TD-9 not grounded: noise problem

[eric_B]

I hooked up my new HP laptop to the TD-9 (mainly because of the USB WAV, 99 files limit) to finally enjoy playing along with ALL my songs: all I got was a lot of crackling, hissing and other noise. I removed the power cable of the laptop, so it was running on battery power, and it was gone.

After experimenting a little, I discovered it was a grounding issue. The laptop and TD-9 were connected to the same outlet. But the power cable of the TD-9 only has two poles (at least here in the Netherlands), so it isn't grounded. Why is that?

I had to connect a grounded plug to a non grounded mutiple power outlet (so only two wires were connected) to (almost) solve the problem (there's still a little hissing noise).

Anyone also experienced this? Anyone has a better solution?

[Colquhoun]

Are you sure it is grounding?
I have a MacBook Pro, and I had a lot of distortion with the power cord plugged in. It was fine on battery power. I did a ton of things, from using different cords to running to different outlets in the house.
I FINALLY figured it out. The USB port on the laptop is RIGHT NEXT TO the power in. It was causing so much interference. Luckily there is another USB port on the other side of the laptop. As soon as I plugged it in that USB port, no more distortion.

[daveybabes]

Aha aha oh rhubarb

Yes i had ground noise on my laptop some years ago and assumed that as my PC can also run off a 2 pin euro plug that it isn't grounded - well i found out that the ground is actually built in to one of those 2 pins, yikes!

Best solution a di box with a ground lift switch that elminates earth noise. You may need a stereo input one and this step could be taken if nothing else works. Place di between PC and speakers.

Also try separating where the two items are plugged in. so it's possible that at the moment you are playing the kit in an unsafe way ie ungrounded. It could be a hair raising experience.

Thomann have one - http://www.thomann.de/gb/behringer_di20_di_box.htm (email them to make sure it's 100% ok for what you need)

Ground noise thread here too from a recent time - http://vdrums.com/forum/showthread.p...t=ground+noise

[eric_B]

The USB port on the laptop is RIGHT NEXT TO the power in. It was causing so much interference. Luckily there is another USB port on the other side of the laptop. As soon as I plugged it in that USB port, no more distortion.

I'm using the headphones ouput of the built-in sound card of the HP (yes I now an external sound card is probably a lot better). So not much choice to use another output. But I'll certainly remember this, as it could be of use.

Yes i had ground noise on my laptop some years ago and assumed that as my PC can also run off a 2 pin euro plug that it isn't grounded - well i found out that the ground is actually built in to one of those 2 pins, yikes!

Hmmm, I didn't know this!

Also try separating where the two items are plugged in. so it's possible that at the moment you are playing the kit in an unsafe way ie ungrounded. It could be a hair raising experience.

I tried separating, helped a bit but not enough.
I don't know how it is in your countries, but in the Netherlands not all power outlets are grounded. The newly built houses (I guess after 1990) do have them, but older houses only have grounded outlets in the kitchen and bathroom (so the "wet" rooms). So if you're using an outlet in any other room it isn't grounded anyway...

Maybe I'll try the DI box. It more or less "cleans" the sound?

[daveybabes]

Yeah

Here's what they do ...

http://www.astralsound.com/di-boxes.htm

No earthing system eh? mmm things going bang! all over the place. If your country uses modern resetable trip switches then it's fine but if it's old fashioned ceramic fuses, must be a pain having to replace em... mmm

Yep if something blows then the person holding it can become the earth and carry the current, as an ex electrician i've had plenty of shocks and i'm fine, schoodle ooo oooh! patang rubber chicken

[ige87]

The problem isnt a lack of grounding. You are getting the noise precisely because of the grounding. This is a common thing with audo devices known as a ground loop, where audio signals end up being passed along the ground circuit as well as by the desired route. This is usually caused in devices where the power suply is near the audio components (like a laptop). There are 2 ways to fix this, either remove the ground entirely or use a DI with a ground lift to break the circuit between the 2 devices.

[rbressers]

Laptops don't have and don't need any grounding. The two pins are "Fase" and "Nul" in The Netherlands, so no grounding whatsoever.
The solution would be a DI box with ground lift for sure.

[Colquhoun]

I'm using the headphones ouput of the built-in sound card of the HP (yes I now an external sound card is probably a lot better). So not much choice to use another output. But I'll certainly remember this, as it could be of use.

I didn't mean audio OUT....My concern is that your audio IN is too close to the AC power IN, causing interference. I was THIS CLOSE to buying a ground lift when I moved the audio IN to a different port on the other side of the laptop. For me, it was problem solved.

[BarT]

I am not an electrician....

But, if a laptop isn't grounded and a TD-9 module isn't grounded, how could noise be caused by a ground loop and how could a ground lift help???


Bruce

[eric_B]

@Daveybabes: new houses (like mine, 15 months old) have 'schakelautomaten', I guess these are 'called resetable trip switches' in English. But a lot of older houses do have ceramic fuses. But unless there's a short circuit due to malfunctioning of a tv or coffee-maker or whatever, you never have to touch the switches or circuits, they work fine.

@rbressers: I checked it again: the adapter of laptop does have three poles. I didn't bother to open it (opening is always easier than properly closing ) to check if all three wires are connected but it makes sense that they are. I know about 'Fase' and 'Null' (the brown and blue wires and yellow/green for the earth/grouding), as I've done a lot of 'electrical jobs'. But I'm curious why some new devices use only 2 poles and others only 3. Why not ground every new device just to be sure?

@Colquhoun: I'm using the audio out of the laptop to connect it to the mix-in of the TD-9 and either connect headphones or an amp to the TD-9. So, apart from using a mixer or an external sound card or break-out box, there's no other way to connect it.

@BarT: that's what I don't get. And I thought a grounding problem would cause the 50Hz hummmmmmmmm, not crackling, hissing, etc.

Well, those are a lot of replies...any technicians out there who can shine a light on things?

[eric_B]

Well, I tried using an external E-MU 0404 USB interface.....same problem .

The strange thing is that, as it's connected through USB, it would make sense the audio signal itself isn't going through this connection, just the instructions the PC gives the E-MU's audio chip to produce sound. So there should be no (or less) noise.

Well, it seems the only solution is to give a DI-box a try? The noise and crackling is LOUD, just overwhelming the audio and TD-9 sound.

If the TD-9 only supported unlimited MP3 files....it would save me a lot of time (and also money)....

[BarT]

The strange thing is that, as it's connected through USB, it would make sense the audio signal itself isn't going through this connection, just the instructions the PC gives the E-MU's audio chip to produce sound. So there should be no (or less) noise.

I don't think that's true. The USB connection is providing an audio signal.

Well, it seems the only solution is to give a DI-box a try? The noise and crackling is LOUD, just overwhelming the audio and TD-9 sound.

Have you tried a different audio cable and/or size adapter to the TD-9 MIX IN?


Bruce

[eric_B]

I don't think that's true. The USB connection is providing an audio signal.

Have you tried a different audio cable and/or size adapter to the TD-9 MIX IN?

Bruce

I tried using different audio cables, power outlets, grounded/not grounded power outlets, etc, etc: the noise remains.

But I don't believe the USB connection is providing an audio signal. That would imply that the digital-analog conversion would always be made by the HP's on-board sound card and that adding a better external sound card/device would be useless as it would only pass through the HP's generated sound: why should you buy one?

[BarT]

But I don't believe the USB connection is providing an audio signal. That would imply that the digital-analog conversion would always be made by the HP's on-board sound card and that adding a better external sound card/device would be useless as it would only pass through the HP's generated sound: why should you buy one?

I didn't realize that when you say audio you mean analog, because I wouldn't describe digital audio as "just the instructions".


Bruce

[eric_B]

I didn't realize that when you say audio you mean analog, because I wouldn't describe digital audio as "just the instructions".


Bruce

Well, maybe that's somewhat of an understatement by me. But technically the PC just gives "orders" which tell the audio chip (or midi device) which sound to produce and how to produce it.

That reminds me: once I solved a PC problem for a guy who's one of the (semi-) top piano players in The Netherlands. I made the remark that recording (sequencing) the music he was playing just was recording the time, velocity and length (and aftertouch, but that didn't apply to his keyboard) of the notes he was playing. You should have seen the look on his face: no, no, he was playing with feeling, not just mechanically. Well, but that IS the way a PC records it: just plain old 0's and 1's, whether you like it or not....