Apache - Current Feedback Amplifier 27 Watt and 7 MHz

[attalostesla]

What is the input impedance? Does need opamp buffer?

 

[lineup]

These potentiometers usually don't work well enough, because DC offset changes with temperature.
You will set it to some value, just to watch it drift away later on...

Now I have a DC-Servo to keep DC-offset close to zero.
So there is not that problem with drift.

 

[lineup]

I would try: omit C1;-)

Why?
It is good to keep from input DC voltage.

 

[lineup]

Can C3 be deleted without replacement, R8 perhaps be set to 910 ohms, a parallel resistor to C2, perhaps 22kOhm !?

I dont like such suggestions.
It works well enough anyway.

 

[lineup]

What is the input impedance? Does need opamp buffer?

The input impedance is very high.
It is set by R11 = 47kOhm.

 

[cumbb]

Why?
It is good to keep from input DC voltage.

May be, the predicted high offset drops at the source;-)
I would always set up practically first. Then the problems become visible, only then would I react - many do not occur or are not relevant for audio.

 

[hbtaudio]

I dont like such suggestions.
It works well enough anyway.

I'm sorry, it was just a quick thought /question - I didn't mean to offend you.


kindly,
HBt.
I would try it out, no more and no less.

Can

• C3 be deleted without replacement
• R8 perhaps be set to 910 ohms
• a parallel resistor to C2, perhaps 22kOhm

!?

 

[lineup]

What I meant to say was: I dont consider THOSE suggestions, your changes.
I really like when people suggest here.
But I will not often do any changes.
I think amplifier is good as it is.

 

[hbtaudio]

It doesn't have to be, it's your circuit suggestion - and it should stay that way.



Thanks for the brief explanation, I can understand that /you.
I like these topologies. I wouldn't have thought of an LM334, interesting.

🙂