XL6009 based DC/DC Converter for sensitive audio voltages like e.g. phantom power?

[rock soderstrom]

Hi guys,

modern switched-mode power supplies are slowly arriving in my lame tube audio world. Lately, I've been trying to question my cherished habits and take a different approach to realizing my projects.

Out of curiosity, I bought two of these DC/DC up converter boards on aliexpress.

https://de.aliexpress.com/item/1005...t_main.11.21ef5c5fshABJR&gatewayAdapt=glo2deu

As supplied, these boards can convert over 38V from 9V. The promised 52V can only be achieved after a feedback resistor hack.



52VDC minus some filtering makes good 48V?

What do you think, are such boards suitable for obtaining a clean phantom voltage from lets say the heater voltage (or a separate DC voltage)?

Could you heat an unusual single tube (P or U tubes) with these boards to operate them with other conventional E-tubes?

...or would it be better to stay away from such solutions, as they contaminate everything in their vicinity with HF noise?


20mV/5muS per division, Vout=24V

What do you think? Does anyone have experience with this?



PS: I'm a beginner with this stuff and have almost no experience with it. So, dear experts, bear with me. (Yes, you too Khron )

 

[rock soderstrom]

I played a bit more with the DCDC converter board and would like to show my new findings here.

I simulate a phantom power supply, since the board is not yet hacked (I don't have the right SMT resistors yet), here only with approx. 38V instead of 48V.


My test circuit looks like this, I have installed an RC filter to see what effect I can achieve with it.



What is noticeable (at least to me) is that the switching peaks of the DC DC board rise sharply with a light load (such as an LDC microphone).

Comparison idle vs light load without filter: (20mV/5muS)


Here now with light load and 50mV per division

Now the 470R/4700uF filter comes into play and clearly shows its effect (again in the original 20mV setting!)


To make the signal more visible, now in the highest resolution of my scope 5mV.

For me this is pretty interesting