This is a good paper on op amp decoupling, and it also shows why replacing op amps in a circuit can come with side effects. https://www.analog.com/media/en/technical-documentation/application-notes/AN-202.pdf Thius has some good words on cap choice. https://www.analog.com/media/en/training-seminars/...

38V on the front end, 51V on the power stage. Of course I don't know the circuit, but what is the point of having lower voltage on the driver than the output stage? Normally the output stage is limited by the headroom of the driver stage. I would have thought that pair of voltages would only give t...

38V on the front end, 51V on the power stage. Of course I don't know the circuit, but what is the point of having lower voltage on the driver than the output stage? Normally the output stage is limited by the headroom of the driver stage. I would have thought that pair of voltages would only give t...

:grin: You are of course correct Nick and your views are always welcome. I was relying on others who had done the same with the same cdp and regulator (which they knew inside out) and who had sillyscopes. This opamp based feedback regulator was well known to cause issues for the unwary especially i...

True. My thoughts and those of others on pfm (who were far more electronics aware than me) were that the inductive nature of the output of the regulator needed a bit of resistance (provided by the extra wiring) to prevent oscillation with the low esr caps that are decoupling at the input of the opa...

It was interesting in the sense that i learned a few things

Without want8ing to be awkward, I don't know exactly what you could have learnt from that without a scope to see just what was actually happening.

karatestu wrote: ↑Sun Jan 12, 2020 12:10 pm Hi Nick. We are talking about two psu's on the same channel (front end and output stage) not two separate channels.

Ok. Point taken.

May be missing the point but as they are class II why connect the 0v from the two channels together at all?

Most anything I buy should measure acceptably. That means it won't go unstable, go on fire, put a lot of DC through my speakers etc. I agree, unfortunately none of the measurements that are normally published for a amplifier will cover any of those cases. There are a number of things you do during ...

Any business wants the largest possible customer pool to sell into, unless they're stupid. That assumes fully informed and rational behaviour on the part of all parties. I don't publish numbers for the power supplies I make for the same reason as NVA, In reality the numbers are good enough, but wha...