Adrian C wrote:
On 11/01/2010 15:26, Brian Gaff wrote:
Its independent of volume and on headphones. Yes, its general whining
stuff, and does change with processor load, and drive access as far as I
can hear. I have moved some leads about and its less now, but still
audible.
Obviously the psu is a heap of junk. If I could see I'd go in and put
capacitors all over the place!

It's also many other things, EMC related. If you could get done some of
the following it may help.


Yeah but the point is it only happened after he installed a new psu so the
problem is probably an el cheapo psu...we've discussed the limitations of very
cheap psu's ad nauseum in uk.comp.homebuilt and I suspect this is another of
them.
--
Bill Coombes

On 11/01/2010 16:20, bcoombes wrote:
Yeah but the point is it only happened after he installed a new psu so
the problem is probably an el cheapo psu...we've discussed the
limitations of very cheap psu's ad nauseum in uk.comp.homebuilt and I
suspect this is another of them.

Er, whoops. :-)

--
Adrian C

Le 11/01/2010 10:55, Jim Lesurf a écrit :


Why not simply change to an outboard DAC like the DACMagic? That works very
well in my experience.

BTW It does not *have* to just conducted by the power line. Could be
radiated or EM coupled.

FWIW Personally I avoid using any analogue stages inside a computer as they
generally aren't designed to provide a suitable environment. Instead I
either take out optical SPDIF or USB (as for the DACMagic). Of these
optical is probably best if you have a serious interference problem, but
USB works nicely in the cases I've tried with the DACMagic.

Slainte,

Jim


I tried plugging my Acer Aspire One 751H nettop into a dacmagic via the
usb connection using foobar & asio4all.
The sound was absolutely vile!
It sounded like a gurgling 78rpm played on a distant AM radio.
Am I doing something wrong I ask myself?

:-)

--
Froggy


"Les cons ça ose tout, c'est même à ça qu'on les reconnaît."

Michel Audiard, "Les Tontons Flingueurs" (1963)

On Mon, 11 Jan 2010 15:23:35 GMT, "Brian Gaff"
wrote:

Already done the ground thing, indeed, I have too good an earth and had to
be very careful with cable length to stop earth loop problems with
connected gear.

Well, the psu is not actually new, spare would have been a better term..
However it seems robust enough, but the fact the previous dead supply did
not have this does point to some of the switching artifacts getting into the
computer.

For ultimate low noise you could always swap the dead psu back in :-)

On Mon, 11 Jan 2010 16:20:29 +0000, bcoombes bcoombes@orangedotnet
wrote:

Yeah but the point is it only happened after he installed a new psu so the
problem is probably an el cheapo psu...we've discussed the limitations of very
cheap psu's ad nauseum in uk.comp.homebuilt and I suspect this is another of
them.

Still worth checking everything else though. When the computer box
was pulled out for psu transplant SOMETHING may have been re-connected
differently - maybe a cable that was realised to be redundant? That
may have been the very one that stabilised the grounding system!

Laurence Payne wrote:
On Mon, 11 Jan 2010 16:20:29 +0000, bcoombes bcoombes@orangedotnet
wrote:

Yeah but the point is it only happened after he installed a new psu so the
problem is probably an el cheapo psu...we've discussed the limitations of very
cheap psu's ad nauseum in uk.comp.homebuilt and I suspect this is another of
them.

Still worth checking everything else though. When the computer box
was pulled out for psu transplant SOMETHING may have been re-connected
differently - maybe a cable that was realised to be redundant? That
may have been the very one that stabilised the grounding system!

You are absolutely right in that respect but I'd still replace the psu with
something decent first.

--
Bill Coombes

Hi, you are indeed right, its one of those times when the fact that it does
what it says on the tin, is not enough. If I put a portable radio on medium
wave on a clear channel, when I switch the machine on, the same or similar
whining gurgling is heard. Other machines here have little radiation at all.


Oh well, I have another one here somewhere!

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"bcoombes" bcoombes@orangedotnet wrote in message
o.uk...
Laurence Payne wrote:
On Mon, 11 Jan 2010 16:20:29 +0000, bcoombes bcoombes@orangedotnet
wrote:

Yeah but the point is it only happened after he installed a new psu so
the problem is probably an el cheapo psu...we've discussed the
limitations of very cheap psu's ad nauseum in uk.comp.homebuilt and I
suspect this is another of them.

Still worth checking everything else though. When the computer box
was pulled out for psu transplant SOMETHING may have been re-connected
differently - maybe a cable that was realised to be redundant? That
may have been the very one that stabilised the grounding system!

You are absolutely right in that respect but I'd still replace the psu
with something decent first.

--
Bill Coombes

Brian Gaff wrote:
Hi, you are indeed right, its one of those times when the fact that it does
what it says on the tin, is not enough. If I put a portable radio on medium
wave on a clear channel, when I switch the machine on, the same or similar
whining gurgling is heard. Other machines here have little radiation at all.


Oh well, I have another one here somewhere!

Brian


Yeah I've heard that the Iranians jam BBC radio simply by powering up a 1000 low
end Chinese PSU's.

--
Bill Coombes

In article , froggy
wrote:
Le 11/01/2010 10:55, Jim Lesurf a écrit :


Why not simply change to an outboard DAC like the DACMagic? That works
very well in my experience.


I tried plugging my Acer Aspire One 751H nettop into a dacmagic via the
usb connection using foobar & asio4all. The sound was absolutely vile!
It sounded like a gurgling 78rpm played on a distant AM radio. Am I
doing something wrong I ask myself?

Maybe you were listening to a net radio station of someone playing a 78.
:-) Can't tell as you don't say what source material you were using.

However you may need to check that the data is being sent reliably via USB.

With my ancient laptop I had to tweak some of the ALSA and Pulse settings
to avoid occasional breaks. But not had to do that with my new laptop.
However if you are using Windows I can't comment on any software tweaks.

FWIW It works well here from a Shuttle using Ubuntu. Details on the
audiomisc website.

I don't use the DACmagic via usb with my fairly new Acer 5738Z as that
works nicely via its optical spdif output using Xubuntu.

BTW For both the above I have a 60GB SSD fitted as the HD.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Nice to know where to send it then....grin.

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"bcoombes" bcoombes@orangedotnet wrote in message
...
Brian Gaff wrote:
Hi, you are indeed right, its one of those times when the fact that it
does what it says on the tin, is not enough. If I put a portable radio on
medium wave on a clear channel, when I switch the machine on, the same or
similar whining gurgling is heard. Other machines here have little
radiation at all.


Oh well, I have another one here somewhere!

Brian


Yeah I've heard that the Iranians jam BBC radio simply by powering up a
1000 low end Chinese PSU's.

--
Bill Coombes