Check to see if the input impedance between the two channels is different.
You may just have an 'open' signal ground on the effected channel. That
could be a cold solder joint on the active circuit board or something as
simple as a bad stereo jack connection. The human body effect would seem to
indicate an open signal ground or at least a high resistance signal ground.
Have Fun,
Dave
Wa3gin
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Gary Smith
Sent: Thursday, January 15, 2009 12:04 PM
To: Rfi@contesting.com
Subject: Re: [RFI] Hum in Bose QC2 headphones
Tim,
Anything is possible. I am going to my girlfriend's place this
weekend and have an antenna there as well albiet only for 40 - 20M.
But... if the problem is present I won't need to have the antenna
connected. I'll have my laptop with me too so I can A>B that with
them as well.
I do not have this problem with my Sony, Sensheiser or el cheapo Koss
headphones, only these powered noise cancelling ones.
Tree mentioned something about perhaps my body having AC and my
grounding myself reduces the AC & possibly testing for it by moving
the headphones away to see if that stops the hum: The sounds from
within the headset are too low for my hearing & I couldn't test that
as once removed however little, I can barely hear anything from
within the phones; but there's an interesting thought he brought up
there as nothing I can connect or disconnect anywhere that kills the
hum in that right side except when I touch something metal that is
connected in any way to ground and that stops the hum 100%.
Seems like in some integral way that being proximal to the headphones
and them with the wiring attached is a functional part of the
problem.
Gary
KA1J
> I wonder if there is a problem with your AC house/shack wiring? Missing
> ground at the breaker panel or a connection between the ground wire and
> neutral missing or miss wired?
>
> It might be worth trying your K3 setup (or even the other related hum
> devices) at another Ham's house to see if the hum in the QC-2 is there.
>
> 73,
> Tim K3LR
>
> -----Original Message-----
> From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
> Behalf Of Gary Smith
> Sent: Thursday, January 15, 2009 9:00 AM
> To: Rfi@contesting.com
> Subject: Re: [RFI] Hum in Bose QC2 headphones
>
> Ron,
>
> I hadn't thought to do that but it is worth while & I'll check that
> out. It would have to be a wall wart in that everything else here is
> three prong.
>
> Interesting that while running my laptop plugged in to its PS I have
> the same problem. I just disconnected the laptop and the hum goes
> away.
>
> Same with my Sansa MP3 player, it works perfectly with these QC2
> headphones. However I just now connected the Sansa to the USB charger
> and with that the hum is back.
>
> The connector in the headphone is a custom one designed to mould
> seamlessly with it's ajacent insertion surface; I'll have to see if
> Radio Shack has a straight stereo cable that will fit in there, It's
> seeming more & more like it's either a design defect or the wire is
> in some way defective. There is a switch on the headphone end of the
> plug which changes the Z to match the input source and changing the
> setting does nothing. Maybe the issue is in that mechanism...
>
> The real issue for me is the quality of reception with these noise
> cancelling headsets is the best I have ever heard, It's like
> listening through the worlds best headphones in relative silence.
> They're to this point perfect for copy and far better than other
> headsets I have including a nice studio set that is arguably more
> accurate in reproduction quality but do not cancel the outside noise
> anywhere close to these. Given the two options, the QC2 is miles
> ahead except for that %^&*()@ hum.
>
> Last night I gave in & ran a connector from the computer chassis to
> my ankle and that killed the buzz 100% & worked the TS7C on 160M He
> was faint here but with the quality of the K3's diversity receive &
> those headsets, he was perfect Q5 as in a true 519.
>
> Gary
> KA1J
>
> > Is it worth checking to see of there are any two prong plugs on the 120V
> > circuit and plugging them in 180 the other way (including wall warts)??
> >
> > 73 es God Bless de KK1L...Ron Rossi (kk1l@arrl.net) <><
> > QTH: Jericho, Vermont
> > My page: http://home.comcast.net/~kk1l
> >
> > WX5L wrote:
> > > Gary,
> > >
> > > At this point you need to check that the ground(s) in the headphone
jack
> are still secure to the chassis of the rig. It seems that the result of a
> poor ground from the jack to the chassis could be the culprit. Open the
rig
> and inspect the grounds. There may be seperate ground paths for tip and
> ring(stereo). The ground for one side may have been interrupted.
> > >
> > > Randy
> > > WX5L
> > > --
> > >
> > >
> > > WX5L
> > > Thibodaux, LA
> > >
> > > ---- Gary Smith <wa6fgi@sbcglobal.net> wrote:
> > >> >From the other Gary Smith.
> > >> Are those Bose headphones *really* worth that kind of money? Have
seen
> their ads, just curious if they are that much better in service on a HF
rig
> than other brands.
> > >> 73,
> > >> Gary...wa6fgi
> > >>
> > >> ----- Original Message -----
> > >> From: Gary Smith
> > >> To: Rfi@contesting.com
> > >> Sent: Wednesday, January 14, 2009 6:32 AM
> > >> Subject: Re: [RFI] Hum in Bose QC2 headphones
> > >>
> > >>
> > >> > Are you certain that both ends of the cable are plugged
> > >> > in securely? I've heard the symptoms you described when
> > >> > the plug on the headphone wasn't fully seated. Please
> > >> > let us know what you find.
> > >> >
> > >> > 73
> > >> >
> > >> > -Kirk K4RO
> > >>
> > >> Hi Kirk,
> > >>
> > >> Indeed they are all the way in on both ends & that pesky hum
remains.
>
> > >> While assuring they are seated well I tried something, which was to
> > >> have the headphones on and the stereo plug unplugged at the distal
> > >> end.
> > >>
> > >> When not connected there was no hum but when I touched the bare end
> > >> of the plug to the equipment ground the right sided hum showed up.
> > >> Nothing surprising here but the same hum showed up regardless of
> > >> which terminal was touched to ground be it tip, ring or ground.
> > >>
> > >> Interestingly if I touch the bare connector with my fingers, there
is
>
> > >> no hum whatsoever.
> > >>
> > >> The plot sickens
> > >>
> > >> Gary
> > >> KA1J
> > >> _______________________________________________
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> >
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>
>
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