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Powerbase 3 Sensitivity


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#1 chris226

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Posted 04 April 2006 - 12:32 AM

Given: PB3 reaches full power at 0.775v input @ at full gain.

Question:  Where (approx) would I set the gain dials (as the clock points) to have a sensitivity of 1.23v (or +4dB)?

Thanks,

Chris
Christopher Ping
Pro Audio and Lighting Consultant
Lexington, KY

#2 Elliot Thompson

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Posted 11 April 2006 - 06:51 AM

QUOTE(chris226 @ Apr 4 2006, 12:32 AM)
Given: PB3 reaches full power at 0.775v input @ at full gain.

Question:  Where (approx) would I set the gain dials (as the clock points) to have a sensitivity of 1.23v (or +4dB)?

Thanks,

Chris
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If you look at the rear of the amplifier, you'll see a rectangular removable
panel. Behind the panel is an input sensitivity switch. You can flip the switch
to 1.4 volt, (Crown, factory defaults @ 0.775 v) which will give you the headroom needed.

I generally calibrate my PB3/CSL1400's with my MA's. So, the MA's will act
like an input level indicator for the PB3/CSL1400's If you own MAs you
can do the same.

Either way you put it, owning the manual is essential. So, you should download
the instructions in Crown's PDF section.

Best Regards,

Elliot Thompson

#3 DGlass

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Posted 13 April 2006 - 09:52 AM

Elliot is correct in that there is a switch on the back of the amplifier to select the input sensitivity of the amplifier. The PB series Reference manual can be found on our web site at: http://www.crownaudio.com/gen_htm/legacy/legacamp.htm
Just a side note on gain: It has been a common misconception that the input level controls on an amplifier are gain knobs. This is probably because so many people will say “I need to turn the gain up on the system”An amplifier will have a fixed amount of gain basically set by the input sensitivity switch. The input level controls only adjust (attenuate) the amount of input drive signal that the amplifier is receiving. In other words with the input level controls turned all the way up and the amp set for .775 volts input sensitivity should the amp get a .775 volt input signal you will get full output of the amplifier. Likewise if the amp is set for 1.4 volts and the input level controls turned all the way up and the amp input gets a 1.4 volt input signal you will get full power from the amp.
Now…… if you turn the input level controls down…. Yes…. it will take a larger input signal to get to full output because the input signal is being attenuated but the gain of the amplifier hasn’t changed only the amount of signal getting to the amplifier.
Think of the input level controls as being the same thing as if you had an external level control before the amplifier (and the amp had no level controls). smile.gif
The 1.4 volt setting is as close as you are going to get with our amps to +4 db(1.23 volts), or in most cases 0VU, from a mixer.