Another newbie question
01-16-2008, 02:16 PM
#1
50 Watt CAFz'r
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Join Date: Jan 2007
Posts: 221
Another newbie question
Was wondering, you see RMS this, wattage that. What would be the proper way of going about and finding how much your wattage your subs are actually getting, to make sure I don't push that too hard. Obviously with a DMM, but on what setting? And Postive lead and negative lead on what?
Last edited by SheHateMe; 01-16-2008 at 02:21 PM.
01-17-2008, 11:53 PM
#2
What you want to do is not very practical. The best way to make sure you sub or main speakers are not overloaded is by listening...
Listen at a good level and then start to increase the volume until things start sounding distorted. Do this for the mains and the sub. Learn what distorted sound sounds like weather a tweeter cracking or a sub bottoming out.
Any one into car or home audio should be able to hear overloaded speakers or amps. You should not need test gear.
Why? because for a sub, the maximum power handling is dependent on many things and will be different at different frequencies.
At higher frequencies subs are thermally limited. This is the normal maximum power spec. You could somehow measure voltage accross the sub and the current thru a very small resistor and to VxI=Watts. But this way you are robbing power thru the small resistor.
You could simply measure voltage accross the sub and do Watts=V*V/R where R is the nominal impedance of the sub. But Sub impedance varies with frequency anyway so this may not be very accurate.
At lower frequencies the sub is excursion limited (XMAX) This is especially tru for a vented sub because the cone is uncontrolled below the port tuning frequency. Even a 1000 watt sub may only be able to handle 200 watts below the port resonance and bottom out very easily, physically destroying the voice coil or ripping the surround or suspension.
So. no easy technical answer. The best way is to use your ears!
Listen at a good level and then start to increase the volume until things start sounding distorted. Do this for the mains and the sub. Learn what distorted sound sounds like weather a tweeter cracking or a sub bottoming out.
Any one into car or home audio should be able to hear overloaded speakers or amps. You should not need test gear.
Why? because for a sub, the maximum power handling is dependent on many things and will be different at different frequencies.
At higher frequencies subs are thermally limited. This is the normal maximum power spec. You could somehow measure voltage accross the sub and the current thru a very small resistor and to VxI=Watts. But this way you are robbing power thru the small resistor.
You could simply measure voltage accross the sub and do Watts=V*V/R where R is the nominal impedance of the sub. But Sub impedance varies with frequency anyway so this may not be very accurate.
At lower frequencies the sub is excursion limited (XMAX) This is especially tru for a vented sub because the cone is uncontrolled below the port tuning frequency. Even a 1000 watt sub may only be able to handle 200 watts below the port resonance and bottom out very easily, physically destroying the voice coil or ripping the surround or suspension.
So. no easy technical answer. The best way is to use your ears!
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