Audible VCO signal Without Touching any Keys

[alan bg]

I too have this problem. Very frustrating indeed. Also, having just now updated the firmware i find the sequencer no longer plays ! I have tried resetting to defaults and recording new sequences but to no avail. Silence is all
Any ideas?

[alan bg]

Ah...ooops. Scrap the sequencer comment....somehow changed to Step on....Gate in the software without intending to . sorry , honest.

Audible vco comment still holds tho

[Activ-8]

Hi guys.
I returned mine and got a new one without the VCO noise  It's a lovely machine!

dude i need you to please study your new microbrute and make sure you have absolutely no vco noise/bleed because if this fact is true with your new microbrute then i'm getting mine replaced!.. for some to have this bleed and others not to is unacceptable!.

[derpityderp]

I have a similar problem to the many described here.  My microbrute plays the tone of the last key I pressed (continuously, even after the key is released, until a different key is pressed) when all the oscillators, filter, resonance, etc. are set to zero.  It's worse in the headphones and when the volume knob is set between 1 and 3 o'clock.  It's not hum or noise.  It's a tone, and its pitch can be modulated by the LFO, although changing the position of other controls besides the volume and LFO does not affect it.  I didn't expect to get a perfectly quiet machine for $300.  My Monotrons, for example, hiss and hum a bit.  But this is different and quite distracting.  I like the Microbrute a lot otherwise, but I'm disappointed with this defect, which seems to be quite common from what I've read on this forum.

[darkflow]

Ah...ooops. Scrap the sequencer comment....somehow changed to Step on....Gate in the software without intending to . sorry , honest.

Audible vco comment still holds tho

This happened to me too updated the firmware and I thought it killed the seq. Took me a while to figure out that the firmware update changed the setting on me haha. This should be changed in a future version.

[dhdaniel]

I have a similar problem to the many described here.  My microbrute plays the tone of the last key I pressed (continuously, even after the key is released, until a different key is pressed) when all the oscillators, filter, resonance, etc. are set to zero.  It's worse in the headphones and when the volume knob is set between 1 and 3 o'clock.  It's not hum or noise.  It's a tone, and its pitch can be modulated by the LFO, although changing the position of other controls besides the volume and LFO does not affect it.  I didn't expect to get a perfectly quiet machine for $300.  My Monotrons, for example, hiss and hum a bit.  But this is different and quite distracting.  I like the Microbrute a lot otherwise, but I'm disappointed with this defect, which seems to be quite common from what I've read on this forum.

same here. sent a message to tech support. they said: "CAn you make sure that the switch on the back of the unit is set to KBD?"

I don't see a switch labelled as such on the back of the unit. They also mentioned that it could be caused by a grounding issue, and asked me to explain the setup, which is just headphones. Someone suggested it might be "dirty power", so I hooked it up through a power conditioner. That did not solve the problem.

They haven't replied to me since I sent a message on the 3rd, so I thought I'd try here. If I find the issue to be too detrimental, do I send it to Arturia or to the music shop from which I purchased the unit for a refund?

[achtungmark]

I have exactly the same problem, a little annoying I must say. Am running mine from headphones out to the analogue in on my Xone DB4. Can't say that I've noticed much change while changing the master volume control either.

[kikendo]

I hear this too, I can hear like background noise, from Master volume positioned at 9 o clock all the way to almost the end, with the loudest being at about past 1 o'clock, summed to a faint VCO bleed (I can pitch it with the pitchbend wheel).

When volume is at max, it goes away.
The VCO bleed doesn't bother me, but the background noise does!

[shawbro]

I have found that by turning the master knob all the up to full the vco bleeding disappears. It's very present between 2-8 say. I'm also using the line out. I don't notice it much in the headphones output.

[astraltraveler06]

I am glad to see this is a common problem. Mine also has it.
I have owned many analog synths and, although you can expect a bit of a noisy signal, this "ghost VCO' phenomenon is unacceptable for any synth, no matter the price point. It makes it virtually unusable, particularly in a live, amplified setting. I get the feeling the problem is in the Master Volume potentiometer itself. If it was a crosstalk problem, it would be present throughout the volume range but, as other have noted, it only occurs between 10 and 2 o'clock.
Arturia needs to find a solution to this problem and soon, otherwise they'll be facing massive amounts of returns on this otherwise wonderful little synth.

[pabloevaristo]

No problem here.
But I also think the price is not an excuse for that kind of issues. It's a manufacturing problem, I think, because some of us have it and othes don't.
Sad about that (glad about me! )

[kassu]

Just to add my findings: I found the same VCO bleed problem with a unit when trying it out in the store. I then asked for a second unit, which had no problems (and which I then bought, no VCO bleed in any headphone/mixer configuration so far).

The problem in the store unit sounded very clearly like some electromagnetic coupling between the VCO and the output circuitry. It was not affected by any filter/mod settings, and also not by any VCO settings, so I assume there is a fundamental square or pulse VCO internally that is always on and from which the other wave shapes are derived. Square wave/pulse signals easily couple to anything else, because they contain so many high frequency components.

It would be best if someone with this issue is willing to experiment a bit with his/her microbrute. Since Bruno here suggests these signals are going through ribbon cables, it is quite likely that the problem can be solved by just opening up your MB and moving the ribbon cables around a bit. Maybe just opening and closing the box again is enough, with a bit of luck.

[Bruno@arturia]

The problem in the store unit sounded very clearly like some electromagnetic coupling between the VCO and the output circuitry. It was not affected by any filter/mod settings, and also not by any VCO settings, so I assume there is a fundamental square or pulse VCO internally that is always on and from which the other wave shapes are derived. Square wave/pulse signals easily couple to anything else, because they contain so many high frequency components.

It would be best if someone with this issue is willing to experiment a bit with his/her microbrute. Since Bruno here suggests these signals are going through ribbon cables, it is quite likely that the problem can be solved by just opening up your MB and moving the ribbon cables around a bit.

indeed, I thinks it's coupling between two ribbon cables, you should open the machine and move the ribbons so that they are not perfectly parallel, coupling is should be much attenuated with an angle between the wires.

[JayBee808]

I've been watching this thread unfold, mine HAD the same issue but was past the return period...

I was feeling ambitious after rebuilding a Wurlitzer last month so I tore the MicroBrute apart.  As suggested in the previous few posts, this is an issue with the ribbon cables inside.

The good news is this was an easy fix, the most time consuming bit being removing the screws.  You don't need to remove any knobs, the ribbons are accessible under the bottom panel.  There are a couple of very thin ribbon cables near the envelope controls.  The one folded back under the envelope sliders is the offender.  I plugged the unit in, played notes and moved the ribbon until it became quiet.  I did find a spot where the noise got louder, so it is highly likely that some of these are shipping with the problem way worse than others.

Bottom line, it is an easy fix and I didn't have to go a day without my Micro.  It's unfortunate that we have to deal with this at all but for a sweet synth, I won't complain.

Good luck!
-J

[Ptr]

I also have this, between the 11 and 2 settings of the master level knob it's the most audible. So, what's the recommended course of action: contact the shop, Arturia costumer service or just (have someone) open te unit and look at those ribbons. I am not technically able myself, but I could let my father have a look, if it does not require specific insight but rather general technical feeling.

However, won't I void my warranty when opening the unit?

Thanks!