NE5532 Bass and Treble Preamplifier Circuit Board

This NE5532 stereo bass and treble preamplifier circuit board has manufacturing origin of China and goes by names such as L1099, WS16, MT Hi-Fi, and XY Hi-Fi. It uses the NE5532 operational amplifier ICs to produce approximately ×10 gain, and has bass, alto (mid), treble, and volume, controls making a complete preamplifier solution for connecting to a power amplifier. This preamplifier is usually available as a kit, and in ready-assembled forms. The PCB measures 53 mm × 114 mm (approx) and has stereo RCA input sockets, whilst the output is through a screw terminal block. It operates on a split-voltage rail, and consequently requires a balanced AC voltage with a centre ground tap. The manufacturer recommends 12 V AC to 18 V AC for feeding into the circuit via a 3-pin screw terminal.

Review

Today, modern amplifiers tend to rely increasingly on digital signal processors (DSPs) to produce the bass and tone; consequently, the preamplifier and input signal switching is usually within the same DSP IC. However, what would happen if this DSP stopped working or the microcontroller that controls it failed and there was no way to replace it. I just recently had such an amplifier where the preamp section was no longer operating, however the power amplifier on a dedicated board was fine. Hence, I decided to remove the digital control circuitry and turned it into a pure analogue system by using this preamp board.

The NE5532 is a dual high-performance low-noise operational amplifier with internal compensation that is ideal and cost-effective to use as a preamplifier in this application. In a good design, and clean construction, you will certainly get hi-fi quality sound. In recent years, we have been seeing huge numbers of bass and tone preamplifier designs utilising this IC block. The competition is fierce and that is good for the consumer as it brings the price down. This particular one cost as little as three pounds including postage and bought from an online auction site.

In the circuit board that I bought, the circuit design, construction, and component selection were to very high quality and standard. One can expect a Texas Instruments NE5532 Op-Amp IC, Nippon Chemi-Con (NCC) BP Series capacitors, Philips CBB capacitors, and 1 % tolerance (brown band) metal film resistors. The stereo potentiometers are the sealed mini-series types with damped response, and come with the mounting nut and plastic knob.

This board also has built-in split voltage circuitry consisting of a bridge rectifier to convert AC to DC, capacitors to smooth the split voltage rails, and voltage regulators L7815CV and L7915CV. Hence, it is ready for installation into an amplifier application that may already have a suitable AC transformer.

Price/eBay

There is a huge plethora of bass and tone control designs on offer these days, and I bought the one that I thought was the best and cheapest. I paid approximately three pounds including postage and it came all the way from China after two weeks. They also had a kit version that was a few pence cheaper, which would have been an attractive option when I was younger, but these days anything that saves my time is good! Hence, I bought the ready-made one, which appears to be produced to an adequate standard for my needs.

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