The updated compact mixers in Mackie"s VLZ range may look the same as ever on the outside — but inside lurk new, high‑grade microphone preamps. Hugh Robjohns tries out the new design.
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Mackie"s popular 1604 model defined a new standard in compact mixers when it was launched in 1991 (see Sound On Sound đánh giá Dec "91), offering a chất lượng combination of operational versatility with high sound chất lượng and construction values. Given an extended lease of life, via enhanced facilities & a cosmetic makeover, in its subsequent "VLZ" incarnation, both the 1604 VLZ and its companion models in the range now find themselves the recipients of a further revision in the size of Mackie"s latest "XDR" "premium studio‑grade" mic amp.
It is the sound unique of this most crucial element of any console that really determines the sonic standard which can be achieved and, with the new "XDR" design, even the smallest Mackie mixers now offer a performance which is comparable to, and maybe even better than, most high‑end £100,000+ studio consoles. A very sobering thought for the industry big boys! XDR stands for "Extended Dynamic Range" — something the new design has in abundance — but the update is about rather more than just greater headroom.
Ultimate Preamplifiers
As the owner of four expensive, but wonderful, channels of GML mic preamplification, I openly support the view that, when used in the appropriate circumstances, high‑end mic amps are worth their relatively high price. This concept is probably not too surprising, và I would guess that most people reading this will already subscribe khổng lồ the idea that the better (and inherently more costly) the microphone, the more accurate it is likely khổng lồ be. However, the subtle nuances and intricate detail captured by the best microphones in the world are all too easily lost during passage through the rather average microphone preamplifiers found in a typical trang chủ recording desk.
Mackie are claiming that "no other company in the world has spent the sheer number of research hours and $250,000 in R&D costs on a single mic preamp design"! Their new XDR design has apparently been two years in the making, and was driven by Greg Mackie"s wish lớn bestow his mixers with preamps capable of matching or exceeding the performance of any esoteric outboard unit.
The main kiến thiết goals for the new preamp were that it should be able to lớn protect itself from destructive external forces, not be prone khổng lồ Radio‑Frequency Interference (RFI), & that its performance should not vary with different mic‑cable impedance loads. Above all, it had to be accurate, sound good, & have very low noise and wide bandwidth at any gain level. Basic though these goals may appear to lớn be, it is surprising how few commercial designs actually stand up lớn careful scrutiny in any of these respects. For instance, many mic preamps suffer long‑term degradation from "hot‑plugging" mics when phantom is turned on. The voltage spikes caused during hot‑plugging lead to lớn a gradual breakdown of the input devices, with increasing noise & eventual total failure! I have personally experienced at least two professional studio multitrack desks which have fallen prey lớn this phenomenon.
It has been well known for many years that, lớn convey the most detailed & accurate sound, a preamp needs a very wide bandwidth. Unfortunately this approach can also make the kiến thiết prone to lớn picking up external RF interference — radio transmissions from broadcasters, smartphone phones, và so forth. Mackie have addressed this issue with good solid engineering practice — bifilar‑wound DC pulse transformers that reject RFI but don"t attenuate the sound at 20kHz và above. They have also used matched precision components in the most critical areas of the XDR mic preamplifier, và employ a direct‑coupled circuit topology with instrumentation‑style balanced differential architecture và linear constant current biasing. Nothing revolutionary, but well engineered và carefully designed using surface‑mount devices và automated assembly to keep the costs as low as possible.
The inherent capacitance (and inductance) of microphone cables can have a very dramatic effect on the performance of a microphone preamplifier, particularly with very long cable runs, such as in a stage multicore, for example. A microphone"s frequency & transient response is strongly affected by the load it has lớn drive — the combination of the mic amp input & cable. The Mackie XDR thiết kế incorporates a "Controlled Interface đầu vào Impedance system" which works to maintain a flat frequency response within about 0.1dB, irrespective of how long the mic cable is, or what source impedance the microphone has.
Listening Test
I auditioned the XDR mic preamp in two different Mackie models, the 1604 VLZpro & the 1402 VLZpro. Both performed identically, và easily passed every real‑world chạy thử I could come up with. I was also ablto compare the performance of both of these "budget" desks with my own GML 8304 "esoteric" mic pre.
The most obvious thing about the new design is its astounding noise and distortion — or rather the complete lack of either. This really is a very, very quiet mic pre, which passes the signal from the microphone with the absolute minimum of degradation, even with high‑level and complex sources. The vị trí cao nhất end is sparkling và detailed, but without any unnecessary emphasis, the mid‑range is neutral & accurate, & the bass is tight và clean, although possibly tending slightly towards the lean side for my tastes.
The investment Mackie have made in developing the XDR mic pre benefits the kết thúc user at all levels. After all, the smallest mã sản phẩm in the updated range, the 1202 VLZpro mixer, costs only around £300, yet boasts highly competent mic stages which certainly compare favourably with anything provided in consoles costing 10, 100, or even 1000 times as much! In a straight comparison with the GML, everyone who I bullied into listening confirmed that the noise và distortion subjectively sounded the same, và no one could favour one over the other on these grounds alone.
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The mid và treble bands were equally similar, but identifiable differences could be found at the bottom end. Although both mic amps measured virtually identically in terms of their frequency response, the GML sounded somehow warmer, & the bass better integrated with the mid and high frequency regions. Instruments và voices had a greater solidity & a totally natural, three‑dimensional image to lớn them through the GML, which the Mackie suggested but could not quite deliver. However, I should point out that it took a considerable amount of listening and experimentation before we were happy that these differences were real và repeatable — it really was that close.
The Bottom Line
Without directly comparing the Mackie XDR to lớn any other mic pre, anyone would have to judge it lớn be a very fine‑sounding đầu vào stage. Put it up against a Focusrite or GML, however, and you will still be very impressed. The differences are extremely small — certainly far smaller than I expected — and whilst the "esoteric designs" might just retain a sonic edge, the enormous price differential should be enough lớn keep a smile on the face of the Mackie owner!