How about this one??

darkfenriz · 6th August 2004, 11:00 PM

Hi everybody
after slight development of my mind (hopefully) I've made up this.
Is this gonna be OK?
Loking forward to comments
cheers

Gofer · 7th August 2004, 12:02 AM

Your fet's will go up in smoke. (thermal runaway)
Lose the opamps and work with a dual or single diffy input stage with a proper VAS.
The opamps (no matter how fast) are too slow to compensate for anything. (you need at least 50 Mhz bandwith)
The + side is in real life never a mirror image of the - side.
It looks like a balanced output stage instant bridge mode amplifier.
Any way it is allways nice to think (experiment) about something in your mind.

Keep on thinking and don't be shy like me ! Keep on posting.

Greetings from Govert-Jan

MikeB · 7th August 2004, 10:40 AM

I don't think this will work good.

There is one major designflaw:

- As the emitter of the upper driver is connected to ground, it will
never supply a negative voltage, thus the upper irf540 won't
work correct for negative voltageswing. The lower irf540 will open,
but the upper can not close. By exceeding the max Vgs of 20volt
the mosfet blows up.

Some minor designflaws:

- your capacitors to the drivers disable/reduce DC-feedback.
- 0.22uF for the feedbackcap is very small.
- The lower outputstage gets a delay through the extra inverting
opamp, this might produce heavy crossoverdistortion.
- The 800ohm to the gates are very large.

Mike (hoping that i had not some brainfart)

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7th August 2004, 12:02 AM	#2
Gofer diyAudio Member Join Date: Oct 2002 Location: Amsterdam	Your fet's will go up in smoke. (thermal runaway) Lose the opamps and work with a dual or single diffy input stage with a proper VAS. The opamps (no matter how fast) are too slow to compensate for anything. (you need at least 50 Mhz bandwith) The + side is in real life never a mirror image of the - side. It looks like a balanced output stage instant bridge mode amplifier. Any way it is allways nice to think (experiment) about something in your mind. Keep on thinking and don't be shy like me ! Keep on posting. Greetings from Govert-Jan

7th August 2004, 10:40 AM	#3
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	I don't think this will work good. There is one major designflaw: - As the emitter of the upper driver is connected to ground, it will never supply a negative voltage, thus the upper irf540 won't work correct for negative voltageswing. The lower irf540 will open, but the upper can not close. By exceeding the max Vgs of 20volt the mosfet blows up. Some minor designflaws: - your capacitors to the drivers disable/reduce DC-feedback. - 0.22uF for the feedbackcap is very small. - The lower outputstage gets a delay through the extra inverting opamp, this might produce heavy crossoverdistortion. - The 800ohm to the gates are very large. Mike (hoping that i had not some brainfart)