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Old Sep 18, 2018 | 07:47 PM
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Voltage = square root of Watts x Ohms

My B52 is rated at 200 Watts @ 4 Ohms and 250 Watts @ 2 Ohms

Why do all the voltage calculation examples for odd impedance speakers, 2.7 for example, always show the 2 Ohm Watts X 2 Ohm, why not 4 Ohm Watts X 4 Ohms? Neither one is accurate. If 2 Ohms is 250 Watts and 4 Ohms is 200 Watts, then 2.7 is somewhere in the middle, so I assume that one calculation would be too high, the other too low?? In this example wouldn’t you calculate the voltage both ways and split the difference?

Jim
 
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Old Sep 18, 2018 | 08:13 PM
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Originally Posted by roussfam
Voltage = square root of Watts x Ohms

My B52 is rated at 200 Watts @ 4 Ohms and 250 Watts @ 2 Ohms

Why do all the voltage calculation examples for odd impedance speakers, 2.7 for example, always show the 2 Ohm Watts X 2 Ohm, why not 4 Ohm Watts X 4 Ohms? Neither one is accurate. If 2 Ohms is 250 Watts and 4 Ohms is 200 Watts, then 2.7 is somewhere in the middle, so I assume that one calculation would be too high, the other too low?? In this example wouldn’t you calculate the voltage both ways and split the difference?

Jim
Here is a little helper/cheater to help you calculate


https://www.rapidtables.com/calc/ele...alculator.html
 
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Old Sep 18, 2018 | 09:35 PM
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Doesn't work if you don't know how many watts your amp puts out at 2.7 ohms. The only known value is 2.7
 

Last edited by roussfam; Sep 18, 2018 at 09:37 PM.
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Old Sep 19, 2018 | 04:50 AM
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you want to set to what the speaker can handle not what the max output of the amp is. If the speaker is only rated 100w rms then 200 or 250 would be way to high. Plus, it's only a starting point and shouldnt be your final setting
 
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Old Sep 20, 2018 | 07:45 AM
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Originally Posted by USAproud
you want to set to what the speaker can handle not what the max output of the amp is. If the speaker is only rated 100w rms then 200 or 250 would be way to high. Plus, it's only a starting point and shouldnt be your final setting
While that does make sense, that's the first time I've heard that. If you read the Sticky or google "Setting Gains with a DMM" speaker rating is never mentioned or taken into account, only impedance.
 
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Old Sep 20, 2018 | 08:04 AM
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Why would you set your amp to max output without knowing what your speakers can handle. Use the chart in that sticky it’s very helpful. Figure out what you want to send to your speakers on left hand side. What ohm they will be receiving on top and follow down that’s what younger your gain output to. Then after that tune by ear.
 
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Old Sep 20, 2018 | 08:12 AM
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And the tune by ear is the part that I bank on. In the long run, like USA says. It's simply a starting point.
Kris
 
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Old Sep 20, 2018 | 09:10 AM
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Using a DMM has fried more **** than you can imagine when using one to set gains as a complete Noob to Audio. Always set by ear until you have a good feel for what you're doing. Your ears will tell you when it's not right versus trusting a meter reading.
 
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Old Sep 20, 2018 | 10:04 AM
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Originally Posted by roussfam
Doesn't work if you don't know how many watts your amp puts out at 2.7 ohms. The only known value is 2.7
Well this isn't quite true you do know the RMS Value of the speaker lets say its 100 Watts RMS Voltage = square root of Watts x Ohms

So lets say you want to know what your voltage setting should be to obtain 100 watts to the speaker with a volt meter the your looking at Voltage = Square root of 100 Watts * 2.7 Ohms which would be Voltage = 10 * 2.7Ohms so Voltage to your speakers would need to be 27 Volts as a starting point

I personally depending on the speaker would start a % of Full RMS watts and then as everyone has said finish tuning by ear when you hear distortion back up a bit on your gains
 
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Old Sep 20, 2018 | 11:15 AM
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Then there's this.
Gain Setting Question-photo279.jpg
 
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