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Mackie SRM550, SRM650 & SRM1850

Active PA Speakers By Mike Crofts

The latest additions to Mackie’s established SRM range offer the same level of flexibility, but in traditional wooden–box enclosures.

Mackie’s SRM range of portable, plastic–enclosure active loudspeakers is popular and well established. Now the company have extended the family, by adding three new high–powered, all–wood models with increased functionality. The new models complement rather than replace the existing and familiar SRM350, SRM450 and SRM1801, and are aimed at potential Mackie users who prefer the traditional approach of wooden cabinet construction.

Mackie SRM550, SRM650 & SRM1850

The three new models are the SRM550, a full–range two–way speaker based around a 12–inch woofer; the larger SRM650, which is a 15–inch two–way design; and the SRM1850 subwoofer, which uses a single 18–inch driver. The full–range models all use the same Class–D amplifier type rated at a total of 800W RMS (400W each for the HF and LF sections), and the subwoofer amp is rated at 800W RMS.

Polar Audio, who represent Mackie in the UK, sent along a pair of each for me to take a look at. On unpacking the full range units (at a live gig, as it happens), my first impression was that these are well–built cabinets that are surprisingly light in weight: the SRM550 is listed at 16.8kg and the SRM650 only some 4kg heavier at 21kg. The unusual thing about them is the cabinet shape — they are considerably deeper than many 12–inch and 15–inch units, and this is partly because Mackie have designed them to function either as FOH speakers or as floor monitors. When used for the latter, they project at a 60–degree angle, which is ideal for close–up positioning and generally much more practical than traditional 45–degree types when your artiste is standing right above them. The depth and sharply angular shape at the rear makes them a bit awkward to handle and load though (flight cases are always recommended of course), and the edges could be vulnerable to knocks and scrapes.

From the front the units look very traditional, with their matte–black finish and attractive steel grilles, which cover the whole front surface — all in all a good look and distinctly more ‘pro’ in my book than their moulded counterparts. The cabinet shape more or less dictates that they are picked up from the front, and I found that the plastic side handles were large and deeply recessed enough to avoid knuckle damage, although the handle bar grip is aligned vertically which actually makes the speaker easier to carry one–handed, suitcase–style, on its side. The metal grille is made from powder–coated, punched, 18–gauge steel, and is well secured by many fasteners, and I would guess that it also benefits from an adhesive fixing as it stayed firmly in place after I removed all the screws to get a look inside. But regardless of how it’s held on, the cabinet exhibited no rattles, creaks or squeaks when I later subjected it to some fairly rough handling by bumping it around on a carpeted, but otherwise unforgiving, floor for a few minutes. The grille does flex in and out, but it has a supporting brace running across its full width below the HF horn area, so I wouldn’t anticipate any creasing or denting in normal use. To complete the construction side of things, the textured paint finish looks good and appears to be quite thick (one of the cabs sustained a small corner chip when in collision with a building), and the rubber feet on the bottom are large and, well, rubbery. The SRM550 and 650 can be pole/stand mounted and have standard pole sockets but no mounting angle options.

The Inner Workings

The input/control panel is set into the nearest thing the mid/tops have for a ‘back’, which is one of the angled surfaces — obviously the upper one when the unit is used on its side. The control panel is neat and well laid out, with plenty of workspace around the knobs and connectors. There are two inputs, which accept either XLR or balanced/unbalanced standard jacks (the jack connections and a pair of unbalanced RCABoth the SRM550 and SRM650 feature basic two-input mixer functionality, as well as a  built-in four-band feedback suppressor.Both the SRM550 and SRM650 feature basic two-input mixer functionality, as well as a built-in four-band feedback suppressor. inputs on channel 2 only are routed through 20dB attenuators for use with hotter line signals if needed), and the sensitivity range is such that microphones can be plugged directly into the XLR sockets. As both inputs have individual level controls you effectively have a mini mixer built in, so for small solo/duo-type gigs you could actually connect straight into the SRM unit without an external mixer.

The two level controls are labelled ‘gain’, but they actually adjust the signal attenuation before the input stage. The user manual describes these controls as adjusting the gain from – (fully counter clockwise) to +50 dB (fully clockwise), so I interpret that as the system having 50dB of gain with a fully on level control, and the wide range of input sensitivity available means you can use anything from a microphone to a full line signal to drive the speakers. The ‘combi’–style input connectors are neat and save space on the panel, and their other advantage is that it’s not possible to try and plug in an XLR and a jack input at the same time. I like the provision of the unbalanced RCA phono inputs, which is a small touch but can make life a lot easier when using MP3 players and the like.

The mixer’s post–level output can be sent to the ‘thru’ connector, which can also be used as a hard–wired link pre–level from the channel 1 input. No analogue EQ controls are provided, however the SRM550 and SRM650 can operate in four different preset EQ modes depending on the application. The user manual illustrates these by printing the response curves, which give a good idea of what’s going on here: the three ‘main’ modes are called PA (the flattest response for most front–of–house work), DJ (slight LF and HF boost with a bit less in the lower middle) and Solo, which rolls off around 100Hz and adds a pleasant emphasis towards the upper mid and high frequencies (I particularly liked this mode when operating the SRM650s with subs in a smallish space). The fourth mode is for monitor operation, and introduces a sharper LF roll-off and more pronounced shaping in the middle band. When changing EQ modes (or when adjusting the manual crossover point on the SRM1850), there’s a short delay during which the output is muted, which means you can’t actually do an instant A/B comparison, so it’s best to run each mode for a minute or so to decide which works for you at that time.

Many new speaker designs released into the wild will have some new feature to set them apart from what has gone before, and the SRM550 and 650 is equipped with a built–in feedback destroyer that can, if required, automatically assign four sharp (16th of an octave) notch filters when feedback is detected. It’s a potentially useful feature for solo performers who may well be otherwise occupied and unable to get to the knobs when feedback strikes — it works well and kicks in fast, and as far as I can tell the filters, once applied, are locked in until manually cleared. To get the most benefit I’d tend to use this at setup time by opening the mic(s) and increasing the level gradually so that offending frequencies are detected in a controlled way. If things do get too hot for the SRM speakers, the integral protection within the DSP should prevent damage to amps and drivers, providing the system is being used within its capabilities!

The DSP within the SRM550 and SRM650 takes care of the necessary time and phase adjustments to produce the best results from the cabinet, amp and driver designs, and the two models have the same power amplifier ratings: dual 400W power amps driving the woofers and the 1.4–inch titanium–compression drivers, which are coupled to a one–inch throat waveguide for nominal 90 x 50 degree dispersion (the user manual has the HF voice coil and horn entry sizes the other way round, but I checked with the incredibly helpful Mackie tech guys at Woodinville).

The new SRM subwoofer has both filtered and full-range outputs, as well as a  polarity invert option and mono/stereo switching.The new SRM subwoofer has both filtered and full-range outputs, as well as a polarity invert option and mono/stereo switching.

Power ratings are what they are, but it’s how the things sound that really matters. Suffice it to say that, when I usedthese speakers, they had plenty of output for the job in hand and didn’t sound at all stressed when working hard. Of more interest to me was the 3kHz crossover point of both full-range versions, which should fall well within the safe long–term operating range of the HF driver and hopefully lead to good reliability in this department.

Sub World

The SRM1850 sub is a front–ported design with a single 18–inch driver, powered by an 800W RMS Class–D amp module. The enclosure, like the full-range models, is made from 18mm ply and has a good metal grille protecting the front. The control panel round the back is fairly standard in that it has left and right inputs for summing when used as a single unit in a stereo setup, and provides both high–pass outputs for feeding to the tops and full–range link outputs for connection to another sub or system. The full–range outputs are direct connections to the inputs, but the high-pass outs are ‘active’ so the sub needs to be switched on for them to pass any signal.

One feature you don’t always find is that the left and right inputs can be summed to the full-range outputs by means of a selector switch on the panel, giving the option of feeding on to other downstream speakers for additional full–range mono coverage. This sub can be used in any sound system you want, with any make of speakers, and it has a variable active filter which sets the crossover point for the high–pass outputs anywhere between 60Hz and 120Hz, which should be enough for any situation I can think of. When used ‘in–family’ with either SRM550 or SRM650 units, there are dedicated crossover presets available, which operate at the same point of 110Hz but which also include the correct alignment delay. There’s a polarity invert button, and the main level control, which, unlike on the SRM550/650, doesn’t completely cut off the signal when turned fully counter–clockwise, but provides 12dB of level control. During the time I used the rig, the SRM1850 delivered an impressive and really solid amount of good deep bass. Although the full–range cabs were fine on their own, using the sub really unleashed the system’s potential — at one time I owned a few of the old SWA1801 subs, and I like these SRM1850s much better. I found the recommended crossover selections perfectly usable, but it’s nice to have the ability to try different settings; the benefit here is that crossover adjustment is possible, and as no two venues are the same it’s worth spending time to get the best results.

Going To Town

I had intended to set up both the SRM550 and SRM650 speakers in the workshop and get to know them a bit better before going out on a first date, but time ran out and a job came in (you know the feeling), which required outdoor live sound on two stages, for which the Mackie gear seemed perfectly suited. Consequently all six speakers were loaded into the van in their still–sealed shipping boxes, and I hoped that Mackie’s quality control would be all I could hope for.

I used the SRM1850 subs and the SRM650 tops on the main stage, and despatched the crew to rig the smaller SRM550 units on the smaller second stage in another part of the town centre. On the main stage I ran the main left and right signals into the subs, with high-pass outputs to the SRM650s above, using the default crossover settings for those speaker models and with the DSP switch in the ‘PA’ position.

Getting it all wired up including power took about 10 minutes once the speakers were in position. Since time was short (we had waited quite a long time for vehicles to be moved, generators to arrive, and generators to be replaced with more suitable generators), I simply set the level controls to the ‘line’ point and away we went. I tweaked the sub levels (generally downward) as we went through the programme, and there was plenty of output available — easily enough for this town–centre location — and I didn’t get anywhere near the system’s full power capability. Vocal announcements from various dignitaries were clearly heard above the general town–centre noise, augmented on this occasion by numerous cheery street vendors and assorted fairground rides (I hadn’t noticed before that every single trader brings their own generator to these events). Musical performances from school choirs, solo acts and pop/rock bands were all delivered with good projection and a clean, balanced sound. The SRM boxes did their job without any fuss, and did it well.

The SRM650s and 1850s in situ at a  town–centre gig.The SRM650s and 1850s in situ at a town–centre gig.

Down at the second stage the pair of SRM550 speakerswere being used for dance group accompaniment and acoustic guitar/vocal-type acts, and in addition to being plenty powerful enough for the job, we were impressed with the amount of clean bass they produced without the benefit of subwoofers. Packing away was quick and easy, and when all was back in the van the event organiser told us that he had been very pleased with the sound on both stages, and that he liked our new speakers. We just said that we liked them too.

Back at base, I set the speakers up again to have another play and check out some of the other functions. The controls and DSP settings work just as you’d expect them to, and I spent some time experimenting with the variable crossover facility on the subs. One of my ‘Write that down, quick!’ settings was using the SRM650s on their ‘solo’ EQ setting and the SRM1850 subs crossed somewhere around 95Hz. This combo sounded particularly sweet in the studio area even at high volume, and I noticed that the HF and upper–middle register stayed smooth even when hitting the limiters — the sound was still perfectly listenable while delivering at a serious level for that particular space.

Final Thoughts

As noted during the outdoor event, the full–range SRM550 and SRM650 have a respectable amount of low–end output on their own, but it’s when used with subs that they really show what they can do power–wise. As floor monitors, these speakers aren’t exactly low profile, physically speaking, but on a larger stage, or where high monitoring levels are required, I’d definitely like to give them a go! I tried both versions in the studio and the two singers who used them as monitors were both very impressed. My overall impression is that I like the sound of them, and I would be more than happy to use them for a variety of live–sound work. I was particularly impressed with their performance as monitors (especially the 15–inch model), and provided you had enough available I think these would hold their own on almost any stage of any size. As a main PA system the SRM550/650/1850 family would be worth serious consideration for club/DJ applications, and for live sound they are good contenders in the small/medium–venue market, as installations or for mobile use. I still find the cabinet shape awkward, but other than that they don’t disappoint, and offer a good level of performance and flexibility. These are well worth a closer look.

Alternatives

If you’re in the market for a system of comparable quality, check out the Yamaha DXR and DXS range, the ELX speakers from ElectroVoice, JBL’s PRX series, the QSC K series RCF ART models, DB Technologies Flexsys and Opera systems, and the Milan range from Turbosound.

Pros

  • Good balanced sound.
  • Easy to set up with useful EQ modes.
  • Very effective as powerful stage monitors.
  • Consistent sound even when driven hard.

Cons

  • Not the easiest shape to handle.

Summary

Whether you’re looking for powerful stage monitors, a mobile PA or an installed system in a small to medium venue, these new wooden–box models are well worth checking out.

information

SRM550 £607.82, SRM650 £694.79, SRM1850 £825.22. Prices are per speaker, including VAT.

Polar Audio +44 (0)1444 258258

sales@polaraudio.co.uk

www.polaraudio.co.uk

www.mackie.com

SRM550 $599.99, SRM650 $699.99, SRM1850 $899.99. Prices are per speaker.

Loud Technologies Inc +1 425 892 6500

www.loudtechinc.com

www.mackie.com

Published March 2014