pfm2 with yellow OLED : high frequency solution

[Xavier]

Without the modification described in this thread., some people hear this peak.
As you use PCB R5d you already have step 1,2,3 done by just soldering the 22ohm OLED resistor, so the peak is smaller that it was on PCB R5c.
If you make a shield as described it will be even smaller.

[kylelandstra]

Just a quick question on the aluminum shield mod:  Do you just stuff the bag between the OLED screen and the PCB?  Do you secure it all?  Is it okay if the bag is touching the board?

[Xavier]

Just a quick question on the aluminum shield mod:  Do you just stuff the bag between the OLED screen and the PCB?  Do you secure it all?  Is it okay if the bag is touching the board?

As far as only plastic touch the board it's totally OK.

[mmontag]

I definitely noticed the squeak after upgrading to OLED, but the shield fix was easy and effective. No extra soldering needed with the recent board revisions. Thanks Xavier.

 

[served]

Hi.

We have now had some time to test the noise issues.

Some remarks:
We have tested various inductors, to look for a low-noise unit that may have some better characteristics. No success in practice.

We have stopped producing and adding the metal sheet behind the screen. It shields the noise from the audio, but produces a new issue. Physical noise in the unit.

So the new Rev2 solution is a Aliuminium tape + coppertape with soldered cable and grounded + Plastic tape for isolation.
A Grounding cable will give you better shielding properties.

We are now basically following Xavier solution except added a GND cable.

[sixbyseven]

Sorry, (I am new to this conversation), if these questions don't seem relevant.

1) Does this same signal (around 14Khz) appear when the OLED is in sleep mode (blank).
2) Has anyone tried a different colour OLED (example:Blue) from the same manufacturer?

Thank you,

Todd

[Godric]

I made a shield as described, which seems to be working (at least I'm not aware of any noise). I was then sent a shield by Ardi at Vandaal, as it (and a volume knob) had been missing from the kit when it was posted out.

I notice Ardi's shield has a wire soldered to it and I assume that the other end needs to go to Ground or 0V. Any suggestions about the best place to solder this shield to?

Godric

[Godric]

I'm assuming the power connector ground would be a good place?

[lokki]

yes, that would be ok.

[molpho]

Hi! I bought a Preenfm2 from Van Daal. I'm really loving it, but I hear the "OLED noise" and since I don't know anything about soldering and DIY I was wondering if there is a way to delete that freq without affecting the timbre of my patches... may I use an eq? could be enough?

[clément]

If you are monitoring through a DAW you may use an EQ around 15.5 kHz with a really narrow bandwidth, that will work and should be quite discreet.

[molpho]

Thank you clément, I'll try to follow your advice!
Althought maybe I'll look for someone in my region capable to accomplish Xavier's trick.
thanks again

[ladyday]

Hello to all!
I am a newbie here.
I bought an assembled blue preenfm2 and I can hear the high noise that you are talking about.
It seems that if I use earphones it disappear.
Now, my problem is very big: I can't solder and I have no one that can help me.
The noise is a big problem to use the preen in the studio.
And now I have to use it in Conservatory too for my studies.

PLEASE: CAN YOU HELP ME?!

THANKS A LOT

[Xavier]

EDITED : i thought it was a blue OLED. Seems like it's a yellow OLED in a blue metal box

Hello,

I have a blue OLED and it makes lots of noise (not the 13.5Khz noise though), unfortunately i don't have a solution for the blue OLED.
The only solution you have if you cannot modify the hardware is to have a look at the noise with a spectrum analyser and set an EQ to remove it.

Xavier

[served]

We will solve it. Its a yellow OLED screen.

Hello to all!
I am a newbie here.
I bought an assembled blue preenfm2 and I can hear the high noise that you are talking about.
It seems that if I use earphones it disappear.
Now, my problem is very big: I can't solder and I have no one that can help me.
The noise is a big problem to use the preen in the studio.
And now I have to use it in Conservatory too for my studies.

PLEASE: CAN YOU HELP ME?!


THANKS A LOT