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External Mic on EX90


The EX90 Admin Guide states, that either a Headset or the Cisco TelePresence Table Microphone 20 can be connectet to the 3.5mm input on the rear.

These two microphone types are quiet different:

Headset: has a 3.5mm mono connector plug, asymmetric output and needs a PC-Soundcard-Style Power Supply.

CTS Mic: has a 3.5mm 4pin plug, symmetric output and needs a 12V Power Supply

Can anyone from Cisco tell us something about the technical backround, how the EX90 handles these two very different Microphone types?

And is there a way to use the Headset Mic only, but keep the output on the internal speakers?



John Regan

Hi Tino,

You are correct these are quite different mics.  I cant offer you much in the way the EX90 handles these two different types, just that it does work but only on EX90 and not EX60.

Here are the specs for the Table Mic 20:

CISCO Performance Mic 20 Specifications


  • Intuitive mute function directly on microphone with status indicator
  • Omni-directional, boundary microphone.
  • Excellent RF resistance and low self noise.
  • 3.5 mm four-pin mini-jack connector and 7.5 meter cable.
  • Robust and well suited for long-term meeting room use.

Technical specification

  • Directivity: Omni-directional (uniform in hemisphere above boundary)
  • Frequency response: 80-15 kHz | 80-3 kHz ± 3dB | 80-15 kHz ± 6dB
  • Sensitivity: -35dB ±3dB rel. 1V/Pa.
  • Max SPL: 110dB (3% THD @ 1kHz)
  • Self-noise: < 29 dBA , > 65 dB SNR (Signal to Noise Ratio)
  • Mic. output: Differential
  • Phantom power: 12 V
  • Output connector: 4 pin 3,5 mm mini-Jack (Shield: GND / ring 2: mute detect / ring1: signal - / Tip: signal +)

As for your question regaring using the Headset Mic only, but keep the output on the internal speakers, this is not possible.



Hi John

thank you very much. Seems, that you´re familiar with this theme, so I´ve got some other questions and inputs on that

  • Mic 20 Mute: Does the mute button also work with EX90?
  • Mic 20 Frequency response:  Is 80-15 kHz ± 6dB really correct? Shouldn´t it be 3-15 kHz ± 6dB instead?
  • Mic 20 Power: Does the Mic use 12V Phantom Power or the Voltage from ring 2? Or both, either or? Could we run the mic also with an external 48V phantom power supply if we need a longer cabling? (I´m aware, that this is not officially supportet) I know, that C20 does provide phantom power but the SX20 doesn´t.
  • Headset behavior on EX90: Is there a chance to write this behaviour into the admin guide? Today, it´s not documented, that the Headset Mic switches off the internal speakers.



Hi Tino,

  • Yes the Mute works on the EX90.
  • 80-15 kHz ± 6dB  Thats the way we have the info cannot comment on that however 3 - 15 would be quite low range
  • unable to test with  separate adaptor.
  • Would be a feedback to put a Note : That the Headset Mic switches off the internal speakers.


Ravi kr.

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