Tom Danley and Yorkville offer more...

It's right under the HF drivers, the DCX50, it's a new design, I believe someone else put the link here also... Anyways, here's the link.

http://www.bcspeakers.com/index.php?sez=1&categoria=4&id_descrizione=46&prodotto=199&id_descrizione_prod=54

What is interesting about the coaxial design is that B&C also is doing a version of their own, so perhaps the idea is not as bad as I/you might think. Well, if you look at the B&C version's distortion, heh, now that's a high distortion figure!

Like I said in my previous post, I've only done measurements in practical situations, so there's always something else that might cause the feeling of a good sounding unit. Perhaps it's because in large format systems you need quite clinical drivers so that they have enough throw and the sound gets better with a little bit more distance to the speaker. This is just what I've experienced when doing concerts outside.

When I heard the F1 Res4 + F218 set in small inside space, they did sound a bit harsh but clean and crystal clear, just as the line array using the BMS top end. But go outside when there's more that 5m distance to the closest speaker and it really starts to sound good. So that's why I don't always look at the HD figures because they're close range measurements, not from a distance and they don't always tell the truth in real situations.

But like I said, that's just what I've experienced, so here's my 2 cents!

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

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.

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.

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

 

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

Edited by staiper - 20 January 2008 at 11:40am