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QUESTION: 1 - if my power amplifier give 1120 watts @ 4 ohms and i require 900 watts @ 4 ohms for 600 watt 4 ohms speaker. how can i control output watts 1120 to 900 watts?

2 - volume control given in power amplifier on both channel what is its uses. to control input signal or to control output signal?

3 - if power amplifier give 750watts @ 8 ohms,1120 watts @ 4 ohms,1500 watts @ 2 ohms. then my question is that the transformer of amp working load for 750 watts @ 8 ohms is the same as working load for 1120 watts @ 4 ohms and same as to 1500 watts @ 2 ohms?
sir please give all three answer with healthy explanation.
thanks.

ANSWER: Best way is to control the volume you feed into it.  It is audio; audio power is very low compared with sine wave input.  And, if you calculate the reduction in power, 3db is half power point.  So, 3db down from 1120 watts is 560 watts.   To the human ear, it takes about 2db reduction in power level to discern a difference.  Therefore, going down in power too 900 watts in your case is hardly discernable to your ears.

Your system is just fine. You don't need any further apparatus or technology; only a proper setting of the volume control.

Transformer must be power enough to handle the increased current requirements when load is reduced.  This is called voltage regulation of the power supply.  Only a strong power transformer can give the greater power delivery at lower impedance loads. In reality, most amplifiers will droop a little and the power out of the lower load impedance will not deliver the double power when load is halved.  Do you understand my explanation? If not you should look into audio power amplifiers in more detail.

Have a happy solution.

Cleggsan



---------- FOLLOW-UP ----------

QUESTION: so then what i have to do?
1 - i can operate 600 watts 4 ohms speakers to power amplifier give 1120 watts at 4 ohm and make sure that it never get peak.
2 - i can operate 600 watts 4 ohms speaker to power amplifier give 1120 watts at 4 ohm by reducing input level by -2db.

which way is the best to operate suggest me.
thanks.

Answer
It won't make any difference.  You should just be careful with the volume control on a powerful system like this.

Please be aware that speaker systems are complex impedances and do not take power like a fixed resistance for which we make the power calculations.  The speaker impedance may dip to 50% of its nominal impedance below and above resonance but go 3 times higher than rated impedance at resonance.  So, we must remain able to live with approximations.

Best wishes.

http://www.churchsoundcheck.com/imp1.html  

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Cleggsan

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Audio Design Engineer; systems, loudspeakers, cd/dvd players, etc. I am knowledgeable in all high end audio equipment and installations. MAKE SURE YOU GIVE A MAKE AND MODEL NUMBER AND CAR IF IT IS AN AUTO QUESTION. Note: I am getting some who ask good questions that take a lot of time to research but then the questioner fails to read the answer. Please don't ask questions unless you are seriously looking for an answer. If you find an answer to your question otherwise then let me know with your reply. Thank you.

Experience

Have been associated with audio design, standards, testing and component systems for over 40 years.

Organizations
Life Fellow Member of Audio Engineering Society Life Senior Member of Institute of Electronic and Electrical Engineers

Publications
Review technical manuscripts for IEEE Spectrum Write occasionally for high-end audio publications

Education/Credentials
BSEE/MSCS/MBA

Past/Present Clients
Past Employee/advisor to several well known audio products manufacturers

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