Hello,
This is my first post. I need help with a problem I am experiencing with hum that has appeared with use of my LP12.
My turntable is far from Linn standard being a cirkussed variant with Origin Live DC 200 motor, OL Ultra power supply with uprated transformer with OL Illustrious tonearm and Shelter 501 cartridge.
In all the time I have used it with a variety of MC phonostages I have never had a problem with hum. Indeed, looking under the turntable there are no earth wires to be seen at all. There is however, an integral tonearm earth wire that accompanies the tonearm cable but I have never needed to connect that either to my pre amp or phono stage as hum has been completely non-existent.
I recently decided I would like to try a step-up transformer into a moving magnet phono stage as an alternative to an MC phonostage and so I purchased a Cinemag SUT and tried it with a valve phonostage and an Ant Kora MM phonostage.
I got hum with both stages and no amount of re-positioning the SUT or phonostage would eliminate it. The hum was worse with the valve stage.
I have purchased the Kora and have spent time connecting the tonearm earth wire to the pre amp, then to the Kora and then to the Cinemag. All to no avail. I have connected a separate earth wire between the Cinemag and the Kora and that has helped ever so slightly.
Can anyone offer any alternative suggestions? I am aware that Linn normally fit an earth wire between the sub-chassis and the central wiring strap/bolt....however, I don't understand if this was only deemed necessary for the various Linn AC power supplies?
I'm really struggling to eliminate this annoying hum and would appreciate any knowledgeable or helpful suggestions.
Thanks.
LP12 - Hum
Moderator: Staff
Hi Sondekker and welcome to the forum!
The parts you mention are too unknown for me to give any useful advice without "being there". The only thing I'd like to point out is that correct grounding is important to sound quality, regardless of whether one has a hum problem or not. So even if you've never had a hum problem, I can't see any reason why your LP12 should have the internal ground connections between arm, subchassie, crossbrace and top plate removed. They seriously affect the quality of sound.
Now that you have a problem, I'd personally take it as an opportunity to restore the grounding to original LP12 spec. Any change in that (such as what Klaus is describing in another thread) should be done for a reason and carefully evaluated.
The parts you mention are too unknown for me to give any useful advice without "being there". The only thing I'd like to point out is that correct grounding is important to sound quality, regardless of whether one has a hum problem or not. So even if you've never had a hum problem, I can't see any reason why your LP12 should have the internal ground connections between arm, subchassie, crossbrace and top plate removed. They seriously affect the quality of sound.
Now that you have a problem, I'd personally take it as an opportunity to restore the grounding to original LP12 spec. Any change in that (such as what Klaus is describing in another thread) should be done for a reason and carefully evaluated.
Hello Lejonklou,
Thanks for your response and for your suggestions.
Although my LP12 has never seen any internal grounding wires in all the time I've owned it (other than on the tonearm), I did today fashion a home made ground wire and attached it between the rear of the sub-chassis and the front crossbrace fixing bolt.
I have listened to it this afternoon and whilst I still have a slight hum when the volume is increased, I am thinking that there may be a slight audible improvement in the bass response which seems a little fuller.
I am guessing I will just have to live with the slight hum, after all.....
Thanks for your response and for your suggestions.
Although my LP12 has never seen any internal grounding wires in all the time I've owned it (other than on the tonearm), I did today fashion a home made ground wire and attached it between the rear of the sub-chassis and the front crossbrace fixing bolt.
I have listened to it this afternoon and whilst I still have a slight hum when the volume is increased, I am thinking that there may be a slight audible improvement in the bass response which seems a little fuller.
I am guessing I will just have to live with the slight hum, after all.....
Hi Sondekker.
I really would not "learn to live with" the hum. As the guys are telling you (and they know a lot about LP12s!) if the earthing is not correctly set up then you will lose out on sound. If you manage to configure it yourself to reduce the hum, you will always wonder if it might sound better if it were configured "properly".
Have a chat will a local Linn dealer.
It is a shame to have such a fine turntable and not be certain that it is firing on all cylinders (metaphorically speaking).
Good luck and let us know how you get on.
Happy new year
Don
I really would not "learn to live with" the hum. As the guys are telling you (and they know a lot about LP12s!) if the earthing is not correctly set up then you will lose out on sound. If you manage to configure it yourself to reduce the hum, you will always wonder if it might sound better if it were configured "properly".
Have a chat will a local Linn dealer.
It is a shame to have such a fine turntable and not be certain that it is firing on all cylinders (metaphorically speaking).
Good luck and let us know how you get on.
Happy new year
Don
Thank you both for your latest suggestions.
I feel I perhaps ought to put my original post into context. The hum of which I have complained is not really a major issue for me.
Having fiddled with my turntable by installing the ground wire between the SUT and the phono stage and more recently between the sub-chassis and the front fixing bolt, I believe the quality of the sound I am now getting is the best I've ever had from the turntable (I have used an LP12 for around 35 years!).
In fact, so clean is the sound that I am finding myself playing my system at a higher level than before. It is only when playing at this slightly higher level that I am just aware of the slight hum in between tracks. At a slightly lower volume the hum is inaudible.
In all the fiddling I've been doing to try and eliminate the hum completely, I have had the volume turned way higher than I would ever have it for listening to music......I am just wondering whether I might have had the same hum with my previous MC phono stages but never noticed it because I never turned the volume up that high? Who knows?
I will try connecting the long tonearm ground wire either to my phono stage or to my pre amp just to see if there is any further improvement in sound quality.
I've become absolutely fascinated with all that I've been reading elsewhere on this site about torque issues in so far as they relate to setting up an LP12 and other components. Will probably have to try and get one. The SR variants only seem to be sold in the USA though.
Thanks for the help and assistance offered thus far.
I feel I perhaps ought to put my original post into context. The hum of which I have complained is not really a major issue for me.
Having fiddled with my turntable by installing the ground wire between the SUT and the phono stage and more recently between the sub-chassis and the front fixing bolt, I believe the quality of the sound I am now getting is the best I've ever had from the turntable (I have used an LP12 for around 35 years!).
In fact, so clean is the sound that I am finding myself playing my system at a higher level than before. It is only when playing at this slightly higher level that I am just aware of the slight hum in between tracks. At a slightly lower volume the hum is inaudible.
In all the fiddling I've been doing to try and eliminate the hum completely, I have had the volume turned way higher than I would ever have it for listening to music......I am just wondering whether I might have had the same hum with my previous MC phono stages but never noticed it because I never turned the volume up that high? Who knows?
I will try connecting the long tonearm ground wire either to my phono stage or to my pre amp just to see if there is any further improvement in sound quality.
I've become absolutely fascinated with all that I've been reading elsewhere on this site about torque issues in so far as they relate to setting up an LP12 and other components. Will probably have to try and get one. The SR variants only seem to be sold in the USA though.
Thanks for the help and assistance offered thus far.
Fredrik,
Further to your below advice:-
The grounding seen from the phono stage goes like this:
Phono stage - arm cable ground wire - arm - subchassie - crossbrace and top plate (bolt)
Can I just check I am understanding you correctly. Are you suggesting there should be a separate ground wire between the arm and the sub-chassis? If that is what you are saying, how do you connect that ground wire to the arm?
My OL Illustrious tonearm has captive phono leads and ground wire emerging from the bottom of the arm. It does not a tonearm cable that is connected via a plug.
As such, I am able to connect the long captive tonearm ground wire to either the phono stage or my pre amp (even though I can't hear any difference when this wire is connected). I do not have an extra ground wire to connect from the arm to the sub-chassis.
However, following your earlier suggestion I do now have a ground wire between sub-chassis and front cross-brace bolt (together with a ground wire between SUT and phono stage. It is this configuration that is now giving my best ever performance from my turntable.
I would be grateful if you were able to clarify whether there should be a ground wire between arm and sub-chassis too.
Thanks
[/quote]
Further to your below advice:-
The grounding seen from the phono stage goes like this:
Phono stage - arm cable ground wire - arm - subchassie - crossbrace and top plate (bolt)
Can I just check I am understanding you correctly. Are you suggesting there should be a separate ground wire between the arm and the sub-chassis? If that is what you are saying, how do you connect that ground wire to the arm?
My OL Illustrious tonearm has captive phono leads and ground wire emerging from the bottom of the arm. It does not a tonearm cable that is connected via a plug.
As such, I am able to connect the long captive tonearm ground wire to either the phono stage or my pre amp (even though I can't hear any difference when this wire is connected). I do not have an extra ground wire to connect from the arm to the sub-chassis.
However, following your earlier suggestion I do now have a ground wire between sub-chassis and front cross-brace bolt (together with a ground wire between SUT and phono stage. It is this configuration that is now giving my best ever performance from my turntable.
I would be grateful if you were able to clarify whether there should be a ground wire between arm and sub-chassis too.
Thanks
[/quote]
On Linn arms, the arm cable has an extra lead going out from the DIN plug that goes into the base of the arm. This lead carries the ground from arm to subchassie.
I'd try replicating that connection, after measuring that the ground wire of your arm really connects to the metal of the arm (and perhaps from arm to cartridge).
Another option (less optimal) is to tie crossbrace/subchassie/top plate to mains ground. Occasionally, this was done on older LP12's through the power cord to Basik/Valhalla or the cable from Lingo. This works when the phono stage is also grounded to mains ground, but in my opinion it's better to use the phono stage ground and tie that to all parts of the turntable.
I'd try replicating that connection, after measuring that the ground wire of your arm really connects to the metal of the arm (and perhaps from arm to cartridge).
Another option (less optimal) is to tie crossbrace/subchassie/top plate to mains ground. Occasionally, this was done on older LP12's through the power cord to Basik/Valhalla or the cable from Lingo. This works when the phono stage is also grounded to mains ground, but in my opinion it's better to use the phono stage ground and tie that to all parts of the turntable.