[TorbenGB]

I use a set of Wharfedale amplified speakers via mini-jack to play
music from my computer. I have noticed that the speakers are humming
when the power is turned on - even if the mini-jack is plugged into
anything. This humming is annoying because it is rather loud -- well,
not loud as in loud but as in not-quiet.

I must fix this humming because it is annoying!
What tips can you give me to get rid of this humming?

I suspected the cable between speaker and player to be the culprit,
because the mini-jack was not original but had some poor-looking
soldering. The cable itself seemed fine, but rather than soldering on a
mini-jack, I decided it would be better to use a factory-made
Sennheiser cable with mini-jack already attached, which I then soldered
onto the board inside the powered speaker. But it still hums just as
loud as before, so this was not the problem in the first place. Who
knew.

What else can I do, apart from throwing away rather good(?) speakers
and buying new ones?

[Dave Plowman (News)]

In article om,
TorbenGB wrote:
I use a set of Wharfedale amplified speakers via mini-jack to play
music from my computer. I have noticed that the speakers are humming
when the power is turned on - even if the mini-jack is plugged into
anything. This humming is annoying because it is rather loud -- well,
not loud as in loud but as in not-quiet.

I must fix this humming because it is annoying!
What tips can you give me to get rid of this humming?

I suspected the cable between speaker and player to be the culprit,
because the mini-jack was not original but had some poor-looking
soldering. The cable itself seemed fine, but rather than soldering on a
mini-jack, I decided it would be better to use a factory-made
Sennheiser cable with mini-jack already attached, which I then soldered
onto the board inside the powered speaker. But it still hums just as
loud as before, so this was not the problem in the first place. Who
knew.

What else can I do, apart from throwing away rather good(?) speakers
and buying new ones?

You can check if it's pick up on the lead by shorting out the input jack.
If it still hums, there's likely inadequate or failed smoothing in the
power supply. Other possibilities are hum pickup from something else in
the room - does moving the entire unit make any difference?

--
*I'm not as think as you drunk I am.

Dave Plowman London SW
To e-mail, change noise into sound.

[TorbenGB]

Thank you for the suggestions, Dave!

You can check if it's pick up on the lead by shorting out the input jack.
I'm not sure I understand what you mean.
If I short the minijack then it buzzes LOUDLY.
I'm careful not to do that.

there's likely inadequate or failed smoothing in the power supply
Can I fix it?

Other possibilities are hum pickup from something else in
the room - does moving the entire unit make any difference?
No, it hums happily wherever it is.

*I'm not as think as you drunk I am.
But if I come back before I return, please ask me to wait.

-Torben

[Homer J Simpson]

"TorbenGB" wrote in message
ps.com...

What else can I do, apart from throwing away rather good(?) speakers
and buying new ones?

It isn't the speakers or the speaker cable. Swapping new ones would prove
that.

[CJT]

TorbenGB wrote:

Thank you for the suggestions, Dave!


You can check if it's pick up on the lead by shorting out the input jack.

I'm not sure I understand what you mean.
If I short the minijack then it buzzes LOUDLY.

If you short both the tip and ring to the sleeve it should not buzz
loudly.

I'm careful not to do that.


there's likely inadequate or failed smoothing in the power supply

Can I fix it?


Other possibilities are hum pickup from something else in
the room - does moving the entire unit make any difference?

No, it hums happily wherever it is.


*I'm not as think as you drunk I am.

But if I come back before I return, please ask me to wait.

-Torben



--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

[TorbenGB]

If you short both the tip and ring to the sleeve it should not buzz loudly.
You're right. I now unplugged the minijack and shorted all three parts
of it, and the humming WENT AWAY completely. When I removed the metal,
it started humming again.

Then I plugged it into my (cheap old) MP3 player instead. It still
hummed.
I powered the player ON. The humming STOPPED. It also didn't hum while
playing.
I stopped the player. No humming.
I powered the player OFF. The humming is there again.
I unplugged the MP3 player. Still humming.
I plugged the speakers into my audio unit again, and now it doesn't
hum!

I also noted that plugging/unplugging the minijack in my audio unit
creates that brief, loud buzzing, but plugging/unplugging the minijack
in my MP3 player gave no loud buzzing.

Does this indicate a poor connection inside my audio unit??!
I hope not because it was expensive, but if so then I would get in
touch with the manufacturer (www.slimdevices.com).
I have several of these audio units, so I just tried swapping in
another one. Turns out it's the same the when plugged in, the
speakers are quiet only if I wiggle the minijack a little, otherwise
there's a little humming. And WHILE wiggling it's making a buzzing
noise like hell.


Thank you all for your help so far! I hope you can answer this too.
-Torben

[Dave Plowman (News)]

In article .com,
TorbenGB wrote:
You can check if it's pick up on the lead by shorting out the input
jack.

I'm not sure I understand what you mean.
If I short the minijack then it buzzes LOUDLY.
I'm careful not to do that.

Short the tip and ring to sleeve with some wire.

--
*It was all so different before everything changed.

Dave Plowman London SW
To e-mail, change noise into sound.

[CJT]

TorbenGB wrote:

If you short both the tip and ring to the sleeve it should not buzz loudly.

You're right. I now unplugged the minijack and shorted all three parts
of it, and the humming WENT AWAY completely. When I removed the metal,
it started humming again.

Then I plugged it into my (cheap old) MP3 player instead. It still
hummed.
I powered the player ON. The humming STOPPED. It also didn't hum while
playing.
I stopped the player. No humming.
I powered the player OFF. The humming is there again.

That suggests that when the power is off the player presents a high
impedance, similar to no connection.

I unplugged the MP3 player. Still humming.
I plugged the speakers into my audio unit again, and now it doesn't
hum!

I also noted that plugging/unplugging the minijack in my audio unit
creates that brief, loud buzzing, but plugging/unplugging the minijack
in my MP3 player gave no loud buzzing.

Does this indicate a poor connection inside my audio unit??!

That it sometimes hums and sometimes doesn't suggests the jack in the
audio unit might be a bit weak -- these things have little pieces of
springy metal that make the actual connection, and they can sometimes
lose their springiness.

I hope not because it was expensive, but if so then I would get in
touch with the manufacturer (www.slimdevices.com).
I have several of these audio units, so I just tried swapping in
another one. Turns out it's the same the when plugged in, the
speakers are quiet only if I wiggle the minijack a little, otherwise
there's a little humming. And WHILE wiggling it's making a buzzing
noise like hell.


Thank you all for your help so far! I hope you can answer this too.
-Torben

I'd suggest getting a pair of resistors of appropriate value (this will
depend on what the player is designed for, but something like 200 ohms
might be generally suitable) and putting them across the input of the
speaker amplifier -- unless, of course, you also need to be able to use
it with a high impedance device.

But before doing that, you might also consider another possibility --
are you sure the plug and jack are the same size? There shouldn't be
much "wiggle" if both the plug and jack are the same size. If they're
not, adapters are available.


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

[TorbenGB]

CJT wrote:
are you sure the plug and jack are the same size? There shouldn't be
much "wiggle" if both the plug and jack are the same size.
Yes, the plug and the jack are the same "walkman-type" size. But
apparently the jack in the audio unit is weak, as you suggest. A real
disappointment in a $300 device.


I got the humming stopped for now, at least until someone wiggles the
cable again.
Thanks for your help.