2-way crossovers

[89-300ce]

I'm thinking of building my own crossovers. I'd like to run the 511b horn/BMS 4550 driver out of phase with the 2235 or ME150H and use a baffle step on the woofer to time align both drivers at 800Hz. I kinow I should use as steep a slope as possible when trying to time align this way, but too steep a slope will show the crossover more. I'm thinking of a second order Bessel.

Will Zilch's HF attenuation for the 811b/BMS 4550/N-800F (1200Hz) but adjusted for 8 ohm drivers work?

Is this a steep enough slope to not get out of phase cancellations as I move away from the 800hz crossover point?

Is the Bessel an appropriate curve to integrate the horn and cone?

Jorg

[Zilch]

http://audioheritage.org/vbulletin/s...687#post163687

I believe you'll find its asymmetry, highpass being 1200 Hz, lowpass 800 Hz, performs part of the compensation, which is completed by the final parallel trap.

The serial notch knocks down a 19 khz spike characteristic of BMS drivers on these horns.

Compensation portion constructed and retested here:

http://audioheritage.org/vbulletin/s...77&#post165377

Some JBL ~800 Hz LF filters:

http://manuals.harman.com/JBL/HOM/Te...L200B%20ts.pdf

http://manuals.harman.com/JBL/HOM/Te...S3100%20ts.pdf

http://www.jblproservice.com/pdf/Net...%20Network.pdf

http://manuals.harman.com/JBL/HOM/Te...ummit%20ts.pdf

[89-300ce]

Thanks Zilch,

I'm trying to work my way through this.
Is there a freeware calculator that you can enter component values and get frequency? I can only go from frequency to components and it's a pain to work it backwards.

Jorg

[Mr. Widget]

Is there a freeware calculator that you can enter component values and get frequency?

Here is a calculator that does your basic textbook filters... easy to use and it works pretty well. It isn't exactly what you are looking for, but you can probably make it work for you.

http://ccs.exl.info/calc_cr.html


Widget

[89-300ce]

Here is a calculator that does your basic textbook filters... easy to use and it works pretty well. It isn't exactly what you are looking for, but you can probably make it work for you.

http://ccs.exl.info/calc_cr.html


Widget

Yes, thanks, I can make it work. It's just a pain. My numbers never seem to come out exact to the schematics. The coil and cap values never seem to match the network schematics. For the HF driver for instance. The cap determines the Hz and the coil the slope? So if the cap is 1200Hz and the coil number doesn't match the calculators it means they used other than a standard 16db slope?

Jorg

[Zilch]

The slope is fixed by the topology.

The Q is variable, and chosen in combination with frequency for the specific design.

The "textbook" transforms are rarely optimum for any given system.

They are merely points on continua, by this perspective....

[speakerdave]

I'm thinking of building my own crossovers. . . .

To begin to get a sense of what's involved from an informed perspective, read this:
http://sound.westhost.com/lr-passive.htm

David