KVR Audio

bezza · Post by **bezza** » Sat Oct 27, 2007 7:25 pm

I wonder if anyone can help me with a problem.

I am planning to do some gigs in the new year and want to use my laptop live. I want to run a backing track and play one live VSTi within Cubase LE (probably Atmosphere).

I've bought a Tascam US144 interface but (if I have the laptop plugged in to the mains) I am getting lots of constant noise and interference through the line outs on the Tascam. Even mouse pad movements seem to cause some minor interference.

Unplugging the laptop from the mains seems to cure the noise completely but I don't want to play live without mains power so that is not an option. Performance was getting to around 30% in this scenario.

I have tried Asio4All without my laptop plugged in and there is none of the noise but the latency is not great and I get the odd drop out. Performance was hitting 40%.

My laptop is an Acer Aspire 5102wlmi AMD Turion 64 x2 TL50.

I have looked around for known issues with the Tascam but no joy - yet I seem to think it must be thhe Tascam that is at fault. The whole reason I bought the 144 was for live performance. Can anyone shed any light on this problem please?

UltraJv · Post by **UltraJv** » Sat Oct 27, 2007 7:29 pm

This is a common laptop issue. Most people have this. Its a ground loop. The noise will vanish on battery only operation. The cure is to remove the earth on the laptop PSU. Its being grounded through the audio equipment its connected to as well as through the laptop, thats the cause. A few people will say you must never do this, FWIW - you do this on batteries.

bezza · Post by **bezza** » Sat Oct 27, 2007 7:40 pm

Cheers UltraJV - I'm not too clued up on electronics so I'd never have thought of that.

I don't like the sound of removing the earth on the laptop so I guess I need to invest in a longer lasting laptop battery!

Sascha Franck · Post by **Sascha Franck** » Sat Oct 27, 2007 8:06 pm

I have removed the ground on my laptops PSU permanently. There's more than enough laptop PSUs coming without any grounding, so I think it's quite safe.
Just don't take my word on it.

Selfik · Post by **Selfik** » Sat Oct 27, 2007 10:49 pm

bezza have you tried this driver http://www.usb-audio.com/
I'm thinking to buy Tascam US-144 next week...also as a mobile solution for my laptop...either that or Lexicon Lambda...

bezza · Post by **bezza** » Sun Oct 28, 2007 9:51 am

That looks interesting but the website states that the US144 ships with that driver - but it didn't with mine.

Selfik · Post by **Selfik** » Sun Oct 28, 2007 10:53 am

You can download demo version and test if it works

kabolins · Post by **kabolins** » Wed Oct 31, 2007 5:51 pm

Hi Selfik,

I had the same problem with my laptop. I went thru 3 interface cards looking for a fix. I finally solved the problem by using spdif to my monitors. Staying in the digital domain until the end eliminated the noise for me. The us144 has spdif in and out so you might want to explore that as a way to get out and into your laptop. If that is not a possibility, you may want to explore an all-in-one pc which would be more portable than a desktop.

Karlis

Lord Snarebottom · Post by **Lord Snarebottom** » Wed Oct 31, 2007 6:53 pm

bezza wrote:Cheers UltraJV - I'm not too clued up on electronics so I'd never have thought of that.

I don't like the sound of removing the earth on the laptop so I guess I need to invest in a longer lasting laptop battery!

I recommend you do NOT remove the ground. Just because some internet

(no offense) says it's okay, doesn't make him an electrical engineer. Batteries are not alternating current, and that's a BIG difference. Anyone who's ever gotten a nice jolt from a microphone on stage would tell you the same thing (I HAVE gotten a quite substantial zap myself in said fashion).

I suggest you get yourself a high capacity UPS and remove the lead to the beeper so it doesn't incessantly go off warning you that you're not powered. That way you can stay isolated from the venue's grid and still have plenty of power for the show.

thecontrolcentre · Post by **thecontrolcentre** » Wed Oct 31, 2007 7:02 pm

Radial JPC™ Stereo PC-AV Direct Box

"The Radial JPC is a stereo direct box that has been specifically designed for use with computer sound cards and other consumer electronic products to allow these to be connected to a professional sound system. It is unique in that it combines the advantages of transformer-isolated inputs with an active drive circuit, giving you the 'best of both worlds' in a compact and extremely flexible package.

Transformer coupled inputs have the unique advantage of isolating the 'source' from the 'destination'. This proven approach eliminates 60-cycle hum and buzz caused by so-called ground loops when two pieces of electrically powered devices are connected together. Because the active circuit does all of the impedance conversion and balancing, a dedicated 1:1 transformer can be used. This results in a hybrid design that is at once great sounding, compact and more affordable."

Lord Snarebottom · Post by **Lord Snarebottom** » Wed Oct 31, 2007 7:19 pm

...maybe if we reconfigure the solar matrix in parallel for endothermic propulsion...

Yeah, we'll do that!

Probably cheaper than the UPS approach, but the UPS approach does also have some interesting applications for location (nature, wilderness) shoots.

SenatorAdam · Post by **SenatorAdam** » Fri Nov 02, 2007 11:40 pm

I have the same problem. I have 4 ground loop isolators (my apartment has crappy wiring)..

I use these

For power, works most of the time:
http://www.musiciansfriend.com/product/ ... sku=150452

For audio source, works all the time (99.999%..):
http://www.musiciansfriend.com/product/ ... sku=155370

Solves your problem instantly.

Why does my Tascam US144 hate my laptop's mains power?