70-Volt Transformers
The transformer is the “heart and soul” of any 70-Volt Speaker system – the examples below will explain how to set up and connect a typical 70-Volt transformer as a “Main” transformer and as a “Speaker” transformer.
Now, look at a Main transformer example (right). Note: Disregard the 100V or 25V labels. Example: We want to tap the Main transformer at 60 Watts to be able to feed five 70V Speakers (tapped at 10Watts each). First, connect the amplifier’s (+) output to 8-ohms on the front of transformer, and the amplifier’s (–) to SPKR COM (front of transformer). The PRI COM (Primary Common – front side of transformer) and 60W – 70V (back of transformer) feeds all the speakers connected on the line.
70-Volt Amplifiers – Video Clip!
70-Volt Transformers – Typical Individual Speaker Connection Example
The “Speaker” transformer example below shows the 70V Combo Amplifier’s Common (COM) connecting to the 70V Side of the transformer Common (C – Black Wire). The 70V Combo Amplifier’s 70V Positive (70V) connects to the 2 Watt Tap on the 70V side of the transformer (2W – Orange Wire). Then the 8-Ohm and Common side of the transformer connects to the 8-Ohm speaker Positive and Negative.
The example (below) has the 70V Amplifier output going to the 70V Transformer input, and the 8-ohm Transformer output to the Speakers 8-ohm input. 70V to 70V, 8-ohm to 8-ohm. All Matched!
The 70V Speaker can be one of these types:
Tech Note: It is very likely that you will never have to wire or connect an external 70-Volt “Main” Feed Transformer to a “regular” Power Amplifier, and only experience the current 70-Volt amplifier models. With that being said, there are still some older 70-Volt Systems that incorporate an external 70-Volt “Main” Transformer powered by an amplifier. We briefly covered both of these configurations on this webpage to ensure the reader understands both concepts.
