Messages

61

preenfm2 and preenfm3 / Re: Hello, new to the board :) / High frequency parasite?

« on: October 04, 2014, 12:12:28 PM »

Hello everyone,


First of all thanks a lot for taking the time to reply!

Unfortunately so far my research wasn't very successful… I tried to put a big electrolytic cap across the spot you talked about Xavier but the reduction is not enough for me I'm afraid. Didn't get great success around the 220uF neither.

Mmarsh: indeed I found a topic in the Mutable community, the idea was to put a cap at the spot Xavier was referring to, but straight on the OLED pins, which I tried also.

Martin: I suppose I'm a bit over-sensitive in this frequency range, but I'm sure my synth is somehow faulty, I'm going to double check again the soldering because I'm usually not really difficult with background noise.


I did find one solution that works 100%: plug the PreenFM through a passive D.I. with GND Lift. Like this I have a regular background noise, there might be this frequency a bit stronger (when you know it), but it's more than reasonably quiet!


EDIT: I forgot, does anyone know of a compatible non-OLED screen?

62

preenfm2 and preenfm3 / Re: Hello, new to the board :) / High frequency parasite?

« on: October 03, 2014, 08:17:27 PM »

Thanks Martin, I think the OLED seems to be exactly the problem. I just checked on google and the first answer is from… the Shruthi community! I have never noticed this on mine because I don't have an OLED screen it seems (I have to say the screen of the PreenFM looks so nice!). Anyways, some people have been struggling with the same issue, there's even someone who measured it around 15kHz so I guess I'm getting close. I can confirm that in the last 5% of the Volume course it gets worse, but still, to me it's not usable like this on a long term.

Although I was sure of my soldering I soldered again everything with no result. If I'm patient enough I might take the screen off and take a listen…

To be continued!



EDIT:
OLED removed => no more noise!
Now I have to find a way get rid of it because I do need the screen

63

preenfm2 and preenfm3 / Hello, new to the board :) / High frequency parasite? [workaround found]

« on: October 03, 2014, 06:27:29 PM »

Hello everyone,

My name is Clément, I'm from France but relocated for a few years in Brussels.
I put my PreenFM2 (got the metal box kit) yesterday and could not stop playing with it since! I can not say how much I am pleased and impressed by everything. The design of the case if wonderful it's amazing to have such a nice piece of equipment kinda half DIY. The sound is great, the navigation easy and the program on the computer makes it even easier to create sounds, even for a total FM noob like me


Since I completely fell in love after such a short time of using it, I also have to report something that is bugging me, and I haven't seen this problem reported so far…

I have a high frequency parasite, kinda like this more or less 15kHz old TVs were producing. It's not that loud, be enough to drive me crazy and not to use it on stage.

I tried all kinds of plugging, with & without USB, power adapter, and even a 9V battery, so I'm 99% sure it comes from the PreenFM.

It's here always at the same volume wether I turn the Vol knob up or down, so I would guess it's not exactly on the signal path, but more in the Ground?


Has anyone experienced this? Any idea what could be the source of this parasite?



And here's a picture of my build, just for the pleasure