Power supply feedback!

[admin_exported]

Im running a cambridge audio A1 MK1 through Tannoy R1's (old school I know but its the cheap set up I have for uni) and I basically run a phono to jack between the amp and my laptop, the problem im having is static/feedback from the laptop but only when it is plugged into the mains via the power supply, when unplugged it is fine, no hissing or anything.

 

 Any suggestions folks?! Thanks!

 

[Anonymous]

Are you able to get hold of another power supply and give that a try? I had a similar problem once and the change of power supply fixed it.

 

[aliEnRIK]

Sounds to me like you might have a 'bad earth' in your house

 

[John Duncan]

My laptop makes terrible noise as a source when plugged in via the mains, not so via battery. Most foolproof (sic) way of dealing with it would be to get an Airport Express...

 

[aliEnRIK]

JohnDuncan:My laptop makes terrible noise as a source when plugged in via the mains, not so via battery. Most foolproof (sic) way of dealing with it would be to get an Airport Express...

Interesting answer. I could be wrong but are you not one of these people that says mains cables and conditioners dont make any difference either?

 

[Anonymous]

 

[Anonymous]

It's hash from the switch mode PSU. You need to use an audio lead with a ferrite built into it or add a ferrite clamp. This increases the inductance of the wire and it acts as an RFI filter. Ferrite clamps for leads are available on Ebay and Maplin.

 

[aliEnRIK]

Hi Cyril

WOW. You really sound like you know what your talking about. May I ask what you mean by 'hash'?

Whats a 'switch mode PSU'? Whats a 'ferrite clamp' exactly? How does increasing the inductance of the wire help in this case and how can this clamp effect what runs down the wire? What IS inductance? Whats RFI and how does it filter it?

Im really intrigued? Cheers