Hello everyone;
I was in the 10th grade of a technical high school in 2001 when Elektor released the Crescendo Millennium Edition Amplifier. When I saw it for the first time, I was very impressed. But it was a very expensive project for a student.
I wanted to build this amp for many years, but due to lack of time and the discontinuation of Mosfets, I was unable to do so.
I found out that @RM, who I met at Diyaudio, had mosfets for the Crescendo amp. I immediately started drawing PCBs and boxes.
I have no idea about the sound of this amp. Whether it's bad or good, I want to finish this amp, which is a dream of my youth, and have it in my collection. That's why I want to get advice from people who have already built this amp.
For example;
*What are the components that need to be matched? Is hFE matching or offset matching required for the input transistors?
*I am using OPA177 instead of OP77.
I was in the 10th grade of a technical high school in 2001 when Elektor released the Crescendo Millennium Edition Amplifier. When I saw it for the first time, I was very impressed. But it was a very expensive project for a student.
I wanted to build this amp for many years, but due to lack of time and the discontinuation of Mosfets, I was unable to do so.
I found out that @RM, who I met at Diyaudio, had mosfets for the Crescendo amp. I immediately started drawing PCBs and boxes.
I have no idea about the sound of this amp. Whether it's bad or good, I want to finish this amp, which is a dream of my youth, and have it in my collection. That's why I want to get advice from people who have already built this amp.
For example;
*What are the components that need to be matched? Is hFE matching or offset matching required for the input transistors?
*I am using OPA177 instead of OP77.
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Looks like a single pair of mosfets for power transistors. So no matching needed.
More important if more pairs or parallel outputs.
Other than that some do some dont.
Ideally though with any differential amplifier you want the pair closely matched.
This is dual differential so the BC546 pair and 556 pair ideally matched.
And on the pcb they should be mounted close together flat to flat.
So they can thermally stay same temperature. Or thermally bonded.
Not much different than any differential circuit.
This case this one has 2 instead of 1
MJE340/350 at time of publishing seemed to be very popular for some reason.
High voltage, low frequency transistors. More for general purpose use or voltage reg.
Not really considered audio grade.
Only thing I would consider changing, can of worms for opinions.
Reality higher quality audio grade would improve things.
But might require a look at compensation for faster and better gain audio.
If just current sources doesnt really matter, ok choice for heat range
More important if more pairs or parallel outputs.
Other than that some do some dont.
Ideally though with any differential amplifier you want the pair closely matched.
This is dual differential so the BC546 pair and 556 pair ideally matched.
And on the pcb they should be mounted close together flat to flat.
So they can thermally stay same temperature. Or thermally bonded.
Not much different than any differential circuit.
This case this one has 2 instead of 1
MJE340/350 at time of publishing seemed to be very popular for some reason.
High voltage, low frequency transistors. More for general purpose use or voltage reg.
Not really considered audio grade.
Only thing I would consider changing, can of worms for opinions.
Reality higher quality audio grade would improve things.
But might require a look at compensation for faster and better gain audio.
If just current sources doesnt really matter, ok choice for heat range