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Focal Polyglass Speaker and Amp Sizing

Old Feb 9, 2004 | 07:49 PM
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Default Focal Polyglass Speaker and Amp Sizing

I'm looking at going with Focal Polyglass 6.5 and 5.25 in an S-Pod. These are 75W and 65W nominal respectively. Will a 75W amp be enough (i.e. JL 300/4) or should I consider something like 100Wx4 (I just need to ensure it has 4 inputs)?

Thanks, Gary
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Old Feb 10, 2004 | 10:01 AM
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Will a 75W amp be enough (i.e. JL 300/4) or should I consider something like 100Wx4 (I just need to ensure it has 4 inputs)?
75Wrms x 4 should be fine.
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Old Feb 10, 2004 | 10:07 AM
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Thanks, just wasn't sure if it was good to overdrive the speakers to help with distortion.
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Old Feb 10, 2004 | 10:48 AM
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overdriving doesn't hurt, but you can go too far and provide too much power to the speaker...

generally speaking the audible difference in volume between 75 Wrms and 100 Wrms will be minimal.

check this link out: http://www.bcae1.com/2ltlpwr.htm
it's a little technical, but has some insight into the issue.
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Old Feb 10, 2004 | 11:31 AM
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I think I'm going down the 100W amp route, but a question is there a way to easily measure (by a layman) the power going to the speaker to adjust the amp so that it doesn't power the speakers with more than their rating? If not, would a typical audio shop have such equipment?

I can adjust the amp, but would have no way of measuring the output to adjust it.
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Old Feb 10, 2004 | 12:06 PM
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100 Wrms... *nods* no problems there... that's not a super large jump in power, so you should be ok. a 33% increase in power over OEM suggestions is most likely still within a safe range.

yes, there is a technical way to adjust the gains on a system. it requires the use of an oscilloscope, which is something most people will not have.
once again my favorite reference site has a detailed article on the 'how to'. http://www.bcae1.com/settinggainswithscope.htm
most audio shops will not have the required equipment.

here's a good bit more on amp gains and some info on how to set them...
http://www.bcae1.com/gaincon2.htm

from Crutchfield's site, they have a decent little walkthrough on setting gains that will get most people up and running.
http://www.crutchfield.com/S-tzbezin0Nnp/t.../tech/kb39.html

first, you need to know how to recognize distortion... if you're unsure, ask.
[QUOTE]
There are several methods of properly adjusting the gain (or sensitivity) setting on an amplifier.
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Old Feb 10, 2004 | 09:13 PM
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Thanks, that's a tremendous start!

Yah, I don't expect an audio shop to have or even be familiar with operating a scope.
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Old Feb 11, 2004 | 05:40 AM
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no problemo.

and no, i doubt most shops have a scope... sheesh, i don't have a scope, and i'm like a junkie or something...
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