Axoloti noise problem

#1

Hey smile

@johannes : after spending most of my weekend playing round with Axoloti, I must I am really really really impressed with it. I cannot believe that a 60 euro device can do so much. Can't wait to see what the future brings for it smile

But I was wondering if anyone have noticed noise from Axoloti when it is connected via USB? It only happens when it is connected to my laptop, not my desktop, so I am thinking it might be a groundloop?

Would the groundloop be eliminated if Axoloti uses an external power source and not the Micro USB port?

#2

Are you using the line out (big jack) and are you using a stereo split cable? What equipment is connected to Axoloti?

#3

I am using the big line out and using a stereo split cable. There is no other gear connected to axoloti.

As mentioned it only happens when using my laptop. I use the same cables for desktop setup and it works so therefore I am pretty sure it is not the cables. I just noticed that when I disconnect the power supply from the computer the noise/crackles stops. The noise is nonly there when power is connected.

And also I noticed that the Axoloti app also brings my computer to the knees. The processor runs totally wild. When Axoloti app is launched the processor goes to 150% and then drops again to around 40-70%. And that means mine fan of the laptop is running all the time..

My Macbook is an older version that runs OSX 10.7.5. Another user said he had a lot of the same problem that me and he end up buying a new laptop for it, but I would really like to avoid that since I dont really have the money at the moment.

But I am starting to blame the older White Macbook model of being a huge part of the problems I have had for now...... Anyway, any suggestions to work around these problems without having to buy a new laptop would be great smile

#4

Hint: I've had a similar problem. Pelease make following check:

Could you hear the sound when you run you laptop on batteries without any powers supply? I had this problem with bad power supplies more so often. The switching power supplies can create very dirty noise.

#5

@hesspet

It only happens when the power supply for the laptop is connected. When the power supply is not connected, there is no noise. Did you figure out how to solve the issue?

#6

Does the USB cable your using to connect it to the laptop have a 'choke' on one or both ends? If not might want to try one that does.

#7

@ModernKaos

On both ends. Does that matter?

#8

@jaffasplaffa

The USB cable above can help to reduce a little bit noise. But if it's heavy noise, no chance.

You ask: Did you figure out how to solve the issue?

Yipp. on stage I drive my Laptop with a big fat car battery smile when I use my DIY stuff. No yoke.... no noise, silence..., no ground loops etc. smile

You can try to change the power supply with a new one. But the chance that this solve issue is not very good. Most laptops are not really "music aware".

My question is: Do you hear a hum or is it a sort of white noise?
HUM: A ground loop problem is possible. Hard to solve
NOISE: Bad power supply. Laptops have a switched power supply, which works with high frequencies. This is what you hear. Bad design of the PSU. If the design in bad, you have a lot of dirt in the power lines. Often the 5V of the USB are directy tranfered from the power supply to the USB jack,

One thing you could try: Open the USB cable, cut the red wire (the 5V) and drive your axoloti with an external wall wart power supply. So the Axo is no more driven by the power from the Laptop and the data lines are intact. This should work.

The basic problem is the power supply/laptop combination.

All my solutions here are hacks around this problem. So best is buy a better laptop smile smile e.g I bought a used used Lenovo Business Class Laptops which work very well in my music labratory.

#9

You can also try a powered usb hub.

#10

Axoloti Core cuts USB power when you provide it external power through the DC barrel connector. Using an external power supply may help, but cutting the red wire will not.

Don't think this will help.

@jaffasplaffa Does your laptop powersupply have an earth pin? I ask since I think I have seen macbook supplies with and without.

One solution is using a USB isolator, like
https://www.olimex.com/Products/USB-Modules/USB-ISO/

Another is using an active or passive DI-box, a common practice when using onboard laptop audio in professional setups.

#11

The reason I mentioned that is that some of the nicer ones have isolated power lines.

#12

@herrprof can't isolate ground without isolating the USB data lines too.
I'd be surprised if any consumer hub really isolates USB.

#13

so what if you use a different usb chipset, like one on a thunderbolt dock? Would that remove it from the internal noise in a pc case?

#14

Thank you for your answers smile

Of vourse getting a new Macbook would be awesome, but ATM I dont have 1200 euro to get one. I will look into these different solutions.

#15

if the noise is a digital noise like 'cpu computer at work',
I have a similar problem with the teenageengineering op1 (and before with the blofeld)
and i have solved with this galvanic usb isolator. It don't affect the sound.

https://electronics-shop.dk/usb-isolator

#16

@urbanspaceman

I also have Blofled also with same noise problem. Bu the noise from Axoloti is waaaay louder than what get from Blofeld. Anyway, I guess I am going to have to get one to test if it works. Could use it for the Blofeld too.

#17

is this a hum or white noise?
how do you connect the audio output, and to where?

if your not using stereo output, perhaps you could send as a balanced output.

#18

I am using the Stereo out to FF400 in. I have the right cables. But i see another user had same problem with old laptop. When the power supply is connected to the laptop it makes alot of noise.... like hum and crackles combined... BUt works perfect on my desktop... Anyway... I am selling some other gear so I can buy a better computer smile That will hopefully solve most of the issues I have had smile

Anyone interested in A Nord Micro Modular or a TC M-One multi effect? smile

#19

Ground loops are not necessarily cured by a newer laptop. Could you try your laptop with a laptop supply from a friend?
Could you try powering the FF400 (RME FireFace?) with an external power supply (rather than bus power)?

I feel really sorry about the ground noise, I made efforts and believe it resulted in significant improvements on ground loop noise immunity, within a constrained budget and surface area.

#20

do 'crackles' come from ground loops? I've only ever heard a hum...