I am still trying to grasp all the concepts and theory of open baffle speakers, and when browsing images for inspiration, I came across this beautifully designed open baffle hybrid:
Seligkeit Speaker
Now, after having read Siegfried Linkwitz "Diffraction from baffle edge" article, I must assume that the round baffle for the midrange in this OB is a very bad idea... or do I need to unlearn something
An externally hosted image should be here but it was not working when we last tested it.
Seligkeit Speaker
Now, after having read Siegfried Linkwitz "Diffraction from baffle edge" article, I must assume that the round baffle for the midrange in this OB is a very bad idea... or do I need to unlearn something
A round baffle isn't a bad idea by itself. Unless due consideration is given to the baffle design then the disturbance caused at its edges can be significant, not least when it is round. Otherwise round would be the logical starting point.
drterbi, you and SL are right.
A perfectly round dipole has very narrow range of operation (usable passband) Above dipole peak (here at 500Hz) the speaker loses directivity and slowly exhibits normal directivity. This leads to difficult power response and easily to difficulties in achieving balanced sound in typical small rooms with lots of sidewall reflections.
Also the tweeter of this Seligkeit is a very poor "dipole" practically.
But the slot-loaded bass should work fine!
We see this kind of problems in almost any commercial "dipole" loudspeaker. Dipole 8-directivity is lost typically above 1000Hz.
A perfectly round dipole has very narrow range of operation (usable passband) Above dipole peak (here at 500Hz) the speaker loses directivity and slowly exhibits normal directivity. This leads to difficult power response and easily to difficulties in achieving balanced sound in typical small rooms with lots of sidewall reflections.
Also the tweeter of this Seligkeit is a very poor "dipole" practically.
But the slot-loaded bass should work fine!
We see this kind of problems in almost any commercial "dipole" loudspeaker. Dipole 8-directivity is lost typically above 1000Hz.
Attachments
In this design I would assume that the tweeter is not much of a problem, due to its small baffle and directional on-axis output.
But for the midrange, as Linkwitz states "the magnitude of any diffraction effect is greater at the low frequency end of a driver's range." So I would assume that the large baffle around the midrange would cause large dips and peaks all over the place?
But for the midrange, as Linkwitz states "the magnitude of any diffraction effect is greater at the low frequency end of a driver's range." So I would assume that the large baffle around the midrange would cause large dips and peaks all over the place?
Thanks. The red marking looks like trouble.
Anyway, I will stick to a rectangular baffle. I've been doing some prototypes about 16" x 41", and got some pretty decent results.
I took measurements, and then simulated the baffle in Jeff Bagby's Baffle Diffraction and Boundary Simulator. My dips and peaks were pretty much spot on. In the "Edge" not so much... maybe I did something wrong, I don't know.
Now looking for the right woofers... 1x AE Dipole15 or 2x AE Dipole 12 seem to be great options.
Anyway, I will stick to a rectangular baffle. I've been doing some prototypes about 16" x 41", and got some pretty decent results.
I took measurements, and then simulated the baffle in Jeff Bagby's Baffle Diffraction and Boundary Simulator. My dips and peaks were pretty much spot on. In the "Edge" not so much... maybe I did something wrong, I don't know.
Now looking for the right woofers... 1x AE Dipole15 or 2x AE Dipole 12 seem to be great options.
This is all good theory, but we're discussing obstacles that are not completely insurmountable. The implementation is key.
Best,
Erik
Best,
Erik
and of course for the demographic to which some of the more acoustically illogical designs are targeted, the in room results may have sonic signatures that are "part of their charm"
I agree. But, generally speaking, it would be better to avoid as many obstacles as possible in theory, since that would make the implementation easier, wouldn't you agree?
^Yes, avoid loosing pure dipole radiation/directivity range, then you won't get edge interference ripples! This means a 4-way speaker and dsp for eq and steep xo and still one will eventually hit the physical limits around 5-6kHz and get diffraction ripples and loose uniform directivity. And anyway vertical directivity is a mess always!
Some more info
NaO Note Design Objectives
Electro-acoustic models
http://www.dipolplus.de/downloads/Open baffle 1.pdf from Dipolplus - Alles über offene Schallwände
Check also my one-and-only project - my signature down below
Some more info
NaO Note Design Objectives
Electro-acoustic models
http://www.dipolplus.de/downloads/Open baffle 1.pdf from Dipolplus - Alles über offene Schallwände
Check also my one-and-only project - my signature down below
There are always obstacles and tradeoffs. Sometimes taking the non obvious choice takes us to unexpected learning. Of course we usually want to make things easier for ourselves, but I always leave room for serendipity. I may not understand the choices, but id defer judgement until i could listen or measure the results.
Best,
Erik
Generally circular baffles would be a bad idea. However, with an open baffle speaker there are other considerations. For example if the band pass is limited to the frequency range below the first dipole peak, a circular baffle will be superior in that the response will have the same off axis variation regardless of where it's vertical or horizontal or anything in between. Additionally, if the diameter of the baffle is chosen such that the driver becomes directional before the first dipole peak is reached edge diffraction is minimized as a problem. So, with careful design considerations, a circular baffle, even with a conventional speaker, can yield superior uniformity in special response. Like most things, the devil is in the details.
iv had speakers from this guy (bastanis) and frankly his brand is a sham. he sells cheap pro woofers up to several times retail, tosses them on a baffle or in a box, disregards the entire crossover (becasuse any crossover is evil coloration according to him) and calls it "high-end".
huge spl variation, obvious beaming, shouting and coloration. pretty annoying and were easily beaten by cheap econowave type speakers.
wouldnt be surprised if the budget lxmini works better than most of his OB-stuff, because all they have is size and efficiency.
reminded me of hawthorne silver iris, which is another hidious speaker i never should have bought.
sorry.
huge spl variation, obvious beaming, shouting and coloration. pretty annoying and were easily beaten by cheap econowave type speakers.
wouldnt be surprised if the budget lxmini works better than most of his OB-stuff, because all they have is size and efficiency.
reminded me of hawthorne silver iris, which is another hidious speaker i never should have bought.
sorry.
Multitask,
And yet I like the look!
If you've ever been to a high end show, and listend to an untreated room, where the sound is an absolute horrible mess but people still talk about how wonderful the experience was, you wouldn't be too surprised. 🙂
Best,
Erik
And yet I like the look!
If you've ever been to a high end show, and listend to an untreated room, where the sound is an absolute horrible mess but people still talk about how wonderful the experience was, you wouldn't be too surprised. 🙂
Best,
Erik
the baffle is only necessary to avoid short circuit at low frequencies.
for the other frequencies it is best to avoid the contribution of the baffle, need for mechanical design allowing ..
the contribution of the baffle will provide added advantage only if seen through the microphone that measures the frequency response.
when in fact you listen with your ears it is better not to have the contribution of baffle.
for the other frequencies it is best to avoid the contribution of the baffle, need for mechanical design allowing ..
the contribution of the baffle will provide added advantage only if seen through the microphone that measures the frequency response.
when in fact you listen with your ears it is better not to have the contribution of baffle.
another interesting design from this guy. 2x 15" + 2x 12" + 1st order tweeter cap around 12k. how would one go about measuring such a speaker? apparently all woofers run to 4-5khz, and its like 1.5 meter between them at worst.
if you use more than one large woofer you better cross it as low as possible to limit lobing at Fc right?
no acoustic center vertically or horizontally, and no form of EQ either.
if you use more than one large woofer you better cross it as low as possible to limit lobing at Fc right?
no acoustic center vertically or horizontally, and no form of EQ either.
FYI, if a speaker were placed in the hole of a donut (mathematically a toroid), it would not have any edge diffraction. I told this to Linkwitz many years ago, but he was not interested. Always wanted to try it, but hey, there are lots of things one could "try"!
When eyes and brain become part of the "evaluation" the ears tend to take second place.
(PS. the link doesn't work.)