Thank you James and Chris,
Yes Zen, the bias current is a bit high. You adjust it by altering R6 and R11. Increase the value of R6 to decrease the bias current in the pnp (Q10) side, increase R11 to decrease the current in the npn (Q9) side.
It's set high in the simulation to balance the npn and the pnp halves of the amp for the majority of it's operation, giving mostly class A operation.
Cheers, Neil.
Yes Zen, the bias current is a bit high. You adjust it by altering R6 and R11. Increase the value of R6 to decrease the bias current in the pnp (Q10) side, increase R11 to decrease the current in the npn (Q9) side.
It's set high in the simulation to balance the npn and the pnp halves of the amp for the majority of it's operation, giving mostly class A operation.
Cheers, Neil.
I know how to do it, saying just in case
Had my share of fun with MF A1
in fact, still having one, sitting on shelf ...... most likely nostalgia thing
Had my share of fun with MF A1
in fact, still having one, sitting on shelf ...... most likely nostalgia thing
So why muck about with the A-100 then ?
i have a great respect for the late Tim de Paravicini, his dry humour and innovative circuit design. We only met and chatted a couple of times but i enjoyed him.
The A-100 was, as Zen says, based upon the A-1.
===
A rather unusual bipolar transistor based design. The A-1 sounded nice but got rather warm. The Sugden A25a was also a good tranny amp, i don't know anything about it's workings. The Audio Innovations 300 valve amp was also around.
At the time (late '80's/early '90's) i'd started building valve amps. First a phono equipped preamp, then power amps. It was, at the time, cheaper to build than buy.
Recently, being too poor to buy parts or pay for the electricity to run valve amps, i've been mucking about with transistors.
===
Apart from the troubles which started this post, i think the A-100 can be set up far better than the original.
Attached is a LTSpice model of the original A-100 power amp, also a screen shot of test results from this circuit.
;o)
i have a great respect for the late Tim de Paravicini, his dry humour and innovative circuit design. We only met and chatted a couple of times but i enjoyed him.
The A-100 was, as Zen says, based upon the A-1.
===
A rather unusual bipolar transistor based design. The A-1 sounded nice but got rather warm. The Sugden A25a was also a good tranny amp, i don't know anything about it's workings. The Audio Innovations 300 valve amp was also around.
At the time (late '80's/early '90's) i'd started building valve amps. First a phono equipped preamp, then power amps. It was, at the time, cheaper to build than buy.
Recently, being too poor to buy parts or pay for the electricity to run valve amps, i've been mucking about with transistors.
===
Apart from the troubles which started this post, i think the A-100 can be set up far better than the original.
Attached is a LTSpice model of the original A-100 power amp, also a screen shot of test results from this circuit.
;o)
