Aleph 5 low level buzzing at output both channels - diyAudio
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Old 30th July 2012, 06:49 PM   #1
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Default Aleph 5 low level buzzing at output both channels

Hi:

I am a recent proud owner of a lovely Aleph 5 which sounds incredibly wonderful, but there is a low-level buzzing in its output on both channels, either with no inputs or inputs shorted. Speakers are Gallo Reference 3.1's, 88db/W/m sensitivity. The sound is more of a buzz than a 60 Hz hum. It is not mechanical in the amp and disappears when I disconnect the speakers.

Can I assume buzz is Power Supply caps aging? If so, would you please recommend a good replacement cap with the correct physical dimensions? If not, do you suspect something else? I can open the amp and scope the ripple on the rails if that would help diagnose.

Thanks!

- Jack
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Old 30th July 2012, 07:20 PM   #2
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Caps would normally produce "Humming". Buzzing could be down to a failed or failing diode in the PSU.

Have you access to an oscilloscope ?

If not you could try the following:-

Disconnect both channel amplifiers from the PSU(s).

Make up a little test rig with a capacitor in series with a crystal earpiece. Then touch two test leads across each power supply, they should both be silent.

Now load each supply with lamps and repeat the experiment, you can do one at a time.

Finally load all four supplies (+/- L) and (+/- R) with lamps and test again.

It is UNLIKELY that both or either amplifier has developed a fault.
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Old 30th July 2012, 07:21 PM   #3
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Afterthought. Does the A5 buzz with the mains OFF ?

At low volume does it run happily for a few minutes after POWER-OFF.
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Old 30th July 2012, 07:39 PM   #4
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I have an o-scope and will test the rails. I agree ripple would be a hum not a buzz. I'm now wondering if it's an induced noise from a nearby UPS. Will test that theory also. Buzz almost sounds like TV sweeps but there's no CRT's nearby to induce such a thing.

Turning off amp kills buzz and audio output (if any) almost instantly. One thing I really like about this amp is no turn on or off pops (unlike a certain amp I had that shall remain Naim-less).
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Old 30th July 2012, 07:44 PM   #5
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Quote:
Originally Posted by jefromson View Post
Hi:

I am a recent proud owner of a lovely Aleph 5 which sounds incredibly wonderful, but there is a low-level buzzing in its output on both channels, either with no inputs or inputs shorted. Speakers are Gallo Reference 3.1's, 88db/W/m sensitivity. The sound is more of a buzz than a 60 Hz hum. It is not mechanical in the amp and disappears when I disconnect the speakers.

Can I assume buzz is Power Supply caps aging? If so, would you please recommend a good replacement cap with the correct physical dimensions? If not, do you suspect something else? I can open the amp and scope the ripple on the rails if that would help diagnose.

Thanks!

- Jack
is it original or DIY? have it buzzed all the time?
it can be the caps. or diodes. or it can be a bad soldering. or ground issue.
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Old 30th July 2012, 07:45 PM   #6
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Old 30th July 2012, 07:47 PM   #7
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This is an original genuine Aleph 5. Only had a couple of weeks. Not sure if buzzed when I received or started after.
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Old 30th July 2012, 07:49 PM   #8
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Quote:
Originally Posted by jefromson View Post
I have an o-scope and will test the rails. I agree ripple would be a hum not a buzz. I'm now wondering if it's an induced noise from a nearby UPS. Will test that theory also. Buzz almost sounds like TV sweeps but there's no CRT's nearby to induce such a thing.

Turning off amp kills buzz and audio output (if any) almost instantly. One thing I really like about this amp is no turn on or off pops (unlike a certain amp I had that shall remain Naim-less).
At low volume it should take a good few seconds to quieten down and die.

Unless you have a DIY amp with PSU monitoring to prevent turn-off thumps.
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Old 30th July 2012, 07:54 PM   #9
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Being the Grim Reaper - It is possible that one of the output MOS-FETs has failed and has caused a PSU diode to fail.
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Old 30th July 2012, 07:58 PM   #10
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In that case I would hear some nasty audio output, don't you think? Sounds glorious and perfectly balanced L/R.

The amp is not DIY but its output dies almost instantly at turn-off. Do you know for sure that an Aleph 5 should hold a charge and output something for a few seconds?
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