Kf730/ux8800 help please (limiting)

Shane Presley

Shane Presley

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Jan 12, 2011
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Ottawa, Ontario, Canada
www.bssproductions.com
So, I'm running 4 kf730 per side and a single sb730, (w 4 sb1k per side) all grey box settings on the ux. I'm powering with lab Gruppen fp10000
Ch a&b on 4 tops and c&d on the sb730 (seperate fp10k amps for subs) I am noticing that the lows are limiting on the kf boxes sooner than everything. What do I need to get that to "stop" more speaker surface, or more power? I was running a Celtic festival at reasonable volume, 85-90 db (estimated) at Foh outside at 60ft. Instrumentation was fiddle/acoustic/keys/vocals/a "foot board" for rhythm.
Suggestions?

I have 6 tops, and separate the power out into 3 cabs and 3 cabs and again the lows hit first....
I thought adding the sb730's would lessen the load , but the 10's are still limiting first...
Frustrating...
 

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Re: Kf730/ux8800 help please (limiting)

Shane Presley said:
So, I'm running 4 kf730 per side and a single sb730, (w 4 sb1k per side) all grey box settings on the ux. I'm powering with lab Gruppen fp10000
Ch a&b on 4 tops and c&d on the sb730 (seperate fp10k amps for subs) I am noticing that the lows are limiting on the kf boxes sooner than everything. What do I need to get that to "stop" more speaker surface, or more power? I was running a Celtic festival at reasonable volume, 85-90 db (estimated) at Foh outside at 60ft. Instrumentation was fiddle/acoustic/keys/vocals/a "foot board" for rhythm.
Suggestions?

I have 6 tops, and separate the power out into 3 cabs and 3 cabs and again the lows hit first....
I thought adding the sb730's would lessen the load , but the 10's are still limiting first...
Frustrating...
Click to expand...


Where do you see it limiting? On the UX itself? Those LED limit lights come on when it starts to limit. Its might be .25 db of limit who knows? If you hook a computer up you will see how much its actually limiting....We tried the SB730 and they didn't help us with the low freq problem in that box either. You don't want the answer for what fixes that....lol kf740
 
Re: Kf730/ux8800 help please (limiting)

Scott LaRochelle said:
Where do you see it limiting? On the UX itself?
Click to expand...

YES

Scott LaRochelle said:
It might be .25 db of limit who knows? If you hook a computer up you will see how much its actually limiting....We tried the SB730 and they didn't help us with the low freq problem in that box either. You don't want the answer for what fixes that....lol kf740
Click to expand...

Yeah, THATS not even funny Scott... lol

Okay well at least I'm not crazy, and I am experiencing what you did (lack of low mid).
Maybe I can replace my 730 boxes with these Meyer lyon cabinets that I am working with, and nobody will notice.... lol
 
Re: Kf730/ux8800 help please (limiting)

Agreed on needing more LF cone area. Many line array boxes are designed around the LF coupling that comes from having reasonable length lines, and will run out of LF if the line is too short From the KF630 data sheet, it looks like this particular box was designed around 6 boxes for flat array response, and you'll want more than that if you are used to the LF build up that typically comes with point-source systems stacked over subs.
 
Re: Kf730/ux8800 help please (limiting)

Hi Shane,

Please feel free to give us a call here in the office, we would be happy to help you look into this issue further. Alternatively, you can email us at [email protected]. If you send along your pilot file as well, we can take a closer look and see what might be causing this behavior.

Best,
 
Re: Kf730/ux8800 help please (limiting)

Shane, look up some old posts from Langston Holland (can't remember if they are here or on PSW). He spent a lot of time tweaking limiters on the KF730 presets and concluded that it was possible to safely get quite a bit more out of them (ie the greybox limiters may be overly conservative). And in typical Langston fashion his posts are always backed with detail.
 
Re: Kf730/ux8800 help please (limiting)

The 10’s in the 730’s are in a sealed enclosure, so they are not very efficient, around 90-92 dBw/m. The way to get more SPL is raise the crossover frequency – 100 even125hz.
Once you have a reasonable number of 730’s it’s not aproblem. HF then becomes the problem, in which case put a low pass filter in at about 15-16KHz.

...and when your 730s are physically inline with your subs you will need to add some delay to the sub ... from memory about 4ms. The Gunness focusing in the UX800 takes about 7ms on the 730's but the sub processing only takes 3.13ms. If you don't do that you will have a hole at the crossover frequency and you will think there is an issue with the 10's.
 
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Re: Kf730/ux8800 help please (limiting)

Peter Morris said:
...Once you have a reasonable number of 730’s it’s not aproblem. HF then becomes the problem, in which case put a low pass filter in at about 15-16KHz.
Click to expand...

Peter,

Have you tried this technique and found it empirically works re: extending maximum HF output? HF drivers usually have an impedance rise at HF that means they're taking very little power. Reducing input level at 15kHz by 3dB in my mind wouldn't gain you much, but perhaps the phase shift spreads out HF information in time and gains you something that way.

file.jpeg
 
Re: Kf730/ux8800 help please (limiting)

Bennett Prescott said:
Peter,

Have you tried this technique and found it empirically works re: extending maximum HF output? HF drivers usually have an impedance rise at HF that means they're taking very little power. Reducing input level at 15kHz by 3dB in my mind wouldn't gain you much, but perhaps the phase shift spreads out HF information in time and gains you something that way.

View attachment 10508
Click to expand...
The problem with a focused KF730 is there is about 24 dBof boost / difference between 1.5kHz and 20kHz! A significant amount of that is above 15kHz.

Focused 730s sound great but never seemed to go as hard as the non-focused 730s, part of the reason was this additional VHF boost they used.

Adding the low pass filter seems to give you a bit more of the orginal output ...
 
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