My Beolab 3500 is and MKI (SW 1.2) with the MCL connector. I have used the service manual for the BL3500 (its called LCS9000 servicemanual) available on Beoworld but also a lot of other servicemanuals, and MCL related documentation to get information and inspiration and I will try to mention them as we go along. To get A baseline for testing I choose to start with a test of the BL3500 in a MCL network as it was supposed to be used to confirm everything working and to know what to expect for certain scenarios. I have a Beomaster 5500 I have used as the audiomaster in the MCL setup. BM5500 – MCL Cable - BL3500 Tested with both the setting ML off and ML on in the BL3500 service menu (Menu+0+9+GO) The sources from the BM5500 is controlable, and volume control is possible. This setup seems to be working as expected. With a multimeter I tried to measure voltages on the different pins, and I got a voltage reading of 4,68 V on the data pin (pin 6) relative to all other pins. The voltage would drop slightly for a second when I turned the system into standby, and then continue at 4,68V. I know that the signal has embedded data, so these measurements might not tell everything.

As we already know that sound input on the MCL port of the BL3500 is possible when a ML source is also connected, I wanted to try if this was also the case if the MCL source has a datasignal. So I made this setup: BM5500 – MCL cable – BL3500 – ML cable – 1611 beolink converter – DIN to minjack cable – iphone. Tested with the setting ML on in the BL3500 service menu (Menu+0+9+GO) Only the source from the 1611 Beolink converter was available Tested with the setting ML off in the BL3500 service menu (Menu+0+9+GO) Beolab 3500 froze and didn’t react to any remote commands at all. So I guess the conclusion of this test is that the BL3500 can’t handle data signals on both the MCL and ML connector at the same time.

The MCL connector on the BL3500 MKI will accept both speaker level inputs as stated in B&O specifications, and line level inputs as shown in the use case for the MCL connector in post 3 in this thread. I have also made some tests with this connection in this post  Login to view image But where should I connect that in my custom cable? Looking at MCL pinout’s answers that question: Login to view image Ground on both speaker connectors as well as data shield is all connected which means that pin 3, 5 and 7 in the BL3500 MCL connector all has to be connected: BM5500 pin 2 - > BL3500 pin 3, 5 and 7 BM5500 pin 1 - > BL3500 pin 1 BM5500 pin 4 - > BL3500 pin 4 BM5500 pin 6 - > BL3500 pin 6 Tested with the setting ML off in the BL3500 service menu (Menu+0+9+GO) Success This is working just the same as with the MCL connection :-) Voltage readings on the data pin (pin 6) are the same 4,68V as I registered with the MCL connection One thing to note from this test is that the BM5500 is the only product where I have found that the data pins in the Aux connector and the MCL speaker connector are connected internally in the Beomaster, so the result of this test might not be the same with other audiomasters. One other note that I don’t know if has any relation to this is the description of an obsolete Powerlink cable in the Beolink handbook where it is stated that pin 3 and 7 are short circuited. In my head that doesn’t make much sense in a powerlink cable where pin 3 is signal and 7 is data ground, but might make sense if it was used somehow with the BL3500??  

After I found out the pin 3, 5 and 7 has to be connected for the BL3500 to work with data signals and communicate with an audimaster I decided to try this in combination with voltage injection of 5V on pin 6 and 7 and afterwards on pin 1 and 7 with No result. I also tried it in combination with remote control commands as if the 5V would only be enough to get the speaker ready for receiving commands. Also tried it with the BL3500 in option 0.

Open Questions/to be investegated further: What is the purpose of option 0 on BL3500? I have a hard time seeing a use case. The reference manual mentions option 0 if you wan’t to disable the IR receiver, but not for what purpose. Can the BL3500 work on the AUX conenctor on other Audimasters? Or the MCL2AV? Can the BL3500 work with powerlink and the right adapter? Are the datasignals the same? This thread will be continued with my inputs when time allows it, but hopefully also with other inputs

Hi, option 0 is used then you have a wireless 1 with linkeye connected