White 4100A Dual Channel Inductor Equaliser (Modified & Recapped)


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This 4100A has been refurbished with an upgraded power supply with higher-value reservoir caps and better decoupling. Electrolytics in the audio path have been bypassed or replaced with higher-value, premium, Panasonic bipolar caps. All other electrolytics and tantalum capacitors have been replaced. In addition, each frequency band has been tuned by ear to enable broad EQ boosts & cuts without the “pinched” sound of narrow EQ bands

The 4100A is a twin-channel, 10-band inductor equaliser with rotary controls. Unlike the typical White 27-band, 1/3rd-octave room equalisers, this EQ has ten bands on octave spacing plus a sweepable, 12 dB/Octave high-pass filter. It has controls for each channel so can be used as a stereo or two-channel unit

This 4100A has been modified with wider EQ bands (lower Q) from 500 Hz upwards. At lower frequencies the narrow (octave) bands are useful for targeted equalisation but, at higher frequencies, wider bands allow for smoother, broader EQ changes. With lots of overlap between bands there’s plenty of scope for sound shaping

White equalisers are built in a no-compromise fashion with inductors for every band, sealed pots, RF filtering and switchable 110 / 220 Volt power supplies. This 4100A has transformers on the input and output

Many White EQs have been installed in studios for decades and have been reliable


Two-channel inductor equaliser with minimalist electronics. Each channel has ten EQ bands plus low-pass and high-pass filters. Transformer-balanced inputs & outputs
Standard rack-mounted device. Shallow depth
Very good, vintage condition. Tested & working 100%