Waveguides and horns

[Tytte71]

Looks like a nice improvement with the Aquaplas, needing less correction and better time domain performance (wonder if distortion figures improves as well). Have you done any listening comparison?
Also, how much Aquaplas did you add?

 

[454Casull]

It was 6 or 6.5° (I don't remember the decimal places) - half angle.

6.5 degrees half angle would make it 13 degrees included angle as I mentioned.

 

[jzagaja]

Have you done any listening comparison?
Also, how much Aquaplas did you add?

Will send sample diaphragms to Autotech for evaluation. Hard to say how much Aquaplas - just to cover diaphragm completely with white coating. About 7-10 layers.

 

[noah katz]

The sensitivity takes a big hit from the extra mass of the Aquaplas.

Standard application recommendation for optimum damping of diaphragm resonances is to cover the center 25%, as that is where amplitude is greatest.

If you wanted to get fancy you could effect constrained layer damping by adhering a small disk, or maybe two crossed strips for less mass, of aluminum foil to the center of the diaphragm.

 

[jzagaja]

Applying Aquaplas using table top fan:

https://docs.google.com/open?id=0ByP8kkW_h00uM05GWmhoN2huaEE

 

[jzagaja]

First day of using Bruel Kjaer 2012 Audio Analyzer - setting up Mummy crossover (12BR70+D800Ti). I would like to contact anyone familiar with this nice machine.

 

[jzagaja]

Intermodulation distortion with and without Aquaplas.

 

[jzagaja]

Interesting isn't it? Both ends are nicely lowered but waveguide modes region is not. I need to change base frequency and check again - maybe I hit a HOM

 

[jzagaja]

D800Ti when equalized (2 notches) has dip at 2.6kHz - Aquaplas may help.

 

[jzagaja]

Problem with stiff suspension drivers like D800Ti is crossover point below 1kHz. Higher is problematic due to driver/waveguide resonance. Don't be afraid of 12BR70 higher midrange distortion - it's not a problem as seen on below picture.

 

[anubisgrau]

Hi jzagaja

did you ever get a chance to listen and measure the B&C DCM50 with one of your horns?
i would be especially interested how it sounds and measures w/ the Iwata 300 ?

thanks

Not yet. We use BMS and Radian/Truextent.

jzagaja, was there any development re B&C DCM50 and your horns?

if you haven't had a chance, what would you recommend as the best horn from your production to extend a lower end as much as possible (recommended by B&C is 400hz but i would love at least 350hz with few watts...) while having clean dispersion without beaming or other nasty artefacts.

also i can't find more comments on your minphase 200 horn, the price is much more affordable than JMLC and it looks like it has a very similar lip-over. how does it behave in the mids?

are there any plans for really big OSWG, like 18" or similar? since i've heard geddes OSWG (from summa), i think it's a way to go in smaller rooms....

 

[jzagaja]

B&C DCM50 is uknown for me. JMLC-200 is too beamy for your needs. Minphase with BMS 4590 is 400Hz (-6dB) and optically large, Biradial still untested.

Large SEOS/EOS - still waiting for group buy (end of this year?).

 

[anubisgrau]

thank you, re beaming mind that the desired range for DCM50 in my application is 350-1.5 (even less)....

 

[jzagaja]

Now it's simple - Tractrix200.

 

[jzagaja]

Today I've learned how to store graphs in BK2012. This is quite easy - you have to chose plotter as output device, then open in ABViewer for example and format. Quick and dirty comparison between 12BR70+D800Ti vs. 12B100R+DE500. Level was quite low a bit below 1Vrms but I couldn't set more because of family members. I'm sending Mummy 4 (12BR70+D800Ti) with minimalistic crossover to Lukasz for voicing, attaching Aquaplased diaphragms.

Pink is 12B100R

 

[jzagaja]

Second Aquaplased sample - one I've sent to Lukasz so couldn't compare but it looks worse. Practice needed.

 

[tuyen]

For a tweeter (bms 4540nd 1") that is to play >2000hz, would the choice of the iwata 600, e-jmlc 600 or 1000 be the best choice?

I'd be interested in a pair..

Cheers

 

[jzagaja]

Yes any 600Hz horn or SEOS-15 waveguide is a good choice depends on your taste.

 

[jzagaja]

For comparison Harwood AM35 direct radiator with 6" woofer.

 

[jzagaja]

Mummy 3 (12B100R+DE500) measured in BK 2012 analyzer with and without reference resistor versus LIMP with reference resistor 18Ohm. Obsereve change in tuning frequency and Q of resonance peaks.