Stage Accompany Efficiency Series ES 20 Amplifier

Breakthroughs in ribbon speaker technology and Stage Accompany's new XL-Bin subenclosure have moved the company to a new status in a country also known for diamond cutting.
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Making a home in the Netherlands since 1977, Stage Accompany has made quite a niche for itself manufacturing loudspeakers and amplifiers. Early on, the company got a good reputation building "w-bins" and flight cases for gear. Twenty-two years later, breakthroughs in ribbon speaker technology and Stage Accompany's new XL-Bin subenclosure have moved the company to a new status in a country also known for diamond cutting.


The ES 20 ($2,205) is a stereo (two-channel) amplifier rated to deliver 500 W x 2 into an 8-ohm load, 770 W x 2 for a 4-ohm and 960 W x 2 into a 2-ohm load. Peak power ratings are much higher for this amp. Roughly, 1,000 W/channel can be attained at 4 ohms with the technology built into this amp.

Bridging the ES 20 produces more power to push your favorite enclosures to their limits. Bridged into an 8-ohm load, 1,540 W or almost 2,000 W into a 4-ohm load can be procured overall. A whopping 2,800 W peak power is available according to the manual.

The manual is not only a reference for the operation of the amp but also a reference manual for wire resistance, Neutrik wiring and proportional power loss tables. A broad band of frequencies are covered, from 10 Hz to 20 kHz, with a commendable rating of 75 dB for channel separation, measured at 1 kHz. Signal-to-noise is a grand 110 dB, using A-weighting.

The ES 20 amp does quite well with its distortion ratings. With an 8-ohm load, at 1 kHz and 100 W, Stage Accompany reports 0.01% distortion. This is quite good for an amp in this price range. As with most amps built these days, the main supply voltage can be switched internally from 110 V to 120 V for U.S. standards, to 220 V to 240 V for European standards.

Eating up only three rackspaces and weighing in at 46.2 lb, this amp is 18" deep. In comparing a few specs, the ES 20's operation resembles that of the Crown Macro Tech 2400 and the QSC EX 2400 amps.

Although every amplifier company has its claim to fame, the Stage Accompany ES 20 has two great features. What the company terms Class G operation and the DDC circuit set this amp apart from the others. This Class G type of amp is made up of four small amplifiers that operate as two. One of the amps (per channel) is dedicated to producing the output signal while the other amp picks the power supply voltage.

This lets the amp operate at lower voltages when used in lower-power modes, keeping internal temperatures down and efficiency up. Stage Accompany has made provisions for internal heat dissipation installing a variable speed fan - as temperatures go up, so does the speed of the fan.

Dynamic Damping Control (DDC) is a company-designed circuit that measures the voltage at the speaker terminals and sends this information back to the amplifier. Stage Accompany states that the speaker signal and input signal are compared and adjustments are made, allowing for infinite damping control of the driver. Specific wiring for this circuit is diagrammed within the manual. (The amp can still be used on cabinets without DDC prewiring.-Ed.)

Other standard defense devices have been installed, such as a soft-start circuit, and short circuit, DC overload and overtemperature protection. One other item that should not slip by without mention is the Extended Function Network (EFN) circuit. Somewhat similar to a plug-in card, but in the form of a module, the EFN circuit allows additional duties like crossovers, equalization and high- or low-pass filtering.

The front panel consists of two heavy-duty amp handles for moving this unit in and out of racks easily. The power on/off switch is a thumb-sized rocker-type switch on the lower right of the front panel.

Between the handles are individual gain controls for Channel 1 and Channel 2, a series of LEDs and venting for the internal fan. The gain knob indents (potentiometers) need to be changed with stiffer ones, as they can be bumped and changed easily by the slightest touch.

From top to bottom the LEDs represent operations for each channel as follows: DC, thermal, clip, signal and power. Top-of-the line metering here allows for constant monitoring of each amp. Moving to the rear, the ES 20 is chock-full of goodies. The easily accessible main power fuse is just above the power cable exit point - exactly where it should be and not inside. The ground lift switch is also where it belongs - situated to the left of the power cable and main fuse.

Centered on the rear panel is a row of five Neutrik NL-4 connectors. The outside pairs are for Channel 2 and Channel 1, respectively. A center Neutrik NL-4 connector is dedicated to an output for the amp during bridge operation. This is "Bridge Output for Dummies," as all that is needed here is a flick of the bridge mode switch and plugging in speaker connections to the bridge output connector.

On the far right, four high-quality XLR input and output jacks have been installed. The one pair of female input jacks are the main inputs, while the second set of male XLR panel mounts allow for linking channels to other amps from the same input. This is soon becoming one of my favorite features built into amplifiers these days. As mentioned before, a small switch to the right of the input section switches the amp in and out of bridge mode.

In use

After just 15 minutes of setup time sound was coming from the amp. I used the amp as power for a small, biamped pair of speakers. The pair of Stage Accompany powered speakers were on house-left, along with four other enclosures powered by Crown MT 2400 amps. House-right was powered with Crown amps as well, and stacked exactly the same, three wide, two high.

Each of the amps, Stage Accompany and Crown, saw exactly four drivers total, two 15" speakers on Channel 1 and two horn drivers on Channel 2. By hooking up the Stage Accompany ES 20s to an onstage pair of cabinets, they were heard better from the FOH mix position.

Compared to the other amps, the Stage Accompany had a brightness around 6.3 kHz to 8 kHz and was lacking a bit at 250 Hz. Frequencies above 10 kHz were present in the Stage Accompany amp that were not in the other enclosures. The ES 20 did have a smoother midsection, from 500 Hz to 2.5 kHz, than the Crowns.

This midrange smoothness produced a more accurate reproduction in the vocal range. Frequencies below 100 Hz were accurate and tight during CD playback. Although the output Wattages are somewhat close with the Stage Accompany and Crown amps, they have many different specs and they cannot be compared apples-to-apples. This was a test of two different amps' reproduction of the same speaker drivers and enclosures.

In my tests, the output of the Stage Accompany amp was louder and had to be turned down to match the output of the Crown amps. This could be due to unmatched sensitivity settings.


There are many notable features to this Class G amp created by Stage Accompany. The ES 20 would make a great addition to an inventory for powering midrange drivers or an intermediate-size DJ system. When I removed the lid, the ES 20 revealed an impressive circuit board layout and quality construction materials. Stage Accompany managed to keep all input information away from output related circuits.

After looking at the interior construction, I concluded that Stage Accompany is in this for the long haul and intends on continuing to manufacture quality products of this nature.