faster transistors

[Elso Kwak]

I saw amplifier which use one(!) pair of MJL21193/94 and gives almost 200W on 4ohm load. The owner use it since 2 years, and it still running. I was totally frustrated, when I opened the top. I tried to find more transistors inside, but there was only two.

sajti

Hi sajti, What amplifier was that? Any schematic?

 

[sajti]

I will try to find some schematics from my archive. I planned, and made that amplifier. But the owner made some modification
He put bigger transformer 2x36V instead of the 2x28V, i used. Add fan for the cooling.
The amplifier is very simple, use double differential for input, and triple EF output, with MJ340/350+MJE15030/31+MJL21193/94.
I think, that the full speed 4" fan keeps the output cool enough, to survive this action....

sajti

 

[Elso Kwak]

I will try to find some schematics from my archive. I planned, and made that amplifier. But the owner made some modification
He put bigger transformer 2x36V instead of the 2x28V, i used. Add fan for the cooling.
The amplifier is very simple, use double differential for input, and triple EF output, with MJ340/350+MJE15030/31+MJL21193/94.
I think, that the full speed 4" fan keeps the output cool enough, to survive this action....

sajti

Only one differential pair at the input, no full complementary circuit?

 

[sajti]

Only one differential pair at the input, no full complementary circuit?

I wrote double differential. The amplifier fully complementary, and use
BC546/556 for differential, and 2N5551/5401 for VAS. Use low feedback - about 14dB

sajti

 

[Elso Kwak]

I wrote double differential. The amplifier fully complementary, and use
BC546/556 for differential, and 2N5551/5401 for VAS. Use low feedback - about 14dB

sajti

Sorry sajti, I did not read carefully, not quite awake yet......
Looking forward to the schematic. Unusual VAS transistors.

 

[MikeB]

Unusual VAS transistors.

Not for a triple darlington ! With tripledarlington you have the choice
to use lowcurrentvas, means you can use nice smallsignaltransistors.
And for this voltages the 2n5401/5551 are the best choice !

 

[skout]

What is VAS?

Could someone explain what is the acronym VAS?

 

[PMA]

Voltage Amplifying Stage.