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Linn LP12 phono connection issue?

W

Wayne C

pfm Member
As a few may know I had my Sondek set up last week , tested with other equipment fine at service. Brought it home and connected it to my as new pre amplifier via the RCA plugs on the Linn Krane lead. Attached earth cable and have noticed a hum
coming from right speaker, I rotated the phono lead in the socket on the pre amp and the hum went away immediately, no further hum on that listening session. Turned pre amp on the following day and hum was back on that right channel??, same thing move rca and it goes away. Thought there may be an issue with the RCA cable so tried another pre amplifier and no hum at all via headphones?. Could this be an issue with the pre amp phono inputs please?. How can it be that you rotate an RCA plug and it goes away , and returns the following listening session. I didn’t insert the plug any further as that isn’t possible. What would you think was causing this hum the phono connection on the preamp itself?.
The pre amp is covered with a 6 year warranty but I’d like to confirm it’s one or the other first.
 
Wayne C said:
As a few may know I had my Sondek set up last week , tested with other equipment fine at service. Brought it home and connected it to my as new pre amplifier via the RCA plugs on the Linn Krane lead. Attached earth cable and have noticed a hum
coming from right speaker, I rotated the phono lead in the socket on the pre amp and the hum went away immediately, no further hum on that listening session. Turned pre amp on the following day and hum was back on that right channel??, same thing move rca and it goes away. Thought there may be an issue with the RCA cable so tried another pre amplifier and no hum at all via headphones?. Could this be an issue with the pre amp phono inputs please?. How can it be that you rotate an RCA plug and it goes away , and returns the following listening session. I didn’t insert the plug any further as that isn’t possible. What would you think was causing this hum the phono connection on the preamp itself?.
The pre amp is covered with a 6 year warranty but I’d like to confirm it’s one or the other first.
Click to expand...

Good question!

When you noticed no hum in the other preamplifier you tried ... you didn't rotate that channel's phono plug in the new socket - so you haven't ruled out that the phono cable isn't faulty.
 
Firstly I would try putting the left channel in the right & vice versa to see if the hum appears in the other channel. If so it will be the cable, if not you either need to clean the phono socket & plug or it's likely the phono socket is slightly loose & twisting it just tightens it up sufficiently to make good connection or possibly temporarily cleans the plug & socket.
 
Maybe just needs a clean ? Both the RCA plug and socket. Deoxit is good for this and certainly won't do it any harm.
 
The leads pick up noise. If you move the leads away from power cables you should be able to get rid of the hum. It's a problem with MC cartridges as the signal is being amplified so much.

Also try not connecting the ground cable. Sometimes it's quieter without it depending on what else is going on with grounding in the system.

What I don't understand is why other companies don't use the same grounding arrangement as Rega. They didn't use a separate earth lead, they connect ground to the return on the left channel, and I've never had a hum issue on a Rega turntable.
 
The only issue with removing these linn RCA connectors to check things is they are so darned tight like the QED Qunex ones which did endless damage to previous amplifiers pulling off the metal covers due to this tightness. I would much prefer having them changed out to ones like the nordost blue heaven type connections do Neutrik make connectors like them perhaps. As I worry for my amplifier which is only 3 months old. I realise they have to be a good solid connection but there’s solid and ridiculously tight.
 
I have just attached the linn connectors to some Blue Heaven connectors as below to ensure no stress on the pre amp phono imputs when trying to isolate the issue, my thinking is if i use differing phono at the amp end that would rule out that been the problem I reversed Left on right channel as advised and the hum was still present on the right speaker when rotating the RCA in the phono socket it deceased and increased markedly so I’m guessing it’s the phono connection on the ATC Pre amp? , what do you think please. To add when putting L to L and R to R it was the same.

This is what I used

https://imgur.com/a/q86j1ZB
 
Anyways I’m booking the pre amp in for repair it shouldn’t be happening to a new product pre amp is fine on balanced inputs via Dac etc
 
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