The Pro64 64-channel digital multicore puzzle is now complete.
Text: Christopher Holder
When Aviom released its A16 personal monitor mixing system back in 2002, squirting multi-channel audio down a Cat5 cable wasn’t particularly revolutionary. Saying that, Cat5 audio was largely the preserve of big installs, like stadiums and shopping centres, and this was the first time it’d been placed into the hands of studios and musicians… who loved it; they still do. They loved the way they could tailor their own monitor mixes and hang multiple mixers off the one system – inexpensive, flexible, easy to use. What people weren’t that concerned about was audio quality – after all, this was ‘just’ for headphone monitoring (mostly) – but Aviom’s own A-Net protocol seemed pretty good. As it turned out, after years of use, the A-Net protocol actually sounded excellent and, along with the very low latency, it got people wondering why it couldn’t be applied to the task of replacing conventional multicores. Re-invigorated, Aviom got to working on its Pro64 range. Using A-Net, the Pro64 system has the ability to send and receive up to 64 channels on a single Cat5 cable.
There are a couple of key advantages in switching from a conventional copper multicore to Cat5. The main advantage is flexibility. The Aviom Pro64 system works much like any other Cat5 PC network – if you have the right hub you can park input/output devices just about anywhere you like. Sonically, the big advantage is not having to drive mics down long cable runs. The preamps are on the stage near the mics, not 50 or even 100 metres away.
The Pro64 range has been gathering strength for a while now, but the missing piece in the puzzle has been a microphone input module. That has now been released, along with a nifty desktop remote controller. So now seems like the perfect time for a review. Well, actually, this is more like a user report. AT caught up with the first Australian customer of a full-blown Pro64 setup – System Sound.
As many will be aware, System Sound rules the musical theatre market in this country. Whenever a show like Phantom of the Opera or Billy Elliot rolls into the country, more often than not, System Sound will supply all the audio requirements. Currently it’s out and about with some five large theatre shows including Cats in South Korea.
I caught up with System Sound’s Julian Spink and Nick Reich to hear their Pro64 experiences. I started out by finding what prompted the purchase.
LIKE A PRO
Julian Spink: “We had a couple of analogue cores coming to the end of their useful lives, and we had a number of shows coming up, so we thought we’d start investigating the digital alternatives. We were aware of Aviom, because we’ve got quite a few Pro16 headphone systems. They work well and are inexpensive.
“The system we’ve purchased here is 64 channels ‘up’ [from stage to FOH] and 32 channels ‘back’ [from FOH to monitors and the PA]. Of the 64 input channels, 32 are mic pres. We’ve also invested in two of the Merger Hubs and the remote control. All up, it’s a cost effective way of getting into this gear, without necessarily spending hundreds of thousands of dollars.”
Okay, so let’s look at the key components of the Pro64 range. This isn’t an exhaustive inventory, but it’s representative.
6416i LINE LEVEL INPUT MODULE
The 16-channel line level module features:
• 16 balanced line-level analogue inputs (XLR).
• 16 balanced line-level analogue thrus (DB25).
• Four gain settings per channel.
• Three-segment level meter per channel.
• Individual channel activation switches.
Julian Spink: “We have four of these devices, comprising one set of 32 line-level inputs and a second set of 32 line-level returns. It works well for us, matching up nicely with the 32 channels of radio mics we have racked up. Interestingly, because of the headroom on the line-level inputs, we had to knock back these line inputs to –6dB, so we’ve got enough headroom out of the Sennheiser 1046 receivers. It just seemed to be a better match.”
6416m MIC INPUT MODULE
Remote controllable 16-channel mic preamp features:
• 16 mic-level inputs (XLR).
• Switchable pad per channel for line-level inputs.
• Passive splitter/alternate input (two DB25s).
• Continuously variable gain control per channel, in 1dB steps.
• Phase, low-cut filter, and +48V phantom power per channel.
• Six-segment level meter per channel.
• Individual channel activation switches.
• Remote controllable over A-Net with the RCI and MCS combination.
Julian Spink: “We have 32 channels (two racks) of mic inputs. It’s great to be able to pop these out like stage boxes, placing them where the microphones are. The mic preamps sound very respectable.”
The RCI Remote Control Interface and MCS Mic Control Surface combo provides full real-time remote control over 64 channels of mic inputs. The MCS features:
• Control of the selected channel’s gain, phase, mute, pad, +48V phantom power, and low-cut filter.
• Metering of a 64-channel network stream, including hi-res metering of the selected channel.
• Switchable peak hold.
Julian Spink: “It gives us random access to any of the 64 inputs at the stage. You can use it to monitor the mic- and line-level inputs but only remote control of the mic preamp features like gain, phantom, phase etc. Having a readout of all 64 channels is useful – there are 64 bi-colour LEDs so you can see activity and clipping. And there’s a peak hold button, which you can also clear.
“You can have four of these RCI/MCS combinations in the system. From the rack input/output device you can decide which ‘control group’ each MCS is looking after – although you can’t have two remotes managing the same input box.”
6416o OUTPUT MODULE
The 6416o provides 16 balanced mic- or line-level analogue outputs from a Pro64 audio network.
• 16 balanced mic- or line-level analogue outputs (XLR).
• DB25 alternate audio outputs.
• Three-segment level meter per channel.
• Individual channel activation switches.
• Virtual Data Cable connectivity for GPIO, MIDI, and RS232.
• Variable sample rates: 44.1k to 192k.
• 24-bit D/A converters.
System Sound has six of these. Four sit at FOH feeding the console, and two are on stage sending signal to the PA and monitors.
MH10 MERGER HUB
The 10-port hub supports bi-directional parallel connections in a Pro64 audio network, and features:
• Distribution and merging of up to 10 A-Net streams.
• 10 bi-directional ports on EtherCon connectors.
• Three channel-routing configurations.
• Supports redundant cable paths.
Julian Spink: “We have a Merger Hub down at stage and one at FOH. This allows us to run two Cat5e links between stage and FOH – providing for redundancy. Which means, of course, if you pull one out then you won’t get a break in the audio. The hub allows you to star out to each component – no need to daisy chain units. On stage we have four input devices going into the hub. There’s a fibre version of the hub but we decided to stick with one transmission medium – Cat5e.”
Those are the main components but what are the key features that have caught Julian and Nick’s fancy?
Julian Spink: “It has an extremely powerful data transmission system – RS232, MIDI and GPIO. For us, we run RS232 and MIDI in shows as a matter of course, so this has been quite handy. For example, we might use it to remotely trigger a conductor track. There are 14 ‘VDC’ slots, with any of the 6416 series boxes acting as a data input or output device. RS232 – being a bi-directional protocol – takes up two slots, so when you assign it to, say, Slot 1, it automatically occupies Slot 2 as well. It’s also worth noting that it’s not an RS232 distribution system, but point-to-point. For example, we run a little device that allows the backstage folk to type on a keyboard, which shows up on a matching LCD at FOH. So if there’s a microphone fault or something urgent that needs to be communicated with the FOH operator that can’t be done using a two-way… then it gets typed. So we are able to use Aviom’s VDC to carry the RS232 to and fro.
With MIDI it gets better because the data is not point-to-point. Instead, any device can pick up the MIDI output if it’s set to the right slot – it’s a MIDI distribution system. Over the years we’ve had some problems with long haul MIDI transfer so this feature has been very useful.”
Nick Reich: “We did an A/B test using the preamp in the 6416m Mic Input Module and a high-end Amek preamp going into the Aviom 6416i line level module using the same mic – an AKG C414EB. We A/B’ed by switching between the dual inputs of the same channel on the Cadac J Type. If pushed, I guess you’d say the Amek’s sound was preferable on the key jangle test wearing headphones, but there wasn’t much in it. Even if you were doing a critical orchestral recording, you might think about using esoteric high-end pre’s on the main microphone pair and the Aviom pre’s would be more than adequate on everything else.”
The Pro64 is 24-bit and is capable of sampling up to 192k.
Julian Spink: “As far as the sampling rate goes, for our purposes running 48k is fine. Double the sample rate and you halve the channel count. Double it again (176.4k and 192k) and you drop to 16 channels up and back. The top-end detail is more revealing at the higher sample rates, but like all of these things, you can only tell when you directly compare.”
Julian Spink: The Merger Hub has four modes. The default Auto mode gives you 64 channels in total, which go in every direction in whatever configuration you might have –any and all of the inputs will turn up in any of the output units. It’s the ‘no-brainer’ mode.
We use a mode called Managed C where the eighth Ethercon output on the back of the hub has a local mimic of 64 input channels. Which means you can take a split out for monitors, or for recording or the like. It’s very useful: you want more splits? Then buy or rent more boxes and plug in the Cat5 cable.
Nick Reich: “Half-way into a two-year show season it’s not uncommon for someone to decide they want to do a live recording. Having to insert analogue splitters for a week is a huge imposition, it means your entire orchestra balance goes out the window. No matter what you do, and no matter how carefully you do it, just a fact the additional load from the splitters onto the mics will change the gain of the mics.
“With the Pro64, taking a split is completely transparent, and has no effect on the rest of the system. Run a Cat5 cable out to the OB van, and you have instantaneous splits with no impact on the gain structure at all.”
I asked Julian what disappointed or surprised him about the Pro64.
Julian Spink: “One ‘gotcha’ that took us a little while to nut out happens after changing ‘Slots’ – each device will occupy a bank of 16 channels, or what Aviom call ‘a Slot’. When you change the slot, the system automatically mutes all that device’s inputs. And it’s not something you can un-mute remotely, you have to manually press the switch on each channel after the re-assignment. That had us scratching our heads for a while.
“The other caveat: ensure you have a good connection between each and every device. If there’s a dodgy connection then you’ll experience a very clean, very graceful dropout. After about three seconds of silence – long enough to think, “what’s going on here?” – the audio returns. The advantage of this is that you can pull out a Cat5 cable while you have a full-blown self-powered PA going full throttle and you won’t hear any splats, cracks or farts – it disconnects extremely cleanly. The downside is it’s very hard to hunt down the culprit if there’s a momentary drop out.
“Finally, it’s worth remembering that Pro64 doesn’t go beyond 64 inputs. For us, that is a little disappointing. Our ideal core would be 96 inputs and 24 or 32 returns. To get more inputs you need to set up a parallel Pro64 system.”
Thanks to Julian, Nick and System Sound for the benefit of their experience. Which leaves me to sign off by asking: who is likely to buy a Pro64 rig?
I don’t think Aviom considered the likes of System Sound (a high-end musical theatre production company) as its core market. But the fact that System Sound relies on analogue consoles (Cadacs mostly) illustrates a point. Any live venue – pubs, clubs, RSLs, churches etc – happy with its analogue console, that needs to upgrade its multicore should check out a Pro64 system. You’ll hear the difference immediately and it will afford you the flexibility of scaling and re-configuring your system as and when that’s required.
Smaller rental companies will also see the benefits of Pro64. A corporate gig one day, a mini-festival the next… a Pro64 system will slip seamlessly into your existing rig and you lose about half a tonne of copper multicore into the bargain.
A-Net is a proven performer. It’s a great-sounding digital transmission protocol and after six years there’s no question mark over its dependability. Crucially, the final piece in the puzzle, the 6416m Mic Input Modules sounds pretty good as well. Finally, I think we can say, the Aviom Pro64 is a complete system.