Beyond the Ariel

So what is the subject at this point. Beyond the Ariel was Lynn's concept of his next speaker system. He has not completed that so where do we go from here. The original topic was an open question and this is where we are at, theoretical determinations about what is important and what we can hear. Who wants to direct the question at this point?
 
So what is the subject at this point. Beyond the Ariel was Lynn's concept of his next speaker system. He has not completed that so where do we go from here. The original topic was an open question and this is where we are at, theoretical determinations about what is important and what we can hear. Who wants to direct the question at this point?

my comment was not criticism, merely a statement.
 
nuconz,
I was somewhat serious, what does someone want to talk about? Buzzforb just asked a question that is always one of those interesting questions, how wide do you really need to make a baffle? Sometimes I think as narrow as possible with a large edge radius is just as valid as a wider baffle that may have a smaller radius. With a horn things change, but with a direct radiator it would appear to be more critical.
 
on this topic, i have found that wide baffle speakers sound "better" in terms of imaging than narrow baffle ones. perhaps they are more 'mellow'.

narrow ones might be best in a multi-speaker system. i prefer stereo.

the large polk sda speakers were pretty wide, as were the tannoy ardens.
 
So what is the subject at this point. Beyond the Ariel was Lynn's concept of his next speaker system. He has not completed that so where do we go from here.

Silence is golden. There is no time limit on Lynn's project. Lynn is still working on it. The list notifies one of new posts. But of course theoretical background and assumptions related to the project are of interest to all.

martin
 
So let's discuss baffle width then. How do you chose the baffle width that you use when you build an enclosure? Many just work from the size of the largest device to go on the baffle. Some will taper the baffle size from top to bottom and some will go with the widest baffle practical and change the depth of the box to end at the optimum enclosure internal volume.

If we look at the radiation angle as determined by the baffle width at what point do we consider this the most practical size, how wide is wide enough? Obviously if we could mount the speakers in the wall we would have almost an infinite baffle size and would remove front wall reflections and have no baffle step concerns. What about an on wall enclosure, what problems would you see with say a 4" depth to the wall and the very short first reflection time combining with the on axis first impulse? Wouldn't that be almost a worst case situation as the timing would be so short and the superposition would smear the imaging? Just a few things to discuss.
 
So let's discuss baffle width then. How do you chose the baffle width that you use when you build an enclosure? Many just work from the size of the largest device to go on the baffle. Some will taper the baffle size from top to bottom and some will go with the widest baffle practical and change the depth of the box to end at the optimum enclosure internal volume.

If we look at the radiation angle as determined by the baffle width at what point do we consider this the most practical size, how wide is wide enough? Obviously if we could mount the speakers in the wall we would have almost an infinite baffle size and would remove front wall reflections and have no baffle step concerns. What about an on wall enclosure, what problems would you see with say a 4" depth to the wall and the very short first reflection time combining with the on axis first impulse? Wouldn't that be almost a worst case situation as the timing would be so short and the superposition would smear the imaging? Just a few things to discuss.

is there a correspondence between baffle width and speaker system efficiency? intuitively, it seems there is. an acoustic shell helps project the sound of an orchestra, band, chorus, etc. no shell, no projection.
 
nuconz,
That is the magic question. How wide is wide enough to reinforce the wavelengths produced in the pistonic range of the device/ At some point you have to make a judgement call. At very low frequency the radiation pattern is practically omni directional so there is a practical limit to baffle width. You also have to consider baffle shape. A flat baffle will have to end at some point or be truncated and blended into the side walls. If it is a sharp corner as in a simple box you will have a fairly sharp diffraction band of frequency before the longer waveforms become the omni pattern. So how large a radius do you need to use to minimize this sharp diffraction band and smooth the response curve? The real answer to all of this is that whatever you do it is a series of tradeoffs, a balance from high directivity to omnidirectional polar response. What is practical when using wood to create a box before the construction methods become extremely difficult to produce?
 
i'm also wondering if there is a possible relationship between baffle size and f3 in system repsonse.

anyway, at some point in the future i hope to have a speaker system that 'blends' into the home without actually having a cave. people boast that systems integrated into the walls sound vastly superior to free standing ones and you don't have to dust around them!

oh yes, and you don't have to worry about 'how wide is enough'?
 
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nuconz,
Yes a speaker in the front wall makes things much easier to understand and takes away many factors of room reflection. It is as close to an infinite baffle as you can do. If it is open in the back then that is one way to do it. but if it is a closed box in the wall you will have to determine the correct enclosure size and if a bass reflex design the proper port size. And wives love it when the speakers disappear from the room so to speak.
 
nuconz,
Yes a speaker in the front wall makes things much easier to understand and takes away many factors of room reflection. It is as close to an infinite baffle as you can do. If it is open in the back then that is one way to do it. but if it is a closed box in the wall you will have to determine the correct enclosure size and if a bass reflex design the proper port size. And wives love it when the speakers disappear from the room so to speak.

hope to have it open into the utility/laundry area. with some hardware cloth around the back to keep 4 legs from playing with the drivers and some good padding about, should be about right. maybe a couple of the dayton ib woofers will do good.
 
The horn I will be trying first is wooden Iwata 290. It has a width of about 25". The original plan was to have the baffle flat for about 16-17" and then have it follow the contour of the Iwata. This would give me a wide baffle as well as large, smooth round over. The back will be slightly swept back. Haven't decided whether to make it straight or curved side.
 
The horn I will be trying first is wooden Iwata 290. It has a width of about 25". The original plan was to have the baffle flat for about 16-17" and then have it follow the contour of the Iwata. This would give me a wide baffle as well as large, smooth round over. The back will be slightly swept back. Haven't decided whether to make it straight or curved side.

Similar to this.

Wardsweb DIY 3-way horns
 
Buzz,
That will work well for the horn but what about the direct radiator. It is much better than a square corner that is for sure and would help with the cone speaker also. That was a major consideration when I built the speakers in my avatar. Each horn has a radius around it and blends into curved sides ending with a curved back. This was something I did before B&W came out with their enclosure with the extended rear flares on their snail enclosure. Funny how people laughed when they first saw the design and then loved it when B&W took the concept and built their enclosure after me.........The bottom section is a down firing bass speaker that went with the top horns and limited the diffraction problem and any floor bounce from the driver.
 
Buzz,
I thought that you were direction your attention only to the horn mounting. I think what you are proposing is fine. Could you just leave the majority of the curvature to the face and make a minimal recess to blend the edges of the frame into the curvature? It would perhaps take some hand carving but you could have a nice contour around the frame.
 
Hi Kindhornman
So far as the baffle dimensions, if your source is too small to have it’s own directivity (simple radiation is a good thing generally), then you can treat a flat baffle just like a horn (a baffle less than 180 degrees).

This is possible because the way sound propagates from a source and behaves over a boundary is the same in a horn or flat baffle, only the words are changed to obscure the innocent as they used to sort of say..

Just as a horn has a point (dimension vs frequency) where the impedance transformation ceases (when the horn > K=1 or about 1WL in circumference) and at a much larger dimension where the directivity is controlled.

From that it is interesting to note that at 20KHz, ALL of the impedance transformation has taken place within the compression driver well before reaching the 1” exit into the horn and a 1” exit “large enough” to already confine the radiation to about 60-80 degrees within a horn..

For a flat baffle or simple horn, Don Keele’s thumb rule for pattern loss frequency still holds true.

The pattern loss F goes down with increasing size and increasing angle, for example, a 20 inch wide 90 degree horn has a pattern loss F about an octave higher than a 20 inch wide flat baffle and a 20 inch wide 45 degree horn has a pattern loss F about an octave higher than the 90 degree horn.

The same pattern control point moving back into the horn is why so many curved wall horns have narrowing directivity with increasing frequency.
Anyway, the thumb rule appears first in Don’s paper here;

http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1975-05 AES Preprint) - Whats So Sacred Exp Horns.pdf

Best,
Tom
 
Tom,I was really trying to just throw out hypothetical's so others would have to think about the problems. I wasn't thinking much about horns, just direct radiators on a flat front baffle. Yes we can look at the baffle as a 180 degree horn, but if the baffle isn't much wider than the direct radiator it isn't really adding much in the way of directivity.

I haven't looked at one of Keele's books in a long time. I found in the past some of what were in earlier books were just repeats of incorrect information that many would site. Don't ask for a specific instance I don't remember any more.