No, ordinary power supply is OK. My active PSU regulator contains needed protection, as loudspeaker protection, overload protection, but you can use any other suitable protection.
I did some quick simulation, first AXL in class B(AB) and then with some TPC compensation. Original AXL is typical low negative feedback amp with high LTP degeneration and VAS resistive load. To use TPC efficiently it need more open loop gain and this amp is not good example where is easy to achieve that. I decreased LTP degeneration, increased LTP tail current and lowered VAS load.
This is THD at 30W/8ohm:
AXL THD1k =0.0057%, THD10k =0.037%, THD20k=0.077%
AXL mod THD1k=0.00029%, THD10k=0.0069%, THD20k=0.0212%
Used Cordell's models.
THD at 1 kHz was lowered a lot, but THD20k was not lowered so much.
This amp is nor very suitable for TMC or TPC.
Attached LoopGain plots of both amps.
Damir
This is THD at 30W/8ohm:
AXL THD1k =0.0057%, THD10k =0.037%, THD20k=0.077%
AXL mod THD1k=0.00029%, THD10k=0.0069%, THD20k=0.0212%
Used Cordell's models.
THD at 1 kHz was lowered a lot, but THD20k was not lowered so much.
This amp is nor very suitable for TMC or TPC.
Attached LoopGain plots of both amps.
Damir
Attachments
Damir, my thought was to insert a driven cascode (Hawksford) in the driver stage, that will remove a lot of the charge the driver needs to throw and youll get a lager open loop bandwith and a much better higer frequency performance. Normally I never chase performance through different compensation, to me it's most often better to try to get the effects of device capacitance out of the circuit.
I really like the shunt feedback in a way it's purer.
I really like the shunt feedback in a way it's purer.
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Michael, I understood Joachim wants to change the compensation to TMC or TPC, not to much change the circuit.
By the way, semiconductor capacitances are not linear and are one of distortion reasons. I prefer multipole compensation over simple Miller compensation. I am very satisfied with the sound of my CFA using complex compensation.
I simulated AXL with TMC with less success, THD20k and THD10k was only twice better then ordinary AXL amp, THD1k was much better, but I came to conclusion that without changing radically the circuit TMC is not worth here.
R31+C14 add too much HF loading to the output stage.
If you keep this as the sole Output Zobel, then I suggest you investigate adding about 4r or 5r in series with C14.
Alternatively look at adding an Output Zobel from Output device output rail direct to Supply Rail Decoupling Ground (Power Ground) with ~10r+100nF and keep your second Zobel after the output inductor but this time add ~9r in series with C14.
If you keep this as the sole Output Zobel, then I suggest you investigate adding about 4r or 5r in series with C14.
Alternatively look at adding an Output Zobel from Output device output rail direct to Supply Rail Decoupling Ground (Power Ground) with ~10r+100nF and keep your second Zobel after the output inductor but this time add ~9r in series with C14.
Agree, My mistake with the Zobel
Damir AXL mod THD1k=0.00029%, THD10k=0.0069%, THD20k=0.0212%
MB AXL-mod THD1k=0.000161%, THD10k=0.001753%, THD20k=0.005964%
+/-20V output swing.
JG- I dont know what you a looking for, one thing that is really different here is the shunt-feedback (I like) the shunt feedback can also be used for compensation in the feedbackloop .
I put in some matched biss transistors in the input, then you can degenerate less and thus have more gain.
Damir AXL mod THD1k=0.00029%, THD10k=0.0069%, THD20k=0.0212%
MB AXL-mod THD1k=0.000161%, THD10k=0.001753%, THD20k=0.005964%
+/-20V output swing.
JG- I dont know what you a looking for, one thing that is really different here is the shunt-feedback (I like) the shunt feedback can also be used for compensation in the feedbackloop .
I put in some matched biss transistors in the input, then you can degenerate less and thus have more gain.
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