Rational Acoustics



Kip Conner
April 11th, 2012, 12:38 PM
One of the things that I love about this job is the introduction of new gear to my brain when I am at the mercy of the local guy. I have a system that works great for me so I spend what little free time I have maintaining it and not looking for what the latest and greatest stuff is on the market.

The weekend I'm being a brought a KS system that employs FIRtec technology. It has some interesting characteristics that I can't wrap my head around. I was wondering if anyone has used it and how might it affect our "normal" way of thinking. I think the biggest thing is this electronic crossover network and what looks like All Pass Technology on the high frequency driver.

http://ksaudio.com/ks-technology/firtec/firtec.html

If it's too good to be true...?

Rasmus Rosenberg
April 12th, 2012, 07:49 AM
One of the things that I love about this job is the introduction of new gear to my brain when I am at the mercy of the local guy. I have a system that works great for me so I spend what little free time I have maintaining it and not looking for what the latest and greatest stuff is on the market.

The weekend I'm being a brought a KS system that employs FIRtec technology. It has some interesting characteristics that I can't wrap my head around. I was wondering if anyone has used it and how might it affect our "normal" way of thinking. I think the biggest thing is this electronic crossover network and what looks like All Pass Technology on the high frequency driver.

http://ksaudio.com/ks-technology/firtec/firtec.html

If it's too good to be true...?

Interesting reading. I have only seen it at a exhibit, not used it. Not sure what your after Kip? How they exact do their processing is hard to tell, but seems like a lot to do (cost vs effort). And the price is latency. Lucky we have and get faster and faster processors, but it still takes time.. Don't think that its a surprise that the more you know about every component in the chain the more you can optimize it, And in the digital domain there are "new" and interesting ways of manipulating the signal. My main concern is what happens if the speaker don't get the right processor signal? and how much does the sound quality actually improve vs cost? (not to mention usability).
I don't think it will affect the normal way of thinking too much.. I mean we strive hard to get the systems to have a "good and equal" frequency response and phase response, if the system delivers then all good, if not then its just like the rest of them. For the Mixing engineer it will always be hard to be on a system thats different, to what your used to, prefer or used last.

I don't really understand the crossover graph?


The first of the next two graphs shows a crossover point using analog filtering, illustrating a “trough” or dip in volume around the crossover point. In typical applications the loss in volume is noticeable especially in the vocal range, and is therefore misleading the engineer on critical equalization judgments. A two-, three-, or four-way analog filtering system will produce a non-linear output response curve over the entire frequency range of the system!

The second graph shows our digital FIR filtering, which achieves no loss in volume. No loss in volume means the engineer is actually hearing the vocal performance as the microphone hears it, too--completely flat! Therefore, a KS two-, three-, or four-way system will achieve a fully linear output response curve over the whole frequency range of the system.
So they are comparing the individual response to a sum? Im sure they, have got something good going on but aren't they just saying (like every one else) other manufactures can't figure out how to do a "good" crossover between drivers.. We can!

Hope you will write a review of some kind, and have a good gig.
mvh
Rasmus

Kip Conner
April 12th, 2012, 10:02 AM
I'll be sure to take some screen shots of the of the individual pass band TF's. I'm giving him a Left/right/Sub signal so I should be able to see exactly what the roll off is at the XO points. The guy whom I advanced with tried to tell me the audio just stops like a brick wall or some insane infinite dB per octave which I find a little hard to believe. By all means I don't design this stuff, I just walk in slap a coat of paint on it and put out to sea for a three hour tour. :)

My biggest thing is that after reading their one sheet they claim to have limited number of arrivals after the impulse response. The best I can equate my gut feeling is the move from traditional trap boxes to line arrays. There was a tonal difference that we can all heard, different but good. Just curious how the PA will sound vs. what I used to hearing. I plan to treat like every other show.

I'm going in with an open mind, there's just something suspicious about their claims.

Arthur Skudra
April 18th, 2012, 09:15 AM
I'm going in with an open mind, there's just something suspicious about their claims.That sums it up really well. While new technologies brings us new tools and techniques, remember that the laws of physics do not change. ;)

Ferrit37
April 18th, 2012, 01:22 PM
Hey Guys,
I looked at these a few years ago when I was at PRG the downside seems to be that each amp is 'married' to an individual driver and if you change a driver you have to re-program the filter. It also means you must keep the same amp with the same cabinet, not exactly easy/possible in a rental environment

reztek
April 21st, 2012, 12:14 PM
Smells like Digital Room Correction (http://en.wikipedia.org/wiki/Digital_room_correction) to me.

Kip Conner
April 24th, 2012, 06:43 PM
The boxes that the guy brought out were just antiquated powered boxes, looks like he sold the promoter on the brand and what it could do... if you had a current line. The rig wasn't very impressive in the power department, but the crowd was happy. That's what matters, right?

Rasmus Rosenberg
April 28th, 2012, 09:01 AM
Hey Kip,
Did you get to do any measurements or?

gluis
May 1st, 2012, 10:22 AM
One of the things that I love about this job is the introduction of new gear to my brain when I am at the mercy of the local guy. I have a system that works great for me so I spend what little free time I have maintaining it and not looking for what the latest and greatest stuff is on the market.

The weekend I'm being a brought a KS system that employs FIRtec technology. It has some interesting characteristics that I can't wrap my head around. I was wondering if anyone has used it and how might it affect our "normal" way of thinking. I think the biggest thing is this electronic crossover network and what looks like All Pass Technology on the high frequency driver.

http://ksaudio.com/ks-technology/firtec/firtec.html

If it's too good to be true...?

Maybe there's something else I'm not seeing, but I believe they are just using FIR filters in their crossover. With FIR filters you can have flat phase crossovers and depending on processing power available, +100dB per octave slopes, at the expense of some latency. Latency will be bigger as you use a lower crossover frequency, using same DSP power and Xover slope. As FIR filters does not have feedback in their design, Impulse response is better behaved, with less ripples as there is no filter ringing. Also, if you correctly design arbitrary coefficient FIR filters, you can correct some driver's FR anomalies as you cancel them out without touching phase response.

By the way, tis new trend is gaining a lot of traction, and is used by many manufacturers, so it is not as exclusive as KS Audio claim it to be. Anyone who had used EAW or EV last generation's Speaker processors, or JBL's Vertec V5 processing (or VTX system) had already tried it. It is important to mention that basically no one use them on Sub or LF crossovers because the latency will be too big.

My knowledge in the subject is not very deep (I'm not a mathematician or design engineer), I just understand the basics of it. Hopefully this will help

GS

gluis
May 1st, 2012, 05:23 PM
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