Many Siedle call stations can be rewired internally so that the loudspeaker is led out at terminals 12 and 13 (without the built-in transistor amplifier). Connect terminal 12 of the Siedle module to one of the door intercom contacts (make contacts 1/2 on the TSA-a/b), connect the other door intercom contact to terminal LSP of the TSA-a/b. Connect terminal 13 of the Siedle module to the 0V contact on the TSA-a/b. This results in a greater maximum volume.

Both phenomena occur if the gain of microphone and loudspeaker together is too high and/or (with 2-wire door stations) the adjusted impedance is not correct. First change the set impedance (600 Ohm or Zr) and see if you get an improvement. If not, you must reduce the gain.

If the door intercom should work after installation, but still have an unpleasant humming noise, the following points can be considered:

1. The microphone of the door intercom ages, loses amplification and becomes sensitive to hum. Usually this can be recognized by the fact that the signal from the door in the called telephone is too quiet. And if you put your finger on the microphone from the front, it will hum louder. The only thing that helps here is to replace the microphone capsule with a new one. Due to the existing environmental influences (heat) this damage pattern is quite common.
2. The TSA-a/b is powered by a bell transformer. An audible ripple current is produced when one of the bell transformer's terminals is directly or indirectly connected to the 0V, U+, MIC, LSP or NF terminals. Make sure that there is no connection here. If necessary, you will need a second bell transformer.
3. A ripple current can be coupled into the connection cable between TSA-a/b and doorbell station by electrical fields. If the hum changes by touching the cable, this is probably the problem. Use a shielded cable. The shielded cable is connected to earth/protective earth or to 0V (one end is sufficient).
4. The bell transformer can inject a capacitive ripple current due to its internal structure. Here the connection of the 0V connection to earth / protective earth helps.

The COMpact 3000 analog/ISDN/VoIP PBXs don't feature an interface for FTZ-standard doorphones.

However, you can use analog doorphones such as our TFS-Dialog 20x/30x/universal plus. In addition, you can use the TSA - a / b use this converter can convert different doorphone to a / b port .