[gabriel-dan]

Hi, I own a Stratos dual mono amplifier that has been working without problems 24/7 for 10 years, however it recently
 
developed what sounds like white noise on the left channel. It still amplifies the material been played, but the loud white noise can be heard in the background.
 
If you switch the amplifer Off, let it cool down and then switch it back ON the output is clean, however about 15min after it has warmed up the white noise comes.

Has anyone experienced a similar problem? with the Stratos?
Tx

[geowak]

Yes I did. But my amp never made it to 10 years. Better call Odyssey, maybe they can fix it....

[gabriel-dan]

Thanks geowak, I live in the United Arab Emirates and FedEx would be quit expensive. I will try to troubleshoot it and fix it, just trying

to get some pointers from people who might have had the problem.

A stratos schematic would be ideal for the job, but I guess no body in the forum has it.

[klaus@odyssey]

Hey GB, 

never mind that other post and comments.....

Well,  after 10 + years ??? Obviously there is nothing else in your system or your behavior that induced the noise,  as the amp ran perfectly after a decade plus...
In your case and looking at how you describe it,  it's probably the capacitors....caps can get old,  and I usually advise changing power supply caps every 7-10 years.  They can dry out,  not holding a charge or get noisy when charging up.

You know what,  best thing is to email me through the web site,  and I'll help you out,

Klaus

[avahifi]

Any chance you can find a shop with an oscilloscope and load bank that can look more closely at your hiss issue?  It might be useful to see if the noise has an ultrasonic component.  I would expect a leaky power supply capacitor to produce more hum then hiss. Is the hissing channel getting hotter then normal?

Frank Van Alstine

[geowak]

Hey GB, 

never mind that other post and comments.....


Klaus

Not sure what you mean here? The comment is true, my amp never made it to ten years, even when you fixed it. So my experience is valid. Also suggested the fellow call you. Not sure what is wrong with that advice...... maybe you can tell him what to do, to correct the problem over the phone.

To the OP, hope you can get your amp fixed with the help here on AC. 

[paul79]

First thing to do is make damn sure it's the amp... You mentioned powering it down and letting it cool, are you powering the whole system down or just the amp? This could be caused by anything upstream as well, unless you took the proper steps to isolate the amp as the issue.

[srb]

In your case and looking at how you describe it,  it's probably the capacitors....caps can get old,  and I usually advise changing power supply caps every 7-10 years.

That seems like a somewhat short life expectancy, but I guess it would depend on whether the amp is powered on for 8, 16 or 24 hours per day.

The parts used may vary depending on the model vintage, but several photographs of Stratos amplifiers I have seen with green circuit boards have 85°C rated power supply capacitors.  As several capacitor manufacturers give a ballpark estimate of halving the capacitor life with each 10°C increase in temperature, wouldn't 105°C rated capacitors potentially have up to 4 times, or at least double the service life, which would be more in line with what I would expect and have experienced with some other amplifiers?

Steve

[avahifi]

Re:  Make sure its the amp.

Whoops I forgot to suggest that.

There is a really easy test for this.

Turn system off and let die down completely.  Then reverse the interconnect cables between the preamp and the amp at one end only, so left channel of the preamp is feeding the right channel of the amp and vice versa.

Turn system back on again.  Does noise issue change to the other channel (speaker)?  If so it is not the amplifier.  If the noise issue remains on the same channel then it is the amplifier, unless you have recently switched to high capacitive braided or woven speaker cables.  If so get rid of them as they are causing the amplifier to oscillate.

Frank Van Alstine

[klaus@odyssey]

Frank,  very true...but then again,  it's after over 10 years of use that this problem arose...so,  I definitely think caps.

And also true,  in the beginning, when we had our first caps made for us we did use 85 caps.
However,  in the past 7 or 8 years, all of the units are 105 degrees....BUT  I still recommend a cap "oil change" kind of deal every 7-10 years for normal use,  with the amps being on all the time................

[G Georgopoulos]

Frank,  very true...but then again,  it's after over 10 years of use that this problem arose...so,  I definitely think caps.

And also true,  in the beginning, when we had our first caps made for us we did use 85 caps.
However,  in the past 7 or 8 years, all of the units are 105 degrees....BUT  I still recommend a cap "oil change" kind of deal every 7-10 years for normal use,  with the amps being on all the time................

so leaving amp on 24/7 will limit lifespan.."even with caps on 24/7"..

[klaus@odyssey]

Did I say that ????? That's what I do recommend though, and that's what I base the change of caps on.......Usually it is harder on caps to charge and discharge then keeping the amp on anyway....but over time,  electrolytic caps simply "dry"  out,  nature of the beast.............

[jtwrace]

What does a cap change cost on your amps?

[gabriel-dan]

Gents,
Thank you all for your reply and suggestions. I isolated the problem to the amp by disconnecting it from the rest of the system and connecting my Ipod as

the sole input!. I agree with Klaus about the problem been the power supply caps. As I mentioned the amp has rarely been switched OFF for the last 10

years which IMHO is very reliable.

Klaus, I have the tools required to replace the caps. Just tell me the caps specs and I will try to get them locally or I buy them from you.
 

[TAULISA]

Hi everybody...

From my long-term personal experience most amplifier noise issues resulting from old capacitors is one of the main cause although my Stratos monoblocks  have been running well since 2001 !
CAPACITORS BEHAVE LIKE DOMESTIC BATTERIES AND ONLY MOTHER NATURE CAN TELL HOW LONG THEY WILL LAST.
Unlike my Stratos monoblocks my much younger MSB PLATINUM DAC converter I purchased in 2008 revealed capacitor issues last year resulting in my loudspeakers to buzz continuously ! 
Again, another second-hand Symphonic Line integrated amplifier of mine I bought in Dortmund Germany in 1997 is still running effortlessly withouth having replaced any capacitor so far !
Therefore do not bother searching for technical reasons ! No one can predict lifespan !"
Best thing to do when noise is caused by capacitors issues is to replace them all through and through and your Stratos Amplifier will
have a secondf life resurrection as I did with my MSB PLATINUM DAC converter.