FocusOn – QSC PLD 4.5

You find us here in the midst of this particularly warm summer season, one equally hot in terms of events and concerts. As a group of editors who never lose the “vice” of attending FOHs and stages, it provides us the perfect opportunities to test products in their respective fields.

This time around, we set out to get to know a product from QSC – the new PLD 4.5 amplifier. We have tested the unit alongside a set of E215 and an E218sw subs, giving us the opportunity to provide a through test with an ample setup.


The PLD 4.5 amplifier is able to drive most speakers on the market thanks to 20 factory preset configurations that can be modified and stored within in the 50 user presets. It also allows for customisable configurations by distributing the total power of the amplifier to one, two, three or all four channels. This is possible thanks to FAST (Flexible Amplifier Summing Technology), a real plus for the flexibility and versatility of this amplifier.

On-board there are four DSP channels each with EQ, crossover, limiter and Delay. This results in completely independence by eliminating the need for external processors.

The equipment includes an integrated front panel with channel Select and Mute buttons, LED input and output meter, 400 × 240 LCD screen, intuitive navigation buttons, LED power button and indicator and cast aluminum handles. All of this makes for a design clean, with a solid and professional look.

On the back we find 4 XLR inputs with 4 relative parallel XLR outputs, a USB port to connect it to the computer and make updates or import / save presets, as well as 4 Speakon NL4 outputs plus another two in Bridge. This provides for an output power divided into:

  • 4x 1150 W/ 8 Ω
  • 4x 1250 W/ 8 Ω
  • 2-channel operation 2x 2250 W/ 8 Ω
  • 1x 4200 W/ 8 Ω

The amp is 2U in total, with a total weight of 11.8 Kg.

  • Typical Distortion: 0.01–0.06%
  • Maximum Distortion: 1.00%
  • Frequency response:
    20 Hz–15 kHz ±0.2 dB
    20 Hz–20 kHz +0.2/-0.7 dB
  • Noise (Unweighted Output Unmuted): -101 dB
  • Noise (Weighted Output Muted): -109 dB
  • Gain: 38.4 dB
  • Damping factor: > 150
  • Input impedance: >10 kΩ, balanced or unbalanced
  • Maximum rms input level:
    3.9V – 12.28 V (+24 dBu)
    12V – 3.88 V (+14 dBu)
  • Amplifier and load protection: Short circuit, open circuit, thermal, RF protection. on/off muting, DC fault shutdown, active inrush limiting, input current limiting
  • AC Power Input:
    4.2: Universal Power Supply 100-132/200–240 VAC, 50–60 Hz
    4.3/4.5: Universal Power Supply 100–240 VAC, 50–60 Hz

We chose to first unbox the system simply to take stock and to examine the measurements of the setup which, as already mentioned, was composed of the PLD 4.5, two E215 tops and a E218sw subwoofer.

We must admit that opening any new product always evokes certain emotions and, despite the sultry heat, it seemed to be Christmas morning with our four packages! This euphoria, however, left room for a moment, when we found ourselves having to move the tops. With dimensions of 420 x 1125 x 464 mm and a weight of 49.1 kg, this was no mean feat. But just to clarify, this weight and substance is there for a reason, and we will soon explain what we mean by this. As for the lack of a handle on the upper side of the cabinet, who knows…

As mentioned previously, the substance is there for a reason. Given that the impact of the speaker’s construction is not merely a subjective topic – dimensions and weight are justified by the fixture’s chassis structure (completely in wood) and above all by the internal components used. E215 is a 2-way trapezoidal diffuser, equipped with a pair of 500W (continuous) 15″ low frequency speakers, with cast aluminium baskets and a 3.5 inch moving coil. The loudspeaker uses a special frequency-shading topology on both low-frequency loudspeakers, to optimise the impact of low-frequency output, whilst minimising interference in the HF crossover section. The unit is particularly suitable for applications where high power and low frequencies are required by a single full-range speaker. The large 2.8 “compression transducer, connected to the 75 ° DMT waveguide, is dedicated instead to the mid-high and high sections of the spectrum, ensuring coverage for even the most distant of listeners. The sub, as you can see from the photo, has slightly larger dimensions (1180 x 616 x 640 mm) and a weight of 76.4 kg.

This is a direct radiation subwoofer and is equipped with two 18-inch speakers, with aluminium baskets. This is a configuration chosen by the manufacturer to “beat hard”. It has been designed to be positioned both vertically and horizontally and is capable of delivering high-impact low frequency content both in live performances and, possibly above all, for high-volume dance music.

Once the system was connected, the sound produced immediately put smiles upon our faces. Indeed, when we thought hard about it, it had been a while since we’d heard such a  “solid” and impactful sound from this type of “point source” system. Here was a sound that was both powerful and balanced, with plenty of headroom – an unequivocal sign of the performance of the amplifier driving the system. This configuration produced a deep level of sound, with a great sensation of frontal projection whilst expressing a perfect basic balance.

It was pointless for us to try to find the “limit” of this amplifier and system, because it would have been impossible for us to drive the system any harder in the square where we were testing without triggering public order problems. The lateral coverage of the system was also precise, certainly in keeping with QSC’s official data, which is appreciable in terms of homogeneity and range.


First of all, we have to admit, this test was a lot of fun! Don’t get us wrong, it is always interesting for us technicians (ok… geeks) to test microphones, LED spotlights of various shapes and sizes, mixers and so on, but driving these speakers certainly got our hearts beating – so much volume and so much headroom without the slightest fatigue. In short, this was one of those situations where there was a need to keep the craving at bay and to remove ones finger from the master faders!

Reflecting calmly on the day, especially in relation to ease of assembly, we note how instinctive the setup process was. Indeed, there was no need to consult the instruction manual, as we so often need to in these cases of first power-up .

This is because the amplifier offers a simple, intuitive and effective user interface, with additional help offered by the clear menu, always legible and designed in order to have everything in sight.

The product is solid, in every sense, both in terms of construction and sound performance. The only flaw, as already mentioned, is the weight of the tops and the lack of a top handle that would have better facilitated assembly.

In our opinion, the “package” is suitable for anyone who needs top-of-the-range power, reliability and quality. This is a system suitable for being thrown from the warehouse to the truck for event after event – a typical “service” product. Distributor (Exhibo in this case) must of course be contacted for accurate and reliable pricing information, but from what we have understood, the total price of the system is certainly appealing…

Info: (PLD 4.5)
Info: (E215)

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