The M2 Output Stage in Class A/B, and maybe a Power WHAMMY?
- Thread starter EUVL
- Start date
This is only to illustrate how it works.
The LT1010 represents a unity gain buffer, which of course can be the M2OPS.
Note that Vin must always stay well between V+ and V-.
Only think about actual application when you have it working on breadboard.
In the test case, you need to remove the LT1010, as it will not survive 25V rails.
Patrick
.
The LT1010 represents a unity gain buffer, which of course can be the M2OPS.
Note that Vin must always stay well between V+ and V-.
Only think about actual application when you have it working on breadboard.
In the test case, you need to remove the LT1010, as it will not survive 25V rails.
Patrick
.
Of course it works.
What else do you expect.
Look at the base current.
Patrick
What else do you expect.
Look at the base current.
Patrick
Just a quick layout, not proven; so build at own risk.
You should check against the Spice circuit using your Gerber reader.
Then suggest you use 1mm thick PCB.
It can go directly on top of a DIP8 pin header, which you should solder first of all.
The SOIC single opamp should go on last.
And it should fit directly onto the opamp location on the Power Whammy PCB.
You need to route the OPS output and Gnd to this adaptor board.
Resistors and Zener are 1206 / MELF footprint.
Caps are 1210. Opamp SOIC8, without saying.
Patrick
.
You should check against the Spice circuit using your Gerber reader.
Then suggest you use 1mm thick PCB.
It can go directly on top of a DIP8 pin header, which you should solder first of all.
The SOIC single opamp should go on last.
And it should fit directly onto the opamp location on the Power Whammy PCB.
You need to route the OPS output and Gnd to this adaptor board.
Resistors and Zener are 1206 / MELF footprint.
Caps are 1210. Opamp SOIC8, without saying.
Patrick
.
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Patrick
sorry...i do not want to blame you.
you are an expert/designer.
i am not worry that it is not working what you are posting.
chris
After the sound sessions I pushed the task to make the comparison more fair and with equal parts for the comparison Fairchild vs. Toshiba
1) Preamp BA-3 with Fairchild: Change from Glassware 18V to Mark Johnson´s VRDN and 20V (as it is in The Toshiba Pre)
2)Power amp got the modification for opamp rolling, e.g. my loved OPA828.
After modification I measured the usually things, BW, load, gain,.....reactive load....
during testing I discovered an oscillation problem with the OPA604 and OPA828, but NOT with OPA551 and LT1793.
results: - pls also look at datasheet of these opamp´s
OPA551 has a CLBW of only about 50kHz with a small drop
LT1793 has a CLBW of only about 100kHz with a harder dropout of gain.
therefore a test with a load 8R//100nF to 300nF got NO issue.
But I want to have my favoured opa828 and due the fact that the CLBW is more then 420kHz I have to find a solution..
Run a load test with 8R//100nF I got oscillations, also low pass filter on my signal generator (2k and 220p) does not help!
changed gate stopper to 470R and Oscillations come little bit down but present oscillatioins at about 666kHz...
I decide to reduce the CLBW and set a Mica 22pf in parallel to RFB2 isolated with a kapton tape.
this shows a -3db point at 8R load about 159kHz with opa604 and with opa828 I measured about 163kHz.
So a reactive load with 8R//200nF with no sign and a small blip only on input with 8R//300nF..
The opa604 setup is now with bias 1,42A (0R562) and gate stopper 470R and now with 22pf//Rfb2
with 8R gain 22,27dB; 10,23W@8R, clipping more then 700Vrms input; fg about 159kHz
with 4R gain 22,23dB; 19,29W@4R clipping more then 680Vrms input; fg about 150kHz
next: sound comparison now......for short I can now say after 6 hours of listening they come very close.
It is amazing how Fairchild power amp with opa828 do the dry and controlled bass in e.g. "Victor Wooten´s -the loniest monk"
1) Preamp BA-3 with Fairchild: Change from Glassware 18V to Mark Johnson´s VRDN and 20V (as it is in The Toshiba Pre)
2)Power amp got the modification for opamp rolling, e.g. my loved OPA828.
After modification I measured the usually things, BW, load, gain,.....reactive load....
during testing I discovered an oscillation problem with the OPA604 and OPA828, but NOT with OPA551 and LT1793.
results: - pls also look at datasheet of these opamp´s
OPA551 has a CLBW of only about 50kHz with a small drop
LT1793 has a CLBW of only about 100kHz with a harder dropout of gain.
therefore a test with a load 8R//100nF to 300nF got NO issue.
But I want to have my favoured opa828 and due the fact that the CLBW is more then 420kHz I have to find a solution..
Run a load test with 8R//100nF I got oscillations, also low pass filter on my signal generator (2k and 220p) does not help!
changed gate stopper to 470R and Oscillations come little bit down but present oscillatioins at about 666kHz...
I decide to reduce the CLBW and set a Mica 22pf in parallel to RFB2 isolated with a kapton tape.
this shows a -3db point at 8R load about 159kHz with opa604 and with opa828 I measured about 163kHz.
So a reactive load with 8R//200nF with no sign and a small blip only on input with 8R//300nF..
The opa604 setup is now with bias 1,42A (0R562) and gate stopper 470R and now with 22pf//Rfb2
with 8R gain 22,27dB; 10,23W@8R, clipping more then 700Vrms input; fg about 159kHz
with 4R gain 22,23dB; 19,29W@4R clipping more then 680Vrms input; fg about 150kHz
next: sound comparison now......for short I can now say after 6 hours of listening they come very close.
It is amazing how Fairchild power amp with opa828 do the dry and controlled bass in e.g. "Victor Wooten´s -the loniest monk"
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I suppose OPA828 is on some SOIC to DIP adapter. You could try to add 100 nF capacitor across +- supply pins on the adapter bottom. It could help (or not).
What are pins 4&7 in DIP8 socket for ?
Patrick
Patrick
Really ?
What are DIP8 pins 4 & 7 on your PCB connected to ?
Have you not removed your LM329's ?
Why would you still need them ?
Patrick
What are DIP8 pins 4 & 7 on your PCB connected to ?
Have you not removed your LM329's ?
Why would you still need them ?
Patrick
