The Expounder, from Scotland-based CLM Dynamics, is a unique equalizer that responds dynamically to program material. It provides a level of control and enhancement unavailable in other equalizers, regardless of price.
Product PointsApplications: Recording studio
Key Features: Frequency response 15 Hz to 60 kHz; dynamic noise reduction; dynamic linking; extensive controls
Contact: PMI Audio Group at 877-563-6335
+ Sounds fabulous
+ One-of-a-kind tone shaping power
+ Unique sound
The Score: The power of a traditional equalizer and the ability to respond dynamically to program material – control and creativity unavailable in any other equalizer.
The Expounder runs $3,299 retail, however its distributor, PMI Audio Group, sells it direct for $1,799. Its rear panel is equipped with XLR connectors for audio input and output. All connectors are wired pin-2 hot. Each channel has an operating level switch that allows the unit to be set for +4 dBu or -10 dBu. Changing the operating level has no effect on headroom – it sets the broad operating range for the Expounder’s dynamics engines. The input impedance is 10 kilohms.
The rear panel is equipped with a signal ground lift switch. This isolates the output ground via a 10-ohm resistor, leaving the chassis and internal circuitry grounding intact. Operating voltage is selectable and the Expounder is powered through a standard IEC molded power plug.
The front panel’s 30 knobs (and nearly twice that many switches) allow extensive control of the powerful machine, which boasts a frequency response of 15 Hz to 60 kHz. Both the Expounder’s channels have identical and independent controls.
Two PPM output meters indicate output signal level relative to selected operating level. The meters have a PPM response characteristic with a peak holding circuit, which indicates when output levels reach 0 dB or higher. When the master enable switch is out, the meters can be used to read the input level. The Expounder handles +23 dBu signals before clipping.
Input gain trim adjusts the input signal level +/-15 dB before the EQ circuit, allowing the user to compensate for large amounts of boost or cut in the machine’s four bands. Trimming the input level before equalization allows greater headroom than if the level was adjusted after the equalization section.
The dynamic link switch links the dynamics control side chains of the two channels for stereo operation. It is necessary to set both channels’ controls identically for precise stereo operation. The dynamic link function accounts for differences between left and right signals and eliminates any shift in the stereo image. Not only is this a powerful stereo tool, it also can yield interesting results when using one mono source to dynamically control another.
The high-cut section is a sweepable low-pass filter with a selectable 12 dB or 24 dB per octave rolloff. The frequency can be adjusted from 75 Hz to 24 kHz. If the RES (resonance) switch is selected, a resonant peak is introduced at the selected cutoff frequency. This peak can be varied from 0 to +12 dB. At the maximum setting, resonance stops just short of self-oscillation.
If the track switch is selected, the high-cut filter can be used for dynamic noise reduction. In this mode the cutoff frequency tracks dynamically the high frequency content of the music, with the frequency control setting the frequency to which the filter will close in the absence of any high-frequency content. Although using this section of the Expounder for noise reduction potentially causes the loss of some high-frequency content, with a little practice this high-frequency loss is barely audible.
The low-cut section is a sweepable high-pass filter with a selectable 12 dB or 24 dB per octave rolloff. The frequency can be adjusted from 15 Hz to 16 kHz. As with the high-cut section, if the RES switch is selected, a resonant peak (from 0 to +12 dB) is introduced at the selected cutoff frequency.
At the maximum setting, resonance stops just short of self-oscillation. If the track switch is selected, the low-cut filter can be used for dynamic hum or rumble reduction. As with using the track function in the high-cut section to remove unwanted noise, there is a tradeoff. In removing a low frequency hum or rumble some of the low frequency can be lost but careful adjustment of the low-cut parameters will keep this amount barely audible.
The LF and HF sections contain identical controls. The frequency knob adjusts the turnover frequency from 40 Hz to 300 Hz on the LF section or from 1.5 kHz to 20 kHz on the HF section. The bell switch changes the section from a high-pass shelf response to a bell response.
The slope switch changes the steepness of the bell curve from 6 dB to 12 dB per octave. This function only works if bell is selected. The dynamic switch expands the dynamic range of the frequencies selected in the section. This function only works if the gain control is set to boost and it emphasizes the dynamics of the selected frequency.
With a large boost, there can be a dramatic dynamic increase of up to 5 dB. Small amounts of boost in the LF section increase the warmth and punch, and small amounts in the HF section increase high frequency detail and clarity. The gain knob allows a variable boost or cut of up to 20 dB while the /3 switch divides the gain amount by three, allowing greater precision and adjustment of up to +/-6 dB.
The LMF and HMF sections contain identical controls. The frequency knob adjusts the center frequency from 200 Hz to 2 kHz on the LMF section and from 1 kHz to 8 kHz on the HMF section. The Q knob varies the Q of the bell curve. The gain knob allows a variable boost or cut or up to 15 dB unless the unique notch switch is pressed. The notch switch disables the boost function and allows the cut to be increased to ö30 dB.
All four bands of the Expounder offer peak LEDs and enable switches. The peak LEDs light at +12 dBu (12 dB below clipping). The enable switch has an accompanying LED, which lights if the corresponding section is enabled.
Until you get a strong grasp on the Expounder’s controls, you feel a bit at the mercy of the unit. You soon realize that you can shape the audio signal to your liking.
The Expounder is an equalizer that works well for both individual audio tracks as well as for stereo material. I don’t typically use any equalization across the stereo bus but I used the Expounder to experiment with it and I was very pleased with the results.
In a mix that had a very noisy lead vocal track, I found using the dynamic tracking on the high-cut section to be a perfect tool for handling this problem. I was able to virtually eliminate the noise without gating and the result was very natural sounding.
On another mix I used the dynamic tracking feature on the low-cut section to eliminate a ground hum on a guitar amp. I had originally tried to gate the sound but due to the nature of the guitar part (it had several long sustaining chords) it didn’t sound natural. The Expounder was the perfect solution.
Rather than being classified as a general-purpose equalizer, the CLM Dynamics Expounder is a unique and powerful dynamically controlled equalizer that not only fulfills the user’s equalization needs but also adds its own personality to a sonic source.