And this difference between different manufacturers of the same transistor model that got me confused.

In general, devices with the same part number from different manufacturers are only approximately the same. There's also little that prevents a manufacturer from "improving" their version of the part. This is why it's important to use the datasheet from the manufacturer of the part you are actually using, whenever feasible.

 

They are free to make their own specifications (and they do!) though the tend to be careful about getting too far away from what would be expected by the part number.

I think what you are looking for is a way to find transistor equivalents or lists of replacement parts. Often these guides are referred to as "cross references"

For example:
https://nvhrbiblio.nl/biblio/boek/14-2nd-Transistor-Equivalent.pdf
https://hudsonvalleyhifi.com/technical-data/transistor-substitutions
https://alltransistors.com

 

They are free to make their own specifications (and they do!) though the tend to be careful about getting too far away from what would be expected by the part number.

I think what you are looking for is a way to find transistor equivalents or lists of replacement parts. Often these guides are referred to as "cross references"

For example:
https://nvhrbiblio.nl/biblio/boek/14-2nd-Transistor-Equivalent.pdf
https://hudsonvalleyhifi.com/technical-data/transistor-substitutions
https://alltransistors.com

Thank's for link's!

 

Did you read the specs and see the curves in the datasheets?
1) The 2N3904/2N3906 have a max allowed current of 200mA but their specs and curves show poor performance above 50mA.
2) The 2N4401/2N4403 have a max allowed current of 600mA but their specs and curves show poor performance above 200mA.

Instead of many weak little transistors, why not use two power transistors with little heatsinks? Also their emitter resistors can be 0.22 ohms for much less voltage wasted.

The transistors have a max allowed voltage of 40V so make your circuit safe with 30V. Your paralleled transistors have 20 ohms/5= 4 ohms of emitter resistors in series with the 8 ohms speaker then the max peak current in each group of 5 transistors is 14V/(8ohms+4ohms)= 1.17A or 233mA for each transistor.

Your amplifier with a 30VDC supply might produce 8.2W RMS total in the 8 ohms speaker in series with the 4 ohms emitter resistors or 5.5W RMS in the speaker plus 2.7W in the emitter resistors. The transistors heat with about 800mW each. Then they will overheat and be destroyed.
Using TIP31/TIP32 power transistors with a 30V supply, the amplifier output power will be about 12W RMS and each output transistor needs a little 8W heatsink.

You are correct. Why do not use one bigger complementary couple? I had tried to do the same thing with bigger transistors like the BD139-140 pair but I saw that it needs more current to be driven , important point to be looked especially if the previous stage is run by jfet. Furthermore because I liked the idea of using lots of small transistors like Nelson Pass did with his JFet amp.

 

I once tried to make a power amplifier with 50 BC182/BC212 pairs as the output stage. It was rubbish.

 

I once tried to make a power amplifier with 50 BC182/BC212 pairs as the output stage. It was rubbish.

50 pairs is a big number but do you have encountered some particular problem?

 

50 pairs is a big number but do you have encountered some particular problem?

It worked, but it was no better than an amplifier made with a MJ15003/MJ15004 output stage, and it was a lot more trouble to make.