Klas Strandberg <telinga@...> wrote:
>
> Could be an overlooked thing...
>
> For the ones who donŽ't know about the principals of a pip circuit,
> have a look at telinga.com / whitepapers / this is plug in power.
>
> I wouldn't worry if, like in the old days, a resistor was used to
> give pip voltage. But it isn't, it seems: For some reasons, perhaps
> to increase input impedance, (?)
> a current generator is used.
> This may cause noise. On the other hand it could also lower the
> noise, compared to a battery and resistor...
>
> The tests I made last night with the LS-10 didn't show any
> difference. But I had some difficulties setting the reference tone
> because of insects.
>
> I'll be back when I know for sure.
>
> You noise measure people, Rod, Raimund, e.t.c. what do you think?
>
> I mean, - for the mic-fet it doesn't matter if it's running on pip
> voltage or a battery.
> So what could cause the recorder to start generating low freq. noise
> internally?
>
> Klas.

Hi Klas,

I also noticed the increased levels of noise caused by the activated PIP voltage
option on the various recorders that I have tested (using a 150 ohm termination
resistor).

I would also think that this additional (pink) noise is probably caused by a
current generator inside the recorder.

However, I guess that this increased PIP noise is not relevant when using a
typical PIP microphone, which itself usually also exhibits a higher inherent
noise level that probably masks this current generator noise. This would most
likely also apply for your quieter Telinga PIP mics as long as they provide a
sufficiently high absolute output level.

In any case, it would be safe to switch off the PIP voltage option when using
self-powered microphones such as the Sennheiser K6/ME6x series models for
instance.

Regards,
Raimund