Alesis M-EQ 230

The Alesis M-EQ 230 is as cheap, small and light as a two-channel one-third octave eq gets. That's why I bought two. It was a great way to get eq for my monitors. Pogrammable digital parametric eq has replaced these in my monitor system.

M-EQ 230 at 1kHz

Frequency Response Curves of an Alesis M-EQ 230 @ 1kHz

Black is bypassed, red is active but fiter sliders centered. The curves for +12dB and -12dB are self evident. Note the drop in level, slope and LF rolloff. Also note that the filter doesn't actually center precisely on 1kHz but closer to 1.11kHz during boost and 1.15kHz during cut.

M-EQ 230 "Death to 100" Curve

Frequency Response Curve of an Alesis M-EQ with 100Hz and below @ -12dB

This is what "Death to 100" looks like on the Alesis M-EQ 230.

Rane Mojo MQ302

The Rane MQ302 is a handy stereo one-third octave graphic eq with one shared set of controls for both channels making it useful for speaker/room equalizing.

MQ302 at 1kHz

Frequency Response Curve of a Rane Mojo MQ302 at 1kHz

Clearly there's a problem here. The boost should look as sharp as the cut. This unit is in need of service. Intermediate curves were taken with the slider at the silkscreened marks.

MQ302 "Death to 100" Curve

Frequency Response Curve of a Rane Mojo MQ302 with 100Hz and below @ -12dB

The "Death to 100" on the Rane MQ302.

Tascam PE-40

Designed to interface with their open-reel recordering systems, Tascam's PE-40 has four channels of four-band parametric eq, with 60Hz and 160Hz HPFs and a 15kHz LFP. Interface is all RCA.

PE-40 at 1kHz

Frequency Response Curve of a Tascam PE-40 at 1kHz

Full boost and cut at 1kHz with Q set to minimum, center and maximum.

PE-40 High-Pass Filters

Frequency Response Curves of a Tascam PE-40 with High-Pass Filters On

Here we have the response curves of the PE-40's high-pass filters. Shown are zeroed, 60Hz and 160Hz.

Mackie 1604VLZ Pro

You've seen 'em, probably used 'em. Here's what the eq does.

1604VLZ Pro LF EQ Section

Frequency Response Curves of the LF EQ and HPF of a Mackie 1604VLZ Pro

Shown are the various combinations of the low frequency eq and high pass filter on a channel of a Mackie 1604VLZ Pro mixing board. It looks like some 60Hz line noise got into the signal.

1604VLZ Pro MF EQ Section

Frequency Response Curves of the MF EQ of a Mackie 1604VLZ Pro

This series of curves shows the mid frequency eq response with the knob pointing to 100Hz, 200Hz, 800Hz, 2kHz and 8kHz. Note that the lower three don't quite line up with the frequncies marked on the mixer.

1604VLZ Pro HF EQ Section

Frequency Response Curves of the HF EQ of a Mackie 1604VLZ Pro

HF eq set to maximum and minimum.

White Instruments Series 4000

This is a 1/3 octave equalizer with rotory pots.

Series 4000 at 1kHz

Frequency Response Curves of the White Instruments Series 4000 at 1kHz

Traces are bypassed, centered, 1kHz at maximum boost and cut and at intermediate silkscreened markings.

Series 4000 High-Pass Filter

Frequency Response Curves of the White Instruments Series 4000 High-Pass Filter

Traces are bypassed and at the silkscreened markings.

Yamaha Q2031A

This was a popular affordable 31-band 1/3-octave equalizer.

Q2031A at 1kHz

Frequency Response Curves of the Yamaha Q2031A at 1kHz

Traces are bypassed, centered, 1kHz at maximum boost and cut, with the range set to normal and 6dB.

Yamaha Q2031A High-Pass Filter

Frequency Response Curves of the Yamaha Q2031A High-Pass Filter

Traces are bypassed and frequency at lowest and highest settings.

The "Death to 100" curve on the Q2031A

Frequency Response Curves of the Yamaha Q2031A with 100Hz and below @ -12dB

"Death to 100" on the Yamaha Q2031A. The effect on the higher frequencies is different than other eqs, but still significant.