Interesting curves Markus and good for your for doing the work.
It doesn't perform as we would expect though. You are getting 5 to 10dB reduction on axis (up direction in conventional orrientation) and maybe a 5dB increase at high frequencies at 70 to 90 degrees (the lateral plane). It doesn't turn the radiation pattern into a donut pattern and it isn't very smooth.
I wonder about its size as well. From most vantage points you can see the cone as well as its reflective surface. Acoustic radiation to a point will be a combination of 2 sources: the driver and its reflection. This is probably the cause of the peak that's varying with frequency. A much larger reflector might improve that, or at least increase the blockage (reduce diffraction) to the upwards angles.
David S.
So you are not agreeing with Toole that multiple lateral reflections are a good thing in domestic listening rooms?
David S.
Hi Rudolf,
I don't read HH anymore - did they show measurements?
@all, here's a picture:
An externally hosted image should be here but it was not working when we last tested it.
I agree with Toole, but he is talking about US size rooms. The ear/audio processing in the brain is very adept in distinguising direct sound from reflected sound. The reflected sound is important to give a feeling of emersion.
This is not to say that I subscribe to the HH design shown above. I am convinced it will sound quite horrible, because the setup with a cone reflecting the sound from a driver leads to huge artifacts in the FR.
I could imagine this speaker to work if slightly adepted. If run < 14-1500 Hz, the upfiring driver would radiate in 4 Pi over its entire frequency band, as is also used by Linkwitz in his Pluto. In combination with a front firing tweeter that can go really low, it might actually be quite nice.
vac
This is not to say that I subscribe to the HH design shown above. I am convinced it will sound quite horrible, because the setup with a cone reflecting the sound from a driver leads to huge artifacts in the FR.
I could imagine this speaker to work if slightly adepted. If run < 14-1500 Hz, the upfiring driver would radiate in 4 Pi over its entire frequency band, as is also used by Linkwitz in his Pluto. In combination with a front firing tweeter that can go really low, it might actually be quite nice.
vac
Yes and no, it depends on the timing. Later lateral reflections are all good, very early ones are not. Floyd does not make this distinction and to that I do disagree. There are many other consultants that I have talked to who agree with me on this point.
well, this is quite fundamental disagreement, with immense impact on practical speaker design principles, isn't it?
Am I missing something? I've always found that placing a standard set of non-directional speakers on the long wall of rectangular room always provided better imaging and overall quality. This seems like a very fundamental aspect and not difficult to figure out. It's primarily based on the difference in lateral reflections, with the exception of differing excitation of room modes. Why would he not make such a distinction?
Dave
I believe its because of the difficulty in doing any experiments on it. The data sets for Floyds position are not that precise, but rather weak. Based on this rather loose data it is not possible to discriminate very early reflections from later ones. In his studies you either have lateral reflections or you don't and in that situation the lateral reflections add to the spaciuosness so they are prefered to not having any lateral reflections. I don't have a problem with that extreme position at all. But if it is possible to delay the onset of the lateral reflections, then I am of the very strong opinion that this approach provides a much better image without sacrificing the spaciousness. But doing such "pure" tests is almost impossible because it requires two completely different speaker and room designs and now you are not comparing the reflection patterns per se, but the speakers/room themselves.
Which studies are you referring to? Most studies I know used different delays, levels and signals.
I agree that this creates better envelopment but spaciousness? I believe spaciousness is created by multiple strong reflections coming from the sides and elevated locations.
Floyds studies used real speakers in real rooms. You are refeering to his research into the audibility of resonances or single reflections.
As to your second comment, I think that you need to reread what I wrote, because we said the same thing. There should be a direct sound and no VER, which will create good imaging (very flat direct field assumed of course), then after a sufficient delay there should be as many lateral reflections as possible for as long as possible (small room). I've never heard that the height of them makes much difference, but in general in a small room they are going to be elevated because the furniture is all on the floor, not on the ceiling.
As to your second comment, I think that you need to reread what I wrote, because we said the same thing. There should be a direct sound and no VER, which will create good imaging (very flat direct field assumed of course), then after a sufficient delay there should be as many lateral reflections as possible for as long as possible (small room). I've never heard that the height of them makes much difference, but in general in a small room they are going to be elevated because the furniture is all on the floor, not on the ceiling.
Here are some measurements of the study object in post 1.
I'm building this speaker for certain reasons documented on my web site. For that it is easy enough and should suffice. If it turns out to be a good speaker, great. If not, I have a big basement 🙂
Amongst these reasons are the following, which are spelled out in more generic terms on my web site:
- Is 360° radiation constant directivity desirable or is less better ?
- If less is better, where should the response start to roll off ?
- If it is not better where is the minimum that will be good enough to create what I want from a speaker for recreational listening.
Sorry for not adding the pictures here directly. But this is additional work and it's late now.
Demokrit Measurements
Have fun !
Oliver
I'm building this speaker for certain reasons documented on my web site. For that it is easy enough and should suffice. If it turns out to be a good speaker, great. If not, I have a big basement 🙂
Amongst these reasons are the following, which are spelled out in more generic terms on my web site:
- Is 360° radiation constant directivity desirable or is less better ?
- If less is better, where should the response start to roll off ?
- If it is not better where is the minimum that will be good enough to create what I want from a speaker for recreational listening.
Sorry for not adding the pictures here directly. But this is additional work and it's late now.
Demokrit Measurements
Have fun !
Oliver
Yes, misread your post.
We're probably talking about a different perception. I was referring to images that fill a space (ASW). This requires very strong early reflections around 10ms and up. A high directivity speaker design can't create such reflections. A wide dispersion design could but it also creates all sorts of detrimental reflections. Furthermore ASW is poured over all sounds which might not be appropriate for all program material.
Thanks but did you also measure different angles and cone distances? You would also need to apply a gate to the impulse response in order to filter out unwanted reflections.
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good observations too! it took some time 😉 but now You are talking guys! 😀
So, am I to understand that we can agree that some ASW is better for realistic sound reproduction than no ASW?
so the questions are:
1) which of room reflections are detrimental and why and what can be done?
2) reproduction of what kind of program material specifically will not benefit from a fixed amount of ASW?
3) can we somehow when designing speakers and their room interface adjust ASW to suit a specific program material or at least fix an amount of it suitable more or less for most program material?
Sorry, Markus, you are very demanding. This is what a regular person can achieve on one evening after regular working hours. So I suggest that you are a little patient or you do this sweet labor yourself. And please don't forget that I don't do all this only for your thread here.
I measure outdoors in a controlled setup far enough from boundaries creating reflections that would mask what I want to see. The setup is able to create pretty highly repeatable results.
I am not bothered by the floor reflection. It is just reality.
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