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Headset YAMAHA CM500 settings

Hello to all,

I bought a YMAHA CM500 headset and want to operate it on my Flexradio 6400

The headset has an in-line battery pack which is correct connected to the radio.

With the mic profile "Default FHM-2 DX" I am able to let the headset "work". PTT is via footswitch by the way.

But...the ouptut is not ok. It only works if you press the mic directly to your lips with a normal speach volume. So my question: Is someone out there who works with this headset succesfull and could give hints to the correct setup settings??

Have to say BIAS is on, +20db is on, mic gain far to the right level but I am still struggeling with it.

Help would be really appreciated...

73 Jan,DL7JAN


  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Jan, I have a CM500 and have it set up like this:

    BIAS ON (I do not use the battery, but did wire up an adapter cable with a .1 uf capacitor to block DC from the mic element)

    +20dB OFF

    mic gain 45 (for my voice and distance of mic to my mouth)

    TX EQ OFF (it seems to be just right for my voice)

    Adapter wired like this:


    Tip Mic+, BIAS (+3VDC)

    Ring Mic-

    Sleeve GND


    Tip Mic+ to .1uf cap to Flex Tip

    Ring BIAS to Flex Tip

    Sleeve to Flex Ring and Flex Sleeve

  • ShawnQuinn
    ShawnQuinn Member ✭✭

    Hi Jan

    I use a Yamaha CM500 headset with my 6400m and love the TX audio results. Keep in mind this is subjective of course. The headset mic is very hot and does not need much gain. It is a condenser mic however, some of the package does say dynamic mic, but that is not the case it is an electret condenser mic. So you will need the radio Bias turn on to power the mic. You do not need the battery inline.

    On the mic connection to the radio 1/8  3.5mm jack, the mic jack on my 6400m was wired differently so you need to make up an adapter or buy one. ”The new 6400(M)/6600(M) models use a 1/8” TRS jack on the rear for pseudo-balanced mic connections. The tip is Mic(+) and passes +3vdc when “bias” is activated in the SmartSDR settings (Phone/CW tab). The ring is Mic (-) and the sleeve is Ground.

    I wired a new adapter consisting of a 1/8” TRS jack (to receive the mic plug from the CM500), three wires, some heat shrink tubing to cover the wires, a 10μF capacitor and a 1/8” TRS plug that goes into the 1/8” TRS mic jack on the 6400(M)/6600(M).”

    Below is links to both.

    Make Adapter: https://community.flexradio.com/discussion/7700793/wiring-a-yamaha-cm500-headset-for-a-6400-m-or-6600-m

    Buy Adapter: https://www.amazon.ca/Hosa-YMM-261-Stereo-Breakout-Cable/dp/B000068O5H/ref=sr_1_1?dchild=1&keywords=hosa+ymm-261+3.5mm&qid=1617378552&sr=8-1

    When setting up you audio use the level meter and keep it between -10 to -5db, try to keep it out of the red end of scale. If I use the +20dB setting my mic level is 10. Without +20dB is 40. I use PROC on and NOR settings.

    Here is my transmit eq settings: Enabled

    63hz  1dB

    125hz   -1dB

    250hz  0dB

    500hz   3dB

    1khz      5dB

    2khz      7dB

    4khz     5dB

    8khz     2dB

    This is truly subjective, maybe use these as a starting point and tune to your liking. As everyone you ask will give a different answer.

    Good luck I also have the Radio Sport headset with m350 and m360 mic elements and I prefer the Yamaha cm500 headset, their lighter and I like the mic on cm500 better. The ear muffs on Radio Sport however are far superior, but I miss the supper call when wearing them. HiHi




  • John KB4DU
    John KB4DU Member ✭✭✭✭

    Depending on the transmit bandwidth selected, be cautious about boosting highs. For example, if the transmit bandwidth goes above 3000 hz, boosting highs above that frequency can cause clipping and distortion artifacts.

  • KE7FD
    KE7FD Member ✭✭
    The adapter at Amazon looks to just be a y-adapter no DC blocking capacitor.

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