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Tom Danley and Yorkville offer more...

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_djk_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2008 at 10:19am
" I don't think this is any sort of waveguide though - as soon as you start deflecting/bending the wave around, you will get a massive reduction in high frequency response. "
 
Ever seen the phase plug of an EV DH3?
 
For that matter, ever seen the phase plug of the BMS driver used in this system?
 
They're both long, and go through a couple of 90° bends.
 
The key is the size of things relative to the wavelengths involved, and that looks correct.
 
If they didn't work great, I doubt anyone would pay Tom for the use of it and create a new company just for this (sure to be expensive) product.
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Tony Wilkes View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tony Wilkes Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2008 at 10:20am
The drivers look like standard BMS Neo's. I cannot work out the waveguide at all!!

Tony
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steve_B Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2008 at 12:04pm
I think Earl Gedes used a system where he acoustically coupled one diaphragm to another. He called it an acoustic lever.

In this system I think it would create more problems than it would get round. If the red section were some sort of diaphragm it would have different resonant modes which would cause response irregularities; at higher frequencies it is several wavelengths long. Cone resonance is what causes the uneven response at the upper range of conventional drive units. If the diaphragm were stiff enough why not mechanically couple it to the voice coil. Also if acoustic perfection were the goal, why worry about making it compatible with conventional compression drivers?

Call me cynical, but I would tend to go with the simple approach. It is based on proven acoustic principles, is sufficiently novel in design to get a patent and could be incorporated directly into a compression driver phase plug opening more licensing possibilities.

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_djk_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2008 at 3:45pm
" Gedes used a system where he acoustically coupled one diaphragm to another"
 
Strictly for a subwoofer.
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ArthurG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ArthurG Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2008 at 5:09am
another nice new concept from Tom. This guy never stops Thumbs%20Up

but one thing hurts me is the use of the BMS drivers. First I hope the xover point is higher than 1,6k since they sound awful below even if the specs say otherwise... and secondly I don't understand why they are so popular (many German brands use and L-Acoustic too). IMHO, they have a lot of distortion and sound clinical/harsh at high volume... really, I don't understand their success...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote staiper Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2008 at 11:30am

I believe that "thing" is simple..  (simpler than-we-want-to-be) Smile

 
That is just double parabolic line splinter which equates distances from HF driver throat to vertical slot plane... (ofcourse cleverly dimensioned in respect to wavelengths in "game")  + some grade of expansion.
.. I may be wrong .. but that is my opinion Embarrassed


Edited by staiper - 20 January 2008 at 11:40am
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_djk_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2008 at 6:18pm
"but one thing hurts me is the use of the BMS drivers. First I hope the xover point is higher than 1,6k since they sound awful below even if the specs say otherwise... and secondly I don't understand why they are so popular (many German brands use and L-Acoustic too). IMHO, they have a lot of distortion and sound clinical/harsh at high volume... really, I don't understand their success..."
 
I suppose one could substitute another brand of 1" driver.
 
But how does the BMS sound with only 18.75W?
 
Because of the difference in efficiency the BMS drivers only need handle 18.75W each (in the crossover region) to keep up with 1200W input to the pair of 10s.


Edited by _djk_ - 20 January 2008 at 6:20pm
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MarjanM View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2008 at 11:52am
I cant imagine the crossover point to be higher than 1KHz. If you look at the spec for some of the 1inch BMS drivers they handle 80W from 800Hz up.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gazman Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2008 at 8:02pm
Arthur you've mentioned distortion in BMS drivers before, is that based on measurements you've taken vs other similarly priced drivers (eg. B&C) or listening tests? I just find it hard to believe that Danley of all people would use a HF driver that let down the rest of the system, he uses BMS in the SH-50's as well...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Calitri Quote  Post ReplyReply Direct Link To This Post Posted: 22 January 2008 at 6:28am
We had a previous conversation about the BMS drivers so you might want to look back a bit on the general forum, that was about the coaxial driver 4590. But in a general consensus, it seems to divide people into two, others who like and others who don't. Personally I do like them, especially their higher priced neodym range.

The basic ferrite models like the 4538/48, can't remember which one, which is in the HK Audio LP115 series and simular newer ones, is a bit harsh'ish as it's crossed so low but it's not bad, it just has a bit of downward tweaking to do in the 1-2.5 kHz range but other than that is pretty good driver considering the price.

The reason might be that their harmonic distortion is higher than many other manufacturers' so people might think them as a bad drivers but their manufacturing quality is superb and they can take incredible amount of power and not give out relative distortion or square wave which is the one what I'm more interested about. If you compare lets say a cheap manufacturers drivers and the BMS, then the cheap ones might have less HD in them but when pump more power to them, they start to push out square wave even though you might not exceed the RMS rating as compared to BMS where you can push them easily past the RMS rating without getting any square wave or actual/relative distortion. So, summa summarum, they basically sound the same pushed with low or high power.

Tony A.S.S has knowledge about their manufacturing quality and commented about them. Make a search for it in general forum about if you're more interested.
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ArthurG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ArthurG Quote  Post ReplyReply Direct Link To This Post Posted: 22 January 2008 at 10:29am
Originally posted by MarjanM MarjanM wrote:

I cant imagine the crossover point to be higher than 1KHz. If you look at the spec for some of the 1inch BMS drivers they handle 80W from 800Hz up.

well it seems that you never had experienced a BMS 1" crossed at 800Hz as it sounds completely un-natural and harsh... Confused
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ArthurG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ArthurG Quote  Post ReplyReply Direct Link To This Post Posted: 22 January 2008 at 10:51am
Originally posted by gazman gazman wrote:

Arthur you've mentioned distortion in BMS drivers before, is that based on measurements you've taken vs other similarly priced drivers (eg. B&C) or listening tests? I just find it hard to believe that Danley of all people would use a HF driver that let down the rest of the system, he uses BMS in the SH-50's as well...

FYI, I have a 50Hz 4PI anechoic chamber with calibrated Earthworks and Clio mics, Audio Precision ATS-2, Clio8 FW QC, EASE 4.2 with Aura module and Easera in my lab. I've made distortion measurement with more than 100 HF drivers from European & Chinese manufacturers during the last 2 years, so my claim is based on facts.

Now, I never said BMS is a bad brand. I only said that I'm surprised that many manufacturers use them despite the high distortion numbers. Personally, I don't like them, it's my taste but I can understand that others don't agree. But when you listen side by side BEYMA CP380M ad BMS 4550, it's hard for me to imagine that you can chose the BMS. The Beyma sounds so more natural, with lot of presence compare to the dry, analytical BMS and the Beyma still shows significantly lower distortion numbers...
To give you an example, with same horn (90x60 elliptical 210x210x120mm),  with 1W/1m, distortion at 2,5kHz (where the human hear is very sensitive):
H2 on BMS 4550: 3,98%
H3 on BMS 4550: 0,25%
H2 on Beyma CP380M: 0,63%
H3 on Beyma CP380M: 0,05%

with 10 and 30W the ratio is nearly the same...

--Arthur
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