SS-115 Equalizer

The SS-115 (also known as ADC Sound Shaper SS 115) is a Stereo Frequency Equalizer (also known as Graphic Equalizer) manufactured by the ADC Professional Group in Japan. It has ten frequency bands per channel ranging from 31.5 Hz to 16 kHz, with boost and cut ranging ±15 dB. It has stereo line in and line out facility as well as stereo input/outputs for two tape decks with switched dubbing options. It is very similar to the model SS-115X, which uses similar build and electronic design.

This was a wonderful analogue system that provided ±15 dB cut and boost, whilst many modern graphic equalizers today have only ±10-dB capability, with digital signal processors (DSP) that totally ruin the sound. This analogue system uses discrete components including the JRC4559D operational amplifier IC, and therefore the sound quality was good on my unit after service and capacitor upgrade. This unit has a wonderful bar graph display driven by a pair of AN6877 ICs (one for each channel) for displaying the total output level. Each frequency control consists of a slider potentiometer with a stepped action and LED illumination. The ADC logo is also illuminated by a powerful light bulb, although by now it does not usually still work because it is a filament type.

When I received this it was in a right old state with dents and scratches to the outer casing. It was very filthy with years of grime inside and outside. It was producing a terrible humming noise that became worse with the low frequency boost.

The slider potentiometers were also crackling and making awful noises hence these needed cleaning as well. Unfortunately many years of dust had settled into the pots and squirting some electrical cleaner would only have resulted in a sludge-like mess, that would cause more problems when it dries, therefore I decided to clean it under flowing tap water which removed all the dust.

Capacitor Upgrade

Opening the unit, I noticed that the electrolytic capacitors within the power supply section had leaked leaving a residue. Therefore, I had to remove the main board for a thorough cleaning and then capacitor replacement. Since I had the boards out, I decided to upgrade all the capacitor to high-end ones to improve the sound.

Mains Wire Replacement

The original mains wire was very thin two-core type that had signs of damage; therefore, I replaced it with a proper three-core one and fitted an earth connection to the chassis for safety. In the following pages of this multi-page article, you can see the photographs of the inside when I took it apart for cleaning.

Cost/eBay

These vintage analogue systems are getting hard to find these days and a good working one in mint condition can cost as much as fifty pounds onwards. Unfortunately, a broken one that needs a lot of work is not worth much these days as very few people have the time to renovate vintage hi-fi.

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