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Crown vz3600 amp into JBL Speaker


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#1 iantepper

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Posted 07 February 2013 - 02:30 PM

Hi Forum peeps.

Ok to put the 3600vz (bridged mono) amp with a JBL S128s bass speaker ?

I know JBL recommend a 2000w amp into its 1600w (average power rating),but is this ok to run the 3600vz on 50% maybe ?

Ian

#2 dakos

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Posted 08 February 2013 - 12:25 AM

There is no such thing as to run the amp at 50%, if a strong enough signal gets in it will give its maximum power unless you put a proper limiter before it to prevent that from happening.

I would suggest to limit the amps power going into the speaker even further so you wouldn't Experiance power compression, limit the amps continuous power to about 40% of the speakers continuous power rating.
Avi

#3 iantepper

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Posted 08 February 2013 - 03:24 PM

I ment turn the amp volume knobs to half.

or in other words, how would i work out how far to turn the AMP volume knobs before the amp started to destroy the speaker ?

40% ?

#4 dakos

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Posted 08 February 2013 - 06:58 PM

These are not "Volume" knobs, they are called Gain knobs and I'll explain... When you turn these knobs you change the amps gain or input sensitivity to be more accurate, the maximum power of the amp stays the same. Say you have an amp with a sensitivity of 1.4V at 8 ohms, that means that when you feed the amp a signal with an amplitude of 1.4V the amp will output it's maximum power. When you put the gain knobs at 50% all you did was to change the sensitivity of the amp to 2.8V, so now it will take two times the voltage on the input side to output the maximum power of the amp. So if you want to protect your gear simply turning down the gain knobs is not enough, you will need an actual limiter, preferably with separate continuous and peak settings.

Any way, you start with putting the gain as far as you need and turning it back down if you hear distortion, so the best thing for you to do if you don't want to get a limiter or a DSP containing a limiter, is to keep your ears open for that distortion and turn the gain of the problematic channel on the mixer down a bit, till the distortion is gone and then just a bit more. If it's only one player causing all the distortion it might be worth your while to put a compressor on this specific channel before going into the mixer, this way if he plays in the correct level then his signal stays the way he wanted it to sound, and if he is driving you rig into distortion he gets compressed and you stay in control.
Avi

#5 joust

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Posted 11 February 2013 - 09:19 AM

Hello Avi, A better term for a 'volume' control would be an 'attenuator'; A gain control usually controls the amount of 'amplification' you desire.
The 'gain' control usually refers to a control that will amplify the signal applied; For example, the gain control of the input circuitry of a mixer can amplify the signal to more than 60dB.
The 'attenuator' control fixes the maximum level of the sound to the next circuit when fully open and will attenuate the signal to the desired level.
(Please correct if necessary!)

Alain

#6 dakos

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Posted 11 February 2013 - 11:23 AM

Dear Alain, thank you for contributing to this discussion as well :)

First the term, I know it's not that accurate but I did take the "gain knobs" name from the XTi manual. I would call it the sensitivity control or something like that.

As to the "attenuator" operation you described, it would have to have some kind of a limiter action to be able to not let the signal get above a certain level. I'm not sure how it works in the digital era of amps and I know you know what is going on from the inside of the amp much more then I do but from an end user point of view I always new it to be working the way I explained in the prior post, will try later to find posts on other forums that support what I say and if I can't I will be very happy to be corrected.
Avi

#7 joust

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Posted 12 February 2013 - 08:28 AM

Bonjour Dakos! You are correct that there is no way other than using an equipment such as a limiter to prevent unwanted excursions beyond the desired point. Crown had available for the MA series, numerous PIP cards that could do different jobs (such as the CLP card, for limiting). Today, Crown has available the PIP Lite cards that will need some programming, but should do the job. I'm not sure if it can be retrofitted on older MA series amp (because of the audio and power interface cabling and load).

A.