Here comes the hum

Hum, hum, hum, here it comes...

As anyone who was at the bake off at my place will remember, Ive got this conrad johnson nu-vistor device that steps a MC signal up to MM level.

I fundementally like the sound of it.. (nb its fixed, is back and working)...

But the hum is still there... not as bas as it was at the bake off (I think thats because we had about 1 million hifi components plugged in!!

BUT!
Was wondering if people who were there could help me identify the type of hum they thought it was... I know that sounds silly, but Im trying to track down the fault to get rid of it. I cant live with it like it is right now..

I know its not an earth loop because the mains earth is disconnected...

I know its not coming from the TT because Ive run an earthing lead from the TT ground on it to the TT ground on my EAR 834P.

The hum increases as you turn the volume up. Its a problem in quiet passages of music..

WM suggested it might be noise from the mains transformer.

Anybody got any ideas, ?

Its doing my head in!

Chris

 

Not sure if its the same problem, but I had a humming Rega P3. The cure was one of those ferite ring jobbies on the TT's mains lead. If that does not work you can try them on the IC's from the TT to the pre, the only downside is that some bods have reported a dgredation in the overall sound. I could'nt hear it but then I've got cloth ears.

timbo

 

tis alright.


After many hours of farting about, have discovered its the wiring in the tonearm that is causing the hum.

I'll get there eventually!

thanks though
cheers
chris

 

Chris, glad you sussed it It did say it would be some thing simple, just careful one step diagnosis can work wonders, although it takes time. WM

 

Thats right coz every time you went near it it hummed......so its picking up stray fields ie your electromagetic field [sic] see other post !!

If I'd seen your posts I could have said !!


So what are you doing about it ?

I'd go for earthing all to the same point for starter's and see the effects.

As I remember you had cables going to different sockets across the room, this is asking for ground loops. I'd look to taking your mains from a single point. Not nessesarily a single socket, rather a plug and extension block [of suitable quality] to feed all those hungry mouths/devices.

 

Hi

Yeah, its coming from the turntable wiring 100% definately!

Not an earth loop, or feedback from other components - straight from the TT... Ive tracked it down to that.

1st step will be to multimetre the arm cables, and try and find out which lead it is. I might need to get the arm re-wired.

Thanks to WM for the frantic PMs of advice also.

Cheers
Chris

NB Pete - the CDs from the bake off that were loose were put in the jewel cases of the other CDs. Ive tried to PM you a couple of times, but you need to delete some PMs cos your box is full.

 

Hum it says I've 72 messages but I've deleted loads but can't find them

Thanks .....It probable I've just not opened the right ones after wifey "kindly" refilled them!!

 

I had a bad hum problem, that seems to be exactly the same as yours, on a Linn Basik LVX arm i had. I turned out to be a lack of continuity in the ground from where the ground wire attached to the Arm 'Wand' ( near the bearings) , to the tip of the headshell.
i solved the problem by partially dismantling the arm and then rebuilding it , cleaning and treating any bare metal joints along the way. Basically if you attach a one lead of a multi-meter to your Tone arm grounding connection, you should get low resistance and good continuity on all other bare metal parts of the arm when you prod/prong with the other test lead. There is quite often a bit of bare metal at the Headshell bolt position, this is a good place to test.
Sorting out my grounding continuity within the arm completely eradicated the hum problem instantly.

more recently i had a Hum problem when i introduced a MF X-LPS to my system. This was an Earth loop though and was cured by connecting my LP12 to the Pre amp and missing out the X-LPS , obviously the signal wires had to gothrough the X-LPS.

And even more recently i had yet another Hum problem whilst changing a cartridge. This was traced to the fact that the DIN plug wasn't plugged into the Linn Akito Arm base, when i turned the Hi-Fi on , It would seen that these phono amps are very sensitive tothe body's and other components electro-magnetic fields. i learnt a valuable lesson that night- make sure everything is plugged in properly !
HTH.

 

Hi Sid

Yeah, I think my problem is the same as your first one.

Only thing is I havent got a multi meter, or many technical skills really.

Time to take it down to a shop I think..


Cheers

Chris

 

Well... I called around for some quotes...

my nearest shop is £35 an hour labout to look at things, 2 hours predicted to sort out the wiring... £70 ouch

Price of arm second hand £100.

Doesnt stack up too well...
Dont know what to do now...

Have a think about it I guess.


Chris

PS If anyone knows sources of really cheap arm servicing let me know.

 

Chris, have a word with Len Gregory - http://www.thecartridgeman.com - and see if he has any ideas. He's a very pleasant guy to deal with.

-- Ian

 

You will easily be able to find a Multi meter that is able to check out this sort of thing for less than a fiver, if you search around a few places in your home town. Independant car accessory shops , or market stalls are good places to try, it doesn't have to be a super sensitive machine, even the really cheap ones are adequate.
Talking to some of the people in Hi-Fi shops i often wonder whether they have any technical Know how or experience either .
A Tone arm is a fairly delicate instrument and the wires can be a bit fragile and easily broken ( I've done it !), maybe you are better to get the work done in a shop, just don't let them talk you into a 'fancy dan', internal arm re-wire, when all you need is a joint, or wire end, re-soldering. Make sure they tell you exactly what the fault is, in accurate detail.

What make/model and age of arm is it BTW ?

 

get yerself down to maplins tomorow and pick up one of there cheap and chearfull multi meters shouldn't be much more than a fiver,it will certainly pay for itself.
i assume youve checked for obvious faults like wires coming adrift?.
As for the senstivaty of phono stages i spent ages "fault finding" one id built, turned out it was picking up the magnetic fields of the tv on the end of my workbench,the hum changed as the picture on the tv changed

 

well..

the test I got told to do, was to put an interconnect into it where you'd normally put a turntable in -

and short out the interconnect (connecting the earth ring to the central pin) with a bit of metal.

The hum stopped when I did this (completely) so that leads me back to the tonearms wiring...

Was that a correct test? -

The wiring all looks okay, I think its an earthing problem with the tonearms wiring personally..

These things are sent to try us eh?

:cry:

This nasty little voice in the back of my mind is trying to make me buy a new tonearm, and he must be silenced at all costs!! anyone else have that nagging monster of spend?

 

ok carrying on with this technique wire up you turntable as normal , remove the cartrige and short out each pair of leads,left earth to left signal and right signal to right earth (not sure wot colour wires your arm uses but on mine its red=right signal, green=right earth,white=left signal blue=left earth) whats the hum doing now?

 

thanks hippy

will try that tonight.

Im whizzing round the garden with a mini digger today!!

:club: