Borbely cascode power requirements

[astouffer]

I'm going to build one of the small Borbely cascode amps with the 2SK1058/2SJ162 output pair but would like to know how big a toroid to get for a stereo pair? Also what should the bias current be set for? The rails are going to be +/- 24 volts. Thanks.

 

[astouffer]

Anyone? Heres the schematic...

 

[Zen Mod]

Iq up from 1A
when you decide what Iq , calculate dissipation per channel , then multiply that with 2,5 (or even more , if you wish)

example - PSU +/-24V , Iq 1A , that means 48W dissipation per channel ..... which means at least 125VA xformer for one channel

with adequate cooling - I would go to 1A5 Iq , maybe with 2 pairs of output per channel , meaning that each pair have Iq of 750mA

good for xconductance ( read - dampingfactor ) etc ...

 

[Lumba Ogir]

astouffer,
linearity improves with increasing Iq. Say 250mA would be sufficient to avoid the most nonlinear portion of transfer characteristic. I would set the bias current with just a resistor.

 

[astouffer]

I would set the bias current with just a resistor.

By changing R21/22?

 

[AndrewT]

By changing R21/22?

no.
By removing Q9.
The inherent temperature stability of the Lateral FETs shown do not require a temperature compensated Vbe multiplier. A resistor is sufficient for applying the gate to gate voltage.