USB noise and sampling noise

[ScroogeMcDuck]

Hi everyone...

My MC-808 is my first sampler/drum machine and there is a lot I don't know, even though I practise a lot! I discovered two things that I don't understand, and I would really like to know if there is something wrong or if it is usual for a groovebox:

When I connect the usb cable to a computer there is a constant high pitched whining sound in thew background that you can hear if you turn up the volume a bit. I need to pull out the usb cable from the computer when I record and I have to use MIDI cables instead to control it. Right now I only connect the USB cable when I need to use storage mode. IF I use the headphone jack instead of listening through my speakers connected to my mixer, there is no high pitched sound! I've heard that others had the same problem with their other Roland products such as Edirol sound cards and the X-8 and JUNO-G. Why can that be?

The other thing is that when I have the "MIX IN" button on the MC-808 lit there is a weak buzzing sound in the background (e.g. when I sample) almost like a recorder. It is very weak and sounds a little like if a mic was turned on and nobody is talking into it (or a very week wind). The moment I turn sampling off again this sound stops and the signal is completely silent. Do you hear this sound as well?

Sorry for all my text, I hope anyone can answer my n00b questions, I'm quite a beginner! Just wanna know if my MC is ok!

Thanks!!

Scrooge

[dr_boehm]

Hi Scrooge,

that noise is something that happens when no decoupling of the grounding is done. It is a normal electric effect and no fault of the hardware used.

If you experience problems (noise, humm) you need a decoupling device (in germany it is called a di-box) which has a ground lift. For a more detailed explanation of di-boxes and ground lift see

http://www.thomann.de/gb/onlineexpert_154.html

Hope this helps,

Ciao, Dirk.

[ScroogeMcDuck]

Hi thanks for the reply, never heard of a DI box before! I've read the page you linked me but it's a little hard for me to find out exactly what kind of DI box I need..

Did I understand this right?:

If I connect the jack outs of my MC-808 to the DI box's jack ins and connect the jack outs on the DI box to the mixer's jack ins there will be no high pitched noise when plugging my USB cable from my MC-808 to my PC? (If I turn on ground lift on the DI?)

Maybe this one will be a good choise?:
http://www.bluearan.co.uk/index.php?id= ... e=category

Thanks!!
Scrooge

[dr_boehm]

Hi Scrooge,

those DI-Boxes normal only help against hum 50-60 Hz.
I had high pitched noise with a laptop every time it accesses a WLAN. That was a problem of the laptop.

I am not a specialist. I think the best thing is to test it. Maybe you can order a pair of di-boxes and return them if they do not help.

Maybe also a call to roland helpdesk would give you some hint.

Ciao, Dirk.

[ScroogeMcDuck]

Thanks Dirk, I'll try calling Roland first, then I'll look for other solutions!

Peace, thanks for your help!

Scrooge

[ScroogeMcDuck]

I think I found out what is wrong. I tried connecting a normal power cable (like the ones you use for lamps etc.) from the grounding screw on the back of the MC-808 to the metal on the USB female on my PC. Then the exact same high-pitched noise appeared, even without any usb cable connected! The same happens if I connect the power cable from the USB metal on the 808 to the USB metal on the PC. I also have a MIDI/USB interface and if I run the power cable from the USB metal on my 808 to the USB metal in the MIDI interface the noise is there again! (If the interface is connected to my PC's USB). So Dirk, what you said about grounding was right! I think it is because both the USB and the power supply is grounded so that there is two groundings from the MC-808.

Some people said that you can solve the problem by using a galvanized USB isolator like this one: http://www.crupower.fi/usbgt.pdf

Does anyone know if this works? I've heard a lot of people had problems with ground loops when using their USB to connect studio equipment. The problem is that you can get these isolators nowhere. And maybe it is a DI box that I need. Roland knows nothing about it, they say that there should be no noise from the USB at all.

The weird thing is that my computer is not grounded the plug only has two legs (I live in Denmark).

And it DOESN'T help if I use a laptop that is only using the internal battery, running with no power supply. The sound is still there.

-- I don't know if it is a fault in the hardware so that I should send it to Roland for repair. I mean, shouldn't it just work perfectly by plugging in the USB and jacks? The manual says nothing about that any USB isolators or DI boxes are needed. How about you MC-808 users? Do you just connect it directly with no noise? --

Sorry for all my text.. Just wanted to know if anyone have any knowledge about this stuff..

Thanks
Peace!
Scrooge

[dr_boehm]

Hi Scrooge,

mine works fine without any noise when connected to usb. I got the same plroblems only with the soundcard of my computer not with the mc-808.

For your case: what about the amp? Is it grounded? Does the noise also come in when using head phones?

Ciao, Dirk.

[ScroogeMcDuck]

Hi Dirk!

One of my friends wanted to buy my MC-808 for the same price as I bought it (I bought it used). He didn't care about the USB noise at all. I decided to sell it to him a lil cheaper than I bought it a month ago because my uncle is giving me a brand new MC-808 because we used to make house music together. I kept asking my friend if it really was a good idea to buy it (if the noise is was hardware fault) but he insisted.

This will be very interesting cuz now I have the possibility to see if the sound will be in the new one too! You see, the MC-808 is the best sampler/groovebox/drum machine I have ever tried, I can not live without it! As soon as I get the brand new one I will tell you if the sound is in it too (so that I can maybe tell the reason, if other people should have this problem).
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I have no amp in my setup cuz I'm using powered speakers connected to my mixer. But the noise did NOT appear when using headphones or speakers connected directly from the PHONES or MIX L R out on the MC-808. It only appeared as soon as I connected the jack outs to a computer in some way; to the mixer or directly to the sound card. And it happened on all computers in every house. I've tried connecting it to 4 different computers in two houses (with other speakers), with or without mixer and the high pitched sound was there no matter what I did.

Here in Denmark we do not usually ground stuff like computers, amps and other stuff. When we buy equipment there are always only two legs on the plug and there are only two holes in the wall. So nothing is really grounded here except from in the kitchen and bathroom. I know that in some other European countries and in the US there is almost always grounding, but not here (don't know why).

This is a mystery, but maybe it will be solved when the new MC-808 arrives!

Talk to u soon and thank you very much for your help!

Peace
Scrooge

[krd]

If you're using a laptop -- pull the power supply on the laptop

The high pitch may disapear.

If it does it's caused by noise from the laptop powersupply. It's very common.

It's a real pain

[Elmusico101]

Hi Scrooge,

I'm having the same exact problem that you have but with a Juno-di synth. I have it hooked up to a Tascam 144mkII and when I connect the usb cable to a port in either my desktop pc or laptop I get an annoying hum and some high pitch sync signal. i have tried different usb cables and gets worse or better depending on the cable. I am almost sure it is a ground loop but i donno where the hell it is. All my cables are neutrik or amphenol connector/cable.

Something funny is that when i get my hand close to the tascam 60Hz humming incresases. I think is a shielding problem semi-pro equipment have.

My Tascam has balanced inputs and the juno di is unbalanced. I hooked up a Y estereo cable to the keyboard and the trs output to the tascam and It reduced the problem a lot... what I havent tried yet is to use balanced cables even though my keyboard has unbalaced outputs. I bet this will reduce the problem.

let us know if you try that.

Alex

[emphor]

Hi Scrooge,

not sure if you solved your problem, but I've run into the same issue when connecting my 808 to my MacBook. I had no issues when I had the 808 connected to my 24" iMac, it's only when I connected to the laptop I receive a hum when trying to record via Logic or Audacity.

I'm going to try and source an isolator, did you ever get your issue resolved? If so, how did you do it?

Cheers, Matt