Well it all depends on what the artis/recording/mixing engineer was trying to create, what he or she was able to create and what we at home are able to reproduce.
One day we have to define a better framework for the whole audio reproduction chain, otherwise there won't be any progress.
They tend to measure somewhat flat but lower from 150 to 1000 as this is an annoying part of the spectrum to my ears, a small peak at 4k, and bright at 10k+. I don't really hear above 13k anymore so I wouldn't know what the heck happens way up there but would assume a roll off, (according to the frequency plots). ie: I don't require a supertweeter, your average compression driver is fine for me. 🙂
No not Mackie. Have only talked with Greg once. Driver in the feedback loop has been used about 20 years here to improve dynamics.
Working as a consultant actual driver designs or production changes appeared at Altec, Seas, Scanspeak and Harmony. Loudspeakers system design appeared at Real to Real, Acoustat, mod kits for Dahlquist. Know there are many other but I don't keep track. Almost all the work done is custom or consulting. If "the team" I work with is included- that list it really long.
Pitch center- Yes tested with pinked noise. square root F-Low*F-High. For a wide band system this should always equal 632Hz or the complaints will roll in.
I like objective measurements and always start there with a huge battery of testing. In the end, final system tuning is by ear. Still nothing better.
=SUM
I can't think of another basic big-issue that has anything like the same degree of agreement: you have to fine-tune your speaker frequency response by ear.
But I have never heard, so far, a cogent explanation why. Of all the parameters of audio reproduction, you'd surely think plain old frequency response would be straightforward. Granted, there are different ways of measuring it (and corresponding different theories) but everybody pretty much agrees there's no system of measurement that gets it right. But you more or less CAN get it right by ear, at least for the owner.
I'd say that needs explaining.
But I have never heard, so far, a cogent explanation why. Of all the parameters of audio reproduction, you'd surely think plain old frequency response would be straightforward. Granted, there are different ways of measuring it (and corresponding different theories) but everybody pretty much agrees there's no system of measurement that gets it right. But you more or less CAN get it right by ear, at least for the owner.
I'd say that needs explaining.
Good point Ben. This does it for me:
Haven't measured with the subs on yet.
Dan
Thanks for data points.
Would you say you experience music in that room with that acoustic curve(s) as (1) "flat to your ears" or (2) "right/how you like it" without regard to "flat"? Or other?
I don't really mind whether I see a real name or not if the discussion is good. Knowledgeable people can just treat discussion like data. Like when I read Dan's data and made an educated guess what the design was.
May I suggest that due to a little investigating I did, I can say Mr. sumaudioguy does have many if not all of the credentials of which he speaks. Further, it is his choice whether or not he divulges his name to the members. He's not the only high level person here to wear a cloak you know.
I gather from your reply that you do experience it as subjectively flat and right to your ears.
So back to my question: why isn't there a mic measurement that says the same? Or would you propose your curve as the general "perceived as flat" curve? Would others?
Agreed. As an example Morgan Jones maintained his anonymity for years & years without reducing his contribution.
dave
That's pretty darned flat and smooth off axis. Not perfectly, but as close as anything I've seen. I'd bet it would generally perceived as flat, but would say for all. There just no accounting for some people's taste.
Dan
Yes, by mic, your middle and top very flat and remainder about as flat as you get in the real world and you are saying you hear it as flat and sounds right to you.
In which case, your observations are at variance with others who say they have to fine-tune by ear. If you can make things flat by mic (as you indicate for your system), then you don't need to fine-tune by ear (as others say they must and which led to my question).
In my follow-up question to you (indeed from the start), I especially had in mind the low range and in your case, the octave below 60 where mics, hearing, equal-loudness curves, and preference might part company. I should have said so. Hard to say if the fine-tune-by-ear advocates are thinking of extremes of bass or treble or the whole range. And if treble, where does presbycusis fit in.
I'm a strong believer in the direct sound dominating and power response being fairly inconsequential. Most of what I read, and believe to be on track, describes our perception of frequency response to be best modeled as a time windowed response with the window long at low frequencies and short at high frequencies. For highest frequencies this admits the direct sound only. For mids an early reflection or two.
Still, this is not the same as saying power response or off axis response can be totally discounted. Clearly, power response remains as a secondary issue and will have some effect on perceived frequency response. I can think of two concrete examples from the past: At KEF, when we first launched the Uni-Q models, they were designed to the same curve as previous 2 way systems, even though their directivity was very different. They all sounded dull with too much midrange. Secondly, talking to the Mirage designer of the omni-polar line, they found that the systems needed a fairly constant rolloff slope to not sound too bright. Both systems had a power response shape that was not typical of most speakers of the market.
If we had a measuring system that used the proper variable time window we might be able to simply measure and be done. Without that I find that a dB or so of adjustment can "improve" the balance of a system, at least for the particular listening conditions of that day.
David
Okay I will say thanks for the complement.
I would not make things so black and white as you suggest, please. I believe there are lots of smart people and lots of people who have made an important discovery or two. Everyone makes mistakes. This includes me and you and every other expert. Take Richard Small, fine work from Theil's original work but then he comes up with a measurement technique that can give such erroneous results as to be completely useless. Then he goes on to modify his version of the original Theil model to fit the bad data. Good work, then bad work, then even worse which has lead thousands down paths which just don't work except for a "near perfect" driver. If you want to know about that read my "whining thread" http://www.diyaudio.com/forums/lounge/164047-completely-impressed-saddened-diyaudio.html Details on methods and models therein. This one was rejected also.
Which reminds me I have a question for Geddes. Compact impulse response assuming unit impulse normalization...
Integral from 0 to t of the absolute value of the functional curve generated by the impulse minus the same calculation of the input impulse over the same time? Would like to be able to put some numbers to this.
Respect should be earned and disrespect me if you want but no need to attack. I believe, as example with lots of testing as describe in previous post, being in a single phase is the most difficult thing to do in a system and is poo-pooed by almost everyone.Very tedious and time consuming to know measurements are accurate and then even more difficult to build. This is also the reason no one wants to deal with it. Pain in the sitting place. This is why only 1 out of 3 custom tweeters makes it and 19 out of 20 custom midranges make it into product.
I came here (DIY) more to "be set straight" on perspectives not previously considered, to learn if you will. This is primarily because of having perfected the concepts finally understood after 40 years of making and testing speakers and electronics. A wider perspective was clearly needed. Am pleased to say learning occurs.
Please remember I am not into promotion or fame and in reality, I do not often play well with others. My consulting- I blow in like the wind, fix stuff and straighten out gross mis-conceptions and production problems, learn some of their secrets, and blow out again. Have never worked with any person or company where I did not learn several things. 22 inventor people, many friends, I know have died or disappeared mysteriously. It is just plain luck I am even around.
"There is no product or process designed by anyone or group that cannot be improved by someone else." Quote=SUM That is my philosophy and watching my "babies" be improved by others has become a pleasure rather than a disruption of my ego. After all, better is better no matter who.
Yes, all things at higher levels are political processes include the Journal AES. I quit attempting to publish in 1978. It was just such a joke. That did not stop me from lots of interactions with designers everywhere having made many trips to see them in person and the phone bills to show the discussions. My life is more of a passing wind than a Sequoya tree with deep roots. Blowing around here and there. I have even had my hands inside satellites later shot into space. Tours of duty are seldom over 5 months. Like the Coding Systems gig. Came in after their many man years of hard work and calibrated the +SBR thing which was then sold all over the world. Never went back and never talked to them again. Remember, I simply stand on the shoulders of giants and spew their knowledge. A good portion of what I say is parroted by me from work and statements by others, some giants.
Here is one- Roy at Altec told me every diameter of driver has an optimum voice coil size. This was determined by a huge amount of testing at Altec of Anaheim. Below is the graph.
dantheman- now that last speaker you posted looks like a real "keeper." I do not know what you got but I bet that sounds really good. Wonder if it is in phase?
=SUM
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Hello Bentoronto
I have had at least one system where I wasn't happy with the resolution in my measurements, in this case 750Hz. I was trying to set the attenuation at the crossover point between the woofer and the midrange horn. I got close with the measurements and then dialed in the attenuation by ear. I was doing 1/2 db steps in the syms but couldn't reliably see them in my measurements. So in this case I went by ear.
Rob🙂
About 1977. The graph was generated when later test strongly suggested 1.25 inch was right for a nominal 6.5 inch and the 15 inch referenced during the time at Altec of Anaheim. The blue line was based on another driver that worked pretty well. Years later 1.25 inch is still the preferred size even though mine 6.5" have 1.5 inch voice coil. Credence could not supply 1.25 inch voice coil so the cone had to be made heavier and the efficiency was compromised as well as flatness of frequency response and of course that made cone breakup worse.
Please realize this is for normal cone drivers used for as much bandwidth as those might offer. Special needs change requirements like cost or whatever. I also believe the line probably should not be dead straight but then how to bend it?
Oh yes, thanks Cal.
🙂=SUM
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