Blueprint - Optimize Noise Reduction for the PT2399

[Aentons]

I ordered regular 47u electrolytic caps for the Blueprint without really thinking about it. These are the two power decoupling caps right off of pin 1(V+) and 2(Vref) of the PT2399.

Would low-ESR aluminum electrolytic or tantalum caps work better here to help minimize the pt2399 noise at longer delay times?

[Aentons]

I ordered these caps to try for decoupling pins1/2:
Nichicon 10v 47uF - 4x11mm (tall and skinny) - Low Impedance (ESR) caps
https://www.mouser.com/ProductDetail/647-UPW1A470MDD6

I noticed I had regular caps on the switch board as well so I ordered some of these too:
Nichicon 16v 47uF - 5mmL type (Low Profile) - Low Impedance (ESR) caps
https://www.mouser.com/ProductDetail/647-UMF1C470MDD

This chart came in very handy for tracking down the right ones.
https://www.nichicon.co.jp/english/products/pdf_r/Standardization_p12e.pdf


I also noticed that the Production VFE builds use a LP2950 for the 5V regulator. I'm going to replace the 78L05 I used and see if there is any noticeable noise reduction. I'm hoping the combination of the low esr caps and the lp2950 will make a difference.

This is the relevant noise related info from the LP2950/KY5050 datasheet:

Cap Minimum ESR = (stated as required: 12 mOhm) OR "minimum ESR to approximately 20 mΩ to 30 mΩ"
Cap Maximum ESR to approximately 5 Ω
...
"On the 3-pin LP2950 device, noise reduction can be achieved by increasing the output capacitor, which causes
the regulator bandwidth to be reduced, thus eliminating high-frequency noise. However, this method is relatively
inefficient, as increasing COUT from 1 μF to 220 μF only reduces the regulator's output noise from
430 μV to 160 μV (over a 100-kHz bandwidth)."