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Author Topic: BC218  (Read 25377 times)

David Sturzenbecher

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Re: BC218
« Reply #20 on: August 23, 2015, 11:18:46 am »

Oh,man!!!! That is some serious trouble you have there ;)

Pleas,tell more... Where is that? What amps you use? Why so many 0.o

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

Some details:  This is in an american college football stadium.  Each 218 is powered by two bridged Crown iTechHD 5000's (one per driver).   The need for so many really didn't have as much to do with output as it did to gain pattern control.   The box itself provides good front to back rejection, and the tall stack allows for a bit of vertical collapse, and some steering.   Not having crazy (disproportionate) SPL's  directly underneath these was a big motivation in box count.

Due to scheduling and the limitations of my lectrosoinics wireless test rig, I really haven't had too much time to dig into the raw performance of it.  The one thing I have noticed at this point is when the boxes are really pushed, the impedance of the drivers (as seen via amplifier monitoring) seems to rise a little quicker then other boxes I have worked with.

Oh, and it resonates testing centers on the other side of campus. 
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Audio Systems Design Engineer
Daktronics, Inc.
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radulescu_paul_mircea

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Re: BC218
« Reply #21 on: August 23, 2015, 11:54:45 am »

So, do you have 2 of these stacks? And what you are using for the rest of the range?
 Those drivers have 1700 watts each RMS AES and the bridged crown has 5000. The impedance rise could be because the voicecoil is heating and ,being  a flh,with a small closed chamber in the back of the driver, the heat has nowhere to go so it builds up. Take care and set the RMS limiting to an appropiate value,or you risk to burn the voice coil. The peak limit sould be off to still have good dynamics,this way you will keep that efortless sound.

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

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Keith Broughton

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Re: BC218
« Reply #22 on: August 23, 2015, 12:53:41 pm »

Having heard these things out back of DSL location I can say that terms like "epic"..."mind blowing" and "life altering" are not out of place!
I am consulting on a rig that a local supplier is buying and am desparately trying to get him away from the RCF 2x21 subs and into these.
The front to rear rejection ratio is VERY surprising. They act like horns...imagine that  ;D
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radulescu_paul_mircea

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Re: BC218
« Reply #23 on: August 23, 2015, 01:09:02 pm »

I heard 6 RCF 221's at an rock and pop concert and they weren't so bad. They are smaller than bc218's and the drivers from them are good and reliable. I have a friend who ownes 2 pairs in a near city and he is very happy with them.I haven't heard the bc218s, but i bet they would beat the c**p out of those rcf. At least,they will sound better and lower cu ft by cu ft.

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

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radulescu_paul_mircea

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Re: BC218
« Reply #24 on: August 23, 2015, 01:19:30 pm »

I am also a consultant here (I have just started for a year or so on pro products;until now only in home hi-fi)  and the main problem is getting the credibility I need. It is very hard to get the guy that has the money to understand that if he read three brochures and learn some technical terms like SPL and Frequency responce, it doesn't make him expert in acoustics. He hired me to tell him what to do,and then he tells me what to tell him :)) Sometimes litle information is worse than no information. We have two choices: either we educate them or we don't.

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

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David Sturzenbecher

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Re: BC218
« Reply #25 on: August 23, 2015, 01:32:06 pm »

So, do you have 2 of these stacks? And what you are using for the rest of the range?
 Those drivers have 1700 watts each RMS AES and the bridged crown has 5000. The impedance rise could be because the voicecoil is heating and ,being  a flh,with a small closed chamber in the back of the driver, the heat has nowhere to go so it builds up. Take care and set the RMS limiting to an appropiate value,or you risk to burn the voice coil. The peak limit sould be off to still have good dynamics,this way you will keep that efortless sound.

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

No, I do not have two of these stacks.   That would just cause lobing in the horizontal which I have no need for.   I chose the 5000HD's so that I can get enough "peak room".   Peak, RMS, and Thermal Limiters are set accordingly.
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Daktronics, Inc.
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radulescu_paul_mircea

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Re: BC218
« Reply #26 on: August 23, 2015, 01:44:05 pm »

Ok, so no need to worry about that impedance increase. What about the main speakers?
Thanks for the info so far. I will wait for more pictures if you have 

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

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radulescu_paul_mircea

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Re: BC218
« Reply #27 on: August 23, 2015, 02:08:52 pm »

I've followed the work af DSL and I am always blown away by the fact that using 8 sub and a small number of speakers they can cover an entire stadium. On another stadium,from miami,they used 517!!!!!!! Eaw mk,qx and mqx. 0.o

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts

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Ivan Beaver

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Re: BC218
« Reply #28 on: August 23, 2015, 04:31:23 pm »

I've followed the work af DSL and I am always blown away by the fact that using 8 sub and a small number of speakers they can cover an entire stadium. On another stadium,from miami,they used 517!!!!!!! Eaw mk,qx and mqx. 0.o

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts
I am doing an alignment later this week at a college football stadium near Miami

The system is a single j1 for the mains with 2 sh 46 and I think 2  os80s for fills

It is either 1 or 2 subs bc415 or bc 218 I am not sure which
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radulescu_paul_mircea

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Re: BC218
« Reply #29 on: August 23, 2015, 05:28:44 pm »

Et the event i was describin earlier they replaced the 118 synco subs and they put a total of 24 L'Acoustics sb218 in front of stage.the sound was much better than previous days. Using a bruel&kjaer hand held measurment tool, set to dBA fast peak mesurements,I've measured 114-118 dB at 45 meters FOH. Taking into acount directivity increase, gain, sensitivity and each sub getting 2400 W, what sould I use fro DSL.? Would two J1 and 4 bc218 be enough?

People aren't rational. We're not thinking machines, we're - we're feeling machines that happen to think. Peter Watts
« Last Edit: August 23, 2015, 05:30:47 pm by radulescu_paul_mircea »
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