Decora Style high-quality auto transformer provides advantages of excellent frequency response, low insertion loss and reliable performance for volume control applications in 25 and 70 volt systems. Attenuation is accomplished in ten make before break steps plus positive off position (no stop between the maximum and off position to prevent switch damage). The attenuation features removable input/output terminal blocks, two in, tow out and two optional for through output for daisy chain connection. An attractive alternative to commercial series attenuators mounts into most single gang E.O boxes. UL listed white, bone and ivory plastic plates with matching skirted knobs in Decora style.
The OSD Mono 70-Volt Volume Control provides excellent frequency response, low insertion loss and reliable performance for volume control applications in 25-volt and 70-volt systems. There's no stop between the maximum and off positions, which prevents switch damage. Featuring silver-plated contacts for noise-free operation and a removable terminal block, the OSD Mono 70-Volt Volume Control comes with white, bone and ivory plastic plates with matching skirted knobs.
The 70v mono volume control is rated at 25W, 50W and 100W so the speaker connected to it needs the transformer setting to be equal to or less than the rated watts of each 70v volume control. You can have multiple speakers connected to one 70v volume control but total wattage must be equal to or less than the rated wattage of the respective 70v volume control that you are using.
For a 70v speaker, whether an in-ceiling or wall mounted speaker you shouldn't require more than rated watts to produce more than enough sound. Normal to get the volume right you would need to experiment with the separate wattage settings (10W, 5W, 2.5W, 1.25hW) at each location to get the volume you desire. It is more flexible to add an attenuator (volume control) for each speaker. If you add an attenuator you would turn it to full volume then select the transformer tap which gives you the most volume you could use.