45W@8R 70W@4R CLASS B SO LOW DISTORTION.

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#7
It is probably this amplifier
http://www.redcircuits.com/Page150.htm

ClassB.GIF
 
#9
My expectations of this circuit is very low - performance will be nothing special. The design is very basic and the components used are not state-of-the-art anymore. There are quite a number of ways in which this circuit can be improved. Having said that, I've still got a few of those 2N3055 and MJ2955 trannies lying around - might be fun to knock up this one on a piece of stripboard and run it off the bench supply.

The expense of a new transformer to actually use it would might not be warranted. There are lots of other much better circuits to be built with very minimal setup. Setting the Iq is not such a hardship - all that is required is a cheap multimeter.

PS - LTspice suggests that this would work as advertised. THD for 1kHz at 50W into 8 ohm is 0.07%.
 
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#10
destroyer X said:
Can you explain this to me please?.... i though that for audio we would have more distortion when playing low volumes, while in class B, because of switching.

regards,

Carlos
Click to expand...

hi . the worst distortion of an amplifier is measured when the amp is at the highest output power rate.(highest sound volume)
class B amplifiers have the worst distortion between other amp classes.

i meant this one has a lower distortion than most class B amps.
 
#11
ingenieus said:
My expectations of this circuit is very low - performance will be nothing special. The design is very basic and the components used are not state-of-the-art anymore. There are quite a number of ways in which this circuit can be improved. Having said that, I've still got a few of those 2N3055 and MJ2955 trannies lying around - might be fun to knock up this one on a piece of stripboard and run it off the bench supply.

The expense of a new transformer to actually use it would might not be warranted. There are lots of other much better circuits to be built with very minimal setup. Setting the Iq is not such a hardship - all that is required is a cheap multimeter.

PS - LTspice suggests that this would work as advertised. THD for 1kHz at 50W into 8 ohm is 0.07%.
Click to expand...

HI. I need all those circuits with the ensurance that they are ok to work well. please send me all of THOSE circuits.
thanx man.😀
 
#14
Hi,

What on earth is anyone on about in this thread ?

How does that output stage work with no drive connection ?

Distortion will not be low, its somewhat underbiased, for a correct CFP output.

Edit : ahhh...... drive is via the current in the rails and R11 /R12.
But I still cannot see it .....

There is no reason distortion would be lower than typical.

rgds, sreten.

Edit : Related to the Edwin topology described by Self.
 
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#20
harp mg said:
HI. I need all those circuits with the ensurance that they are ok to work well. please send me all of THOSE circuits.
thanx man.
Click to expand...

Here is the circuit in LTspice - same as in post 7.

The collector currents are not a pretty picture, as shown. The static bias collector current is about 1A for each output transistor, i.e. each transistor dissipates 32W by just being powered on. This probably means that the heatsink has to be little bigger than might otherwise be the case, but I haven't done the math. As my textbooks used to say, that is left as an exercise for the reader. :mischiev:

The less than optimal biasing is the downside of this circuit, and the price to be paid for easy setup.
 

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