Jim Brown wrote:
thanks for the helpful reply
I have reduced the problem to the point where it's no longer an issue by
moving the amp to the left of the operating position. Once I discoverd
the issue I was keen to reduce the strength of the magnetic field in the
vicinity of the K3 and it's transformer balanced line inputs.
From a shack layout point of view it's not quite as good ergonomically
but I can live with it
A bit of sniffing around with a solenoid coil and a scope helped me
identify the best position for the amp. It's an interesting problem and
I wonder how many of the issues one hears on air with Hum and other
background noises is magnetically coupled
The magnetic field has quite a high harmonic content, Due I suspect to
the non-linear nature of the load current because of the rectifiers in
the HT side
> I know those headsets well -- for many years, I've specified them for
> production intercom systems in the theaters for which I design sound
This one has 50 ohm impedance ear pieces and is superb for CW (my
primary mode) In the past I have spent many hours with DT-110's on
> Something else you can (and should) do with the K3 is roll off the low
> octave bands in TXEQ. For most mics and most voices, the two lowest bands
> should be full cut on the K3. That's 16dB for each band, and if they're
> minimum phase filters, they'll combine to add a bit more. There's no useful
> speech content in those two bands, but that's the spectrum where breath
> pops and handling noise are prevalent. Indeed, many mics should also have
> the next higher band cut as well.
I fully agree, my Sole goal hare is for good quality communications
audio that is not unpleasant to listen to.
The K3 EQ settings that I use by default are
I get good reports with this and these settings worked well with my
other headset (DT-234)
> Another headset that works VERY well with the K3 (and most other ham rigs)
> is the Yamaha CM500, which sells in the US for under $60 (I've seen it
> discounted at $40). If that is available to you, it's worth considering.
> Although some catalogs (including Yamaha's) list it as a dynamic, it's
> actually an electret.
The beyer DT 234 is a good choice that is affordable in Europe too but
not as comfortable to wear as the DT-109 and the isolation is not as
good. The rejection of shack noise (& my kids!) is a bit better with the
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