Neil 4 Channel Resolver

The Neal 4-channel resolver is a passive quadraphonic decoder for Columbia SQ and Sansui QS encoded records. It resolves the stereo output of a standard power amplifier into a pair of front and back speakers so that a matrix encoded record can be heard in quadraphonic surround sound. This article has a user manual and photographs showing the inside circuit board.

Review

The quadraphonic matrix system was designed such that decoding could be achieved at low cost, and one such method was to use a passive decoder such as this which consists of a resistor matrix, and one inductor coil. Consequently the unit is very simple and small requiring no external power supply. This made it a very popular method of decoding and this box which was available all the way back in 1978 is very sought after today by audiophiles who wish to experiment with SQ and QS encoded audio. There are many passive decoding circuits shown online, but of course a readymade unit like this is a gem to own.

A nice function of this unit is that it contains switches that provide the user with options to listen in normal stereo or quadraphonic without having to rewire everything. This is very useful as it allows one to compare the sound between the two configurations. This unit uses 2-pin DIN sockets for all the connections, and you will need six plugs in total.

Cost/eBay

I managed to spot this unit going for a couple of pounds as nobody knew what it really was, but I remembered seeing one of these featured in an electronics magazine and jumped at the chance of owning one. If you were thinking of building such a decoder then this is a readymade one that can save you much time and money. I would not let mine go for less than fifty pounds as it is so useful to me. In the following pages of this article you can see the inside of mine when I opened it to clean the switches.

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