Wonder whether anyone can offer some advice .
Recently installed armageddon psu for my lp12
I’m getting a low hum through the speakers when the geddon is powered up . I’m assuming an earth loop is the issue , question is how to fix it ?
I noticed that the tone arm cable has no earth connection to the preamp but is connected to the tt chassis earth . This has always been ok when using the valhalla though .
Andy – I’m surprised you are now getting hum problems with this change. Both the Valhalla and Armageddon (should) connect the cross brace and sub chassis to mains earth for safety so from a earth loop perspective this shouldn’t have changed, but it may be showing up an issue elsewhere.
A few things –
Is the Armageddon plugged into the same mains socket as the Valhalla’d LP12 was ?
Where have you located the Armageddon – away from sensitive kit (pre-amp etc) ?
I take it from your system profile, that the LP12 is the only source connected to the 92 ?
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Hi James
Yes plugged into same supply .
System details need updating . I now have nac 82 , hicap into nap 250 , all olive .
Naim cdx is the other source.
Hum is only there on tuner channel , which is where i have the lp12 connected via Linn linto phono stage .
When i switch to cd , hum disappears , it only started when i connected the armageddon yesterday evening
Ah ok. it does sound a possible ground loop as you also have the CDX in the system. If you remove the CDX connection to the 82, do you still get the hum when you select the LP12 (on the tuner input).
Is the arm lead earth connection connected to the Linto ?
Edit - just to add, you have got the Armageddon positioned away from the Linto and the 82 just to eliminate any hum induced by the transformer in the Armageddon ?
Haven’t tried unplugging the cdx yet . Armageddon is positioned well away from the linto and 82 , on a wall shelf below the Mana shelf tt sits on . Strangely the arm lead earth is missing at the phono plugs so cant connect to the linto .
However this was never a problem before I swapped the valhalla for the armageddon .
I’ve noticed though that the hum is still there regardless of whether the armageddon is switched on or off . I’ve also noticed that it gets noticeably worse when I plug it into another outlet which isnt on the dedicated spur I have for the hi fi
That does sound like it’s a ground loop occurring especially as it gets worse when you plug the Armageddon into another outlet. Does the hum go if you unplug the Armageddon from the mains ?
One thing that might be worth looking at, that you mentioned in your first post, is removing the earth connection between arm plug and sub chassis, attach a piece of wire to the arm plug connection and try connecting this wire to either the Linto ground post, or 82 ground post. You may need to experiment here.
Yes hum disappears when armageddon is unplugged from the mains . I’m going to have a play around with it this evening to see what i can come up with . The annoying thing is that swapping the valhalla for the armageddon has opened up the sound beyond belief so I need to persevere with it to eliminate the hum .
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