CLM Dynamics DB500s Expounder

Stereo / dual mono dynamic equalizer

CLM Dynamics DB500s Expounder Stereo / dual mono dynamic equalizer

Review by George Shilling

In the area of studio outboard, there is always room for a new twist on an old idea, and Scottish company CLM have popped up, seemingly from nowhere, with this ‘Dynamic Equaliser’, an EQ with several new twists. The stunning front panel has a classy appearance mainly due to the unusual and plentiful brassy knobs on its 3-U facing. However, this stereo equalizer has several features, apart from brassy knobs, that set it apart from the competition. Allow me to expound…

Firstly, the four frequency bands on each channel have a terrific range and power. The HF and LF bands can provide a massive 20dB of boost or cut. Each band features a very wide frequency range with much overlap; for instance, 1.5kHz is available on all except the lowest band. All knobs are smoothly damped, (although a few were slightly loose laterally). Gain controls feature a centre (zero) détente. In addition, each band has a separate Enable button (with LED) which usefully allows you to assess the effect of each individual tweak. Every band has a small switch labelled ‘/3’ which reduces the amount of available boost or cut to approximately one-third of normal. This is excellent for subtler adjustments, as with up to 20dB of boost small adjustments can be tricky. The increased knob travel certainly makes matching settings easier when working in stereo or recalling previously noted settings.

The two Mid bands on each channel feature a variable ‘Q’ control, which varies between an extremely narrow notch and a reasonably broad band. These bands also feature an unusual ‘Notch’ pushbutton. When depressed, this disables the boost function and substitutes 30dBs of cut, with flat being fully clockwise instead of at the centre détente. This is useful when trying to remove particularly offensive tones such as feedback howls or nasty resonances, and tape-phase emulation can be achieved by sweeping the frequency of a deep and narrow notch.

The Low and High frequency bands normally operate in shelf mode, but by depressing ‘Bell’ will operate in peak mode. When in Bell mode another button marked ‘Slope’ changes the steepness of the curve from 6dB/8ve to 12dB/8ve for a narrower ‘Q’. One further button on the extreme bands is marked ‘Dynamic’, and serves to expand the selected frequencies. No effect is obtained in a ‘cut’ situation, but with a boost the dynamics of the high or bass frequencies are emphasised. With large boosts there can be a dynamic increase of up to 5dBs in each band, and with fast preset attack and release times the effects can be quite dramatic. With smaller boosts, the low frequency band can add subtle warmth and the high end can exhibit an apparent increase in clarity and detail.

In addition to the above, each channel includes powerful high and low frequency filters, which overlap each other by a large margin. In fact, both high and low frequency filters individually cover nearly the entire audio spectrum. These are powerful 12dB/8ve circuits with a separate switch on each filter for even steeper 24dB/8ve filters. The High and Low filters also each have a ‘Res’ button, which enables a ‘Res’ knob for a variable resonant frequency boost at the cut-off point. This feature is more usually found on synthesiser filters, but certainly has its uses in the studio. The knob is simply marked 0 to 10, but at full boost the gain is approximately 12dBs, safely stopping before self-oscillation is reached. A ‘Track’ button enables envelope following by the filter, which can be used for hiss or hum reduction, or more extreme ‘synth-filter’ special effects using a large resonance boost.

This is particularly good on drum loops, where the fast characteristics of the ‘Track’ function can be put to good effect to create juicy filter squelches. If using the filters for ‘semi-gating’ noise-reducing functions, the resonance control is useful for minimising the inevitable loss of extreme frequencies in the signal by enhancing the remaining ones by a few dBs. Each filter has its own Enable button, and when working in stereo one must be sure to enable both channels or a phase shift will ensue.

Each channel features an overall Enable button, and an LED-bargraph PPM and input gain knob. However, adjusting this does not affect the filter-tracking sidechain. Each channel has a Dynamic Link button for slaving to the other channel. Pressing both buttons enables proper stereo operation with no image shifting.

The painted front panel is exceptionally thick – a sensible move, which makes the whole thing feel robust. The back includes XLR connectors, +4dBu/-10dBV switching, and a useful Outputs Earth Lift button. A torroidal mains transformer is employed, mounted on one of thirteen vertical PCBs.

The Expounder’s notched knob pointers can be a little difficult to set accurately. And perhaps the panel legending could have been a little larger and bolder. Overall, though, this box is a joy to use. For ultimate signal control and power, nothing beats the Expounder. Judging from the smart home-made manual, CLM is a small company, but they have quickly won many admirers with this product, and I am certainly one of them.

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