In my opinion far too coarse to be of any value for assessing a speaker's free field behavior.
Hi Markus
Perhaps in “hifi” land that is true.
At the same time, like I said, our polar information isn’t used as a sales aid; it is for a computer model. Because all of the room related and distance related issues are so much worse than the living room, the concern in commercial sound actually is the loudspeakers spatial field behavior, it is about being able to best use what the loudspeaker does.
Because that is the concern, they might look at “hifi “, at the “importance” of fine frequency resolution in the front half of a 1d Horizontal polar plot or map, often taken much too close to be reliable predictor of far field behavior, some with not enough measured data points as a nearly useless although nice looking spatial view of that loudspeaker.
That is why these measurements are taken every 5 degrees over an entire sphere, there is nothing calculated about where the sound goes, it’s measured over an entire sphere and also far enough away from the source to produce measured data that allow accurate predictions of what you measure in real life at distance X.
Recall, I didn’t establish the standards for this, rather we follow the standard. With some of the more advanced (time consuming) prediction platforms, one can only map but predict the sound one will hear and even listen to it. Here is an example of one of those programs.
Software - EASE - Enhanced Acoustic Simulator for Engineers
In other words, in commercial sound what one measures / hears at the listing position is much more important than what one measured at a standard 1 meter distance.
Hi Scott H
Wow, I remember your name from “back then”. Those were the days, I had a telephone link internet connection to a neighbor who was an isp with a “giant pipe” (later upgraded to a t-3).
I think the bass list one of the things that kept me from going crazy after Intersonics closed down and the NASA days were over.
Anyway, thanks for your kind words and thank you for having been involved with that list back then, having that lifeline really did help and was a lot of fun. Wasn’t that hosted out of U-texas or something?
Best,
Tom
The Dunlavey was only provided as a "best of". 😉
I could be wrong on this next part, but I believe there is very little difference between acoustic phase and derived phase.
I think the real difference is down to the way it's plotted, basically a transform (corrective) process is occurring in examples like the Dunlavy, and not in Tom's. It's a guess though, and I'm sure Tom can provide more detail on the subject. (..or someone else.)
The impedance has an phase and magnitude as does the acoustical response...for all the world it sounds like you're mixing the two. Or are we supposed to go look up the Dunlavy acoustical phase and compare it to the Synergy horns?
Scott H.
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No problem...yeah it was hosted out of U.T. in those days, I was in undergrad. I only understood about 1/4 of what people were saying, but it was all interesting. Now I'm up to a heavy 1/3...and it's more interesting than ever. 😉
Scott (H)
My point was that I don't think the two plots are complementary. The Dunlavy plot is what you would normally expect to see, and Tom's is not. The rest was a guess (as stated), and it's quite likely I'm mixing things up. 😱
I think you might want to take a look at acoustical magnitude and phase. I recommend the Testing Loudspeakers book by D'Appolito...you're comparing apples and oranges.
Scott
I believe it's generally true and not just in HiFi land. 1/3 and 1/6 will cover up resonances that can be audible (especially when listening conditions approach free field conditions).
P.S. Did you get my PM?
For the SH50 phase issue, it would be great if someone could post a measured impulse repsonse, then we could process it and see if there is any uncompensated time delay in the original plot or not. In a FFT log Bode plot it's hard to tell if the phase roll-off is "true" or (partly) a product of a dead time, masking things...
The system that Tom is using seems to be trying to adjust for a causal pulse, setting the phase reference point to where the pulse emerges out from the noise floor, and that initial rise will come from the woofers as they are closest. This could be the reason for the phase starting at "zero" and rolling off to -360 deg (from the 4th order bass-reflex alignement). After that, the roll-off is a very gentle slope reaching another 360 deg after one and a half decade, then finally rolling off according to the falling HF response. And this sure is a pretty excellent result for a 3-way, given the (presumably) steep acoustic slopes of the individual ranges.
The system that Tom is using seems to be trying to adjust for a causal pulse, setting the phase reference point to where the pulse emerges out from the noise floor, and that initial rise will come from the woofers as they are closest. This could be the reason for the phase starting at "zero" and rolling off to -360 deg (from the 4th order bass-reflex alignement). After that, the roll-off is a very gentle slope reaching another 360 deg after one and a half decade, then finally rolling off according to the falling HF response. And this sure is a pretty excellent result for a 3-way, given the (presumably) steep acoustic slopes of the individual ranges.
Interesting you should bring this up. That is essentially the same conclusion I came to a little over a year ago. I ended up buying a pair of used SM60Fs from Forin on AVS. They replaced a set of sealed Statements that I built which replaced Magnepans. The Magnepans had great imaging but little in the way of dynamics. The Statements provided excellent imaging and pretty good dynamics. The SM60Fs are really in another league. The dynamics never cease to amaze me and they disappear in the room even more so than the Statements or Magnepans. Now I need to find another one for my center channel and try to buy or build surrounds that match.
Mike
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Last night I went to the Mad Decent Block Party, and was a bit amused to see that they were covering a crowd of about three thousand people with an array of eight JBL speakers per side. I couldn't tell which model it was, but they were very small, likely with dual eights.
Bottom line - my home speakers are likely capable of producing 90% as much sound as what they were using at that show.
And this wasn't some polite rock show, theoretically this was a big booty bass type thing. But you could tell that the sound system was just struggling the whole time. Temperatures in the 90s didn't help any either.
Hi Guys
This has to be short, am getting ready to leave.
Markus, I saw your msg, I will have to look into it and get back to you when I return.
KSTR I found wave files of the impulse responses and am attaching it.
These were taken in my living room which is fairly (very) cluttered and has a bare hardwood floor so it’s not anechoic haha. One is at one meter on axis, the other is at the listening position about 15 feet away.
I think the two short reflections were from the seat /tank of a Ducati motorcycle that was immediately in front and just below the the speaker.
link;
https://www.dropbox.com/sh/j1patqtdh4gz954/d5V3LRUT1j
Best,
Tom
This has to be short, am getting ready to leave.
Markus, I saw your msg, I will have to look into it and get back to you when I return.
KSTR I found wave files of the impulse responses and am attaching it.
These were taken in my living room which is fairly (very) cluttered and has a bare hardwood floor so it’s not anechoic haha. One is at one meter on axis, the other is at the listening position about 15 feet away.
I think the two short reflections were from the seat /tank of a Ducati motorcycle that was immediately in front and just below the the speaker.
link;
https://www.dropbox.com/sh/j1patqtdh4gz954/d5V3LRUT1j
Best,
Tom
So...I haven't posted my measurements yet because I'm still developing mine...my first built crossover is rarely my last. However, I've finally come to the realization on how to answer the question in your original post.
As far as high fidelity...no...but you put one thing through these speakers that isn't high fidelity and they'll pop you in the face with it really hard. I mean...there's a few lower-fi albums I have that are nearly unlistenable.
Scott
Thanks for that assessment. I'm trying to put this all together still,. Sometimes the sort of detail that some audio guys need is very often sort of at odds with what some consider an acceptable hifi speaker! The truth is this can and do get into some really minute amount of distortion, which most of us would find OK, but the thing is, it is additive. Up front: Modern amplifiers and electronics in general are not going to be an issue if there is a reserve of power (almost guaranteed by an all horn loaded speaker)
There is a "pushed" acceptance of speakers (well obviously direct all radiator units) which do not couple drivers to the air efficiently or use many spread out drivers therefore multi point paths to do so. That this degradation is "Ok" with us is almost always going to be directly related to some sort of personal compromise, a compromise that hifi people in another era did not make nearly as much. This nasty little compromise most of us, certainly myself, has made or are currently making, is driven by aesthetics and/or economic factors, but mostly aesthetics at least on the consumer side. These compromises lead to a sort of dishonesty. It begs for a "good enough, no one can hear that" approach.Obviously tweak heads can and do take it to ridiculous extremes with cables, power cords and such. IMO what we really need to do is stop compromising our own principles and simply stop pulling the wool over our own eyes for whatever reason we do so.
Although I have witnessed some audio/mastering/whatever engineers fall into that "driver distortion is minimal bs", for the most part they do not. They do not simply because they can not afford to. You will see large speakers, you will see speakers with great phase characteristics you will see speakers with very flat FR, you will see perhaps a combo of the above, but you won't see speakers that allow a significant amount of driver excursion, because guess what? That crap is actually audible and ME's better catch it before it adds up to some kind of audible junk in somebody's already compromised speakers (like many of my own personal units)
Yes, Virginia there is such a thing as audible driver distortion, there are annoying phase issues too, A high efficiency all horn loaded speaker that we can use for mastering due to the current standard of pop music, is needed.
And for personal use speakers? I have decided, regardless of my occupation, to put on my big girl panties and get an all horn loaded speaker again.
There is a "pushed" acceptance of speakers (well obviously direct all radiator units) which do not couple drivers to the air efficiently or use many spread out drivers therefore multi point paths to do so. That this degradation is "Ok" with us is almost always going to be directly related to some sort of personal compromise, a compromise that hifi people in another era did not make nearly as much. This nasty little compromise most of us, certainly myself, has made or are currently making, is driven by aesthetics and/or economic factors, but mostly aesthetics at least on the consumer side. These compromises lead to a sort of dishonesty. It begs for a "good enough, no one can hear that" approach.Obviously tweak heads can and do take it to ridiculous extremes with cables, power cords and such. IMO what we really need to do is stop compromising our own principles and simply stop pulling the wool over our own eyes for whatever reason we do so.
Although I have witnessed some audio/mastering/whatever engineers fall into that "driver distortion is minimal bs", for the most part they do not. They do not simply because they can not afford to. You will see large speakers, you will see speakers with great phase characteristics you will see speakers with very flat FR, you will see perhaps a combo of the above, but you won't see speakers that allow a significant amount of driver excursion, because guess what? That crap is actually audible and ME's better catch it before it adds up to some kind of audible junk in somebody's already compromised speakers (like many of my own personal units)
Yes, Virginia there is such a thing as audible driver distortion, there are annoying phase issues too, A high efficiency all horn loaded speaker that we can use for mastering due to the current standard of pop music, is needed.
And for personal use speakers? I have decided, regardless of my occupation, to put on my big girl panties and get an all horn loaded speaker again.
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There you have it. The standard has changed. It's the "Inside your car" level that is relevant, they just don't get it yet, and many many many hip masters suck because a lot of these guys do not see this yet!!! And it does most certainly not end with hip hop, on the contrary, it begins there!! These ain't your mother's Firebird and Madonna Cd's.
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