Hello,
please find attached A200 schematic.
Musical Fidelity A200 - Audiomaniacy
I own Musical Fidelily A120 which has more or less same schamatic as A200.
As you may know Class A is limited to a few watts beyond which (A1, A100, A120) switch to class AB.
Which component should I have to change and trim to SAFELY increase the bias for a wider class A range?
Actually is shown 300mV on 0.47 ohm, that is 0.64A only!
Definetively not a 40+40W Class A as declared.
please find attached A200 schematic.
Musical Fidelity A200 - Audiomaniacy
I own Musical Fidelily A120 which has more or less same schamatic as A200.
As you may know Class A is limited to a few watts beyond which (A1, A100, A120) switch to class AB.
Which component should I have to change and trim to SAFELY increase the bias for a wider class A range?
Actually is shown 300mV on 0.47 ohm, that is 0.64A only!

Definetively not a 40+40W Class A as declared.
These amps like dying from a heatstroke with the factory bias 🙂
Unless you rebuild it using a proper PS and proper heatsinks you should leave the bias alone
Unless you rebuild it using a proper PS and proper heatsinks you should leave the bias alone
"Strongly biased into class A" isn't pure class A .
A hint is the bias you measured in the link I provided the version quoted is biased at 700manot much different from your measurements .
It therefore reverts to to class AB at about (his version) 8watts.
Musical Fidelity A1 › Technical
A hint is the bias you measured in the link I provided the version quoted is biased at 700manot much different from your measurements .
It therefore reverts to to class AB at about (his version) 8watts.
Musical Fidelity A1 › Technical
These amps like dying from a heatstroke with the factory bias 🙂
Unless you rebuild it using a proper PS and proper heatsinks you should leave the bias alone
Very true!
Just looking at the face of my A220 "Class A", manual states Class A too.
Looking at the schema - the MF A2/A220 is a chain of two differential amps with a Push Pull with 2 devices each side for each channel.
It looks class AB1 to use a tube analogy.
Looking at the schema - the MF A2/A220 is a chain of two differential amps with a Push Pull with 2 devices each side for each channel.
It looks class AB1 to use a tube analogy.
So, I need an analog expert that kindly tells me which are the resistors that trim the bias. Anybody here?
Thanks, so in my linked scheme of A200, bias should depend on resistor R30/R31, R36/37, R61/62, problable the last four, correct?
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