I think my amplifier might be affected by some background hum generated through my mains power. It was quieter at Graeme’s than it is at my house. I suspect that is down to my mains supply.
I can’t put in a dedicated ring without demolishing half the house.
Is there anything I can do without sucking all the life and music out of the system?
I’ve always just plugged gear straight into the wall but I’ve heard that some “conditioning” can have a negative effect on the SQ.
Any help or ideas.
Cheers
I bought a couple Wychwood Audionics mains filter things
I don’t think it is a conditioner but it solved the issues I had
The Isotek stuff is often quite effective too. I’ve not noticed any negative sonic effects and they’ve protected my stuff from the horrendous mains in the Granny annex.
You have considerably more sensitive speakers than Graham’s.
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I think your post is excellent.
Why thank you.
The power inspired mains regenerators might assist and won’t ruin the sound.
Just to add a bit more detail, Tim’s noise rises with the volume setting, and the architecture of the Gamma puts the volume control right at the start of the system - it goes: RCA input sockets, wiring to input selector switch, short wiring to volume control, wiring to amp pcb. So the noise is ‘getting in’ in those very early stages of the system.
The amp is also extremely sensitive, as you’d expect given an ECC83 first stage followed by an ECC81 driver and then the 211 and no global feedback whatsoever. I measured one watt out for less than 6mV RMS in !
One possibility Tim is that there is noise getting in via the input interconnect leads i.e. with them picking up the general mains-sourced background electromagnetic field that fills all our houses these days. An indication that this is an issue would be if you could short the amp’s input to ground at the RCA socket and see if that lessens the noise. If it does then you might find that ‘dressing’ the interconnects helps, perhaps so that they are all as close to one another as possible and away from the mains leads, or if they have to cross the mains leads that they do so at right angles. The fact is though that the EM noise field in our rooms can vary a good deal from place to place. This can make any attempt to reduce pickup by repositioning things very hit-and-miss indeed. The only way to optimise the layout is often trial-and-error.
Otherwise, as others have said, plug-in mains filters between the wall socket and the amp can help if the noise is ‘coming down the wires’ rather than introduced via a free-space field.
VB
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Is it worth making up a pair of shorted phono plugs to try on the inputs and thus exclude the possibility of external pick up in the interconnects?
6mV in to 1 Watt output is very high sensitivity. Wouldn’t it be worth reconfiguring the circuit such that the 1st valve was an 82?
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Or maybe adding 20dB of NFB which would drop Zout, broaden the frequency response (actually it’s not bad as it is), lower the distortion and counteract the in-loop noise too 
?
As they say, Get thee behind me Santa …
VB
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Someone on here, still has my Wychwood Audionics mains filter things.
You could borrow that, from them, and give it a try.
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i have a power inspired thingy you could try if it helps Tim
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Fork lift batteries for the faff winning veil lifting experience you’ll have just before the hernia op.
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That’s me, well, I’m due to collect it from JB, as a house move got in the way of hifi for me for a while. I’ll pick it up next week, give it a go then pass on if ok? Apologies @catcando for being so slack
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No problem. Just trying to keep track of it.
Happy for it to be tried, where needed.
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Hi Darren would like to try this please. Thanks
Hi Greg
Would like to try this too if possible.
Thanks
Please see above, as to it’s current location.
I think @J_B has it at he moment, and then it is going to @Spenagio. Contact them.
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I only have it because I took it to Lopwell for Spencer and would have passed it to someone else (I can’t remember who) who didn’t make it.