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[Niels Janssen]

Hi,
funny graphs this. The decay point of the compression driver is 10ms later. Well, the origin of its time axis is also 10ms later. Does not look very scientific to me...
Frank

http://www.alconsaudio.com/site/line-array/line_array_5.html
look at the pictures: both with the same origin time. Maybe this makes more sense for you.

[Iain.Macdonald]

Graphic to illustrate the point being made by Niels. Decay /transient is really important, whether it's a subwoofer or a HF device. A is the alcons 6" ribbon measured on the waveguide. B is a large format line array, with state of the art compression drivers, with a xover point at 1.1Khz approx. You can see that the decay point on the ribbon is 2.7ms and the compression driver is 12.7ms. Please note that the compression driver is not designed to operate below 900Hz. So that big ridge should be ignored. These measurements were done independently, by Production Partner, an entertainment technology magazine from Germany.

Iain.


Hi,
funny graphs this. The decay point of the compression driver is 10ms later. Well, the origin of its time axis is also 10ms later. Does not look very scientific to me...
Frank

Depending on where you set the 'window' for the waterfall/decay curve, it will show you different parts/time of the impulse response. The part of interest here, is how long it takes to decay. Also the character of the decay. In other words, the end part.

The above link from Niels is even more telling!

Iain.

[Peter Morris]

Depending on where you set the 'window' for the waterfall/decay curve, it will show you different parts/time of the impulse response. The part of interest here, is how long it takes to decay. Also the character of the decay. In other words, the end part.

The above link from Niels is even more telling!

Iain.

Things have got a little better - this is what QSC have  achieved with their intrinsic correction, EAW are doing the same sort of thing with their Gunness Focusing.

http://www.qscaudio.com/products/dsp/SC28/intrinsic_correction_whitepaper_2007.pdf

See figures 12 & 13

Sorry there is no scale on the picture but the water fall above 1000Hz is within 2.38ms.

[Iain.Macdonald]

Things have got a little better - this is what QSC have  achieved with their intrinsic correction, EAW are doing the same sort of thing with their Gunness Focusing.

Peter,

Yes that's true. But there is widespread rejection of that technology. I am sure you remember the Gunness focussing threads in the old forum! I remember Phil Graham, you and I and some others were absolutely roasted, for even considering it's merits. People still don't get it.

Iain.

[Peter Morris]

Peter,

Yes that's true. But there is widespread rejection of that technology. I am sure you remember the Gunness focussing threads in the old forum! I remember Phil Graham, you and I and some others were absolutely roasted, for even considering it's merits. People still don't get it.

Iain.

You are so right … people don’t get it, they don’t understand how things are connected it terms of amplitude, phase and time, and how that impacts on sound quality …

That lovely waterfall plot is one of the reasons why those ribbon drivers sound so nice.... just wish I could buy the drivers.

Peter

[Jim McKeveny]

FWIW File- What SA USA had me toy with was "Blue Box" era 8525's...

[Jim McKeveny]

Mark E. is the unofficial "Father of the Waveguide". He knows as much about pro HF as anyone. I'd follow his advice anywhere.

[Mac Kerr]

funny graphs this.

Please go to your profile and change the "Name" field to your real full name as required by the posting rules clearly displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section.

Mac

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