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[Adam Pace]

Hello Folks,

Well, excitement stirs as we are preparing for the arrival of our new QSC KW rig. With the new rig, comes new processing toys. We have chosen the BSS OmniDrive. Where before, the trusty ole' Rane crossover did a phenomenal job, the new OmniDrive opens fun new doors of adventure, specifically, in Crossover Shapes.

The Rane didn't offer any options in shapes, you just dialed in the frequency and level of each band and added delay if needed to the sub stacks. Now, I read about all the different shapes you can use in your crossover design. Although I am looking forward to the added accuracy in flattening and optimizing the system, I am a little overwhelmed at all the different shapes, Butterworth, Bessel, Linkwitz-Riley, etc.

In reading about them, I am leaning towards the Linkwitz-Riley 24dB/Octave slope, but there is also the Butterworth. So, I thought I would check in with the knowledge pool and see what ya'll use and why? What applications call for certain shapes?

Can't wait to get it out and tuned, and any advice is, as always, greatly appreciated.

Thanks,

Adam P.

[Timo Beckman]

As far as i know there are also the NTM filters in there .
These have a simular behaviour as a eliptic filter . I played around with them a bit and where i needed delay (and pol. rev. if needed) with the standard filters i just had to type in the frequency to the x-over zone and that was it .
I'm using to BSS BLU80 audio network processors instead of the omni drive but the x-overs should be the same as the omni-drives .

http://timobeckmangeluid.wordpress.com/2011/06/01/oefenen-met-fase/ 

I did post on my blog but this artical is still in dutch and i did not (do not) have time to translate it in to english yet . (Most articles on my blog are Dutch/English and have a lot to do with alligning systems so check it out and let me know what you think) .

If you start playing with filters make sure you also have the means to measure the response of the system in phase and frequency response .

I just went trough a SIM set-up and data viewer file and i found a small project with all sorts of filters combined from 6db/oct to 24 db/oct plus the sum of the filters . It might take a few day to put it on the net but if you sent me a e-mail i'll let you know where to find them .... If you're interested 

[Peter Morris]

Hello Folks,

Well, excitement stirs as we are preparing for the arrival of our new QSC KW rig. With the new rig, comes new processing toys. We have chosen the BSS OmniDrive. Where before, the trusty ole' Rane crossover did a phenomenal job, the new OmniDrive opens fun new doors of adventure, specifically, in Crossover Shapes.

The Rane didn't offer any options in shapes, you just dialed in the frequency and level of each band and added delay if needed to the sub stacks. Now, I read about all the different shapes you can use in your crossover design. Although I am looking forward to the added accuracy in flattening and optimizing the system, I am a little overwhelmed at all the different shapes, Butterworth, Bessel, Linkwitz-Riley, etc.

In reading about them, I am leaning towards the Linkwitz-Riley 24dB/Octave slope, but there is also the Butterworth. So, I thought I would check in with the knowledge pool and see what ya'll use and why? What applications call for certain shapes?

Can't wait to get it out and tuned, and any advice is, as always, greatly appreciated.

Thanks,

Adam P.

The QSC KW series comes complete with its own crossover(s) - I'm sure QSC has it worked out just fine - time and phase aligned etc. If you are using a complete KW rig all you will need is a GEQ. An Omni drive will not improve anything. Save your $$$
Peter

[Timo Beckman]

Screen shots from all sorts of standard filters (no fancy ones).

http://timobeckmangeluid.wordpress.com/2011/09/21/verschillende-soorten-filters-tot-24-db-oct-all-sorts-of-filters-up-to-24-db-oct/

[Timo Beckman]

The settings of the manufacturer should work but allways verify them if you have the possibility .
I posted a small artical on my blog . 2 examples of mis-allignment with settings from the manufacturor .

http://timobeckmangeluid.wordpress.com/2011/10/02/tanstaafl-there-aintno-such-thing-as-a-free-lunch-statement-i-got-from-b-mccarthy/

[John Roberts {JR}]

I have been saying this for years, but it bears repeating. The real loudspeaker design engineers working at the manufacturer will have superior knowledge about the drivers being used and box design. They will also generally have superior test equipment and facilities to measure actual box with actual driver response to make corrections.

The only concern I would suggest is that you accurately transfer the manufacturer's advice into whatever DSP you are using. As often as not, problems are not user error, as much as (DSP) manufacturer's lack of discipline in delivering expected transfer functions.

There will be a session at the upcoming AES on this topic.

JR

PS: Perhaps manufacturers could also provide detailed point by point charts of final phase and amplitude response that they are asking for, to act as a second check or back-up for correct transfer function. 

[Timo Beckman]

The only concern I would suggest is that you accurately transfer the manufacturer's advice into whatever DSP you are using. As often as not, problems are not user error, as much as (DSP) manufacturer's lack of discipline in delivering expected transfer functions.

There will be a session at the upcoming AES on this topic.

JR

PS: Perhaps manufacturers could also provide detailed point by point charts of final phase and amplitude response that they are asking for, to act as a second check or back-up for correct transfer function.

Will the aes session be made available on the www because that would be realy interesting .
Also the charts would be nice if they were available .

[Mac Kerr]

Will the aes session be made available on the www because that would be realy interesting .
Also the charts would be nice if they were available .

Audio recordings of the sessions will be available for sale from AES after the convention. The technical sessions at the AES convention are not free, and neither ore the recordings. I don't know how soon after a session has happened the recordings will be available, but it shouldn't be too long, and this session is one of the first to take place.

It should be a good session, Rich Frembes has assembled a good panel of manufacturers and users.

Mac

[Timo Beckman]

Audio recordings of the sessions will be available fro sale from AES after the convention. The technical sessions at the AES convention are not free, and neither ore the recordings. I don't know how soon after a session has happened the recordings will be available, but it shouldn't be too long, and this session is one of the first to take place.

It should be a good session, Rich Frembes has assembled a good panel of manufacturers and users.

Mac

If someone could post a link and the price of the recording that would be much apriciated (? i'm dutch so pardon my englisch)

[Mac Kerr]

If someone could post a link and the price of the recording that would be much apriciated (? i'm dutch so pardon my englisch)

HERE IS A LINK to the recordings from the last convention in NY. I assume the same vendor will be distributing the recordings this year.

Mac

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