Topologies using darlingtons.

[beppe61]

Dear Friends,


in the Sanken's web site I found this statement:" Darlington transistors do not require drive transistors".
I wonder why darlingtons are not much more common as they could be used in simpler circuits.
I mean 1 darlington can replace 1 drive bjt + 1 output bjt.
Am I missing something ?
And also high current darlingtons are available.
Any link to very simple topologies using darlingtons?

Thank you very much indeed.

Kind regards,

beppe61

[richie00boy]

A very good point. One issue is that they tend to be slower, and that reverse biasing the base to switch off quicker/cleaner is not possible. Also there is no control over the main transistors base-emitter resistor.

[lineup]

Originally posted by beppe61
Dear Friends,
in the Sanken's web site I found this statement:" Darlington transistors do not require drive transistors".
I wonder why darlingtons are not much more common as they could be used in simpler circuits.
I mean 1 darlington can replace 1 drive bjt + 1 output bjt.
...
beppe61

Sure is possible very easy make of a strong power amplifier
covering well beyond 40 kHz with good sound quality.
Using powerful darlingtons, that can take a lot of heat!

This thread about the LAB10 Amplifier is only one fine example!
LAB10 Audio Amplifier Project

[beppe61]

Originally posted by richie00boy
A very good point.
One issue is that they tend to be slower, and that reverse biasing the base to switch off quicker/cleaner is not possible.
Also there is no control over the main transistors base-emitter resistor.

Dear Sir,
thank you so much for your extremely kind and valuable reply.
First of all I must confess my almost complete ignorance in electronics.
Anyway this statement makes me think about the possibility to build a minimalist audio power amp with just 5-6 active devices.
It should be very interesting.
By the way, I noticed that darlington were more used in the past (I know of amps using them in the '80s).
I particular like one from the UK firm Albarry audio.
Just one pair of output darlingtons. Very very good sound indeed.
If only I could find the service manual ...

Thank you very much again.
Kind regards,

beppe61

[beppe61]

Originally posted by lineup

Sure is possible very easy make of a strong power amplifier
covering well beyond 40 kHz with good sound quality.
Using powerful darlingtons, that can take a lot of heat!
This thread about the LAB10 Amplifier is only one fine example!
LAB10 Audio Amplifier Project

Dear Sir,

thank you very much for the very interesting information.
To be honest I do not like the op-amp based preamp too much.
Any all discrete option for a let's say 60 W/8 ohm power amp?
It could sound great indeed, if minimalism is the way of course.

Thank you very much indeed.
Kind regards,

beppe61

[richie00boy]

It depends what you mean by minimalism. If you mean physical small parts count then yes, but the same actual number of devices is there whether you use darlingtons or discrete drivers and outputs.

Darlintons can sound good and measure good. It's just that absolute ultimate performance is more readily available from discrete.

[beppe61]

Dear Sir,

thank you so much again for your kind reply.
Let me explain my point of view hereafter.

>

Originally posted by richie00boy
It depends what you mean by minimalism.

I mean minimum number of active devices used in the best operational conditions. But I am not an expert at all.
I just like the idea on principle.

> ... but the same actual number of devices is there whether you use darlingtons or discrete drivers and outputs.

Well, so I was very wrong.
I wanted to reduce the number of active devices.
For instance, if I am not wrong again, at Sanken I understand they build power bjts that are multiple bjts in the same package (multiemitter or something like that).
I like this as well, of course always on principle.

> Darlintons can sound good and measure good.

This is my personal experience as well.

> It's just that absolute ultimate performance is more readily available from discrete.

I am not looking for the "absolute ultimate performance" .
I am looking for a exceptional simple but nice sounding circuit.
I heard for instance some single mosfet class A power amp, but I did not like completely the lower frequencies, not powerful enough.

Thank you very much indeed.
Kind regards,

beppe61

[peranders]

Originally posted by beppe61
Any all discrete option for a let's say 60 W/8 ohm power amp?

This is pretty nice and small!

http://mirand.dk/

[beppe61]

Originally posted by peranders

This is pretty nice and small!
http://mirand.dk/

Dear Mr. Peranders,

thank you very much for the link.
Kind regards,

beppe61

[forr]

It is not possible to have a good external control of the quiescent current of class B output stages when darlingtons are used as power devices. Sanken seems now to provide darlington with internal bias diodes for a good thermal compensation : a thirty years old demand of amplifiers engineers.

~~~~~~ Forr

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