My audio amp is hummmmmming.
My audio amp is hummmmmming.
(OP)
I have a Sony STR-GX800ES I use constantly, in fact it's been on for approximately 7,380 days (175,000 hours).
This is kinda funny since I've always found Sony stuff to be short lived crap so I guess they stuck-it-in-my-eye for telling people Sony is junk.
Alas, about a month ago I started hearing a hum. I've been pretty busy and assumed it was probably coming from PC which is the only source I generally provide it with. Today while listening to a text-to-speech book (Anarchy Rising; The Survivalist Book 2){a quasi-ZA tale} while working, it really started grating on me. Doing a minute of investigation it became clear that it's the STR-GX800ES causing the hum because it never changes a bit regardless of which of the zillion sources I send to the output. It does go up and down with the volume.
It's the classic 60Hz hum. Sounds the same as standing next to any large humming transformer.
I'm guessing it's probably the main power supply and the bulk caps having probably dried out, like prunes being warmed for ++100,000 hours.
Anyone ever tracked that hum to something specific in an audio amp? Is there something else that could cause it I should focus on instead?
STR-GX800ES Schematic
This is kinda funny since I've always found Sony stuff to be short lived crap so I guess they stuck-it-in-my-eye for telling people Sony is junk.
Alas, about a month ago I started hearing a hum. I've been pretty busy and assumed it was probably coming from PC which is the only source I generally provide it with. Today while listening to a text-to-speech book (Anarchy Rising; The Survivalist Book 2){a quasi-ZA tale} while working, it really started grating on me. Doing a minute of investigation it became clear that it's the STR-GX800ES causing the hum because it never changes a bit regardless of which of the zillion sources I send to the output. It does go up and down with the volume.
It's the classic 60Hz hum. Sounds the same as standing next to any large humming transformer.
I'm guessing it's probably the main power supply and the bulk caps having probably dried out, like prunes being warmed for ++100,000 hours.
Anyone ever tracked that hum to something specific in an audio amp? Is there something else that could cause it I should focus on instead?
STR-GX800ES Schematic
Keith Cress
kcress - http://www.flaminsystems.com





RE: My audio amp is hummmmmming.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: My audio amp is hummmmmming.
Dan - Owner
http://www.Hi-TecDesigns.com
RE: My audio amp is hummmmmming.
Do you want to be best friends?
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: My audio amp is hummmmmming.
Your amp may be humming because it does not know the words!
--
JHG
RE: My audio amp is hummmmmming.
20 years? That's a very good run for a domestic amplifier.
Does the buzz go away when you disconnect all the cables from the inputs? That would point toward a bad ground. If that doesn't clear it then start with the main reservoir caps, then move on to looking at other the other electrolytics.
The buzz is probably at 120Hz BTW - rectifier ripple frequency - and not 60Hz.
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
Good chuckles there.
No. :) Not spare time. I'm stuck assembling 20 double sided surface mount boards where I can solder screen one side, parts place, and reflow(solder), but the back side I have to add solder-paste by hand to 120 pads, then place the parts, then hand solder them. Listening to ZA or SciFi type books is the only way to actually retain sanity.
I'll check the ground situation today. Thanks for the suggestions.
Keith Cress
kcress - http://www.flaminsystems.com
RE: My audio amp is hummmmmming.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
Take you o'scope and start looking at various points in the power supply. You should find it fairly fast.
I had one of Sony's first VFET amps, it lasted 20 years, and a good part of that time it was being used as a power supply amp (fed from a HP sine wave generator) running from 50Hz to 10kHz.
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P.E. Metallurgy, Plymouth Tube
RE: My audio amp is hummmmmming.
He says it improves the sound.
Mike Halloran
Pembroke Pines, FL, USA
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
He makes and sells high end guitar amps.
Mike Halloran
Pembroke Pines, FL, USA
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
Match the original capacitance.
Use the same or higher voltage rating.
And replace all of them, not just a few.
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P.E. Metallurgy, Plymouth Tube
RE: My audio amp is hummmmmming.
Seems my amp has 88 electrolytics scattered around 9 circuit boards. I'm guessing about 10 different values. The power amp-board with the 'big six' is buried in the beast too. At the moment I don't have the time it looks like it will take to do the job, so I went to Best Buy and got their bottom-end Insignia tuner-amp for a paltry $80. It works really nicely! I'm actually kinda shocked. It even has Bluetooth so I can feed it with audio sourced from my phone.
Another repair on standby.
Keith Cress
kcress - http://www.flaminsystems.com
RE: My audio amp is hummmmmming.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: My audio amp is hummmmmming.
https://www.monoprice.com/product?p_id=16152&c...
Or if you're looking for something bit more powerful, and just a little over $100, perhaps this one:
https://www.monoprice.com/product?p_id=13194&c...
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: My audio amp is hummmmmming.
I still occasionally repair valve guitar amps for friends, something I used to do a lot when I was younger. The last one bagged me a Marshall T-shirt as 'payment'.
RE: My audio amp is hummmmmming.
It is either in the power supply, or a filtering stage.
Once you narrow it down replace all of them in that (and the other channel) section.
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P.E. Metallurgy, Plymouth Tube
RE: My audio amp is hummmmmming.
Keith Cress
kcress - http://www.flaminsystems.com
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: My audio amp is hummmmmming.
Keith Cress
kcress - http://www.flaminsystems.com
RE: My audio amp is hummmmmming.
That's given me a big smile this morning.
Steve
RE: My audio amp is hummmmmming.
Perhaps all you did was let out the Magic Smoke?
I'd find a knowledgeable tech and send it to him. Note, not every tech out there can or will (or should!) work on vintage equipment. You need to find the right guy. Again, the Audio Karma forum is a good place to look.
RE: My audio amp is hummmmmming.
Keith Cress
kcress - http://www.flaminsystems.com
RE: My audio amp is hummmmmming.
Dan - Owner
http://www.Hi-TecDesigns.com
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
RE: My audio amp is hummmmmming.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: My audio amp is hummmmmming.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: My audio amp is hummmmmming.
Also when I was younger (in my late teens) I used to drive a motorcycle (Honda 305 Super Hawk) and some friends had British bikes. The joke was that at night you could tell it was one of them coming down the road because when they slowed down their headlights would dim and some would even start to flicker.
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: My audio amp is hummmmmming.
When I see the phrase;
"Lucas. Prince of Darkness." I can really appreciate the sentiment.
Whenever you stopped it you had to remove the paper match book from the voltage regulator.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: My audio amp is hummmmmming.
Luckily, it had a big battery. ... or maybe that was by design.
Mike Halloran
Pembroke Pines, FL, USA
RE: My audio amp is hummmmmming.
Lucas Brakes Motto: We press on where others stop.
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: My audio amp is hummmmmming.
Not to change the subject, but just get a 100mfd cap and begin sticking it across each cap on your pcb until you find the one causing the issue... then you maybe dont need to replace all those others until they start acting up.
If on the otherhand your unit was so old to have waxpaper non electrolytic caps,, then just spend $8.00 and buy all 30 of them and replace them all. (these dont usually make the hum tho).
www.KilroyWasHere<dot>com
RE: My audio amp is hummmmmming.
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P.E. Metallurgy, Plymouth Tube