• Registered: 2010-11-27
  • Posts: 53

Topic: Jitter and noise - but not an RME issue!

This is not really related to RME, but I'm sure a bunch of you out there have had the same problem (it's kind of common):

With my laptop plugged in, and when I'm using tube gear (Peluso 2247 and/or ADL 1500 compressor) at the same time, I can hear a LOT of digital jitter and irritating noise. I've had this prob since 2004 or something. With my old laptop I soldered a cable, lifing the ground between the computer and the wall socket. I know, that's really not what you're supposed to do, but it worked so I kept it that way. With this new laptop I've bought I wanted to do it the correct way so I bought a power conditioner from Thomann. Received it yesterday, tried it out and it made things WORSE! I tried some kind of power conditioner/linebox a few years ago and that worked like a charm, but this time it didn't. I really don't know how to solve this. Anyone with the same problem? Anyone with a solution?

I've heard that this could be a firewire cable problem, and that you could solve this issue by "bypassing" the power pins in the cable itself. I don't know if this would work on a FF800 though. What I mean is - could I strip a FW800 9-pin cable, disable (cut of) the 3 power pins and just keep the signal pins? Would I destroy my FF800, or would it just not work? I would like to get this confirmed by an RME tech before I do something stupid..

Sorry if this is not an RME issue, but as I said; I bet a lot of you have had the same problems and since this is the Firewire forum I thought I'd take it here so I (and other people) possibly could get help from the pro's!

Thanks!

Simon.

2 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
  • Posts: 25,599

Re: Jitter and noise - but not an RME issue!

You know the solution already...

The FW power is not connected within the FF 800, so modding the cable wouldn't change anything.

Please don't use technical phrases that have a clear meaning. What you experience has nothing to do with 'jitter' and you also don't hear 'jitter' in your setup. It's just hum and noise from a ground loop.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

Please don't patronize your clients Matthias (at least that's what it feels like when you express yourself in this way).

I've been taught, and I've always thought this was called jitter. Jitter for me; it sounds like a group of digital bird babies twittering like crazy when they see their mommy coming home big a big, juicy worm in her mouth. Or like a bad (and digital) replica of a waterfall with just a few drops of water.

Sorry for my bad choice of words/lack of knowledge. What can you call it then? Noise? It just doesn't seem right in my head. It's more like.. random.. digital... twittering?

So, on to the real issues; When you say that the FW power is not connected within the FF800, that means that I could cut the power (of the cable) without any worries right? I mean, it's worth a shot. I saw somewhere that some guy had done a similar thing and succeeded. He bought a 6-pin to 4-pin male (6-pin connected to his interface), to a 4-pin female to 6-pin (connected to the FW port in his computer), thus bypassing the power, since the 4-pin FW cables don't support power.. It could be worth a shot if nothing brakes within the FF800.

And no, I don't know the solution allready. Otherwise I wouldn't have posted this. What do you mean Matthias? That I once again should lift the ground? I just stated that I DIDN'T want to do it the wrong way this time. Sure, it would probably work, but I would like to solve it without it beeing dangerous, and that I would be able to get insurance money if something brakes. Other than that, what solution could you possibly mean?

4 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
  • Posts: 25,599

Re: Jitter and noise - but not an RME issue!

As FW power is not connected within the unit (the pins at the socket are not connected to the PCB), which difference can it make to cut the wires? What you want to do is already there...

Regards
Matthias Carstens
RME

MC's Website

5 Reply by kasaudio (edited by kasaudio 2011-01-22 18:17:32)

  • Registered: 2007-06-16
  • Posts: 214

Re: Jitter and noise - but not an RME issue!

Hell mrpony.

Jitter is the result of AD or DA clock irregularities and has nothing to do with hum and noise caused by grounding issues. So in fact you addresssed it wrong, but it is not so important here.

When you disconnect all audio singnal cables from your FF800 device (analog and digital, except FW cable) do you hear any hum or noise on your headphones? I guess not. Try connecting things step by step by discovering the problem source. By all means use the same power cord for entire system. Power conditioner has ground bypassed and therefore not a problem solver.

At first keep away all signal conditioners, use simple power line splitter, pay attention to connection of the whole system and you will find the cause. If not, then lift ground wire for your laptop (if it works) and go for it.

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

Thanks KasAudio!
I've allready located the problem, as I mentioned in my first post. It my Peluso 2247 tube microphone that's the biggest crook here. Whenever I use any other gear there's no problem. Except for when I have my ADL 1500 compressor (also tube) plugged in. So evidentley there is something happening between the tube gear and my laptop. But on the other hand I tried my old computer with non-tube gear (mixing desk) and had the same problem. I found a really interesting site which have a possible solution. Just printed out all 63 pages (!!!), so I have something to read tonight..

http://www.fragrantsword.com/twaudio/

  • Registered: 2007-05-09
  • Posts: 174

Re: Jitter and noise - but not an RME issue!

What WOULD be the audible result of excessive jitter in a digital connection?

  • From: Gothenburg, Sweden
  • Registered: 2007-05-01
  • Posts: 441

Re: Jitter and noise - but not an RME issue!

Hi,

maybe this article, can give some answers !?
http://www.stereophile.com/reference/1093jitter

regards S-EH

9 Reply by mrpony (edited by mrpony 2011-01-22 20:38:07)

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

I was just thinking about a thing I'd like to try. I bet it doesn't make any difference, but still. If I would plus in a USB cable to my laptop and just put the other end on/touch the chassi of the FF800, would there be any risk of me getting electrocuted or short circuiting the computer or the FF..? Stupid question, but I suck at electronics so I wanted to be sure before I do something stupid hehe.. The reason I'd like to try this is because I've heard it works for some people..

  • Registered: 2007-06-16
  • Posts: 214

Re: Jitter and noise - but not an RME issue!

Hello again!

That would not help much, as I think that FF800 and the computer share the same ground through firewire cable allready. And as you mentioned it's some other gear that causes problems in your system. As said before; properly wired system should not have any audible grounding noise. By 'properly' wired system I mean that all ground wires target to the same point without cross connections (or ground loops).

I remember some guy had simmilar issues. He connected FF800 with laptop directly on home Hi-Fi, had terrible 50Hz noise and was absolutely shure that there is no ground loop as hi-fi system was not grounded by itself. (2 pole socket without ground). I came to find out the reason and found CATV cable plugged into hi-fi tuner...

  • Registered: 2008-01-01
  • Posts: 3,025

Re: Jitter and noise - but not an RME issue!

Does it make any difference if the laptop's power-supply is plugged in or not? Do you have any external device with a 3-prong plug connected (external display)? Does it make any difference if you plug it on/off?

By the way, how about calling the noise "twitter" (or chirping)?! wink

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

kasaudio wrote:

Hello again!

That would not help much, as I think that FF800 and the computer share the same ground through firewire cable allready. And as you mentioned it's some other gear that causes problems in your system. As said before; properly wired system should not have any audible grounding noise. By 'properly' wired system I mean that all ground wires target to the same point without cross connections (or ground loops).

I remember some guy had simmilar issues. He connected FF800 with laptop directly on home Hi-Fi, had terrible 50Hz noise and was absolutely shure that there is no ground loop as hi-fi system was not grounded by itself. (2 pole socket without ground). I came to find out the reason and found CATV cable plugged into hi-fi tuner...

Hmm, so if they share the same ground, maybe bypassing the ground would be a possible solution.. Or? I mean, I'd like to try everything, so if there aren't any risks with bypassing the ground; why not try it? The Fireface would still be grounded with the power cable. I don't have any hum problems though (50 Hz). The frequencies I hear are more like between 6-10 kHz.

Timur, I was sure I had mentioned it, but obviously I hadn't (sorry); when the laptop is unplugged (running on batteries) everything works like a charm! I heard somewhere that many laptops (or the power supplies/adaptors) run on "negative ground". I don't even know what that means, but when the negative ground correlates with the normal 0v ground from the other equipment, something bad happens.. As said, I've only heard this and have no idea if it's true or not or even what to do about it. I think I have tried plugging out the external screen, but I'll try that again when I come to the studio this evening..

As I relate twitter with something negative (I prefer facebook), I think calling the noise that is a splendid idea! smile

  • Registered: 2008-01-01
  • Posts: 3,025

Re: Jitter and noise - but not an RME issue!

Let's concentrate on the 3-prong (with safety/earth connection) vs. 2-prong power-plug then. Which one does your laptop PSU use? Do you have anything connected to the laptop that uses a 3-prong plug (all external displays should use those)?

Under normal circumstances it should be like this: As soon as you connect any 3-prong powered device to the laptop *all* other devices connected (including the laptop) should share the same 0 V ground (if your 3-prong device and your home outlets come with proper 0 V grounding that is).

You may get some sparks when connecting 2-prong devices because at the moment they touch the grounded laptop there will be a discharge. I did not measure the FF400 yet, but here the UC, the HDSPe+MF2, the Macbook Pro and my powered USB hub all measure alternating current of +- 150 mV on grounding/chassis when being powered by their own 2-prong PSUs.

The Macbook Pro is one example of a 3-prong device that is *not* grounded properly. Because even when using the 3-prong power-plug (instead of the 2-prong one) it measures around 100 mV direct current compared to the ground/earth pins of my power-outlet, and that even changes depending on system load (i.e. CPU load). My display on the other hand comes with practically 0 V on its ground connector and thus puts the whole system on 0 V ground once it's connected to the MBP.

The Macbook always emits noise from its left side power-input/speaker section, both electric chirping and whistling, the latter being correlated in frequency to the audio buffer being used of any audio interface. Unfortunately the only way to get rid of this is to unplug its PSU, grounding has absolutely no effect on it (it sometimes stops for a second during certain load, like when connecting/disconnecting an external display).

So it may also be that this kind of noise travels trough your cables and originally originates from the laptop electronics itself. It does not on my test-setup though or it's not audible enough via speakers (FF400, UC, HSDPe+MF2).

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

Everything in my studio is running on 3-prong plugs, except for my Revox c279 rack mixer. But on the other hand, now I have everything connected to the power conditioner which means that everything has the same ground right? Or at least, that's what I thought would happen when I bought it..

  • From: Gothenburg, Sweden
  • Registered: 2007-05-01
  • Posts: 441

Re: Jitter and noise - but not an RME issue!

Hi,

Why not just try to break ground in XLR/TRS connectors
with Peluso 2247 and/or ADL 1500 compressor

like XLR pin 1 not connected on one side, it's worth a try
or try with Neutrik EMC-XLR connectors
http://www.neutrik.com/us/en/audio/204_ … tlist.aspx

but never break real electrical grounding in studio electricity

regards S-EH

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

Yeah, I never thought of that. Thanks - Tack så mycket!! But couldn't that be really dangerous regarding that it's tube gear..?

  • From: Gothenburg, Sweden
  • Registered: 2007-05-01
  • Posts: 441

Re: Jitter and noise - but not an RME issue!

In this case (tube gear) maybe it's not good to break ground with XLR pin 1 !?

possible to try the Neutrik connectors, you never know !?

check link here to get good info about GroundLoop

http://www.epanorama.net/documents/groundloop/

regards S-EH

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

Thank you very much for the info. I misunderstood you there, as I thought you suggested that I should lift the ground from the mic's PSU. Which you CLEARLY said I shouldn't do! Haha, I must have been really tired yesterday. I don't see any possible danger with breaking the ground in the XLR cable from the mic's PSU though, it's just a mic signal going through that cable anyway right? So if I would just disconnect pin 1 from that XLR cable I don't see how it could be a problem.. But then again, I know WAY too little about these things.

I will try it tonight and report back. If I don't report back, I will probably be 1. lying on the studio floor with a grilled body, or 2. lying in a black, plastic bag in the hospital. Either way, thanks for the advise here, cheers!

  • Registered: 2008-01-01
  • Posts: 3,025

Re: Jitter and noise - but not an RME issue!

Please use a volt/ampere-meter to measure the mic's chassis before you touch it when you fiddle with groundings. We don't want you to get fried.

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

Yeah I probably should. How should I measure that? With my multimeter measuring Volts, one end on the mic's chassis, the other end.. Where? On some ground point somewhere? Sorry again for my ignorance and lack of knowledge.

  • Registered: 2008-01-01
  • Posts: 3,025

Re: Jitter and noise - but not an RME issue!

Yes, on a ground point (like the one on your power outlet). But you should really consider asking a professional electrician if you don't even know how to measure these things. You may be playing with your life and getting rid of hum just is not worth risking being electrocuted.

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

True! But I will not take any risks at all, and the only thing I'll try will be just measuring the mic. I will do it the safest way possible. Let's see how it goes. I know, I'm stupid sometimes..

  • Registered: 2010-11-27
  • Posts: 53

Re: Jitter and noise - but not an RME issue!

I didn't want to take any risks getting electrocuted, so I did it the "safe" way (meaning; I knew it'd work allthough it's not "safe" as in "no risks for my health or gear"); I lifted the ground on the PSU of my laptop instead.. And it works like a charm as I suspected. But I would love to find another, better way of doing it.