What's the correct term for...

[Dubka]

...interference from a units psu getting into the audio of another (neighbouring" unit?

My 1176 really HATES being next to my Dolby 361 and I'm struggling to search a solution without the proper terminology.

But also, if anyone has any ideas ( other than "move one" ) before I try copper plate shielding or re-capping the Dolby - I'm all ears...

 

[JohnRoberts]

If it's magnetic probably EMI, if a switching PS perhaps RFI.

Depending on which it is, matters.

Mu metal is most effective for blocking magnetic fields, RF is a little easier with steel generally adequate, but may need added input filtering to receiving unit.

Distance is your friend... don't rule out moving them apart.  I've seen lots of units that get very unhappy when placed on top of big iron power amps with large magnetic fields.

JR

 

[ruffrecords]

As far as I know, both these units have linear supplies so what you are probably experiencing is magnetic interference from the Dolby mains transformer into one of the signal transformer of the 1176. Is what you hear mostly hum/buzz rather than broadband noise or high frequency hash? If it is then mains transformer interference is highly likely. Have you tried swapping them? If the mains transformer of the Dolby is close to a signal transformer with one right above the other, they might be further apart if you put the other above the one so to speak. If that does not help then you may need more drastic solutions. If either or both units' cases are made of steel (test with a fridge magnet) it will only make the situation worse as they will both act like magnetic conductors and transfer the interference. If the Dolby has a steel case you might get some reduction by separating its mains transformer from its case to reduce the induced magnetism.

Hope that helps.

Cheers

Ian

 

[Dubka]

Thanks for the replies fellas.
Okay, as I suspected, you've pretty much confirmed it's the psu of the Dolby.
Would recapping help at all?  I'm sure it's due...
Also, I might try flipping the Dolby upside down so the power inlet is on the right of the rack...

 

[smallbutfine]

Hi dubka,
recapping the dolby might not help you at all, if it's mains transformer is the problem inducing into the 1176s Signal transformers.
If you want to go to the root of the problem...change the dolby's old transformer to a new torroidal transformer (i do not know, what kind of mains trafo is in there, or if an appropriate torroidal fits in there.....sorry...) - and listen if the problem is gone.

Best regards,
Martin