On 15/06/2021 13:45, Dave Plowman (News) wrote:
In article ,
Peter Able wrote:
On 15/06/2021 00:17, Dave Plowman (News) wrote:
Shame you can't point us to the circuits. Even with your extra notes,
above, there are still many questions arising - not least if your notes
are incorrect. (It does happen!)

Most Op Amps applications are inherently PSU-ripple insensitive.

They are a design from Elliot Sound Products. But the published schematic
doesn't show the supply rail side of the design. You have to buy the PCB
to see it.


Assuming that Fredxx has the right link, I think that you should take it
with a little pinch of salt. An article originated 2000, referring to a
50+ year old Op Amp design (great advance though it was) is the first
hint. Concerns about supply impedance at audio frequencies is another.
If the guy was writing about designing with Dynamic Memory, then he'd be
closer to the mark. A bit OTT for audio.

I'd not read that article before.

Incidentally, you attack power supply noise at the power supply. I
wonder if the last components in your proposed PSU are - electrolytic
and / or other capacitors across the outputs.

The PS shown is fairly typical of a regulated analogue type designed for
use with audio circuits.

And it has some C at the LV output(s)?

PA

PS those of us in engineering at that time were so grateful to see the
741 kick the 709 out of designs.