.22 to .27 ohms more than fine.
The values go up significantly with parallel devices.
Higher value better for thermal stability.
Wing Spread of BJT has been analyzed a million times.
Ideal bias current has been and always will be 100ma per device for Emitter Follower.
The voltage drop will vary depending on emitter resistor value.
Either way 100ma is the goal.
Far as THD and overall effect.
Ideal bias at 100ma should be more observed at 10 kHz or above.
Most the issue is the load, voltage goes out to a impedance ,that simple.
Between Reflex roller coaster impedance and crossover roller coaster impedance.
The current changes quickly over the bandwidth is improved with more output devices.
Which people refuse to do.
Depending on the instrument timbre, the transition of its attack and decay in the recording.
Most your " distortion" is spongy output sections , and spongy weak speaker magnets.
Or not. The transition heard over a timeline is more notable than static THD tests.
If the amplifier frontend is simple and produces poor numbers to start with.
Then might as well settle for the typical minimum of 30 to 45ma per device.
Since 100ma is a waste of time.
A low " THD" amplifier would simply " wake up" if it had more output devices.
If you are shooting for high bandwidth and low THD at high frequency
Then 100ma is default as always.
Seems to be confusion with degen and thermal stability and current sharing.
Emitter resistor values change for parallel devices.
The end of the day, total parallel resistance has been and will always be .22 to .27 ohms
Meaning 2 or 3 pairs of devices will be using much much higher resistor values.
The values go up significantly with parallel devices.
Higher value better for thermal stability.
Wing Spread of BJT has been analyzed a million times.
Ideal bias current has been and always will be 100ma per device for Emitter Follower.
The voltage drop will vary depending on emitter resistor value.
Either way 100ma is the goal.
Far as THD and overall effect.
Ideal bias at 100ma should be more observed at 10 kHz or above.
Most the issue is the load, voltage goes out to a impedance ,that simple.
Between Reflex roller coaster impedance and crossover roller coaster impedance.
The current changes quickly over the bandwidth is improved with more output devices.
Which people refuse to do.
Depending on the instrument timbre, the transition of its attack and decay in the recording.
Most your " distortion" is spongy output sections , and spongy weak speaker magnets.
Or not. The transition heard over a timeline is more notable than static THD tests.
If the amplifier frontend is simple and produces poor numbers to start with.
Then might as well settle for the typical minimum of 30 to 45ma per device.
Since 100ma is a waste of time.
A low " THD" amplifier would simply " wake up" if it had more output devices.
If you are shooting for high bandwidth and low THD at high frequency
Then 100ma is default as always.
Seems to be confusion with degen and thermal stability and current sharing.
Emitter resistor values change for parallel devices.
The end of the day, total parallel resistance has been and will always be .22 to .27 ohms
Meaning 2 or 3 pairs of devices will be using much much higher resistor values.
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@WhiteDragon - This board has examples of both methods. Paralleling transistors while keeping the per-transistor current and emitter resistance unchanged is (IMO) a better choice because it lowers the distortion with nearly no effect on the overall power dissipated at 63% amplitude.
Ed
Ed