Rule of thump says that one pair of transistors may produce about 60W at 8R load if powered between 35-40 V rails in class AB operation .
And will do that while moving in a SOA more or less .
Based on this you can make a very rough calculation looking at the number of transistors .
So i am in a conversration with a car audio guy , looking at a product that is working at class AB , single rails not class G or H , with THAT number of transistors , and with THAT rail voltage ....
I make the calculation based on the rule of thump and say to him that you do expect this machine to produce THAT watt @8R more ore less double at 4R given that no VI limmiter exists rails are low ( lower than the rule ) and given that power supply is enough for that .
Then the argument starts .....
he said a number in Watts that was almost 3 time the numer i said ...
WTF i said and how come you can say that ?
do you have scopes generators and dummy reactive loads to measure that ????
HE looks at me surprised and said
This is not the way to measure amplifers !!!
i am about to get a stroke and said ok .... what is the method ???
Only thing you need to know is OHMS law
use of one multimer
Calculate volts times amps over the load and you have the Watts ....
left the conversation gone for harakiri
And will do that while moving in a SOA more or less .
Based on this you can make a very rough calculation looking at the number of transistors .
So i am in a conversration with a car audio guy , looking at a product that is working at class AB , single rails not class G or H , with THAT number of transistors , and with THAT rail voltage ....
I make the calculation based on the rule of thump and say to him that you do expect this machine to produce THAT watt @8R more ore less double at 4R given that no VI limmiter exists rails are low ( lower than the rule ) and given that power supply is enough for that .
Then the argument starts .....
he said a number in Watts that was almost 3 time the numer i said ...
WTF i said and how come you can say that ?
do you have scopes generators and dummy reactive loads to measure that ????
HE looks at me surprised and said
This is not the way to measure amplifers !!!
i am about to get a stroke and said ok .... what is the method ???
Only thing you need to know is OHMS law
use of one multimer
Calculate volts times amps over the load and you have the Watts ....
left the conversation gone for harakiri
Car audio people live in their own world, i would not pay much attention.
They need at least 1000 watts to move their subwoofer with half a kilo plastic cone with rubber tire surround, with 82dB efficiency.
They need at least 1000 watts to move their subwoofer with half a kilo plastic cone with rubber tire surround, with 82dB efficiency.
You need an oscilloscope and a signal generator capable of good sine or triangle wave. Thus, inject the signal controlling in the scope the point in what signal enters into cutting upper or lower tops of signals, with a rated load resistance. Thus doing the maths you get the power reading rms or peak voktage in the scope and load resistance.
