Laptop sound

[Paulmccthingy]

Hi all, relatively new here and spend most of my time in the lighting forum picking up tips. However now I have a question for the sound guys!

 

Been using a laptop to provide music for dance shows and the 'live' sound is less than appealing. The laptop only has a 3.5mm stereo jack output and I go from there to the normal red and white phono(?) connectors on the mixer. When headphones are plugged in, the sound quality is great.

 

When you plug anything into the laptop a dialogue box appears allowing you to indicate what you have plugged in. I get three choices, line out, headphones or digital line out. I currently use line out, if I use digital out I guess I will need a specific cable? Also would this improve the sound quality?

 

A very confused amateur!!!

[dunk_1984]

Try selecting headphones instead.

 

Unless you can go into a channel and pad the input. Or through a DI box.

[Andrew C]

Line out is correct, but if you get a digital hash as well, you have an earth loop problem. It happens a lot, as a search of the forum will show up. To test, try headphones and try unplugging the power supply. If the sound is now OK, you have the problem many of us have experienced. A pair of isolating transformers can cure this, CPC sell them for isolating car audio systems.

 

If that isn't the problem, but just the poor quality of the sound "card" in the lappy, you will probably need an external sound card, either USB or FireWire. Pay your money and take your choice.

[Mr_Jules]

I always carry one of These - bottom of page with me when I go out with a laptop. Cheapish and have never let me down.

[Doug Siddons]

Thankyou Mr Jules, just got a price for the rapco lt100 which looks identical but is 3x the price SRP£166! :D

[Paulmccthingy]

Not sure I've explained myself well enough. The problem isn't an earth loop hum, just bad sound. Through headphones everything sounds really good, but as soon as I use line out, the resulting sound has lost a lot of middle and top frequencies. I've tried adjusting on the laptop and via the desk, but there just seems to be a chunk of some frequencies missing or at least heavily attenuated? Thought a digital cable may help.

[paulears]

It's not a digital cable you need (that's something the snake oil hi-fi peddlers specify) its an input that can take an sp/dif digital signal. If you select digital output then the analogue audio output through tht socket is switched off, and you plug in a 3.5mm plug to get digits to your CD or MD recorder.

 

Sometimes, the headphone setting, as well as being higher in output sometimes has eq applied to make lightweight headphones sound better. Switching to line, drops the level and removes the boost. The trouble is many internal laptop sound systems really do sound a bit grim when amplified - many saying words like 'thin' - 'weak', that sort of thing. An external sound module works much better and go from cheap (a la Behringer - which has 2 ins and 2 outs, and is pretty ok sounding) up to amazingly priced stuff. All will sound better than the computer. A decent eq or graphic might be able to make what you have a bit better?

[djw1981]

Personally I have found http://www.djstore.com/item/behuca202.htm?affid=froogle using the phono outs to be useful -you can even use the 3.5mm headphone jack if stuck. It has also (in my case) removed the PSU noise issue (though I know it doesn't in all cases and YMMV). Can't remember where I got it, but I paid elss than teh price on that site.

[johndenim]

I'd advise an external sound card.

 

For around £40, you can get one of these.

I have one, it plugs in through usb, and it can also be an 'in' if you need it to be.

 

Works great for me.

[fazJ]

I got a small behringer USB sound card that has phono in and out on it, does the trick for me always sounds good, apart from a few weeks ago I got a big error message come up in the middle of the show with that characteristic windows error noise, oh what fun that was.

[Oddball]

I got a small behringer USB sound card that has phono in and out on it, does the trick for me always sounds good, apart from a few weeks ago I got a big error message come up in the middle of the show with that characteristic windows error noise, oh what fun that was.

 

Control Panel -> Sounds and Audio Devices -> Sounds Tab -> Sound Scheme = 'No Sounds'

 

Always check before a show if you're using your laptop for FX

 

I once forgot to fade out my laptop channels that I'd been using to soundcheck during a gig. The venue also had wifi. Lets just say the whole audience knew that I'd got a new email...

[mutley]

From the symptoms you describe, it's likely that you are getting phase cancellation by mixing stereo and balanced signals. Stereo signals are similar to each other, but with some directional sound; balanced signals are the same as other except they're inverted.

 

So you stereo signal is being handled as a balanced signal, meaning that you lose the bass (low frequencies are less directional, so are often recorded equally in both sides, meaning a difference of zero.

 

If that all sounds a bit complicated, just try making up a lead like this:

 

LAPTOP SOUND DESK

 

( ) Right

[mutley]

From the symptoms you describe, it solunds likely that you are getting phase cancellation by mixing stereo and balanced signals. Stereo signals are similar to each other, but with some subtle difference to make directional sound; balanced signals are the same as other except they're the inverse of each other.

 

So your stereo signal is being handled as a balanced signal, meaning that you lose most of the signal, especially the bass, since low frequencies are less directional, so are often recorded equally in both sides (mono), meaning a difference of zero.

 

If that all sounds a bit complicated, just try making up a stereo, to unbalanced mono lead, by simply joining the left and right signals from your laptop together at the tip of the jack plugged into the sound desk; or use a mono jack lead, but you won't hear anything is it was only recorded on the left side.

 

(Alternatively just get a stereo DI box)

[Bobbsy]

Problems with audio from laptops must now be the number one question asked here in the Sound forum of the Blue Room so, in an attempt to put it all together in one post, I now present:

 

The Evil Bobbsy Guide to Laptop Audio Problems

 

All too often, trying to interface a laptop directly into a sound reinforcement system results in noisy, poor-quality sound. The trouble is, there are several separate potential problems which sometimes occur singly but can "gang up on you" at other times. The main issues are:

 

1. The power supply arrangements on far too many laptops make them prone to problems with earth loops creating the distinctive "mains hum" we all love to hate. To see if this is your problem (or even part of your problem) unplug the mains adaptor from the PC. If the noise goes away (or even part of the noise goes away) then you have an earth loop problem.

 

2. The sound adaptors built into most laptops are sub-standard, both in terms of sonic quality and also isolation from all the electrical noise floating around inside the laptop. Buzzes, clicks, "whirring noises" and data noise are likely down to the sound card.

 

3. On many laptops the only available output is designed for use with headphones and may even feature EQ to make it sound better on ear buds (but like rubbish on a proper PA. Headphone outs are often affected by a "volume" adjustment, either hardware or software, so planning levels can be an issue.

 

4. Even if you have a proper line out, it will be unbalanced and on a 3.5 mm stereo mini jack. Mini jacks can pull out, unbalanced feeds are subject to interference and the necessary adaptors to get the feed into a mixer can go wrong, reverse polarity, etc. etc.

 

5. Laptops have an annoying habit of outputting system sounds at the wrong moment.

 

Some cures:

 

1. If you suffer from an earth loop, some form of DI box or isolating transformer should cure it. This thread and many other contain recommendations. However, before rushing out to buy the first one you see, please read the next part.

 

2, 3 and 4. For any kind of PA work you really need a far better sound adaptor than included in any laptop I've ever encountered. Before Macheads start to look smug, I've measured an appallingly bad S/N on a Macbook--and much of the noise was a form of squarewave indicating digital interference inside the computer. Again, lots of topics in the BR have recommended external sound cards (generally USB2 or Firewire for laptops) and, since the market changes so rapidly I won't date this post by suggesting specific models. The one thing I'd say is "know what you want". Is a simple stereo adaptor enough or would some form of multitrack be more useful? Do you need to record (possibly meaning you need good mic preamps) or is it just for playback? Finally, if at all possible, try to get an adaptor with balanced line level outputs rather than cheaper unbalanced.

 

Sometimes, even if you have earth loop problems, a decent sound card will clean this up for you without recourse to an isolating transformer/DI so my advice is to get the sound card first THEN chase the earth loop if it's still there. However, carrying some form of isolation is a good idea if you plug into 3rd party PA system regularly....you can go for ages with no problem but suddenly have a disaster at a new place.

 

5. Dive into your computer's control panel and TURN OFF all system sounds. If you have the computer skills, set up a dual boot system so you can start up without things like the internet, IM systems, firewalls, anti-virus etc. starting when you will be using your computer for playback.

 

As I say, a big problem with laptops is that, quite often, they exhibit several different problems all at once. Troubleshooting is a matter of being methodical and sorting things out in order--don't assume that what works with one computer will automatically work with all of them. Good luck. I hope this helps.

 

Bob

[timtheenchanteruk]

the above says it all really, but just to add, all the laptops I have had ground/noise problems on all have a PSU with a standard IEC or those clover leaf style things (ie earthed) the older style with a fig8 connector have had no problems.

 

I definatly advocate the removal of ALL windows sounds as well.