My Cary amp - the story of a hum and a bug

I have had a problem with my Cary SA200.2 power amp from the time i bought it 3 years ago. There's a hum from both speakers (doesn't increase when the volume is turned up). The hum is there irrespective of the connected preamp or power source and even if i take the amp to another city or location. I was told by the dealer that such a mild hum is normal in such a powerful amp. It was only later that I realized that a solid state amp with a toroidal transformer, however powerful, should not have any audible hum. By then, it was out of warranty.

With the help of the India dealer, I wrote to Cary in the US. From their delayed and intermittent responses, it appears that the hum is a known issue, inherent in the design of the amp, that needs a 'fix', which is taken care of in the newer model of the amp. The 'fix' consists of a cable with caps and a bridge rectifier. Shockingly, they expect that I should pay around $210 + duties for this. To me, it is not a question of money, but one of principle! Why should I pay for them to fix a bug, even if the amp is out of warranty? I even suggested that it will not cost me more than $30 to build the cable here in India if they can send the diagram and component values for this fix. But Cary is adamant that I either pay for the cable or trade in my amp for a new +1 model!! In desperation, I requested that they send me the service manual of the amp, hoping to address the bug with the help of the manual. Back comes the reply that it is proprietary and that they cannot share it with customers. The dealer has been unable to exert any real pressure on Cary to resolve this issue.

I would like to know, from fellow FMs:
1. Is Cary justified in it's stand?
2. Role of local distributors/dealers?
3. Does any other FM own a Cary SA 200.2 and how he has fixed this issue.
4. Can the electronic experts suggest the specs to filter out the hum?
5. Will adding this filter adversely affect the sound quality?

I have a Chinese made integrated amp (Kinki Studio). It is no slouch, having been awarded the Blue Moon award by none other than Srajen of 6moons. I blew the amp some time ago by an incorrect connection. It was my fault. But within minutes of sending an email, the dealer in Singapore was on whatsapp chatting with me, asking for photographs, communicating with the manufacturer, suggesting diagnostic checks. Within 24 hours, they realized it could not be fixed via distance communication with a non-electronics-trained user like me. Within a week, a pair of new power amp boards arrived by DHL, shipped at the dealer's cost, with detailed instructions on how to replace the boards. The only cost I incurred was the cost of shipping the old boards back to them for diagnosis. So I guess Xi Jinping wins this round :) 

Thanks for reading
Thanks everyone.

Before starting this thread, I had tried all the permutations and combinations to isolate the problem - powering up the amp without any other components connected, installing the amp in a different room, friend's house, dealer's listening room, different city, etc. The hum remains. There is no hum coming physically from the Cary or its transformer. The hum comes from the speakers connected to the Cary, with or without and preamp or source connected!

But anyway, I now have a fresh response from Cary as detailed in my next post.

Thanks for all your suggestions and offers to help :)
To put things in perspective, let me elaborate on Cary Audio's response and position:

When first contacted about the issue, Cary Audio responded with requests for pictures of the inside of the amp. After reviewing these, their initial advice was to make an incision in the trace at the rear of the input terminal. However, this did not resolve the issue, leading to further discussions and sharing of pictures. After a more detailed review of the issue, Cary informed me that the issue could be addressed by a cable harness which they could build for me at a cost. They also sent me a picture of the harness installed in another machine. As this appeared to be a known fix that had been implemented by Cary in other machines, my contention was that this was a known issue and, hence, a defect or bug in the design. Accordingly, I suggested that Cary should ship me the harness free of cost or, alternatively, send me the specs of the harness so that I could build it locally in India. Cary Audio was not willing to ship me the harness unless I paid for its cost plus shipping. As an option, they suggested that I could trade in my old unit and purchase the upgraded version on their website. They were also unwilling to mail me the schematics or the service manual.

Cary Audio does not agree that it is a design fault. In their words, "Some countries have issues with grounding and some with hum. In order to help with these countries and our product we design in more filtering. It’s not always the case in every country, but we have come across some which need our help resolving  issues with their power infrastructure." 

I had already tried the amp in different cities in India. Wanted to check if the issue was a result of the kind of power we get here. So I carried the unit with me on my trip to Singapore and tried it there. The same hum in that country too! 

I do grant that Cary Audio has responded to all my mails and have been reaching out to help resolve the issue. But on their terms, which are not acceptable to me. In their latest mail received yesterday, they have now agreed to build the harness at their cost provided I pay for the shipping. I suppose this is a fair proposal and will take it forward with them. 

I'll post an update after installing the fix.

Thanks for reading.

I actually owned the "newer" model of this amp that had the bridge rectifier installed. It still had low level hum in one channel, so the issue is inherent in the design of the amp. I know this because I called Cary and discussed it with them. To be fair, the hum was tolerable, but I felt unacceptable for an amp otherwise of this level of overall quality and associated cost, so I eventually traded it in to a Cary dealer on another amplifier. Two more comments. First, as SS amps go, I thought it sound really good, more musical than many I have owned. Second, having once owned many pieces of Cary gear and having had several upgraded or modded by Cary, they charge a lot for the parts they provide and their service, but they do really good work and are honest people. It’s really a matter of caveat emptor.
the hum was tolerable, but I felt unacceptable for an amp otherwise of this level of overall quality and associated cost
I thought so too. I also agree that the amp sounds good. I'm just very surprised on 2 counts.
  • Why isn't a company of Cary's stature unable to overcome this design issue?
  • Why do they have such a high handed attitude towards customer service?
Unfortunately, I was unable to amicably resolve the issue with Cary. They refused to acknowledge the issue of inherent hum. They pointed out the possibility of power conditions in India, the possibility of misuse, the fact that the unit was out of warranty, age of the unit, etc., etc. But that they would still do me a big favor by sending me the cable harness at their cost. Understandable, but I am unable to deal with such attitude. I have therefore informed them that I do not need their harness, that I will scrap this amp and buy another brand.

Moderators- please close this thread.
Why not take Cary up on their offer to send you the “fix” if you pay shipping?  Sounds like you rather bash a manufacture than getting your issue resolved. As an alternative, why not purchase an amp designed and made in India that is compatible with their power grid.