25 pin modular system

This is a bit of an ongoing project, but started having thoughts about it after working with an Audio Ltd 2040 system while assisting a production sound mixer on a drama job.  We were having serious range issues throughout the job, the cause of which was possibly something attached to the camera.  The only way we could get round this was to move the receivers closer in ‘remote boxes’.

These were an RK3 rack in a box with a battery and antenna inputs and outputs, and we rolled out either individual XLR cables or a multicore to connect to the main trolley.  As the receivers themselves are very expensive, it’s not really practical having duplicates doing the same thing, so it was a case they could quickly be pulled out of the RK6 and slotted straight into the remote boxes.

However it’s a case that it’s not possible to do this with other receivers, such as the Wisycom MCR42, which I use.  There is, however quite a common standard for camera receivers.  Pretty much all slot in receivers have an option for a universal ‘Panasonic’ standard 25 pin connector on the base, which will output 2 channels of balanced audio.

So, I’ve now got 25 pin bases for all my receivers.  There are a number of options for antenna, audio and power distribution, which have 25 pin options.  I already owned the Audio Ltd EN2  distribution rack (which still isn’t up on their website, it’s about £550 +VAT) but got an additional 25pin base.  I was scatching my head and looking at getting something made up so the receivers slotted in, but realised the camera mount brackets had holes in the same place as the mounting points on the audio CX2 receivers.  Audio do a base for the receivers with a bar with mounting points on. So just screwed on the brackets and  now have slots.  A disadvantage with the 25 pin section on the audio ltd distributor is that it adds a bit too much weight, there’s a steel plate along the back and I’m not sure it really needs to be there.  When I get some time, I may drill out sections from that

The second mounting solution I have is a Lectrosonics Octopack.  Here it’s a case that the screw holes are in different places to those on the wisycom receivers, however Richard Meredith’s Audio Dept made a run of very purple mounting flanges, so the receivers sit in the slots properly and can also be screwed in so won’t come loose:

It’s not just wisycom which will work, almost any ‘slot in’ camera receiver should have a 25pin option (except Sony, who don’t like to play with others).  Other examples are Lectrosonics SRb, Audio Ltd CX2.  There’s also another distribution system, the PSC Six Pack.  There’s another mod to the wisycom camera plates (see the picture further up on the Audio Ltd distributor) where grooves have been drilled in the camera bracket so the cables can fit.

You can also ‘mix and match’ different brands of receiver, however they don’t always orient the connector the same way round. Here’s a Sennheiser EK3041 (it’s actually on, but the display’s nowhere near as bright as the wisycom):

They also work on their own without antennas, here’s a quick and light cable for the back with power and audio connections:

11 Replies to “25 pin modular system”

  1. Hi Richard, firstly great informative website. I’m a sound recordist working out of Johannesburg South Africa. I stumbled on your page by googling wiring lectrosonics 25 pin. I’ve got an octopack with Srb’s and I’m doing a short film next week where I’ll be in the bag and only need 2 Srb’s. I don’t really want to carry octopack if I don’t need to. So in looking for a quick solution I thought I’d search for a way to wire up some 25 pin plugs. The last picture on this page is exactly what I had in mind, is it possible to provide me with pin outs and the type of 25 pin plug you used if you made it up yourself? Thanks in anticipation. Ivan.

    1. Thanks Ivan. I’ve used the unislot pin out from a panasonic camera manual (AG-HPX3100) which I used. I also believe it’s on the sound devices superslot website (pins for audio and power should be compatible) http://superslot.org/specification/

      The DB25 backshells are made by MH connectors, their part number is: MHDCMR25-K

      Another (more expensive) option is that the audio ltd DB25 bracket will work on its own without the RF distro

      1. I just would like to understand if you sell this staff or not. I want to buy a 25 pin cable like the one in the last pic on this page.
        Thank you very much
        andrea 🙂

  2. Hi Richard, Just stumbled across this and love the idea. I want this simplicity of the cable you’ve made at the bottom when switching receivers between an Sl6 and using my receivers with my 633 in a bag. The thinking being I can get rid of the BPA42-HPN plate at the bottom and replace them with the SLK42-XX super slot adaptor instead and not have to switch plates every time.

    Just a quick question. I use the MCR42’s as well and I just want to confirm on the wiring spec for power to the DB25 connector. Do you solder the power Ground to pin 4 and hot power to pin 5 on the DB 25? From what I can see according to the unislot info: (ftp://ftp.panasonic.com/provideo/ajhpx3100gj/aj-hpx3100g_basic_oi.pdf (Page 152)) The wiring is

    1: Ch1 Grnd
    2: Ch1 + Hot
    3: Ch1 – Cold
    4: Power Grnd
    5: Power Hot (12v unregulated)
    14: Ch2 Grnd
    15: Ch2 + Hot
    16: Ch2 – Cold

    I have the specs here: http://superslot.org/downloads/SuperSlot-Specification-v1.002.pdf but I’m just confirming as there is 5.6v on pin 17 too. I want to make sure I don’t overload the receivers power or not have enough juice.

    I assume after this cable is made that it’s compatible with all superslot capable receivers?

    Any help is greatly appreciated.


    1. Hi PJ, both the unislot and superslot specs should be compatible with one another (except no data transmission without superslot). I’m not sure which receivers the 5.6V power is for, the MCR42 are happy with the unregulated power, though. I just have them wired up as you’ve described



      1. Help me please, I want to buy a 25 pin cable like the one in the last pic on this page.

        How is the model called and where do they sell it?

        1. Hello Javier,

          I’d suggest getting in contact with Stuart at locationsoundcables (stuart@locationsoundcables.com), it would be a custom job with a right angled DB25 backshell. I’ve also had some lower profile cables put together by him since doing this post.



  3. Hi Richard,

    First off, Thank you for the informative post. I’m very curious about the RF Distro in the first and second pic. I’m attempting to design my own RF distro and I’m currently educating myself on the various designs out there. (I have an academic background in electronics and communications engineering). Is your RF distro a custom job?

    Looking forward to hearing back 🙂



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