Home > Daily News, HF, Home Brew > Audio Upgrades – Heil PR781 Professional Microphone and Behringer 802 Mixer Combination.

Audio Upgrades – Heil PR781 Professional Microphone and Behringer 802 Mixer Combination.

As someone who worked doing front of house sound for rock bands for over 15 years, I was very interested in making some changes to my shack to improve the audio quality on transmit and receive. I already had a bit of equipment that would help- a Behringer Xenyx 802 mixer-  and felt the addition of a quality microphone and quality speakers would be an ideal match to the mixer. I know Bob Heil uses the same mixer in his shack. I contacted Bob and had a detailed email conversation with him about my plans. He recommended the Heil PR781 microphone and encouraged me to utilise the Behringer mixer just as I had planned.

So the setup now is as follows.

The Heil PR781 microphone is connected to channel 1 of the mixer via a balanced XLR. Balanced audio cables provide far superior audio quality. This channel is stereo so can feed two radios, one via the left channel and one via the right channel. By utilising the pan control on channel 1 of the mixer, I deliver microphone audio to either the Yaesu FT101E or one of my Icom IC706MKIIGs. This is achievable because the main outputs of the mixer go to the two radios via the separate left and right channels.  The left channel goes to the FT101E via the patch socket on the rear panel of the radio, thus providing sufficient audio to drive the FT101E. The right channel of the main output of the mixer goes to the Icom 706MKIIG accessory socket on the rear of the radio.

I don’t, at present, have quality powered monitor speakers, such as  Behringer or JVC, but the accessory speaker/phone patch box of the FT101E has a lovely warm sound, so I utilise it for all radios by feeding it via the mixer.  This speaker is connected not to the radios but to the control room output of the mixer. The receive audio from the speaker jack on the rear of the FT101 goes to channel 3 of the mixer via the line-in socket. The output of Channel 3  can thus be mixed to control room output.  Similarly the receive audio from both Icom 706MKIIGs go to Channel 5 and Channel 6 of the mixer where they too can be mixed to the control room outputs and thus to the same speaker. Of course the mixer also has a headphone socket.

The FX channel of the mixer, normally utilised to send audio to reverb and other effects has been utilised to deliver receive audio to a Mac mini computer.

Microphone - Heil PR781

Microphone – Heil PR781

I am very happy with the result so far and would like to acknowledge Bob Heil for his amazing personalised service.


Behringer Mixer connected and labelled

Categories: Daily News, HF, Home Brew
  1. David vk4mdx
    January 10, 2014 at 8:10 am

    I had this comment on my Facebook about this blog entry…
    Ohh looky,
    It’s another amateur signal that’s going to be as broad as a barn.
    (As if we don’t see enough of them already.)

    Seriously, have you even checked the LCD about permitted transmit bandwidths?
    You cant get hi fi sound from the 3KHz permitted bandwidth (Which is what your trying to do) no matter how hard you try and the sooner that the hams with these mixer setups learn that the better off we’ll all be.
    And Bob Heil should be shot for promoting this shit.

  2. David vk4mdx
    January 10, 2014 at 8:13 am

    I think it only fair that Bob gets to reply to that threatening comment…..
    The situation is VERY simple, Dave.
    The bandwidth of a transmitter is set by the transmit filters. Yes, there are some horribly wide signals on the air but NOT because of the microphone. There is a group of operators that use lots of broadcast and recording processors that overdrive the audio inputs that cause splatter and distortion BEYOND those filters. Many of these operators are replacing the factory filters to create their wide signals.

    When properly used into stock transceivers and not overdriving the ALC or audio pre amp, every one of our Heil Sound microphones create gorgeous ARTICULATE audio. That is the mission I have tried to convey to the entire amateur radio fraternity. ARTICULATION. Paying attention to the Fletcher-Munsen curve of the human ear while understanding the studies of the Bell Laboratories studies about what frequencies the human needs to hear to properly and easily understand the difference between an ‘F’ and an ‘S’. a ‘P’ or a ‘b’. THAT is why a small amount of equalization is necessary. Many do not realize how to set the microphone gain on a transceiver today….no matter if it is driven with just one of our microphones or a microphone mixer, the ALC – Automatic LIMITING Circuit is how you you set that microphone gain.

    I was involved with Dr. Inoue at Icom to lay out the design of the two band internal equalization in ALL iCOM transceivers in their PRO line, 7600,7700,7800. It is only + or – 5 dB and just enough to create that special articulation using our microphones which I designed for amateur radio use. Thousands of stations are on the air using our microphones, properly equalized with the internal EQ of the stock transceivers. These signals, PROPERLY adjusted can only transmit 2.9kHz at the widest.

    Dr. Hasagawa (Yaesu) invited me to lay out the design for his (then) FT 9000, a revolutionary new direction of amateur radio transceivers. I did three major things for Dr. Hasagawa. First, I convinced him that the transmitter need a balanced 600 ohm audio input through the broadcast standard XLR connector. We worked together and the equalizer is a full blown 3 band parametric and the last feature I came up with for Dr. Hasagawa was NOT to label the ALC meter with ALC letters. The meter on the FT 9000, the flagship of the Yaesu line has the meter labeled “MIC GAIN” …. just what ALC is all about.

    The best method of monitoring a transmitted signal is with an oscilloscope, which we talk about quite often on Ham Nation….even spent several programs on how to build a simple RF sampler that one can pick an RF signal from his coax line that feeds any type of scope. I have THREE scopes in my station lab here and NEVER transmit without watching that. I immediately can tell if I am overdriving that front end and causing any splatter, etc. outside of the 2.9kHz filters that are in all of the transceivers I have.

    Your friend on FB is not correct to say that wide signals are caused by a microphone. Sorry. Study the science. Understand the technology and do proper maintenance and monitoring. There IS no argument to science.


  3. January 10, 2014 at 1:40 pm

    You should post that on Facebook!!!!

  4. David vk4mdx
    January 10, 2014 at 8:01 pm

    I did

  5. David vk4mdx
    July 20, 2014 at 12:40 pm

    I knew about all that Bob commented on before I set this up but for those who doubt, I have now been running this setup with the FT101 and the 706s and I get only good reports. Very occasionally I bump a mic gain knob which causes some distortion but even then my signal never exceeds 2.5 kHz. Sorry Mr Facebook commenter, you are so, so, so ,so wrong!!!!

  6. Joe Sienkiewicz - W9ER
    November 4, 2014 at 11:24 pm

    Nice post on your set up! A question I have does the output of the mixer pan right side go to the 706 MK2G via the 13 pin Accessory plug and which pins are they and do you use the AF out from the accessory port back into the mixer to a monitor speaker? The Heil PR781 is a fantastic mic! Great set up! Joe – W9ER

    • David vk4mdx
      November 5, 2014 at 9:09 pm

      Thanks. Yes you should always use the aux in and out where possible because they are at line level

  7. Joe Sienkiewicz - W9ER
    November 5, 2014 at 10:58 pm

    Thanks for the reply! 73 – W9ER

  8. Chris
    November 27, 2016 at 7:49 pm

    How did you feed the audio into the ft101?


    • vk2kmi
      November 27, 2016 at 7:50 pm

      There is audio in at the back which bypasses mic amp

      • Chris
        November 28, 2016 at 8:29 am

        you mean the patch? or a custom audio in?
        I have to same 101e and behringer 1002fx
        I need the foot switch and I’ve been busy restoring the radio so I’m using a turner +3 till I get done to reduce clutter.

        Have a look: http://imgur.com/a/QHkMO

  9. vk2kmi
    November 28, 2016 at 9:00 am

    I can’t recall. I haven’t seen that radio in 15 months, sorry. I no longer can work HF so the radio and all equipment is in storage

    • Chris
      November 28, 2016 at 9:37 am

      ok did you wire the jack yourself…or was it already there?

  10. vk2kmi
    November 28, 2016 at 10:14 am

    already there

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