Mixermend Posted January 19, 2008 Share Posted January 19, 2008 As noted by several people - a transformer isolator will solve the problem in most instances. I make a high quality device that is a little dearer than some of the alternative suggested - but you won't notice any loss of audio quality.....! Link to comment Share on other sites More sharing options...
SoLiEn Posted January 19, 2008 Share Posted January 19, 2008 have used a DI box with great effect to get rid of the hummmmmm Link to comment Share on other sites More sharing options...
soundo26 Posted January 20, 2008 Share Posted January 20, 2008 I've had this in the past with HP laptops, if you disconnect either the Audio or the 15pin HD connector, the noise stops! also, if you disconnect the power supply it stops. It seems to be some kind of earth loop within the laptop, I couldn't figure it out because the mains lead to the PSU is onlt 2 core, we only got round it by running on battery after trying every trick in the book including DI boxes, earth lifts amnd running dedicated power from the ops to all audio & Video items in the room.As a result, we never use HP laptops!! Link to comment Share on other sites More sharing options...
david.elsbury Posted January 20, 2008 Share Posted January 20, 2008 Sure, but what both Tomo and I are describing is an earth loop, in his case without any audio connected (only a USB for control) and in my case, the audio sends and returns to the computer were both turned down. In this case, an audio iso transformer will do nothing. Link to comment Share on other sites More sharing options...
MarkPAman Posted January 20, 2008 Share Posted January 20, 2008 Which unfortunately means I need to buy a d3sktop c0mput3r for my audio work, rather than being able to use my lapt0p... grr... Is getting a better P5U for the lapt0p an option? Link to comment Share on other sites More sharing options...
david.elsbury Posted January 20, 2008 Share Posted January 20, 2008 I was contemplating making myself an 18v power supply out of a huge toroidal transformer, but stopped when I saw the cost... $300 upwards for just the parts... Link to comment Share on other sites More sharing options...
djmatthill Posted January 20, 2008 Share Posted January 20, 2008 Well Garath Iv got a DELL Vostro 1500 and use it for sound playback and its petfectly quiet. Even using cheap mini jack to phono lead its sweet as a nut . So not all Dells are noisy.! Im well impressed with quality of the output from the headphone socket. <_< Link to comment Share on other sites More sharing options...
Ike Posted January 20, 2008 Share Posted January 20, 2008 Ensure as far as possible that your PSU is the one that came with the laptop when new. There are a lot of fakes around which are very hard to tell from originals yet have abysmal EMC. Have a look here for an example. The rest of Mike's site's also highly recommended if you're interested in lasers, high voltage or impressive glassware. If you don't mind voiding your warranty it's well worth having a play with ferrite rings and decoupling capacitors, I've 'fixed' more than one laptop this way. If you want to keep the warranty wrapping the wire from the PSU tightly around a ferrite rod as used in portable AM receiver aerials then covering it in LX/gaffa tape's probably worth a try although admittedly it's not the most elegant of solutions. Link to comment Share on other sites More sharing options...
john_in_spain Posted January 21, 2008 Share Posted January 21, 2008 Whilst all of aspects noted so far are possible they can all manifest themselves because of an earth loop.I drop the earth off my laptop and it cures all. You will need to judge on the safety of such a solution. Link to comment Share on other sites More sharing options...
MarkPAman Posted January 21, 2008 Share Posted January 21, 2008 I drop the earth off my laptop and it cures all. My PSU is Class 2 & this may explain why I've had no problems (yet ;) ). I shall refrain from commenting on "dropping" the earth of a Class 1. <_< Link to comment Share on other sites More sharing options...
Alec Posted January 21, 2008 Share Posted January 21, 2008 Well, I've just got that transformer from maplins, and it works! It seems to reduce the quality very slightly, however for listening to mp3s through the onboard sound card this is fine. The next purchase is a decent (well, better than the onboard) interface. I might give your idea of a long usb cable a go with that then, else its using this transformer, or just batterys. +1 for the Maplin transformer. My 2 laptops (IBM & Fujitsu Siemens) give no problems but some others have been shocking without the transformer. Does it disassemble easily if you remove the shrink wrap? I'd like to change the cabling on it to use better, longer cables with the right connecters on the end rather than have a chain of adapters. Link to comment Share on other sites More sharing options...
jamesperrett Posted January 21, 2008 Share Posted January 21, 2008 Well Garath Iv got a DELL Vostro 1500 and use it for sound playback and its petfectly quiet. Even using cheap mini jack to phono lead its sweet as a nut . So not all Dells are noisy.! Aren't those the ones that have been reported to give electric shocks when you touch the case? Customers have made such a fuss about this that Dell are now supplying earthed power supplies for them. So what is great for one section of the market is causing problems for the average user. Cheers James. Link to comment Share on other sites More sharing options...
djmatthill Posted January 21, 2008 Share Posted January 21, 2008 Well Garath Iv got a DELL Vostro 1500 and use it for sound playback and its petfectly quiet. Even using cheap mini jack to phono lead its sweet as a nut . So not all Dells are noisy.! Aren't those the ones that have been reported to give electric shocks when you touch the case? Customers have made such a fuss about this that Dell are now supplying earthed power supplies for them. So what is great for one section of the market is causing problems for the average user. Cheers James. I know DELL had a small problem with a batch of these vostros something to do with a fault with the Foxcom motherboards they used. But it has been rectified now as far as im aware Jame <_< Iv had my vostro for about 3 months and have used to virtually every night on the road as music playback and no problems yet (touch sideboard) A friend of mine uses a IBM lenovo laptop for Music playback and constantly has ground loop problems even when using external USB sound card device/s. Link to comment Share on other sites More sharing options...
No Longer A Member 220516 Posted January 21, 2008 Share Posted January 21, 2008 Hello I couldnt be bothered to read all the posts but I get this all the time well did anyway. It is the sound card the power supply creates interfearance so I solved this problem by buying an external sound card I bought this to solve my problem X-Fi Xtreme Audio NotebookI have been told by another technician that it doesnt really help to have cheap sound cards!!! Also I know for a fact that a MAC does not have an issue with this problem as they are not cheap <_< Harry. Link to comment Share on other sites More sharing options...
Andrew C Posted January 21, 2008 Share Posted January 21, 2008 If you had read the thread, or even some of it, you'd have found that the problem is extant with both internal, and external cards on laptops. I have since found that even with just a data connection that you can have hideous noise. It is definitely a power supply design issue, and not a "fault". The trick is to work out what the problem is, and how to avoid buying laptps, or power supplies with the problem! Link to comment Share on other sites More sharing options...
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