Having a position is one thing but I also like to see data that proves a position to be objectively correct. I haven't seen that data yet.
If we really start discussing this topic I'd like to do it in another thread and wait for your white paper to be available to the public.
Best, Markus
An externally hosted image should be here but it was not working when we last tested it.
Not a bad example looks like it has a waveguide. Right?
Better picture here:
http://www.avc-group.si/salesprogram/files/db_files/files/genelec-pic-8020azm.jpg
An externally hosted image should be here but it was not working when we last tested it.
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Yes. Otherwise you won't get constant directivity at high frequencies.
Those monitors are used by mixing engineers sitting very close to the speaker (1m). As they're constantly moving up and down the mixing console, the loudspeakers need to have constant directivity. Otherwise the sound's timbre would change with the engineer's position.
This is a fundamental difference to sound reproduction in a living room. Here the directivity of a "normal" piston speaker is constant enough to provide uncolored direct sound within the listening window for one seat and even multiple seats.
However, the indirect sound field in a typical living room is much louder and therefore affects timbre. This is what psychoacoustic studies have revealed. There are now two positions: a) a loudspeaker has to have smooth directivity (Toole/Olive) and b) a loudspeaker has to have constant directivity (Geddes).
Best, Markus
Those monitors are used by mixing engineers sitting very close to the speaker (1m). As they're constantly moving up and down the mixing console, the loudspeakers need to have constant directivity. Otherwise the sound's timbre would change with the engineer's position.
This is a fundamental difference to sound reproduction in a living room. Here the directivity of a "normal" piston speaker is constant enough to provide uncolored direct sound within the listening window for one seat and even multiple seats.
However, the indirect sound field in a typical living room is much louder and therefore affects timbre. This is what psychoacoustic studies have revealed. There are now two positions: a) a loudspeaker has to have smooth directivity (Toole/Olive) and b) a loudspeaker has to have constant directivity (Geddes).
Best, Markus
Markus
I have no direct experince with Genelec - in the sense of having done the measurements myself. But if they use a waveguide then that's different because it does not fit my deffinition of "piston". One could get a fairly smooth polar response with a small woofer and a small waveguide, but it would be much wider than I would prefer.
Markus
You know very well that I use data when it is available and you also know that there is no "proof" one way or the other. Further, my position does not contradict much available data (maybe some of Floyd's if you don't consider his assumptions and test methodology) and it is consistant with the data that is available. My point is that when there isn't direct data available, as I don't believe that there is in this case, then a position has to be made on what limited knowledge that we might have.
The issue over whether the polar response should be narrow or wide has not been resolved in my mind - even if it has in others. I see too much data that contradicts the idea that it should be wide, even if there is some data to say that it should. I see no data that says that a narrow directivity, if well controlled and done in a colorless maner, is a bad thing. It simply has not been tested and lilely won't be in my lifetime.
Hi Markus
I would add that the loudspeaker should also have a narrow directivity and be used in a very live room. The deader the room the less important my additional criteria is (or any directivity criteria for that matter), but also the less of a "real" spaciousness (as opposed to that on the recording) the playback will have. I target a "better" room, not a typical living room. Right or wrong, you have to start somewhere.
And, as I said above, I see nothing that says that a narrow directivity is a bad thing as long as your two points above still hold. So the narrow directivity should always work as well as the wider, but should work better in a more lively room. Given the obvious problem that you cannot get a narrow directivity in a small size, I don't see the downside of making it narrow.
Markus,
What I was pointing out is that Earl was right with his example. Using two pistons isn't going to give you the decent polar response, is it?
But, If your design includes a wave guide then it's not just two pistons, is it? It's a different design.
Your Genelec example is adding some extra "vitamins", so to speak, right? And it is not a correct objection to his assertion:
BTW, It's interesting that the Genelec blurb here reads like it might be written by Earl on a good marketing day:
Genelec Oy - Genelec DCW Technology
What I was pointing out is that Earl was right with his example. Using two pistons isn't going to give you the decent polar response, is it?
But, If your design includes a wave guide then it's not just two pistons, is it? It's a different design.
Your Genelec example is adding some extra "vitamins", so to speak, right? And it is not a correct objection to his assertion:
I may have lost track of things but wasn't Dan's design one using only pistons?
BTW, It's interesting that the Genelec blurb here reads like it might be written by Earl on a good marketing day:
Genelec Oy - Genelec DCW Technology
Really there are a lot of studio monitors with waveguides. I think even M-Audio has one now. I have a hard time finding measurements of my exact monitors. But the whole pro line outside of the studio monitors seem to be constant directivity wave guided designs for wharfedale pro.
This is the closest I could find to mine.
http://www.avmltd.co.uk/uploaded/VC4460bc641cace.pdf
Do those measurements look okay assuming they weren't fudged?
This is the closest I could find to mine.
http://www.avmltd.co.uk/uploaded/VC4460bc641cace.pdf
Do those measurements look okay assuming they weren't fudged?
Member
Joined 2003
I'm in the directivity camp, and a happy camper 😉, but the question I'm tussling with is whether it is better to have:
a) little/no directivity at LF, constant directivity at HF, with a "hockey stick" in the midrange.
b) little/no directivity at LF with a smooth, gradual, transition to reasonably high directivity at HF.
The problem with trade-off questions like that is there are too many other things to consider to make blanket statements. If you showed me two different "accurate" polar maps I could tell you which would sound better, but making generalized statements on this kind of thing always goes wrong.
Why not have "little/no directivity at LF, constant, reasonably high directivity at HF, with no "hockey stick" in the midrange." - thats what I'd do.
It is. It may not be constant directivity but it can be smooth directivity.
Best, Markus
Don't agree. We need to define a goal. Otherwise any solution is as good as the other one.
Best, Markus
Markus, you don't give up do you? Trust me, without a waveguide you cannot design a speaker that does not change directivity - at least as shape as the crossover filter and almost always faster - through the crossover. I don't know why you keep insisting that you can, or I dont understand what it is that you keep arguing about.
Maybe we are talking about different things. Smooth directivity is not constant directivity. I used the wording "smooth directivity" to describe a behavior like this:
An externally hosted image should be here but it was not working when we last tested it.
This is NOT what I would call "smooth" ...
An externally hosted image should be here but it was not working when we last tested it.
... whereas this fullrange speaker (Visaton B200) shows pretty smooth directivity:
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
Markus
Your just not listening. I'm not talking about full range, never have been. Believe what you want, I'm not interested in arguing when you keep changing the assumptions.
Your just not listening. I'm not talking about full range, never have been. Believe what you want, I'm not interested in arguing when you keep changing the assumptions.
One of the things that 90 degree pattern does well when the speakers are properly toed-in (about 45 degrees) is give an unusually wide sweet spot. For most off-centerline listening positions, you still get good imaging because the smooth off-axis falloff of the near (first-arrival) speaker balances well with the louder, more on-axis response of the far speaker.
I don't know how much further optimization in this regard is practical, but in my opinion that wide sweet spot is one of the most attractive attributes of a 90-degree waveguide speaker. I wouldn't want to use something other than 90 degrees in the horizontal plane if it meant significantly degrading the off-centerline imaging and/or tonal balance.
The 90-degree bipolar format I sometimes use simulates the relative level of reverberant energy one might get with a wide-pattern speaker while preserving the early-arrival characteristics of a narrow-pattern speaker, assuming proper setup in a suitable room.
Hi Duke
I don;t understand, because bi-polar should not have a 90 degree CD pattern.
And as you know this 90 degree pattern on my speakers was not an accident.
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