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Re:Mic cables and mic impedance

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  • Syd Curtis
    Hello Klas, Doug, Walt, et al., ... The same goes for me. Only more so! I m so technically ignorant that I ... When I started recording bird song (06:00 hrs
    Message 1 of 17 , Jun 1, 2002
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      Hello Klas, Doug, Walt, et al.,

      JOHN (John V. Moore Nature Recordings) wrote:
      >
      >I hesitate to post this on the list server because
      > some of the questions I have will be very basic to many, but the DELETE
      > button is, thankfully, easy for all to use!.
      >

      The same goes for me. Only more so! I'm so technically ignorant that I
      don't even understand what impedance is. On May 29, Klas wrote:

      >
      > No designs today have low input impedance. The input impedance of a recorder
      > is always 2-10 kiloohms. I know SQN had a transformer input on some
      > pre-amps, but that was long ago.

      > This is the one and only principle for impedance matching: The input
      > impedance must be much higher than the output impedance.
      > All recorders / mic amplifiers today have an input impedance around 2 - 10
      > kOhms.
      >

      When I started recording bird song (06:00 hrs Oz EST, June 21, 1968) I had
      the good fortune to have been well advised on the recorder: I had a Uher.
      (Recently overhauled, and apparently working well. How's that for a 30
      year-old piece of technology!)

      I was also advised that to get a good recording of a lyrebird one needs to
      place a mic on a long lead, where the bird is going to sing, and for this,
      one must use a LOW IMPEDANCE microphone. The Uher mic I got with the
      recorder worked OK with 50 metres of cable, and so too did a couple of
      Sennheisers I got later. I assumed they must be low impedance.

      Of the shotgun Sennheiser (MKH-815), a friend said that what the Sennheiser
      people don't tell you, is that you can put the power supply at the recorder
      end of the long cable. I have soldered up a few connectors, but I thought
      of the cost of the mic. and the depth of my ignorance of electronic matters,
      and didn't try!

      A couple of years ago I got a Tascam DAT recorder and have successfully used
      a small Sennheiser ME 20 on the long cable with it. But I now have the
      great good fortune to have a Telinga mic which is just so much better. I
      feel sure that with the reflector it will be a definite improvement over a
      shotgun mic for recording lyrebirds at a distance - if the poor
      drought-stricken lyrebirds sing this year.

      But can I use the Telinga mic. on a long cable? Is it of low impedance - if
      indeed that is critical?

      If so, is it a matter of getting a suitable cable and connectors and still
      using the Tascam's phantom power? Or is it possible to get an external
      power source for the Telinga? The latter, I would prefer: lyrebirds
      sometimes sing for an hour or more, and battery life becomes critical. One
      doesn't wish to have to change a battery in the middle of a performance:
      Murphy's Law applying, that would be exactly when something unusual
      happened.

      I would use the Services of Music Lab, a local electronics firm, to make the
      cable, and external power supply, if that is possible. Tascam/TEAC are
      pretty big in the music industry, and I'm sure Music Lab would be familiar
      with the Tascam recorder. But not the Telinga microphone. And in the music
      industry they probably don't get much call for recording 50 metres away from
      the microphone(s) and kilometres away from any power supply - 240 V mains AC
      or even motor vehicle 12 volt DC.

      It usually takes me a few days study of an individual lyrebird to get him
      singing at my mic. And if I've gone to that much trouble, it would be great
      to be able to take advantage of the outstanding Telinga quality.

      Any advice would be most gratefully received.

      TIA

      Syd Curtis (Brisbane, Australia)
    • Vicki Powys
      Syd and All, I only know the basics here, but low impedence equipment usually has those 3-pin canon plugs and sockets and is professional style equipment,
      Message 2 of 17 , Jun 1, 2002
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        Syd and All,

        I only know the basics here, but low impedence equipment usually has those
        3-pin canon plugs and sockets and is "professional" style equipment, while
        high impedence gear uses mini-plugs and sockets and is "consumer" style.

        If you use shielded professional Cannare cables you should be fine unless
        the bush rats eat it. There was some discussion in WSRS about powering the
        mic at one end of the cable, or the other. Can't remember which was best.
        But if your mic is to be placed close to the lyrebird, you should get a good
        result either way. Powering the mic from the recording end is preferable so
        that you don't disturb the lyrebird.

        Klas will have to advise you about a separate power supply for the Telinga
        mic, I am sure it would be possible.

        But you might be better just to sort out more power options for the Tascam?
        Mics don't take much battery power to run them, in my experience.


        Vicki Powys
        Australia



        on 1/6/02 9:03 PM, Syd Curtis at sydc@... wrote:


        >
        > I'm so technically ignorant that I
        > don't even understand what impedance is.
        snip
        >
        > When I started recording bird song (06:00 hrs Oz EST, June 21, 1968) I had
        > the good fortune to have been well advised on the recorder: I had a Uher.
        > (Recently overhauled, and apparently working well. How's that for a 30
        > year-old piece of technology!)
        >
        > I was also advised that to get a good recording of a lyrebird one needs to
        > place a mic on a long lead, where the bird is going to sing, and for this,
        > one must use a LOW IMPEDANCE microphone. The Uher mic I got with the
        > recorder worked OK with 50 metres of cable, and so too did a couple of
        > Sennheisers I got later. I assumed they must be low impedance.
        >
        > Of the shotgun Sennheiser (MKH-815), a friend said that what the Sennheiser
        > people don't tell you, is that you can put the power supply at the recorder
        > end of the long cable. I have soldered up a few connectors, but I thought
        > of the cost of the mic. and the depth of my ignorance of electronic matters,
        > and didn't try!
        >
        > A couple of years ago I got a Tascam DAT recorder and have successfully used
        > a small Sennheiser ME 20 on the long cable with it. But I now have the
        > great good fortune to have a Telinga mic which is just so much better. I
        > feel sure that with the reflector it will be a definite improvement over a
        > shotgun mic for recording lyrebirds at a distance - if the poor
        > drought-stricken lyrebirds sing this year.
        >
        > But can I use the Telinga mic. on a long cable? Is it of low impedance - if
        > indeed that is critical?
        >
        > If so, is it a matter of getting a suitable cable and connectors and still
        > using the Tascam's phantom power? Or is it possible to get an external
        > power source for the Telinga? The latter, I would prefer: lyrebirds
        > sometimes sing for an hour or more, and battery life becomes critical. One
        > doesn't wish to have to change a battery in the middle of a performance:
        > Murphy's Law applying, that would be exactly when something unusual
        > happened.
        >
        > I would use the Services of Music Lab, a local electronics firm, to make the
        > cable, and external power supply, if that is possible. Tascam/TEAC are
        > pretty big in the music industry, and I'm sure Music Lab would be familiar
        > with the Tascam recorder. But not the Telinga microphone. And in the music
        > industry they probably don't get much call for recording 50 metres away from
        > the microphone(s) and kilometres away from any power supply - 240 V mains AC
        > or even motor vehicle 12 volt DC.
        >
        > It usually takes me a few days study of an individual lyrebird to get him
        > singing at my mic. And if I've gone to that much trouble, it would be great
        > to be able to take advantage of the outstanding Telinga quality.
        >
        > Any advice would be most gratefully received.
        >
        > TIA
        >
        > Syd Curtis (Brisbane, Australia)
        >
      • Klas Strandberg
        ... As far as I remember, Syd is using a telinga for phantom power, and his DAP1 can power it trough several hundred meters of cable. Klas. This outgoing
        Message 3 of 17 , Jun 2, 2002
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          >
          >Klas will have to advise you about a separate power supply for the Telinga
          >mic, I am sure it would be possible.
          >
          As far as I remember, Syd is using a telinga for phantom power, and his DAP1
          can power it trough several hundred meters of cable.

          Klas.

          This outgoing e-mail is scanned for viruses with Norton 2002

          Telinga Microphones, Botarbo,
          S-748 96 Tobo, Sweden.
          Phone & fax int + 295 310 01
          email: telinga@...
          info@...
          org. no SE440130067001
        • Syd Curtis
          ... Thanks Klas and Vicki. Just what I needed to know. Vicki pointed out that mics use very little power and using the phantom power is the best way to go.
          Message 4 of 17 , Jun 2, 2002
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            >
            >>
            >> Klas will have to advise you about a separate power supply for the Telinga
            >> mic, I am sure it would be possible.
            >>
            > As far as I remember, Syd is using a telinga for phantom power, and his DAP1
            > can power it through several hundred meters of cable.
            >
            > Klas.
            >

            Thanks Klas and Vicki. Just what I needed to know. Vicki pointed out that
            mics use very little power and using the phantom power is the best way to
            go. I've already had to set up an external battery supply for the Tascam,
            so that is fine.

            And lyrebird habitat is generally such dense forest that 50 metres of cable
            is all I need to use.

            One more question for Klas: I need to have the mic in place and connected
            up as dawn breaks. If I put a thin plastic bag over it (in case of
            unexpected rain or cloud drip) and leave it out overnight, am I risking
            ruining the mic? (I guess I should be able to tell from listening whether
            the bag affects the recorded sound.)

            TIA

            Syd
          • Klas Strandberg
            ... No, I don t think so. Hasn t happened to anybody else. Klas. This outgoing e-mail is scanned for viruses with Norton 2002 Telinga Microphones, Botarbo,
            Message 5 of 17 , Jun 2, 2002
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              >
              >One more question for Klas: I need to have the mic in place and connected
              >up as dawn breaks. If I put a thin plastic bag over it (in case of
              >unexpected rain or cloud drip) and leave it out overnight, am I risking
              >ruining the mic?

              No, I don't think so. Hasn't happened to anybody else.

              Klas.

              This outgoing e-mail is scanned for viruses with Norton 2002

              Telinga Microphones, Botarbo,
              S-748 96 Tobo, Sweden.
              Phone & fax int + 295 310 01
              email: telinga@...
              info@...
              org. no SE440130067001
            • Walter Knapp
              ... There is another alternative to cable, much more expensive. That s to go with wireless setups. These used to be not all that great in sound quality, but
              Message 6 of 17 , Jun 2, 2002
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                Syd Curtis wrote:

                > And lyrebird habitat is generally such dense forest that 50 metres of cable
                > is all I need to use.

                There is another alternative to cable, much more expensive. That's to go
                with wireless setups. These used to be not all that great in sound
                quality, but that may be changing. Sennheiser, for instance has one that
                transmits digitally at CD quality (44k 16 bit), and is rated at a signal
                to noise of 100dB. I've been accumulating the stuff to test this out and
                have most everything on hand for two channel digital stereo
                transmission, bought piecemeal off Ebay. Part of the problem being that
                in addition to the transmitter and receiver for each channel, you have
                to deal with power. The mics I'll probably use are mostly phantom
                powered, so I managed to get Sennheiser phantom power battery units to
                put out with the mics. Eventually when I can find the time and get it
                all running I'll see how it does. It may be especially useful with the
                SASS setup I'm working on.

                This setup is rated enough range for the Lyrebirds, but I don't know how
                well it transmits through dense forest. Something else to find out. It's
                rating is 280 feet line of sight, or down to 80-130 feet under "adverse
                conditions". Reports I've read indicate it may do better.

                If it works well, I could put a radio control switch setup for power out
                with it to keep batteries happy. Run that off a small R/C model
                transmitter setup. For overnighting this or larger batteries would be
                necessary, it's rated 5 hours for the transmitter on one 9 volt battery.

                I'm looking at this primarily as a means to set something up out in the
                swamp and record on dry land. Or even set it up, then record from bed
                when camping out. And primarily for less directional mics.

                Walt
                wwknapp@...
              • Vicki Powys
                Syd, It is not clear to what extent you planned to cover the mic with plastic. If wrapped around the mic, a film of plastic would definitely affect the sound
                Message 7 of 17 , Jun 2, 2002
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                  Syd,

                  It is not clear to what extent you planned to cover the mic with plastic.
                  If wrapped around the mic, a film of plastic would definitely affect the
                  sound quality.

                  Here's an idea, could you rig up a miniature A-frame tent over the fixed
                  mic, i.e. made of taut, Scotchgarded cotton-cloth material. That would shed
                  water if it rained, but be acoustically transparent, and not as noisy if
                  condensation dripped onto it while you were recording.

                  Vicki Powys
                  Australia







                  on 3/6/02 6:09 AM, Syd Curtis at sydc@... wrote:

                  >
                  >>
                  >>>
                  >>> Klas will have to advise you about a separate power supply for the Telinga
                  >>> mic, I am sure it would be possible.
                  >>>
                  >> As far as I remember, Syd is using a telinga for phantom power, and his DAP1
                  >> can power it through several hundred meters of cable.
                  >>
                  >> Klas.
                  >>
                  >
                  > Thanks Klas and Vicki. Just what I needed to know. Vicki pointed out that
                  > mics use very little power and using the phantom power is the best way to
                  > go. I've already had to set up an external battery supply for the Tascam,
                  > so that is fine.
                  >
                  > And lyrebird habitat is generally such dense forest that 50 metres of cable
                  > is all I need to use.
                  >
                  > One more question for Klas: I need to have the mic in place and connected
                  > up as dawn breaks. If I put a thin plastic bag over it (in case of
                  > unexpected rain or cloud drip) and leave it out overnight, am I risking
                  > ruining the mic? (I guess I should be able to tell from listening whether
                  > the bag affects the recorded sound.)
                  >
                  > TIA
                  >
                  > Syd
                  >
                • Syd Curtis
                  ... (Snip) ... You beaut! Record from bed. Now that s the way to go! Worth a lot more expense. Please keep us informed of progress, Walter. Syd
                  Message 8 of 17 , Jun 3, 2002
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                    Walter Knapp wrote:


                    > Syd Curtis wrote:
                    >
                    >> And lyrebird habitat is generally such dense forest that 50 metres of cable
                    >> is all I need to use.
                    >
                    > There is another alternative to cable, much more expensive. That's to go
                    > with wireless setups.

                    (Snip)

                    >
                    > I'm looking at this primarily as a means to set something up out in the
                    > swamp and record on dry land. Or even set it up, then record from bed
                    > when camping out. And primarily for less directional mics.
                    >

                    You beaut! Record from bed. Now that's the way to go! Worth a lot more
                    expense.

                    Please keep us informed of progress, Walter.

                    Syd
                  • Walter Knapp
                    ... Remember, you d still have to be camping nearby. But, I ve got some frogs that seem to call only very late at night. Get s hard to sit up waiting. ... Will
                    Message 9 of 17 , Jun 3, 2002
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                      Syd Curtis wrote:
                      >
                      > Walter Knapp wrote:
                      >
                      > > Syd Curtis wrote:
                      > >
                      > >> And lyrebird habitat is generally such dense forest that 50 metres of cable
                      > >> is all I need to use.
                      > >
                      > > There is another alternative to cable, much more expensive. That's to go
                      > > with wireless setups.
                      >
                      > (Snip)
                      >
                      > >
                      > > I'm looking at this primarily as a means to set something up out in the
                      > > swamp and record on dry land. Or even set it up, then record from bed
                      > > when camping out. And primarily for less directional mics.
                      > >
                      >
                      > You beaut! Record from bed. Now that's the way to go! Worth a lot more
                      > expense.

                      Remember, you'd still have to be camping nearby. But, I've got some
                      frogs that seem to call only very late at night. Get's hard to sit up waiting.

                      > Please keep us informed of progress, Walter.

                      Will do. I'm hoping to have some time in the next month or two.

                      Walt
                      wwknapp@...
                    • Marty Michener
                      This morning I got the following e-advisory, as I am sure many members did. I ll check it out when I get back from Mexico (Jun 9 - 15). Marty Michener MIST
                      Message 10 of 17 , Jun 5, 2002
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                        This morning I got the following e-advisory, as I am sure many members did.
                        I'll check it out when I get back from Mexico (Jun 9 - 15).

                        Marty Michener
                        MIST Software Associates
                        75 Hannah Drive, Hollis, NH 03049
                        mailto:marty@...

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