Crest Audio XRM X-Rack Mixer
By Jamie Rio
A lot of small to mid-sized sound companies avoid the jump to a monitor board because they fear the perceived cost and complexity of a second board and splitter snake. Of course, there is some investment required to take such a step, but Crest Audio has made setting up your own monitor world less expensive and easier than ever. The XRM monitor mixer can take as many as 20 mic inputs and feed up to 12 outputs. It measures a mere 19 inches by 17.5 inches and will mount in a rack. It's packed with features and is really fun to operate.
The Gear
I don't want to spend this entire review on a description of the mixer. So let me give you a quick overview of what is being offered here:
Each mono input channel starts with a mic/line switch, a gain knob and a 70Hz lo-cut filter switch. This is followed by lots of EQ. Hi frequency at 12kHz, high-mid
(frequency continuously variable between 400Hz and 8kHz), low-mid (continuously variable between 100Hz and 2kHz), low frequency at 80Hz and an Equalizer on/off switch. Now we have the 12 send pots. One through Four can be either pre or post. The 12 mono sends can become six stereo sends with just a push of a button in the master fader section. The sends are color-coded and followed by a mute switch, channel level knob, peak signal LED and a PFL switch.
The four stereo channels look the same, but instead of a low-cut switch, they have a sum inputs switch. Each send has its own master fader, which can be paired for stereo and has a 40Hz low-cut filter switch. There are a few more cool features up front, but I would like to direct your attention to the back of the mixer.
There are the standard balanced and line inputs for each mono and stereo channel, plus each channel has a split out, which is very nice. Phantom power is available for each individual channel and each stereo channel along with channel inserts for One through 12. There are mix inserts One through 12 and balance mix outs One through 12. Monitor outs left and right are nice and common ins left and right can feed all 12 mixes. Bus inputs to mixes One through 12 are smart, and if you have two mixers you can link them together.
The Show
I enjoy monitor mixing even though I do not have a monitor board myself. I get hired to mix monitors regularly. Although monitors are not as fun as Front of House, they are definitely more important to the artist and players. Anyway, I was excited at the chance to add the Crest to one of my shows. I pulled the thing out of the box and grabbed the manual a few hours before a show with a Latin artist and his eight-piece band. The crew had set up the splitter before I noticed that the Crest has splits. This is a handy feature, especially for a small outfit, because it incorporates and eliminates one piece of gear. Set-up was a breeze, but I didn't mount the mixer in a rack, mainly because I would need a pop-up rack and I didn't have one. Since all the ins and outs are in the back, I set the XRM up vertically on a table, duct taped it so it couldn't fall over, and I was ready to rock. We started with six monitors and four mixes, but the band asked for five, then six mixes. I was using powered monitors, so adding or changing mixes was a piece of cake. The Crest has great EQ, and its knobs are surprisingly easy to operate, considering how much is packed into the small frame. I had an extra powered monitor, which I set up to listen to my mixes through the monitor-out rather than a set of headphones. I like this feature; it gives me a real sense of what the musicians hear. There is another thing about this mixer–it feels good. All the pots, switches and components are top shelf and you can feel it when you work the board. All in all, the show was a success for the artist and I did get compliments from the keyboardist and acoustic guitarist that their monitor mixes were just perfect. That's a lot in this biz, where usually, no news is good news.
What is it: Compact, rack-mount monitor mixer
Who it's for: Small to mid-sized sound companies and installs
Pros: Small, really well built and intelligently designed
Cons: For ideal access you need to have the board in a 90-degree vertical position
How Much: MSRP $2,899.99
Powersoft DIGAM Q4004 Amp
By Jamie Rio
I'm not going to start this review with specs (I will get to them as we go along). Of course, good specifications are very important, but as you all know or will soon learn, specifications and the sound that comes out of your speakers can be two different things. Personally, I want a power amp that looks good, is lightweight, powerful, quiet and has a tight, well-defined low end. Now that I think about it, that's pretty much what I look for in a girlfriend. But before I get myself into trouble with such a politically incorrect comparison, let me just say that the Powersoft DIGAM amp incorporates a lot of what I want in a power amp.
The Gear
The Powersoft digital amplifier is, by design, smaller and lighter than an equally powered analog amp. Powersoft didn't invent digital amps, but they do hold several patents on the DIGAM technology. What this really means for you and me is that there is a lot of bang for the buck packed into this one-rackspace, 1,000-watt @ four ohms, 19-pound amp.
First, let's take a look at the front panel of this four-channel amplifier. It's basic but very functional. The on/off switch is mounted on the right side of the amp. The opposite side sports the four gain knobs, the all-important output level LED bar and an assortment of LEDs, including the Protect light (one for each channel), the Signal Present light (also one per channel), one Over Temperate light per power section and one Ready
light per power section. Let's go back to the beginning of the paragraph for a second. This is a four-channel amp. One rackspace, 19 pounds and four channels
of 1,000 watts each. This amp and a decent processor may be all you need to run four monitor mixes.
The rear panel is just as simply and functionally laid out. Input signal goes via Neutrik combo jack (two per power channel). Output is routed through a female Neutrik Speakon connector, two per power section. Tucked between the Speakons is a parallel signal switch. An AC main cord and cooling fan output complete the rear panel appointments. Shall we look at some of the groovier features?
For about four seconds after turn-on and immediately at turn-off, the amplifier outputs are muted. The output stage of this amp runs at about 95% efficiency (that's quite good), which means only 5% of the input energy is dissipated as heat. There is also a temperature-controlled air cooling system. There are also an onboard clip limiter and permanent signal compressor, gate selection and selectable active filters (HP, LP, 12B/Oct. 65, 100, 120 Hz). That about wraps up all the special features; I bet you'd like to hear how the amp performed in a live setting.
The Gigs
The Powersoft amp was sent out as the power for my Mach monitors and Mach controller (Powersoft is distributed by Mach in the U.S.). The best thing about this amp is that I really didn't know it was there. That is, the amp was extremely quiet and there weren't any buzzes, hums or weird anomalies. It kind of makes for a boring review, but it is what we all look for in an amplifier. I used the DIGAM amp with the Mach monitors at three separate gigs, and each time I got the same result. Once again: good, reliable, quiet power. You really can't ask for anything more.
What it is: Digital Power Amp
Pros: Small, lightweight, quiet, powerful
Cons: I don't own this amp
How Much: $3,495
Extra: How Does it Work?
Analog and Digital Amplification
By Mark Amundson
Microphones are transducers that turn sound pressures into voltages that are replicas (analog) of those pressures. When we keep those mic voltages looking the same but enlarge the voltages, we are indulging in analog amplification through mic preamps, summing amplifiers and power amplifiers. Up to recently, all amplification was just analog, with the signal out an exact replica of the signal in, except larger. Since most audio signals are just oscillating sound pressure levels, so are the inherent analog voltages. A simplistic way to model this is to use a light dimmer control and
frequently dim up and dim down with the statistical average being half brightness.
Digital amplifiers act more like light switches, with just on and off positions. But to create the same function as analog amplifiers, the digital amplifiers must contain a method of smoothing (filtering) the "ons" and "offs" to create the varying degrees of brightness. Most digital audio amplifiers employ a method of Pulse Width Modulation (PWM) where a constant switching frequency is used, but the ratio of on and off time varies with output amplitude (e.g. brightness/dimness) desired at each moment in time. Because the pulses are many times faster than the highest audio frequency, these widths of on and off times are filtered using classic electronic filter components like capacitors and inductors to smooth away the pulse frequency harmonics, leaving just the amplified analog voltage signal for the speakers.
So why all the bother of converting analog signals to digital on/off pulses and filtering them back to analog? The answer is in power efficiency. Using the dimmer and switch controls of lights as the analogy, a half dimmed (half bright) signal requires the dimming element to absorb part of the electricity to throttle back the power going into the light. Whereas a rapidly switching on/off switch looses very little electrical energy in the switch, but your eyes and the lights interpret the amount of on and off times as various shades of brightness when switching fast enough. So analog amplifiers are moderately efficient and lose some electrical energy in the form of heat, whereas digital amplifiers tend to be very efficient and pass most of their energy on to the speakers as required to re-form the analog voltage. The speakers are the final transducers that replicate the analog voltage (and current) back into sound pressures.
Soundcraft GB4 Mixing Console
By Mark Amundson
Soundcraft's new GB4 mid-market analog mixing console has arrived to relieve the Spirit Live 4 console, and take the mid-market feature set a big step forward. I received the 24-channel version of the GB4 for review, but the model is available in chassis sizes from 12 to 40 channels. What "mid-market" means to me is analog consoles that do not have channel VCAs but do include a fairly full feature set on both the channel strips and master section. Soundcraft has also recently introduced an eight-bus version, the GB8.
Starting with the Soundcraft GB4 channel strips, the rear jack panel is slightly sloped for on-the-fly patch changes without leaving the front of the console. As expected, mono channels have a XLR mic input, TRS line input with -20dB pad to the mic preamp, TRS unbalance insert jack and TS direct out jack with a co-located switch and pre-insert/post-fader selection. Atop this single-rack console, the mono channel strip starts with switches for +48VDC phantom power, polarity and 100Hz Hi-Pass Filter selection.
The GB4 channel preamps are called GB30s, and if you are wondering what all this "GB" stuff comes from–it is Soundcraft's co-founder and chief designer Graham Blyth's latest circuit designs for the preamps and equalization. The preamp gain control extends from five to 60dB. Soundcraft also points out that the GB30 preamps use multi-stage linearity techniques, instead of just solving linearity and distortion issues with a global feedback loop. This design keeps the phase response very smooth and stable. Next to the gain control is a red LED that monitors the preamp output and equalization output, and illuminates if the signal reaches beyond +16dBu. This is an extremely handy feature not only for gain setting, but also for keeping an eye on inserted compressors that may receive clipped signal inputs while providing smoothed moderate levels.
The channel equalization can be selectively inserted or left bypassed for signal purity. The GB30 equalization circuit is a four-band design with two swept mid sections with ranges of 80Hz to 1.9kHz and 550Hz to 13kHz with filter Q's of 1.5 for a slightly broader effect than competitive swept mids. The low and high frequency shelving filters are at 60Hz and 13kHz, respectively, and are a touch wider than usual. While the shelving filters are fixed, all bands of equalization have +/-15dB of boost/cut for plenty of frequency response sculpting.
Further down the mono channel strip are eight bands of auxiliary sends, with the first four fixed at pre-fader/post-EQ/post-mute and the remaining four assigned
pre- or post-fader on an individual basis. This allows for either a eight-mix monitor console, or a four-mix/four-effects Front of House console, and anything in-between. Plus, each auxiliary send control has maximum gain of +6dB with unity gain at the three o'clock position.
The pan control is included with switches near the fader for center, left-right, 1-2 subgroup, and 3-4 subgroup assigning. Throughout the GB4, care was taken to permit dual assigns for the center channel, to make the center channel available as a sub-woofer separate feed without having to burn up an auxiliary send. You can even create a subgroup that assigns to the center channel for subwoofer or fill mixes instead of just summing left and right masters.
Besides the required 100mm channel fader with 50% of the taper in the +/-10dB range, a four-LED bargraph meter (-10, zero, +8, +16dB) is centered with the fader for one-eye control of channel level. Just above the channel fader is the illuminated mute button for selecting the single channel mute action or indicating mute group activation from four mute group switches at the bottom part of the channel fader. By putting mute group capability in the GB4, makes this a truly professional console. Finishing off the channel strip is the bottom-located PFL switch with an adjoining LED for quick identification. Each channel in the GB4 is implemented as a single vertical printed circuit board, and not the cheaper but usual four- or eight-channel group horizontal board.
Master Section
While the Soundcraft GB4 console has only four subgroups, the master section is more like its 8-bus competitors, with a 7-by-4 matrix mixing section for zone or fill mixing. Auxiliary send masters each get a rotary control and an AFL switch for monitoring signals. A recessed fader flip switch is located between the four subgroups and the first four auxiliary sends for handy monitor mix control. The monitoring section has the classic stereo in and control room/headphone separate levels with a slanted headphone jack recessed in the front-right of the monitor section for ease of use.
Talkback was unique for me, as the groups and pairs of aux send switches were momentary instead of fixed on/off. The recording/alt section was novel, with a switchable limiter circuit available to keep the two-track outputs at +8dBu and a lower level at the RCA jacks. Master metering includes power supply levels plus seven bargraphs with 12-LED arrays each from -20 to +18dBu. It is interesting to note that the yellow LEDs are only at the +12 and +15dBu marks with just a single red LED at +18dBu. A glorious hint that GB4 likes hot levels at the subgroups and masters, and can dish it out at the output jacks.
At the master jackpanel, all subgroups and masters have a XLR output plus a TRS insert jack. The remaining XLR jack is the dedicated talkback mic input. Two stereo TRS inputs are provided as well for either effects returns or other signal sources. A quad of RCA jacks handle the two-track in/out function plus TS jacks for control room monitoring and line-level rec/alt outputs. The four matrix outputs and aux send master outputs are impedance-balanced TRS jacks for long wire drives.
Road Notes
The GB4 in its 24-channel configuration offered more than most competitive 24-channel consoles. Besides its internal power supply with external power supply input jack, the GB4 includes two stereo XLR/TRS channels that do not get included in the channel count–not like other consoles that include stereo channels in the count, or worse yet, as two channels. So for me, having 24 free mono channels and two stereo channels was much more like having a standard 28- or 32-channel console and having to burn up pairs of mono input channels on effects returns.
Then there is the size and weight of the GB4-24. At 27 kilograms (59.5 pounds) and 42 by 26 by 6.26 inches, this console is compact enough for one-man handling for small sound company use and in tight club spaces. When gigging with the GB4, I found the great-sounding preamps, EQs, metering and mute groups worth many times the cost. With this level of sound quality, compactness, full feature set and price, it is impossible not to consider the GB4 the new standard-bearer in the mid-market console segment.
Looking for niggles, my first thought was the lack of a pad switch on the channel strips. But after working with many input sources, including the dreaded kick drum boundary condenser mic signal levels, I found the gain control low range perfect for taming hot signals. After that, I had nothing to complain about except standard greed items like "more channels," "less price," etc.
What it is: Mid-market mixing console
Who it's for: Users who have high sound quality standards on a budget, but need plenty of channels and portability
Pros: Great mic pre's and EQ section, mute groups and metering
Cons: Zilch
How much: MSRP $3,799.99
