About CD size.
I agree with you that with ca. 800 hz XO 1inch MAY be better option.
BUT and BIG BUT
the problems of any GOOD cd horn or WG are much smaller in compare to lobbing from non coicident woofer and horn.
I use large format CD in big WG and 450 hz XO. Nobody ever convince me that you cannot hear lobing at 800hz /it is inherent because of CTC distance/
Off course HF absolute quality and dispersion are compromised.
JBL M2 had potential to be almost without compromises. But it has to be bigger to XO lower.
I agree with you that with ca. 800 hz XO 1inch MAY be better option.
BUT and BIG BUT
the problems of any GOOD cd horn or WG are much smaller in compare to lobbing from non coicident woofer and horn.
I use large format CD in big WG and 450 hz XO. Nobody ever convince me that you cannot hear lobing at 800hz /it is inherent because of CTC distance/
Off course HF absolute quality and dispersion are compromised.
JBL M2 had potential to be almost without compromises. But it has to be bigger to XO lower.
Isn't it tricky to get a ring radiator to cross over much lower than 800hz?
I'd assumed that the BMS and JBL ring radiators suffer from the same problem that the Vifa and Scanspeak do. Basically you have to use a higher crossover than you would be able to do with a conventional radiator, because the displacement of a dome is superior, if the diameter of the ring and the dome are the same.
The JBL patent lists some other configurations, and I wouldn't be surpised if we saw additional drivers come out that use the same co-axial configuration, but with a larger ring size. (And larger throat, larger mouth, etc.)
That might get the ring down lower, perhaps instead of five and a half octaves of bandwidth from 800hz-30khz we might see five and a half from 500hz-20khz.
Basically scale the whole thing up in size by 50% or so. It might end up looking like this:
I see no reason to believe that this is true and no data that supports it.
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Interesting curves. Totally axisymmetrical horns are tough because any amount of mouth reflection is going to give on axis problems. I had the shop make up a circular wooden waveguide for me for a 1" dome. It started as 90 degree conical and flared out gradually per the typical Keele end flaring approach. The on axis response was horrific (polar curves were nice though).
For home use we can aim the "bad" axis away, no problem, but it does totally exclude them from use in PA or Cinema applications (we can't rope off prime seating area!).
If cheap DSP is a given then maybe the old 2344 was the perfect horn. It certainly had the most ideal polars and d.i. Axial response was an exact copy of the driver's power response. There were no bad angles response wise. The one issue was low end roughness that could easily be handled with a bit of DSP.
Just sayin...
David
Im nobody to argue with you. But lobing is much serious deviation from constant directivity than HOM and much easier to measure. 🙂 Unfortunately very few people can set XO that low and make compare lobing free vs "standart" setup. I make it and its no subtle difference. Im not talking about amp or dac or cable difference /i dont believe to them in reasonable scale/
And yes i know that HOM is bad from different reason than CD deviation - the former sentence was yoke 🙂
The difference with lobing free and standart setup is very easy detectable. Blind too. Most eminent case is mono signal. Lobe free is death center. Standart is QUITE more diffuse - phantom image is much wider and vague. Same effect on standart stereo.
Isn't it tricky to get a ring radiator to cross over much lower than 800hz?
I'd assumed that the BMS and JBL ring radiators suffer from the same problem that the Vifa and Scanspeak do. Basically you have to use a higher crossover than you would be able to do with a conventional radiator, because the displacement of a dome is superior, if the diameter of the ring and the dome are the same.
The JBL patent lists some other configurations, and I wouldn't be surpised if we saw additional drivers come out that use the same co-axial configuration, but with a larger ring size. (And larger throat, larger mouth, etc.)
That might get the ring down lower, perhaps instead of five and a half octaves of bandwidth from 800hz-30khz we might see five and a half from 500hz-20khz.
Basically scale the whole thing up in size by 50% or so. It might end up looking like this:
In fact D2 driver isnt coaxial - it is PUSH PULL. 2 identical phrames - play same thing - no XO.
It is quite clever design. Nothing common with BMS except ring phrame.
It has about same displacement as normal 3 inch coil DOME /which is absolutely capable 450 hz XO on adequate horn and HOME listening level/
D2 driver phrames has almost no breakups and much less problem on HF from cancelations on phase plug.
there is no need to bigger driver for 800hz xo - but you need it for 500. /i mean bigger than standart 1,7 inch dome on 1 inch throat/
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So where was this "blind" test done?
I do not understand how if one is within the main "lobe" and the floor and ceiling reflections are null that this lobe can have any effect. Even if there are floor and ceiling reflections they do not influence the "phantom" image since this only depends on the horizontal directivity and there are no lobes in the horizontal.
I simply do not get the issue with the crossover lobes when the system and/or the room is properly handled. On the other hand anything that compromises the horizontal directivity degrades everything. According to Greisinger vertical reflections don't matter - we ignore them - but the horizontal is everything. I agree with that completely.
If your perceptions are your own then no one can explain them, but the science does not support your conclusions.
Dave
This axial issue can be resolved by making the mouth flare not symmetric.
The axial holes also depend on the mouth radius. The Abbey that John showed is a worse case (the obsolete ESP12). The hole is almost completely gone in the Summa (larger mouth radius helps here), but it is also less in the smaller Nathan because the mouth radius are different even though the mouth flare radius is less.
There can be a standing wave across the mouth, much like a drum membrane and the frequency of this depends on the radius of the mouth. If this resonance corresponds to the frequency where the wave front cancels on axis then the results can be better or worse depending on the phase of the resonance.
I can see all of this with my measurement techniques which allow me to animate the wave front in the mouth from the far field measurements. At the frequency of the hole the Abbey has a noticeable resonance across the mouth. This coincidence of events leads to the larger than hoped for axial hole in the ESP12. The Abbey has slightly different dimensions and its hole is less than the ESP12 (as can be seen on my website).
FWIW, the measurements I provided on the SEOS protos were made with NO smoothing at all. On top of a stand about 6' off the ground about 2m away from the mic, and not on any baffle (except a box below the waveguide to hold it up and some foam between the guide and box to keep it positioned right. Here's SEOS15, for example
Hey guys...we need a little rallying here... - Page 59
[The AVS site's software makes it really difficult to find a post within a large thread!]
http://www.avsforum.com/t/1369780/at-last-the-seos12-measurements
Unless I'm making measurements for crossover sims, I use little or no smoothing for drivers.
Bill
Hey guys...we need a little rallying here... - Page 59
[The AVS site's software makes it really difficult to find a post within a large thread!]
http://www.avsforum.com/t/1369780/at-last-the-seos12-measurements
Unless I'm making measurements for crossover sims, I use little or no smoothing for drivers.
Bill
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Earl Geddes,
I guess it was the same way I felt when I read your paper on the oblate spheroid design that I had previously written a private paper to Bayer corp for funding. Called it something else but was convinced that paper was shown to you at Ford. I think now we can agree that it was simultaneous invention but we did have the same idea at the same time. Still a slightly different perspective on how we did it , you from the mouth backwards and me from the driver outwards but they couldn't have been closer in theory how they worked. You published your paper and I didn't. You win!
I guess it was the same way I felt when I read your paper on the oblate spheroid design that I had previously written a private paper to Bayer corp for funding. Called it something else but was convinced that paper was shown to you at Ford. I think now we can agree that it was simultaneous invention but we did have the same idea at the same time. Still a slightly different perspective on how we did it , you from the mouth backwards and me from the driver outwards but they couldn't have been closer in theory how they worked. You published your paper and I didn't. You win!
Bill
Don't you think that some smoothing makes sense? I played with it a lot and find that the critical band smoothing seems to show exactly what I am looking for. Detail that matches our hearing. It's not too hard to implement, you should do that. As I said Dr. Farina did a very nice study and concluded the same thing.
Well I can't agree that it was a "simultaneous invention" if you can't produce some documents to that effect.
Earl,
Since those were supposed to be for eyes only at the time that would be real hard to show at this time. Very long ago when you were at Ford. Many of the people are dead or retired but I do still know some of those people. Not worth arguing about at this time, but I do know what I did back then. Long before I ever saw a copy of your papers in the stacks at Cornell. I know my brother still has some of the mathematics papers somewhere from those designs, we had to go to a professor at the time to do some of the math dealing with some of the elliptical mathematics.
Since those were supposed to be for eyes only at the time that would be real hard to show at this time. Very long ago when you were at Ford. Many of the people are dead or retired but I do still know some of those people. Not worth arguing about at this time, but I do know what I did back then. Long before I ever saw a copy of your papers in the stacks at Cornell. I know my brother still has some of the mathematics papers somewhere from those designs, we had to go to a professor at the time to do some of the math dealing with some of the elliptical mathematics.
Well that trickled down fast. JBL released some new speakers two weeks ago.
$10,000 for the pair and $10,000 for the amps and processing? (I'm too lazy to google it.)
JBL LSR305, $300 per pair
JBL LSR308, $500 per pair
Amplifiers are included.
An externally hosted image should be here but it was not working when we last tested it.
$10,000 for the pair and $10,000 for the amps and processing? (I'm too lazy to google it.)
An externally hosted image should be here but it was not working when we last tested it.
JBL LSR305, $300 per pair
JBL LSR308, $500 per pair
Amplifiers are included.
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I am goig to try an Econowave style enlosure just for kicks and largely because of this thread. Puuting the big boy on the back burner. I now need some official opinions about which waveguide/horn to use.
Here are the choices. I am leaning toward the Seos or JBL clone simply because it will allow good CTC spacing. In truth, the polars of the DDS waveguide(geddes clone?) and QSC look better, but it wold seem to make crossover a bit more difficult. I am not considering Wayne's horns or Geddes kit just because I am being cheap. I figure I can get the horns and the compression drivers for same price as the wood needed to diy the wood IWata's. If I like what I hear, these will probably be passed on and I will go hole hog on the next one, if there is such a thing.
Box will be a variation of the first pic. It also show s the QSC waveguide that seems to have best response, being very close with Geddes alternative, by DDS. Woofer will be TD12s because it can go low in small box and still get high enough to cross with the HF drivers, at the cost of efficiency, of course.
Here are the choices. I am leaning toward the Seos or JBL clone simply because it will allow good CTC spacing. In truth, the polars of the DDS waveguide(geddes clone?) and QSC look better, but it wold seem to make crossover a bit more difficult. I am not considering Wayne's horns or Geddes kit just because I am being cheap. I figure I can get the horns and the compression drivers for same price as the wood needed to diy the wood IWata's. If I like what I hear, these will probably be passed on and I will go hole hog on the next one, if there is such a thing.
Box will be a variation of the first pic. It also show s the QSC waveguide that seems to have best response, being very close with Geddes alternative, by DDS. Woofer will be TD12s because it can go low in small box and still get high enough to cross with the HF drivers, at the cost of efficiency, of course.
Attachments
If you have room for it, the QSC pictured on the left sounds great. Parts Express stocks it now.
I would tend to think this would like high ceilings. Am i correct in my thinking. Room is 14 x 16, but when i listen for fun, I pull them out and it becomes 32 x 16
8' ceilings. BTW, any woofer alternatives to suggest?
If you're stopping another project to do that, the TD12S may not be the best choice if it still takes around a year to get a pair... I think the 4012HO looks interesting.
I can get the td12s. Only reamaining question is their response vs the 12M or C, which apparently share cone profile and extension. I am wondering how much this affects their upper frequency range.
Are you saying that AE has 12 months backlog on new orders? Why not hire help?
Are you saying that AE has 12 months backlog on new orders? Why not hire help?
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