This is a very nice example of our rare hybrid phase inverter in excellent condition built in our standard small preamplifier chassis.
This unit is used to convert two stereo power amplifiers into a pair of very high power mono amplifiers. Normal single channel power of the stereo amplifier is multiplied by three to four times depending upon the power supply reserves of the stereo amplifiers.
The Ultra II goes between the audio outputs of your preamplifier to each of the two power amplifiers.
The back panel of the Ultra II has a pair of stereo audio input RCA jacks and two audio outputs per channel.
The output jacks for each channel are labeled normal and inverter outputs. For each channel, this pair of jacks connects to the left and right inputs of the power amplifier. The speaker connections at each amplifier are changed to use only the left hot and right hot speaker terminals. The ground speaker connections are not used.
The phase inverter switches one internal channel of the power amplifier to operate out of phase with the other channel. This causes the output voltage to be doubled at the speaker. Since power is voltage squared, doubling the voltage to each speaker increases the power by a factor of four (up to the limits of power supply capability and thermal capacity of the amplifier).
It is a very inexpensive way of providing gobs of extra power and improving separation and imaging musically too.
Note that the phase inverter cannot be used with amplifiers already configured into internal bridge mode or ones without a common internal speaker ground.
One year parts and labor warranty and our 30 day satisfaction guarantee.