Modify a amplifier to have more power...

[Danyele82]

To obtening more power from this ampli can i use 2 braces of output BJT? (the BJT are Sanken 2SA1295/2SC3264)
With 85v power supplies can i have about 200w into 4 ohm?

[Jan Dupont]

For the amp being able to handle the needed current for 4 Ohms load, I would advise you to use at least 3 extra of each output devices pr. channel (and personally I would also add an extra common driver stage to drive to output devices).

[MrTransistorm]

And while you're at it, use a dual rail power supply. Get rid of C6, R21 and R2. Connect R24, R3, C2, C3, C5 and speaker to 0V instead of the negative rail.

[sam9]

When you specify an 85V power supply, may I assume you are choosing a transformer VA rating consistent with the proposed 4 ohm load?

[jewilson]

This amp is strange duck, the negative supply rail is grounded.

[millwood]

Originally posted by jewilson
This amp is strange duck, the negative supply rail is grounded.

it is OTL. perfectly fine.

[Danyele82]

Originally posted by sam9
When you specify an 85V power supply, may I assume you are choosing a transformer VA rating consistent with the proposed 4 ohm load?

I use this amplifier with an smps.
The smps have an output of 85v @ 15A for each channel!!!

[Danyele82]

Originally posted by MrTransistorm
And while you're at it, use a dual rail power supply. Get rid of C6, R21 and R2. Connect R24, R3, C2, C3, C5 and speaker to 0V instead of the negative rail.

I have just modify the amplifier to use a dual power supply (+-43v)...

[Danyele82]

This amplifiers is a Bartolomeo Aloia project(VolskAmplifiers)!

[selim]

Inserting a resistor ( of the order of 100 R ) between the emitters
of Q7 and Q8 and paralleling that resistor with a capacitor ( of the
order of 1 u ) might be beneficial for the switch off performance
of the output transistors.

By the way, more power in amplifiers is only useful upto a certain ( not so high ) limit. A few clean watts is all that we need.

Best Regards

Selim