New set up annoying buzz / hum I can't get to the bottom of......

I've just set up a new system using pre-loved items mostly procured from this parish - WLM La Scala Speakers, Croft 5c Power & Gate Pre Amps.

No matter what I do, I cannot stop background hum, or buzz through the speakers when there's no source playing which I can't help thinking isn't right?

I've tried different cables (speaker, interconnect & power), different wall sockets & although I can find some improvements depending on combinations, the hum is still audible with no source (magnified when using the TT input).

I thought it may have been the speakers as they are super efficient at 93db but it also happens when I've used the amps with my Naim Allae's (for sale actually....)

Sometimes the speaker cones actually move in & out if I turn the volume about half way (with no source playing of course) which does worry me if I'm doing damage to them? The hum is still there even with the pre off & just the power is on feeding the speakers as well.

I can live with it as obviously most times when the amp is on there is music playing but would prefer it not be there of course but I also worry if it is damaging the speakers at all?

Any thoughts?

Do pre and power amps have connection to ground on the power side of things?
You could have a ground loop.

Hi Chris,

Not really sure to be honest - electrics aren't my strong point.....

How would I check?

You mention using different power sockets.
Have you tried using just one mains socket with an extension board?

https://images-na.ssl-images-amazon....7L._SX425_.jpg

Yes, have tried that Chris & still the same.

I did make up my own lead using Belden cable & tried hat but no good.

Interestingly, the Belden cable has another strip of wire inside the casing outside of the regular live, earth & neutral - what should i do with this? I just cut it off!

https://www.psaudio.com/ps_how/how-to-find-and-fix-hum/

It would be helpful to know what the equipment concerned is.

First you need to narrow things down. Unplug everything from the amp except the speakers and check if the hum is still there. Don't turn the amp up to where you see the cones move because that is bad.

Hum is one of the most annoying things to eliminate. Going through the PS Audio process is definitely recommended to establish if there is a ground loop issue and if so how to cure it.

Sometimes I've found that hum is caused by EMI interference where the shielding on interconnects is not sufficient to eliminate such interference. If EMI is the cause then usually (i.e. not always) moving interconnect cables marginally (for example away from amp transformers or from power lines or not running parallel to power lines) can eliminate hum.

On your TT are you running a grounding wire back to your preamp/amp?

Quote:

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Originally Posted by Ali Tait

https://www.psaudio.com/ps_how/how-to-find-and-fix-hum/

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Thanks for the link - I'll have to run through all the checks at lunch & see what I can conclude

Quote:

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Originally Posted by hifi_dave

It would be helpful to know what the equipment concerned is.

First you need to narrow things down. Unplug everything from the amp except the speakers and check if the hum is still there. Don't turn the amp up to where you see the cones move because that is bad.

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Thanks Dave - kit is Gate Valve Pre Amp, Croft 5C Valve Amp, WML La Scala Speakers.

I've disconnected everything except PowerAmp to La Scala Speakers - hum is still there but very feint.

If I connect any leads at all to the Input on the Power Amp, the hum gets louder (even if not connected to Pre amp at the other end).

If I then connect the Pre & Power Amps together, hum gets louder - even if Pre is not switched on.

Louder still once Pre is switched on & then louder again when using the MM Phono input on the Gate pre.

Seems to me like an issue with the Power amp?