Hum in Cary cad 805 AE


Hi Dear fellows.
I recently noticed a hum in one channel of my Cary Cad 805’s.The Hum is present once I switch on the left monoblock.It is not heard through the speakers, only in the amp itself.What could it be the problem??I calibrated the bias of both amps, exchanged power cords, even the 211 tubes but nothing changed...there is still this hum in the left channel.Any recommendations will be more than helpful!

Thanks in advance!
Raf
rafael0054
Is the hum still present when you disconnect the left channel interconnect? 
Yes.Without interconnect cable , the noise is still present.What could it be the problem?Transformer vibration??
Any suggestions are more than wellcome.
Thanks!

Raf
Sounds like transformer hum. Is it secured tightly? even if it is, they still hum sometimes.
Transformers sound is typically more like a buzzing at or around the 60Hz frequency but depending on its surroundings and/or how its attached to the chassis it could sound damped and closer to a hum.
Thanks for feedback!
I opened the monoblock and look at the screws of transformers,  all of them were tight.So I don't know what to say.Could it be due to the rosin or parafine tha covers the big transformers??Actually the sound is more like a buzzing around 60hz.
Any suggestion??Is it posiible to solve it or must I do to get used to this buzzing?
Thanks for your opinions.

Raf


Raf,
Why don't you contact the manufacturer with your question and see what they suggest?
I'm not familiar with this particular amp but if it has an IEC connector, try a different power cord and see if the buzzing subsides. When I was looking for power cords, there were a couple that caused my amp's transformer to make a very slight but audible buzz. Not sure why but they did. How old is they amp?
Thanks for contributions!

The amps have 10 years old and iec connectors.I use them with shunyata venom powercords in both monoblocks.I haven’t tried another brand power cord yet.But what calls my attention is that even by exchanging power cords( left to right and viceversa) the noise persists in the left monoblock.So my conclusion is that its a problem of the amplifier itself more than a suitable powercord.Anyway is only audible when pause is on.As I refer before, I put it off the base to see inside if there were something untight, but all seemed to be tight firmly.I guess that, may be, the vibration could come from the output transformer, but I has a covering with 6 lateral screews and I’m afraid that in taking this covering appart, the parafine or rosine that covers the transformer could result damaged o broken,This is actually my fear.But I guess all the problem is there, some screws that are not visible from the bottom of the amplifier but that will be probably visible under this covering.
Anyone has seen this amp without this covering??
By the way I sent an email to Cary audio but haven’t had any answer yet.

Any info will be of great help!

Sincerely

Raf

Hi Dear fellows.

Finally I decided not to touch anything in the left monoblock.Indeed is a very subtle buzzing in the transformer.I can leave with that, toghether they sound marvellous and I understand that some things must be forgiven in the tube  amplification's world.
Thanks anyway for your opinions!

Cheers!

Raf
Hi Dear fellows!

I finally brought the two monoblocks channels to a highly reputated technician.The problem was an interstage transformer  , a small one inside the chassis that feed the 211 tube.It was replaced in both channels toghether with bypass capacitors.After that repair the sound is marvellous.No hum at all.

Cheers!
Raf
Raf, glad to hear that you found the problem and got it repaired.
Now, once again, enjoy the music!
Thank's lak!!
That's what it's all about!

Cheers
Raf