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Author Topic: How much less than full volume will this be?  (Read 11381 times)

Scott Carneval

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Re: How much less than full volume will this be?
« Reply #20 on: June 04, 2014, 12:23:30 pm »

Yes, one central unit specified. This architect has a history of specifying really bad designs. Sometimes we try to shove a redesign through, but this has always been painful and difficult. This time, we decided to do it as specified, although we made them upgrade the amp from a 125-watt model to 250, and replace the wall rack with one that is deep enough for the gear. Again, maybe we'll get a request for an upgrade next year.

So who's responsible if when the speaker fails and you changed the architect's design to double the power?

I get it that it's sometimes easier to build it to spec, but when you know for a fact that those specs aren't suitable for the application I believe that it's your responsibility to your industry to explain why, in writing, and offer an alternative.  You say that you've worked with this architect in the past, and if he won't budge then I would turn down the job. 
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Mike Caldwell

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Re: How much less than full volume will this be?
« Reply #21 on: June 04, 2014, 02:40:25 pm »

The "upgrade" from a 125 to 250 watt amp is a drop in bucket and basically pointless.
The first time they play some pre game warm up music to pump up the crowd as just about all schools do these days either one of those amps is going to be driven into full clip as they try to get that woefully inadequate speaker to rock the house.

Personally if I was given that system spec to install I would explain to the school just how lacking it's going to be despite what they've be told be the architect and turn down the job. After it's installed the architect will long be forgotten but your name will be all over it and who they come calling to with the problems.

The architect should be made to sit in the bleachers for a couple of games so he could hear his work in action.

My guess it that architect has never been out to hear one of their "designs" in action at all and just stays in the office designing systems based on what they read on product cut sheets. I would not be surprised if they never hooked a speaker to an amp and made sound come out!

John Jackson

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Re: How much less than full volume will this be?
« Reply #22 on: June 16, 2014, 05:00:41 am »

I'm dealing with a gym sound designed specified by non-audio guys.
They specified the Octasound SP820A speaker cluster for a middle school gym, powered by Telecor 125 watt amp. The speaker is rated at 200 watts program.

From the Crown website:

"If you can prevent the power amp from clipping (by using a limiter), use a power amp that supplies 2 to 4 times the speakers continuous power rating per channel. This allows 3 to 6 dB of headroom for peaks in the audio signal. Speakers are built to handle those short-term peaks. If you cant keep the power amp from clipping (say, you have no limiter and the system is overdriven or goes into feedback) the amplifier power should equal the speakers continuous power rating. That way the speaker wont be damaged if the amp clips by overdriving its input. In this case there is no headroom for peaks, so youll have to drive the speaker at less than its full rated power if you want to avoid distortion."

http://www.crownaudio.com/how_much_power.htm
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Tim McCulloch

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Re: How much less than full volume will this be?
« Reply #23 on: June 17, 2014, 12:40:05 pm »

From the Crown website:

"If you can prevent the power amp from clipping (by using a limiter), use a power amp that supplies 2 to 4 times the speakers continuous power rating per channel. This allows 3 to 6 dB of headroom for peaks in the audio signal. Speakers are built to handle those short-term peaks. If you cant keep the power amp from clipping (say, you have no limiter and the system is overdriven or goes into feedback) the amplifier power should equal the speakers continuous power rating. That way the speaker wont be damaged if the amp clips by overdriving its input. In this case there is no headroom for peaks, so youll have to drive the speaker at less than its full rated power if you want to avoid distortion."

http://www.crownaudio.com/how_much_power.htm

Mr. Macre already knows this.  He's pointing out that as a subcontractor, the equipment noted is specified by the project architect.  He is not free to redesign the system, nor is he in a professional position to challenge the architect in front of the client.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Joseph D. Macry

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Re: How much less than full volume will this be?
« Reply #24 on: June 19, 2014, 07:22:22 pm »

Mr. Macre already knows this.  He's pointing out that as a subcontractor, the equipment noted is specified by the project architect.  He is not free to redesign the system, nor is he in a professional position to challenge the architect in front of the client.

Thank you, Tim, that is exactly correct.
No DSP, no power module, no playback (just an AM/FM tuner!). Yes, I do consider this substandard in many ways. I am not the designer, and have not been invited to redesign. I am the installer, and I will give them what they ask for.
I did request they change rack models because the specified one was four inches to narrow for the specified gear. No cost increase, so they went with it.
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Joseph Macry,
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Mike Caldwell

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Re: How much less than full volume will this be?
« Reply #25 on: June 20, 2014, 12:10:42 am »

Thank you, Tim, that is exactly correct.
No DSP, no power module, no playback (just an AM/FM tuner!). Yes, I do consider this substandard in many ways. I am not the designer, and have not been invited to redesign. I am the installer, and I will give them what they ask for.
I did request they change rack models because the specified one was four inches to narrow for the specified gear. No cost increase, so they went with it.

Keep in mind that your name will be the only name associated with that system that any one will remember, the direct customer and any possible future customers who may hear the system in use.

Joseph D. Macry

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Re: How much less than full volume will this be?
« Reply #26 on: June 20, 2014, 09:24:02 pm »

Keep in mind that your name will be the only name associated with that system that any one will remember, the direct customer and any possible future customers who may hear the system in use.

Wrong, Mr Caldwell. The architect and General Contractor have their name on this, not I.
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Joseph Macry,
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Mike Caldwell

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Re: How much less than full volume will this be?
« Reply #27 on: June 21, 2014, 07:43:10 am »

Wrong, Mr Caldwell. The architect and General Contractor have their name on this, not I.

At least in my experience when doing a service call or upgrade on a system the customer refers to who installed the system during the conversation. There are times when I know a system was installed to a designed spec from an architect and the installer's name is still the only name mentioned, that can be good or bad for the installers reputation depending on the design and quality of installation.

Joseph D. Macry

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Re: How much less than full volume will this be?
« Reply #28 on: June 21, 2014, 10:53:38 am »

This thread has migrated from a question about increasing amp power to one about installing a substandard design, which is indeed the more interesting question. I think I'll start a new thread on that topic later today.
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Joseph Macry,
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Steve M Smith

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Re: How much less than full volume will this be?
« Reply #29 on: June 21, 2014, 12:54:25 pm »

Wrong, Mr Caldwell. The architect and General Contractor have their name on this, not I.

Make sure their names are actually on it. i.e' apply a label stating "Specified by  Xxxxx and Yyyyy"


Steve.
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Re: How much less than full volume will this be?
« Reply #29 on: June 21, 2014, 12:54:25 pm »


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