Permanent noise floor on stereo output (not affected by master volume)

Brute PolyBrute
#1

Hi there,
I have a permanent noise floor on the stereo output of my polybrute 12, around -60 dB FS, wich modulates a bit. I have the same result with ou without a DI box (as the output are unbalanced), or using a different and clean power line. The preset volume or even the master volume doesn’t affect it. Not a big deal, but as a very few user mentions this, should I consider it as normal ? Here is a link to a short recording (stereo wave 48/24) with and a +30 dB gain applyed (don’t worry it’s not so loud) : https://www.dropbox.com/scl/fi/9nrwkgn3zyfwhh2sx755o/Polybrute-12-Noise-Floor-01-30.wav?rlkey=kxcz95eu68s13ub4ydohq1np3&dl=0

#2

Hi @zikayan

Do you have USB connected at the same time? I have one or two devices, one in particular that’s actually unusable, unless i use a USB power bank.

#3

Hi matjones, thanks for the suggestion, you’re right, usb can generate noise in some setups. Unfortunatly unplug it was not the solution, same noise still here.

#4

Hi @zikayan
Ah, that was worth a try!

I think it sounds like it would be an idea to log into your account to discuss with Arturia Support.

HTH!

#5

Hi @zikayan,

Honestly, A -60 dBFS stereo noise floor that slightly modulates, unaffected by master/preset volume, and unchanged by DI boxes or power lines is kind of expected for an analog-path massive polysynth like PolyBrute 12 .

What you’re hearing is almost certainly post-VCA / post-voice analog circuitry noise, not gain staging, grounding, or digital artifacts. A -60 dBFS measured at the converters is actually very typical for a wide, expressive analog polysynth.

In a mix, this noise floor will be irrelevant. And in solo parts, you’ll only hear that if you normalize a ton like +30dB like you did.

#6

Hi Lily, I agree ! This floor noise is not a big deal, and it says the beast is alive :slight_smile: I was just wondering if it is normal, or if my Polybrute didn’t have a malfunction.

#7

Yes it’s normal ! and yes, it is indeed alive :smiley:

1 Like
#8

All analog gear has latent background noise. If you think transistors and ICs are noisy don’t try valve / tube gear. :slight_smile:

It’s kind of why I find the current obsession with ‘high definition’ audio a bit crazy. Oooo my 192kHz audio device has a 120dB S/N ratio. That’s nice. TF are you recording with it, cricket farts?

#9

Jon you’re absolutly right, and that’s for sure the main reason why we speak about the warmness of analog gear : generated noise and harmonics. What is a bit surprising about the Polybrute is that the master volume doesn’t affect the noise, so it is probably chained before the final amp output. I also experienced a few times a bug (?), when this same master volume button was somehow dimmed, and needed to be moved again to its original position to ear the correct level. So it seems it is also digitally controlled, in one way or another.

#10

I think the bug with the master volume has been fixed in the latest firmware. And yes, the volume knob is a digital control over the analogue volume. Presumably it controls a final pair of VCAs at the outputs, which would also explain why there’s always some residual noise even when the volume knob is at minimum.

#11

Thanks Dr, yes, sounds logical.
My Polybrute 12 is up to date (3.1.1), and this “bug” happened once or twice since the beginning of my journey with the beast.