of diffraction problems, does not rain from the sky. I know of none. But - I do not say that the pulse response is of large significance for the way the speaker is sonically perceived. The human hearing is in fact not very sensitive for the type of phase distortion that is present in many speakers, but is very small in the QM40. So actually, even if it is fun to show the beautiful pulse response of the QM40, I have to confess it is not an important talent of the speaker.
[Other types of phase distortion, like inter driver coherence (=phase integration), phase common horizontal behaviour (=phantom imaging performance at off sweet spot-positions) and narrow band phase smoothness (=group delay) is of much bigger importance, but they are much more difficult to show in a graph. Naturally - the QM40 excels in all those disciplines too. 😎]
I’ll be back soon with part 2!
/Ingvar
I just want to say that there seem to be a lot of misunderstandings ventilated in this thread. I can not untangle all of them here, and the new questions that will follow makes me even less inclined to involve myself - but I will try to say a few words, regarding things I've seen so for far, here.
Let me first make clear that my English is of poor quality, and there is a risk of me choosing a less than optimal way of explaining things for that reason - but I will try to do my best. Please try to be tolerant back. I’ll be, if you are native English, and try to speak Swedish to me.
1. The problems with diffraction from a cabinet is a complex matter, and formulating the target performance of a loudspeaker makes the problem even more complex. Some diffraction is unwanted, some is unavoidable, and some is (or might be - depending the aim of the design) constructive and wanted! When possible, I'd like to use the middle, to create the latter.
Now before someone believes that the above said is a way of avoiding the critic by just claiming that the diffraction present in the QM40 (and the time smearing and interfering that it causes) is “a good thing” (without explaining why), before you give that thought any weight: Let me make clear, that the direct sound from a QM40 arriving listening position is VERY clean. The time domain problems that some people have indicated might be present due to the properties of the design, is simply not there!
To go in to the reason for it NOT being there, would be a sisyphus-accomplishment, but let me just say this:
The knowledge of physics (namely acoustics) among some of the more sceptical posters (people posting opinions and believes here), might be somewhat... factional, rather than complete enough to grasp the complex situation that is at hand. I can see that some "question risers" are not complete novices, they know some, but maybe not enough to understand their lack of knowledge - significant understanding and ability to grasp the whole and to se proportions, seems to be missing. And that’s all fine - everyone has to learn to crawl before learning how to walk. And stuff will break when falling over, trying to get there faster then the legs are ready to.
Or in short: It is difficult to explain WHY a problem is not there, when there is no physical reason to expect it to be there! (What there are is uninformed guesses, some of them very speculative and formed as accusations, from people perhaps having a lot to learn yet.)
Some of the misunderstandings regarding diffraction are (or seems to be) these:
A. Diffraction causing problem for the boomer driver: A big membrane is much less sensitive to a charp edge very close to the rim of the membrane itself, since a close distance will only cause comb-interferences starting at high frequencies - where the directivity from the membrane is quite high, and protects the wave to bend (diffract) and cause interferences due to reflections. Voila! 😎
B. Diffraction (or other shape-depending behaviours) causing problems for the tweeter driver: The surface beneath the tweeter is at a 90 degree angle from the tweeter baffle, creating a mirror image of the tweeter baffle just continuing on down. This mirror image does contain a tweeter too of coarse, but it is not acoustically seen from listening position, it isn't "seen" until being "viewed" from way up - far above listening position (more about that later...).
(The mirror image parallel is a simplification, but for now, it is accurate enough for the frequency range being analyzed.)
Here is a 0.2 ms sin^2-pulsrespons of the Guru QM40 (or rather the pi60, but they are very close to being identical in this aspect):
http://user.faktiskt.se/IngOehman/bilder/pi60-puls.JPG
And here I compare it to two normal 3-way system with 4:th order L-R crossovers:
http://user.faktiskt.se/IngOehman/bilder/pulssvar_a4-14_BW801.JPG
As you can see, even if the QM40 has the shape that it has (no use denying that!) and is not "perfect" (as viewed from the idea-target "no wave shape-distortion allowed!"), it does not show a lot of delayed energy due to diffraction and hence caused edge reflections...
In fact, I'd say that speakers performing BETTER than the QM40 regarding freedom of diffraction problems, does not rain from the sky. I know of none. But - I do not say that the pulse response is of large significance for the way the speaker is sonically perceived. The human hearing is in fact not very sensitive for the type of phase distortion that is present in many speakers, but is very small in the QM40. So actually, even if it is fun to show the beautiful pulse response of the QM40, I have to confess it is not an important talent of the speaker.
[Other types of phase distortion, like inter driver coherence (=phase integration), phase common horizontal behaviour (=phantom imaging performance at off sweet spot-positions) and narrow band phase smoothness (=group delay) is of much bigger importance, but they are much more difficult to show in a graph. Naturally - the QM40 excels in all those disciplines too. 😎]
I’ll be back soon with part 2!
/Ingvar
Part 2:
C. And here comes the complicated part... The designing of loudspeakers is not a square-shaped art! Components like amplifiers and wires can (and should) be approached as transfer links - the output is supposed to be a copy of the input signal - for a good reason: Then the music is unchanged and we have High Fidelity!
Speakers are very different animals though... They are NOT transfer links - and they neither can nor should be.
One speakers (like one channel of an amplifier) task is not to perform an electric signal that is a copy of the electric input signal.
In fact, the task is not even to put an acoustic signal that is a copy of the electric input signal! No, no...
The loudspeaker should/will put out different signals in millions (well, thousands then...) of different directions, and each and everyone of them will be a part (major or minor) of what we hear when we use the speaker in our listening room (if it is something that differs from an anechoic room).
For some designers, this is perceived as a problem (they consider the room to be a problem that is to be eliminated, or they aim at designing speakers that are very directional, eliminating the room reflections from the equation...).
Other designers (and hobbyists and hifi-listeners) simplify the problem by introducing "the energy response" (but very seldomly being clear over that ER is a very dubious thing to talk about. Many believes that the speaker itself has an intrinsic property called he energy response, and that this thing is hat they see when viewing a measurement being made at listening position. It is not.)
But I do not agree. In fact - I'd say it is the reason that it is possible to make 2 channel stereo create it's magic!
A speaker will, as said, put out sound I thousands of different directions (whether we like it or not). Therefore, one must attempt to sculpture each and every one of them - to meet “the goal”. (Being some type of behaivoir that optimizes the loudspeakers as transperent sound field decoders, i.e. avoiding to add coloration to the music, but yet doing what is neccessary or at least possible to eliminate the colorations of the stereosystem itself*.)
Designing a loudspekaer so that it meets "the goal" is difficult for at least two reasons:
1. There are limits to in what degree they can be individually sculptured.
2. One must find the answer to HOW THEY SHOULD BE DIFFERENT – what is the performance goal? The goal must of coarse be investigated and found before one can have an idea of how to accomplish that very same goal – how to design the speakers meeting the goal.
The former problem (1) is a problem only if the goal (when found) is to create dispersion-propoerties that defies the laws of physics. They don’t! (Yippie!)
The latter however, is what I’ve been spending a significant part of my life working with. I do not claim that I have the single answer to how a speaker should perform (to the contrary – I say that there is no such singular answer, since the stereo-system put up problems that are perceived different in different surroundings). What I have (no more no less) is my suggestion for “the goal”.
If being questioned, I gladly explain how I have come to the conclusions I’ve come to, and what these very conclusions are. And of coarse, I do not claim to have found a single simple answer to the problem. I which I had found such an answer! A rule of thumb-answer.
But I’m afraid that it is complicated and that we will have to continue consider loudspeakers as just a part of the equation. The stereo-system and the room are very significant other halves (making three of them?) and one can not be optimized without making assumptions about the others… All these things must function together.
However – I hope that everyone here understands that I can not do this here. Doing that would be resulting in endlessly expanding discussions and many new misunderstandings i'm sure...
But - anywhere where there is a chance of having a meningful discussion where I can get feedback from all people listening (making sure that there will be no (or as few as possible) pointless misunderstandings, like the ones I’ve seen here). Interviews, lectures or private discussions in small gatherings - and I'll gladly answer any questions that anyone has!
Acually, I really like doing that. It is like the payback for the endless hours spent doing boring research. I mean, what is the point in searching for answers, if no one asks the questions to which they fit?
I even like to be misstrusted if it leads to a situation where I have a fair chanse to prove the points I've made, that are questioned.
Best regards to everyone!
And I which you all a generous (and reasonable agnostic) mind - helping you to, rather than accuse and speculate, ask important questions. (That was a general advice, not me encouraging you to ask me questions that I will not be here to answer.)
/Ingvar
- - - - -
*Having a trumpet playing in front of a listener is (viewed via human hearing) not physically equivalent to having two speakers with linear frequency response trying to recreate the very same trumpet by phantom imaging. Not even in an anechoic chamber is it the same! This is but one example on how the stereo-system in itself is not a transparent thing that can be ignored.
Another example is that we (human beings) can detect the sound source (also vertically) by comparing timbral properties of sound arriving from different angles. This is both the reason for digital room corrections not working, and the stereo-system being very sensitive for relation between listeners and loudspeakers height. It also can, and must, or at least should, be compensated for, if the goal is arriving at a transparent music reproduction. The compensation must of coarse be depending of the radiating angle of the loudspeaker - which says one thing: Loudspeakers should not be neither "as directive as possible", nor "maximally omni directional at all frequencies"! On the contrary - they should have a sculptured behaviour, optimally adapted to both the stereo-system and our psycho-acoustical properties.
C. And here comes the complicated part... The designing of loudspeakers is not a square-shaped art! Components like amplifiers and wires can (and should) be approached as transfer links - the output is supposed to be a copy of the input signal - for a good reason: Then the music is unchanged and we have High Fidelity!
Speakers are very different animals though... They are NOT transfer links - and they neither can nor should be.
One speakers (like one channel of an amplifier) task is not to perform an electric signal that is a copy of the electric input signal.
In fact, the task is not even to put an acoustic signal that is a copy of the electric input signal! No, no...
The loudspeaker should/will put out different signals in millions (well, thousands then...) of different directions, and each and everyone of them will be a part (major or minor) of what we hear when we use the speaker in our listening room (if it is something that differs from an anechoic room).
For some designers, this is perceived as a problem (they consider the room to be a problem that is to be eliminated, or they aim at designing speakers that are very directional, eliminating the room reflections from the equation...).
Other designers (and hobbyists and hifi-listeners) simplify the problem by introducing "the energy response" (but very seldomly being clear over that ER is a very dubious thing to talk about. Many believes that the speaker itself has an intrinsic property called he energy response, and that this thing is hat they see when viewing a measurement being made at listening position. It is not.)
But I do not agree. In fact - I'd say it is the reason that it is possible to make 2 channel stereo create it's magic!
A speaker will, as said, put out sound I thousands of different directions (whether we like it or not). Therefore, one must attempt to sculpture each and every one of them - to meet “the goal”. (Being some type of behaivoir that optimizes the loudspeakers as transperent sound field decoders, i.e. avoiding to add coloration to the music, but yet doing what is neccessary or at least possible to eliminate the colorations of the stereosystem itself*.)
Designing a loudspekaer so that it meets "the goal" is difficult for at least two reasons:
1. There are limits to in what degree they can be individually sculptured.
2. One must find the answer to HOW THEY SHOULD BE DIFFERENT – what is the performance goal? The goal must of coarse be investigated and found before one can have an idea of how to accomplish that very same goal – how to design the speakers meeting the goal.
The former problem (1) is a problem only if the goal (when found) is to create dispersion-propoerties that defies the laws of physics. They don’t! (Yippie!)
The latter however, is what I’ve been spending a significant part of my life working with. I do not claim that I have the single answer to how a speaker should perform (to the contrary – I say that there is no such singular answer, since the stereo-system put up problems that are perceived different in different surroundings). What I have (no more no less) is my suggestion for “the goal”.
If being questioned, I gladly explain how I have come to the conclusions I’ve come to, and what these very conclusions are. And of coarse, I do not claim to have found a single simple answer to the problem. I which I had found such an answer! A rule of thumb-answer.
But I’m afraid that it is complicated and that we will have to continue consider loudspeakers as just a part of the equation. The stereo-system and the room are very significant other halves (making three of them?) and one can not be optimized without making assumptions about the others… All these things must function together.
However – I hope that everyone here understands that I can not do this here. Doing that would be resulting in endlessly expanding discussions and many new misunderstandings i'm sure...
But - anywhere where there is a chance of having a meningful discussion where I can get feedback from all people listening (making sure that there will be no (or as few as possible) pointless misunderstandings, like the ones I’ve seen here). Interviews, lectures or private discussions in small gatherings - and I'll gladly answer any questions that anyone has!
Acually, I really like doing that. It is like the payback for the endless hours spent doing boring research. I mean, what is the point in searching for answers, if no one asks the questions to which they fit?
I even like to be misstrusted if it leads to a situation where I have a fair chanse to prove the points I've made, that are questioned.
Best regards to everyone!
And I which you all a generous (and reasonable agnostic) mind - helping you to, rather than accuse and speculate, ask important questions. (That was a general advice, not me encouraging you to ask me questions that I will not be here to answer.)
/Ingvar
- - - - -
*Having a trumpet playing in front of a listener is (viewed via human hearing) not physically equivalent to having two speakers with linear frequency response trying to recreate the very same trumpet by phantom imaging. Not even in an anechoic chamber is it the same! This is but one example on how the stereo-system in itself is not a transparent thing that can be ignored.
Another example is that we (human beings) can detect the sound source (also vertically) by comparing timbral properties of sound arriving from different angles. This is both the reason for digital room corrections not working, and the stereo-system being very sensitive for relation between listeners and loudspeakers height. It also can, and must, or at least should, be compensated for, if the goal is arriving at a transparent music reproduction. The compensation must of coarse be depending of the radiating angle of the loudspeaker - which says one thing: Loudspeakers should not be neither "as directive as possible", nor "maximally omni directional at all frequencies"! On the contrary - they should have a sculptured behaviour, optimally adapted to both the stereo-system and our psycho-acoustical properties.
Thanks for your reply Ingvar, indeed things are more clearer.
I note your impulse response here:
http://user.faktiskt.se/IngOehman/bilder/pulssvar_a4-14_BW801.JPG
I built a 3.5 way design recently and heres the impulse response at the listening position (approx 2.7m from the speaker):
Other measurements(please go easy Dave 🙂)
Frequency Response showing +0.5dB / -1dB (1/24th octave smoothing)
Overall view individual driver responses and overall response (1/24th octave smoothing). Note that measurement is only valid from 200hz up as bass measurement was omitted.
CSD showing decay behaviour at the listening position within the 1st second after signal excitation with bass traps and digital driver/room correction:
And a photo of the speaker itself: http://img.villagephotos.com/p/2005-7/1050288/tism164.jpg
Obviously this speaker I built measures quite well but what would you say are the pitfalls of striving for accuracy through measurements vs. the subjective quality and believability of a designs sound?
I note your impulse response here:
http://user.faktiskt.se/IngOehman/bilder/pulssvar_a4-14_BW801.JPG
I built a 3.5 way design recently and heres the impulse response at the listening position (approx 2.7m from the speaker):
An externally hosted image should be here but it was not working when we last tested it.
Other measurements(please go easy Dave 🙂)
Frequency Response showing +0.5dB / -1dB (1/24th octave smoothing)
An externally hosted image should be here but it was not working when we last tested it.
Overall view individual driver responses and overall response (1/24th octave smoothing). Note that measurement is only valid from 200hz up as bass measurement was omitted.
An externally hosted image should be here but it was not working when we last tested it.
CSD showing decay behaviour at the listening position within the 1st second after signal excitation with bass traps and digital driver/room correction:
An externally hosted image should be here but it was not working when we last tested it.
And a photo of the speaker itself: http://img.villagephotos.com/p/2005-7/1050288/tism164.jpg
Obviously this speaker I built measures quite well but what would you say are the pitfalls of striving for accuracy through measurements vs. the subjective quality and believability of a designs sound?
Hi IngOehman, since your posts were long, i will only comment in an abstract way, concerning your statements about speaker design in general.
What you describe as a set of millions of different directions is just the wave, that is propagated through the medium air. what you call directions, is an image of the mind, there are no directions to be seen, there are just vibrating air molecules. you cant sculpt a direction, thats just words.
the difference you observe is because speakers start to beam after a certain frequency, as radiation changes from a sphere in the low frequencies to a sharp beam in the higher frequencies.
What would come close to the direction thing, would be early and late room reflections, but those are not covered in your speaker design, as the speaker itself does little about directivity control.
All you do is taking a normal design procedure / topic and coat it with poetic words. that is audiophile marketing mumbo jumbo for me.
central point here is: there is no magic.
What you describe as a set of millions of different directions is just the wave, that is propagated through the medium air. what you call directions, is an image of the mind, there are no directions to be seen, there are just vibrating air molecules. you cant sculpt a direction, thats just words.
the difference you observe is because speakers start to beam after a certain frequency, as radiation changes from a sphere in the low frequencies to a sharp beam in the higher frequencies.
What would come close to the direction thing, would be early and late room reflections, but those are not covered in your speaker design, as the speaker itself does little about directivity control.
All you do is taking a normal design procedure / topic and coat it with poetic words. that is audiophile marketing mumbo jumbo for me.
central point here is: there is no magic.
ShinOBIWAN said:
I did miss that. A proper legend would have been helpful (the little tiny one on the right hand bottom of the graph on a chart that has the right hand 25% of the chart hanging off the screen (and i hate using the horizonatal scroll bar) made it all but invisible ... sorry about that... it did let me get some things off my chest thou 🙂
It does explain some of your/my confusion.
Do you have similar charts for other frequencies.
The amount of 4th order distortion in that device is quite scary.
dave
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