Cyrus 2 buzz. Should I be worried?

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Hi guys,

My beloved second-hand Cyrus 2 amp has recently developed a buzz. I can't remember when exactly I first noticed, but I think it literally started over-night; I didn't notice it develop, so to speak.

It doesn't seem to be getting any worse, but it's not getting better either! I've tried fiddling with the volume control, which has no effect on it, so it seems the buzz is volume independent. I've tried unplugging everything from the trailing lead that supplies it (which includes a mains filter), testing all of the inputs and removing the phono grounding lead, all of which have no effect at all.

Is this a known issue with the Cyrus 2? Is it likely to get worse, or even cease working altogether? I've a mind to flip the lid off and have a poke around (after it's been unplugged for a few hours, of course), but some pointers would be useful. I hope it's not beyond repair - I've only had it less than a year and it's brought me some happy listening in that time.

Any help greatly appreciated ^_^

 

[aliEnRIK]

Have you tried different interconnects?

 

[Anonymous]

Is that for all interconnects, or specifically between components?

Given that the volume and input selector doesn't affect the buzz at all, it seems unlikely that component interconnects would affect this, though I'll give it a go when I get home.

If you're referring to speaker cable, then all I can really do is re-strip the wire at the speakers' binding posts, and fiddle with the banana plugs at the amp. However, given that none of this has changed in months, it seems unlikely to be the cause of the problem.

I'll give them a go, but I'm sceptical.

 

[mikeinbrum]

Have you tried giving the amp a blast with an air-can? just in case the cause of the buzz is due to accumulated dust or muck. Worth a go anyway.

 

[Anonymous]

Disconnect all inputs, if it still buzzes it's a fault.

 

[Anonymous]

This could be a red herring, but I think it's the phono stage.

I disconnected all inputs, and sure enough the buzz was still there. I tried upping the volume on each input, and while all the line-level inputs sounded identical regardless of volume, the buzz got very loud, very quickly on the phono input. I also tried switching between MM and MC (there's a little switch for this), and the buzz sounded slightly different, but just as loud on each.

I thought it might be the grounding post, which was wobbling about all over the place, so I popped the lid open a tightened this up. Reconnecting the phono to the input, the buzz was much quieter on the phono input now, and the volume control lost its potency, but the buzz is still clearly there.

So, what do I do now? Is it really the phono stage, or am I just being mislead because it has extra gain?

 

[Anonymous]

No ideas?

 

[SteveR750]

You cold try ringing the Cyrus tech dept, they appear to be extremely helpful. No. is on their website

 

[Anonymous]

Hi there

Ive just completed a complete restoration project of an Upgraded Cyrus Two and Upgraded PSX. It was well worth the time and effort, the amp sounds better now than I can remember when I first purchased it some 15 years ago.

An unserviced amp of this age will probably require the 4, 22uf mains filter caps, and the two 10000uf Main Power Smoothing Caps replacing, and there are also Two 470uf Non polarised Caps under the main green ribon that form part of the feedback loop that are also troublesome.

The phono stage is on its own regulated 18v supply with two 470uf smoothing caps, that may also need replacing.

Also there could be a dry solder joint somewhere.

The point im making is that any of these could introduce a buzz if they are starting to dry out or fail.

You should be electrically competent to tackle this project, as you could easily do some permanent damage to the amp or worse still, yourself if your not sure what you are doing. Dont just poke around inside blindly. The main caps do have bleed resistors, but really should be properly discharged, and checked with a DVM before doing anything else. If these look like they are bulging or leaking, then they require replacing.

Cyrus will still service this amp for you, at a cost of course. And you can get further advice from http://www.diyaudio.com search for Cyrus Two, and theres a wealth of info there plus my own advice threads on fixing the cyrus two.

These are great amps well worth fixing. Parts can be sourced relatively cheaply.

Hope this helps

Regards Mark.

 

[a91gti]

No big ideas here but I assume while you had the top off you gave everything a thorough clean?

 

[Anonymous]

Thanks for all your suggestions.

taxiboy: unfortunately I didn't really have anything to give it a proper clean. I was surprised at how good the inside looked actually.

There wasn't any obvious damage - certainly no leaking capacitors. I didn't take the board out though.

mark cogley: thanks very much for your advice. I've had a quick look around diyaudio, and there's a lot of useful information there. I also found a complete service manual on another site which will come in handy.

I think I'll have to go down this route, and I'm quite looking forward to it actually. I'd hope that I'm electrically competent - I've just finished my third year of an electronics degree! I'll have to explore the threads on diyaudio further; I'm intrigued about possible upgrades while I'm doing this. I've also considered obtaining a PSX (or building one, but not sure I have the time for that!).

 

[matengawhat]

cyrus will service any of the amps they made but its prob not cheap your prob looking at 150-200 so would have to way up if its worth it

 

[Anonymous]

Glad I Could Help, I too, have the service manual for Cyrus Two, which covers all models. Cyrus charges about £129 + postage to service a Cyrus Two.

One thing that makes it easier to service, is they have made all the components on one channel odd numbers, and the other channel even numbers, so tracing a fault, and comparing one channel with another is straight forward.

Good Luck with your investigations

Mark.