Amplifier buzzing, any suggestions?

Hi all
I have a Proceed AVP/AMP5, and recently the AMP5 has started buzzing when switched on. Having spoken to an ex-Proceed engineer, he said it was most likely due to the poor electicity supply in London, which often outputs at 250V.
I have tried isotek and thor conditioners, which have had quite an effect on the overall sound (but that's another story), but have not done anything to the buzz. I have also tried a mains transformer which (according to Kevin at Living Voice) outputs pure 230, or 220V, but still have the buzz at either setting.
So, things to look at include
Opening the amp and making sure the transformers ( I think there are three of them) are securely screwed into their mountings.
Checking whether removing any of my other kit from the loop influences things. I have quite a lot of boxes and wires in a full AV setup, mostly currently running through relatively cheap gangers, although with quality interconnects.
Living with the buzz, which isn't noticeable at even moderate volumes.

Any advice would be most welcome

 

I have the exact same problrem on my Marantz CD6000OSE LE CD player, my sister has has the problem on her Cambridge Audio CD32, so in my case it may well be the mains.

 

Transformer buzz is a fact of life I'm afraid.

 

So it seem's, but why should it? If it is poor mains then why dont all transformers in the house buzz at the same time?
I think it is quite tollerant of people that they accept a buzzing transformer in a expensive bit of hifi while the telly, transistor radio in the kitchen and your phone charger all carry on there work in total silence.


Paul.

 

...and certainly has nothing to do with any mains-borne noise that may or may not be present. You're only going to get round it with fairly drastic measures involving opening the case up (eg. setting the transformer in resin so it can't hum), or by changing the amp I'm afraid.

 

I was under the impression that mains borne noise could make a transformer hum more...a DC offset on the mains for example makes transformers non to happy and sets them buzzing?

I get a very very tiny buzz from my Marantz PM7000 amplifier, one from my superdac PSU, and a louder one from my cambridge discmagic. Gets a bit annoying in very quiet parts of songs,though its not so bad that I can't sleep through it, but I can sympathise...some people find things like this very very distracting, fortunately I'm not one of them!

 

the tv, phone and tranny will all probably have switch mode psu's which have a somewhat bad rep for hi-fi. mainly i believe thanks to naimies claiming horrifying tales of sonic degradation when plugged in anywhere near their kit. this means the preferred transformers are linear types which have a tendancy to buzz occasionally.
personally i've never had that much of a problem with it as if you can hear the buzz you're not playing your music loud enough.
cheers


julian

 

Thanks for all of your comments.
So it looks like option 3, ie put up with it, is favourite, and frankly, the easiest to achieve. To be honest, I live in central london ,and have far from a noise free environment, what with passing traffic etc.
Still, I might try the opening and examination of transformers in situ, to see if anything can easily be achieved.
Considering how much attention is paid to slight improvements in lowering noise floor, it makes me wonder as to its' worth given all the extraneous noises one puts up with.

 

Transformers can benefit from tightening sometimes. Especially laminated [non toroid] types. Be very careful of overtightening toroids, as the windings are near the surface. If you find you have tightened it usefully, a drop of nail varnish across the screw head will help stop it working loose again. By all means try loop experiments, though those sorts of hum should be out the speakers, not mechanically made. You may have a failing power supply cap leaking current. At that point you need a nice techy who doesn't mind get electrocuted. Maybe LesW at Avondale could give it a bill of clean health? He might replace a dodgy cap BEFORE any damage results from a total failure. Also ask a techy to take measurements of the sort found in a service manual [mainly voltages, idling currents etc] As Isaac will testify, the reason service depts have a headstart on fixing anything is because they know the correct conditions when it's working. Trying to reverse engineer a circuit that's allready stuffed is pure luck, unless it's very standard [which a proceed won't be - will it?]

 

All our wall sockets are on a separate ring, including one in the kitchen the m/wave is plugged in. The Arcam A85 amp is normally quite. But a buzz can be heard when the m/wave is on. Not sure if it coming from the Tx or the caps. After it switches off the buzz fades away, taking about 3 to 4 seconds. I tried plugging in parallel filters but they haven't helped.

First PSU I built for the Super DAC had an ABS case and buzz could be heard. For the second one I used a cast alluminium case and put additional pads under the transformer. Now I can hear the buss only if I put ears close against the case.

Couple of years ago had a Pioneer A400 and a slight hum was coming through the speakers. Then one day I fitted new uprated caps. The hum disappeared.

 

OK here how to fix a laminate transformer ..........I watch a service guy do this !

Take an insulated sloted screw driver
take the lid of the equipment .....be careful mains can and does kill
place the screw driver on the tranny and wedge between the laminates until you discover which is resonating...this stops the buzz. Then with the screw driver still in place stopping the buzz run a bead of super glue along the laminate. Allow to set and repeat for each buzzing plate.

Its not pretty and I didn't like the look of it, but it works. But do be careful.

 

American amplifiers do seem prone to buzzing transformers!

I fixed a buzzing heard from my CJ power amp by powering off and lifting off the top cover. I lined the underneath of the cover and internal sides/back with Dynamat to damp any panel resonances. On top of the transformer housing plate I affixed a 6" X 6" slab of sorbothane which I purchased from Hi Fi News Accessories Club for £12. I put the top cover back on, switched on and the buzzing was gone!

 

Thanks for the tip, I am going to get my sister to do this (she has very slippy hands)

Sorry that was evil. She just drives me mad with her amount of energy. How I wish I was 18 again.

It does sound dangerous though, as I reading that I was thinking no way am I going to try and do that!

 

Am I the only one thinking ''buy a new transformer" ?

 

No your not it's the only real answer

Stuart

 

How about switching the component off and giving two thin coats of polyurethene varnish (Ronseal?) with a small brush?
Just a thought.

 

Thanks again for the input. Looks like I might have a poke around inside to see if I can tighten or damp the transformer. Definitely with the power off!!!

 

As I said ......it's not my idea just a method that I've seen work.