I bought the parts to build a 5X9 volt battery
phantom unit right before I took a chance on
buying a Rolls that proved to work (for quiet
location nature recording). If anyone wants to
take a look at the schematic that Klas was
helping me with and add variations/improvements,
I'll try to pull the collective insights together
and build up one up and test it. I was aiming
for PIP 1/8" HIMD unbalanced mic inputs. This is
a pretty specialized discussion. I'm happy to
move it off list. Rob D.
At 7:12 AM -0800 11/24/05, umashankar wrote:
>i keep forgetting to post this. one of the simplest
>ways to build a phantom power is to wire a number of
>nine volt batteries together 5 of them will do. it is
>larger than doing it with two nine volt batteries, but
>it is a great deal more efficient so you actually save
>money buying batteries, and it is probably the
>quietest thing you can do. two 1 per cent metal film
>resistors of about 6.8 k, to 100 mfd 50 volt
>capacitors and two 1 mfd film capacitors in parallel
>is all it takes.
>
>umashankar
>
>--- Klas Strandberg <> wrote:
>
>> Just add: I have been working with electronics since
>> 1982. I have learned
>> that it is really difficult to weight together
>> different peoples
>> experiences of some device.
>> This is not only a problem caused by everyone's
>> subjectivity, but also a
>> technical. Just remember that standard components,
>> capacitors and
>> resistors, might have a +/- 20% tolerance. Suppose a
>> condensor (whatever)
>> of one power supply is -20 % and another +20%? Will
>> they both work at -20
>> centigrade??
>>
>> We naturesound people run constantly into problems
>> which no one else
>> bothers much about. We often work "on the limit" of
>> what a product is meant
>> for.
>>
>> Klas.
>>
>>
>>
>>
>> At 12:22 2005-11-24, you wrote:
>> >Yes, you are right in a way - Sennheiser made their
>> own power supplies etc.
>> >To make a good power supply is difficult.
>> >But with new IC's, it is easy to make a lot of
>> shortcuts. Then you can also
>> >make a cheap power supply, with uncertain
>> reliability.
>> >However, my old Tascam DA-P1 has such a simplified
>> power supply and it has
>> >never caused any problems...?
>> >
>> >Klas.
>> >
>> >
>> >
>> >At 04:47 2005-11-23, you wrote:
>> > > >According to my friend it is more or less by
>> chance all the time if a
>> > power
>> > >
>> > > >device works or not. He says that all modern
>> IC-circuit for the purpose
>> > > >have a tendency to drift away in frequency. In
>> his experience only one of
>> > > >them work under all circumstances, stable and
>> pure. In his opinion, the
>> > > >Rolls is a very conventional and thereby
>> unreliable device. ... if it
>> > > >works, it works... kind of.
>> > >
>> > > >Klas.
>> > >
>> > > >Does the phantom power supply he's designed
>> produce less noise? Are
>> > > >you free to tell us more? Is it portable? What
>> operating voltage?
>> > >
>> > > >Rob D.
>> > >
>> > >
>> > >Hi Klas,
>> > >
>> > >
>> > >
>> > >Isn't what you are getting at is that the Rolls
>> might accidentally coincide
>> > >with the correct powering voltages on some
>> microphones?
>> > >
>> > >
>> > >That to be certain that you are providing the
>> correct voltages the
>> > >manufacturer would be wise to supply the mic with
>> the correct phantom power
>> > >unit, just as Neumann has always done?
>> > >
>> > >
>> > >By saying if the Rolls works, it works by chance?
>> and should not be
>> > >considered unless there is evidence providing
>> it's powering that microphone
>> > >model accurately?
>> > >
>> > >
>> > >
>> > >
>> > >Best,
>> > >
>> > >
>> > >Mark
>> > >
>> > >
>> > >[Non-text portions of this message have been
>> removed]
>> > >
>> > >
>> > >
>> > >
>> > >"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:
>> >
>> >
>> >
>> >
>> >
>> >"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:
>> =A0
>>
>>
>>
>> ------------------------ Yahoo! Groups Sponsor
>>
>>
>> "Microphones are not ears,
>> Loudspeakers are not birds,
>> A listening room is not nature."
>> Klas Strandberg
>> Yahoo! Groups Links
>>
>>
>>
>>
>>=A0
>>
>>
>>
>
>
>
>
>
>__________________________________
>Yahoo! Mail - PC Magazine Editors' Choice 2005
>http://mail.yahoo.com
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
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