Different between push-pull and quasi-comp?

[motbuddy]

hi,

As what i know, Quasi-complementary also works like push-pull amplifier. Just that push-pull is using 1 NPN and 1 PNP transistor. while Quasi-complementary is using 3 NPN and 1 PNP transistor. They both perform push-pull action. They sure have their own personality which i hope that someone can help me on this. What is the different if we compare both output? is it from a way of power? current?

Can someone help in this?

thanks.

[motbuddy]

or can i say that quasi-complementary amplifier has higher gain?

thanks.

[nigelwright7557]

In my experience they sound pretty much the same but thats probably no recommendation with my hearing !

The quasi is a little odd in that one driver is a buffer and the other is an amplifying inverter. This can cause problems. I found in my design I needed a 220pf from base to collector on the inverting driver to slow it down a bit.

The quasi really comes from the days of weak or none existant pnp transistors.

I built a Maplin 225WRMS quasi in the 1980's and used it on a mobile disco it was really powerful and reliable.

[stratus46]

Originally Posted by motbuddy

hi,

As what i know, Quasi-complementary also works like push-pull amplifier. Just that push-pull is using 1 NPN and 1 PNP transistor. while Quasi-complementary is using 3 NPN and 1 PNP transistor. They both perform push-pull action. They sure have their own personality which i hope that someone can help me on this. What is the different if we compare both output? is it from a way of power? current?

Can someone help in this?

thanks.

Quasi-complementary is not _like_ push-pull, it _is_ push-pull. With silicon power transistors it's usually NPN Darlington pair for the positive and a Sziklai pair for the negative. The Sziklai pair is capable of voltage gain while the Darlington can only provide current gain.

G²

[motbuddy]

what is the advantages for quasi-complementary?The design is out just because of those days the price of a PNP transistor?

thanks.

[stratus46]

Originally Posted by motbuddy

what is the advantages for quasi-complementary?The design is out just because of those days the price of a PNP transistor?

thanks.

It wasn't the price of the PNP transistor because it didn't matter how much money you had. The devices simply didn't exist yet. Some very fine sounding amplifiers were built with quasi-complementary outputs.

G²