Dear Raimund -
- of course! the PRO6 has resistors regulating the phantom power!!
That is the R12 and R13 in your diagram. PRO6 has 10k, instead of
3,3k, as the PRO6 needs much less current.
Please: I don't belong in beginners class!
But "your" pin 2 is also connected to a RF coil and a condensor to
the positive rail.
For an output of 200 Ohms, this coil should be about 100 Ohms. PRO6
has a 100 Ohms resistor instead of this coil. In series with this
coil, "your" diagram has a condensor to +.
Pro6 also, but to -.
The interesting difference is whether "your" diagram shows a kind of
symmetrical output by having the virtual ground swinging up and down
with the signal. It is possible, but I have never seen it before.
The author of "your" article says that the output is "balanced", he
doesn't say that it is "symmetrical."
I will check this with Sennheiser and let them have a look at "your"
diagram . See if it is principally the same as they use. .
But I still claim that symmetry and phantom power noise is not
related, except perhaps sometimes.
If it were, do you think that R=F6de NT1A should have exactly the same
solution as Telinga PRO6??? (just other values)
Again I want to point out that PRO6 works with all inputs I know,
except FR2 and MT24/96.
This kind of tech-talk has been criticized and asked to move to
mic-builders forum, which I think is correct.
I still suggest we take it off list..??
Bye for now,
Klas.
At 00:08 2007-03-23, you wrote:
>Klas wrote:
> > Hmmm, might be a mistake here.
> >
> > Pin 3 of PRO6 IS connected to a 100 ohms resistor and 22 mfd/50 v
> > condensor to ground, just as the usual and as the MKH circuit you
> > refer to. (But connected to + instead)
>
>Yes, that is exactly the mistake. A phantom-powered microphone should
>draw identical currents from pin 2 AND pin 3 through the microphone
>electronics to ground (pin 1). This is achieved by a matched pair of
>resistors (R12 and R13, 3k3 ohms in the schematic that I refer to).
>These two resistors are in series with the two matched 6k8 resistors
>that are connected to +48V inside the recorder. In addition to that,
>there should be no asymmetric capacitive loads to the pins 2 and 3.
>Anything else would be wrong and could cause trouble.
>
>Regards,
>Raimund
>
> > I think Sennheiser had that solution, as they could use a 16V
> > tantalum condensor to "ground" the cold output, in this case pin 2..
> > As you can see on the diagram, there is only 10 v between the 48v and
> > the 38v +rail. High voltage tantalum condensors were expensive not
> > long ago, and connecting the cold output to + instead of to ground,
> > is from that perspective really smart.
> >
> > Klas.
> >
> > At 21:17 2007-03-22, you wrote:
> > > > Raimund Specht wrote:
> > > >
> > > > >Yes, that impedance matching will make sure that the disturbances
> > > > >entering in the cable will be compensated. However, in this
>way, the
> > > > >noise originating from the phantom power will only be present
>on pin
> > > > >2.
> > >
> > >Dan Dugan wrote:
> > > > If you're talking about noise from the phantom power source in the
> > > > recorder, it will be applied equally (depending on the accuracy of
> > > > the series resistors) to pins 2 and 3, assuming equal impedance
> > > > (which is why the dummy network on pin 3 of the mic) and will be
> > > > canceled by the balance of the mic preamp.
> > >
> > >Yes, of course. I just tried to explain to Klas that his unbalanced
> > >microphone output (where pin 3 is not connected to the usual series
> > >resistor) is not able to tolerate any potential phantom power noise.
> > >The debate started here:
> > >http://tech.groups.yahoo.com/group/naturerecordists/message/27021
> > >
> > >Raimund
> > >
> > >
> > >
> > >
> > >"Microphones are not ears,
> > >Loudspeakers are not birds,
> > >A listening room is not nature."
> > >Klas Strandberg
> > >Yahoo! Groups Links
> > >
> > >
> > >
> >
> > Telinga Microphones, Botarbo,
> > S-748 96 Tobo, Sweden.
> > Phone & fax int + 295 310 01
> > email:
> > website: www.telinga.com
> >
> >
> >
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email:
website: www.telinga.com
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