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ESI Pro Maxio XD

192kHz Audio + MIDI Interface For PC
Published December 2005
By Martin Walker

ESI Pro Maxio XDPhoto: Mark Ewing

Firewire and USB 2 interfaces have their advantages, but if you need serious channel counts at high sample rates, the PCI card still rules, and ESI's heavyweight recording system caters for a huge range of input and output formats at up to 192kHz.

Korean company ESI have earned an enviable reputation for rock-solid audio and MIDI interfaces over the years, including their budget Waveterminal and more up-market Wami (Wave MIDI) ranges, and more recently, the Julia and ESP 1010 models. They have also clocked up some impressive firsts along the way: their EWDM (Enhanced Audio MIDI) drivers are particularly noteworthy for the ability to support ASIO 2.0, GSIF, MME, WDM and Direct Sound formats with multi-client capability, so that multiple applications can access the interface simultaneously, and you can even internally patch audio from one application to another using the Direct Wire digital patchbay.

Now they are poised to make an impact in more professional circles with the introduction of the Maxio series, which supports up to 32 input channels and 32 output channels at up to 24-bit resolution, at a 192kHz sample rate. Initially there are two models in this range, both based around a 32-bit buss-mastering PCI card to which you attach expansion boxes or breakout cables.

The Maxio 032 expansion box provides 32 channels of ADAT-format digital I/O and two analogue mic/instrument/line input channels, plus further MIDI, S/PDIF and word clock I/O, but the Maxio XD (eXtended Definition) under review here is rather more ambitious. Its EX8000 2U rackmount interface offers only eight simultaneous inputs and outputs, but each can be chosen from balanced analogue, ADAT, S/PDIF and AES-EBU digital formats, and the analogue inputs have phantom-powered mic preamps with metering and insert points. Up to four EX8000 interfaces are supported by a single Maxio PCI card, so the fully expanded 32-channel system would be impressive, especially as the converters offer up to 123dBA dynamic range and the mic preamps are claimed to be very special.

The Perfect Host?

The Maxio PCI host card is actually quite diminutive considering its capabilities, and is compatible with both +3.3 and +5 Volt PCI slots. It has Sync In and Sync Out connectors on the card itself, suggesting that further expansion might be possible at a later date, and the backplate features four EDI ports, each supporting an eight-channel in/out audio stream at up to 24-bit/192kHz, plus one multiway MDI connector, which in conjunction with the supplied one-foot-long flying breakout cable provides a single MIDI In/Out, coaxial S/PDIF in/out, and BNC word clock in/out. The EDI ports on both the PCI host card and EX8000 expansion box are standard six-pin IEEE 1394 sockets, which means you can use ordinary Firewire cables — a high-quality five-metre one is supplied. However, you'll have to be careful not to plug any actual Firewire devices into these sockets to avoid possible damage.

The EX8000 2U rackmount expansion box is an impressively rugged affair in black with silver legends, with a 3mm-thick front panel. The inside of the case is equally impressive, being almost entirely full of circuitry (in some areas three boards deep), with everything carefully bolted or tied down for reliability. I couldn't see the converter chips, but ESI told me that the ADC is AKM's AK5394A (the same as that used in Digidesign's HD192 interface, as well as Emu's 1212M, 1616M and 1820M) and the DAC is AKM's AK4395 (used in Emu's 0404 among various others).

The EX8000 rackmount unit offers an impressive selection of analogue and digital I/O, though only eight channels per unit can be used simultaneously.The EX8000 rackmount unit offers an impressive selection of analogue and digital I/O, though only eight channels per unit can be used simultaneously.Photo: Mark EwingAll of the mic/line input sockets and associated controls are on the front panel, which will certainly appeal to the live recordist who wants instant access, but perhaps not so much to studio owners who normally prefer to leave items of line-level gear permanently plugged in 'round the back'. For each of the eight inputs there's a Neutrik Combi socket, an associated mic/line button, rotary gain control and very welcome twin 10-segment input and output level meters with a 60dB range.

With the button in the line position either the outer XLR or inner TRS-wired jack can be used in balanced or unbalanced modes, with a gain range from 0dB (+4dBu nominal sensitivity) to +29dB. However, the TRS jack has an input impedance of 10kΩ, so it's not ideal for guitars and the like. In the mic position a preamp is switched in, offering overall gain from +25dB to +73dB, and global +48 Volt phantom power is available from a switch on the right-hand side of the front panel, where there's also a dedicated stereo headphone output with its own rotary level control hard-wired to the output 1/2 signal, and LEDs indicating the current sample rate and clock source. The 'Internal' clock option on the EX8000 comes into play when the expansion box is used in stand-alone mode as a preamp and A-D converter.

The rear panel is crammed with socketry, with eight analogue XLR balanced/unbalanced outputs at +4dBu level, eight duplicate analogue outputs using balanced/unbalanced TRS sockets at -10dBV level, plus eight inserts for the input channels to add hardware compressors, EQs, reverbs, and the like (you could at a push use these as unbalanced line-level inputs if you really wanted rear-panel inputs, but would have to pull out the cable if you ever wanted to use the associated front-panel preamp).

On the digital side, there's another BNC word clock input, a pair of optical sockets for eight-channel ADAT in and out, four pairs of coaxial S/PDIF ins and outs on phono sockets, eight XLR sockets for the four stereo AES-EBU balanced digital ins and outs, two IEEE 1394 connectors for connecting the PCI host card and a Thru connection for 'future expansion', and a fused IEC socket for AC power. This is indeed comprehensive, but do beware when plugging in XLR cables to the analogue outputs, since the identical-looking AES-EBU outputs are immediately above — you won't do your amp or ears any good if you feed them full-strength digital signals by mistake!

The Art Of Installation

The EWDM drivers support Windows 2000 and XP, and I downloaded the latest version 1.81 from the ESI web site. As with many modern interfaces, the drivers installed as four separate devices: the Maxio EWDM Controller, Wave-1, Wave-2 and MIDI. After a reboot the ESI icon appeared in my PC's System Tray and I could use it to launch the Maxio Control Panel utility. The Control Panel is quite complex, but you can save and recall up to five presets storing every setting.

The main Maxio Control Panel has metering for a fully expanded 32-in/32-out system running four expansion boxes, plus zero-latency monitoring and a host of other system options.The main Maxio Control Panel has metering for a fully expanded 32-in/32-out system running four expansion boxes, plus zero-latency monitoring and a host of other system options.Photo: Mark Ewing

On the left-hand side of the Control Panel window is the Input section, with the Output section on the right, each divided into four banks of eight channels with level meters, along with various input and output options. By default, the banks are connected to the four EDI sockets on the PCI host card, but each bank can be switched to 'see' the MDI port instead. In an EX8000-based system, this port is occupied by a flying lead; this provides word clock and MIDI I/O regardless of the bank settings, and S/PDIF I/O that shows up if you switch one of the banks to MDI mode. However, the alternative 032 digital interface connects only to the MDI port, delivering its 32 channels of digital I/O this way.

Immediately beneath the meters are three rows of tiny icons. The top row displays the current MME Channel Mapping, and you can decide here which of the 16 stereo pairs of inputs and outputs are mapped to the Maxio Stereo Wave driver for basic stereo recording and playback. Using the middle and lower rows you can optionally assign the MDI analogue and S/PDIF ins and outs to specific EDI channels instead of the multi-channel ones from the expansion boxes.

Across the bottom of the Control Panel are the Input and Output Monitor buttons (32 in all), which work in conjunction with the right-hand Master Section controls. Here there are two channel faders with a 60dB range, along with routing that lets you allocate them to any one or none of the 16 stereo output pairs. Each of the 32 monitoring buttons has three states — disabled, enabled, and enabled but mixed to mono — and you can set up any combination for your monitor mix.

The Channel Limit setting in the I/O pane can be fixed at 8, 16 or 32, and should be left at its default eight-channel setting if you only have a single EX8000 connected. The lower the setting, the lower will be the transfer rate of the Maxio host card across the PCI buss; a fully expanded system will require a fast PC with a good motherboard and associated chip set, as well as care when choosing other PCI devices for your system. I hope that detailed sample system specs will appear on the ESI web site before long — the only guidelines at present are 'Intel Pentium 4 or equivalent or compatible CPU, motherboard with chip set supporting the Intel Pentium 4, and at least 512MB of RAM'.

Why PCI?

The Maxio system has been a long time in gestation (ESI first showed it at the Winter NAMM show in February 2004), and some musicians may now be wondering whether the PCI format is the best choice — after all, motherboard manufacturers are now telling us that PCI slots may disappear without trace within a couple of years.

The heart of the Maxio XD system is the host PCI card, which supports up to 32 audio input and output channels at 24-bit, 192kHz.The heart of the Maxio XD system is the host PCI card, which supports up to 32 audio input and output channels at 24-bit, 192kHz.Photo: Mark Ewing

Well, as always, the truth is rather more complex than motherboard manufacturers want us to think. First of all, I think it highly unlikely that the PCI slot will completely disappear for at least four years — people worldwide simply aren't going to throw away all their existing PCI expansion cards unless they really can't use them any more, so many motherboards will continue to feature at least some PCI slots. There are some issues with PCI cards installed in motherboards with mixed PCI and PCI Express slots, particularly using the nForce 4 chip set, as I explained in PC Notes September 2005, but a resolution for these now looks more hopeful.

Moreover, the Maxio XD can potentially support 32 input and 32 output channels at 24-bit/192kHz with low CPU load and latency, a specification which simply can't be achieved by either Firewire 400 or USB 2.0 (PCI bandwidth is 133MB/second, compared with the 50MB/second of Firewire 400, 60MB/second of USB 2.0, and 100MB/second of Firewire 800).

Some musicians are managing to run 80-in/ 80-out setups at 24-bit/44.1kHz with Firewire 400 audio interfaces, but at 96kHz this would reduce to about 40-in/ 40-out, and 20-in/ 20-out is a more likely limit at 192kHz. Here, Firewire 800 and PCI are the only real options, with PCI still significantly ahead on bandwidth. MOTU have apparently achieved 32-in/ 32-out operation with their 896HD system at 192kHz with a Mac system by connecting two units to the motherboard's FW800 ports, and a further two to FW800 ports on a PCI expansion card, but on the PC I suspect this to be rather unlikely.

In a year's time, perhaps a PCI Express host card might be more sensible, but at the moment so few musicians have PCI Express slots available that it's not a commercial proposition, so PCI becomes the only real option for a PC-based system with this capability. ESI are confident that their Maxio XD system can realistically be used for perhaps four to five years if bought now.

EX8000 Control Panel

If you leave a channel group as EDI and have an EX8000 connected you can launch a separate control panel that provides comprehensive choices over its clock source, and a routing table that lets you specify which signals are sent to each of the four stereo pairs. Possible input and output signals are EDI, Digital (AES-EBU and S/PDIF), Analogue and ADAT Optical, and here I found the various options tricky to get my head round at first. If you want to send an analogue input pair to your PC, you need to route them to EX8000's EDI Out, whereas if you want to send a stereo signal from your PC to (for instance) an S/PDIF output, you route the appropriate Digital Out to the EX8000's EDI In.

Each EX8000 expansion box has its own Control Panel containing numerous options, although there are only eight channels of I/O between each EX8000 and the PCI host card.Each EX8000 expansion box has its own Control Panel containing numerous options, although there are only eight channels of I/O between each EX8000 and the PCI host card.Photo: Mark Ewing

The Digital Audio input ports can also be either 'RCA (S/PDIF)' or 'XLR (AES/EBU)'; their current PLL (Phase Locked Loop) status is displayed as Lock or Unlock, and you can individually choose from professional or consumer format. Further controls allow the ADAT I/O to provide eight channels at 44.1/48kHz (Normal), four at 96kHz (SMUX), or two at 192kHz (SMUX2) and the analogue outputs to have their levels individually set anywhere between 0dB and -60dB, while even the software meters offer four different modes, with various peak and display options.

Together, these two Control Panels provide incredibly versatile control, yet the EX8000 has yet more versatility up its sleeve: it can also double as a stand-alone device with six selectable modes. It can be used as an eight-channel A-D and D-A converter, either using the four AES-EBU ins and outs, the four coaxial S/PDIF ins and outs, or the ADAT optical I/O with or without S/MUX enabled, and can also convert ADAT to AES-EBU formats and back again, or convert analogue to ADAT and AES-EBU formats simultaneously.

Overall, I was well impressed with the versatility of the Maxio XD, although I suspect that a few people will mistakenly think that they can use all the I/O simultaneously — after all, the system is capable of 32-in/out operation, while the EX8000 box has far more than eight physical inputs and outputs. For those wishing to expand beyond a single EX8000, I hope that ESI release a simpler and cheaper EX box that simply has the eight analogue in/outs, as I can see this being a popular expansion option.

Maxio XD Brief Specifications

  • Sample rates: 44.1, 48, 88.2, 96, 176.4 and 192 kHz available on both PCI host card and EX8000 rack unit.
  • Analogue inputs: eight Neutrik Combi sockets with mic/line switch, variable gain controls, channel inserts, plus low-noise mic preamps with up to +73dB gain and optional global +48V phantom power.
  • Input impedance: 1.5kΩ mic, 10kΩ line.
  • Analogue outputs: eight XLR balanced at +4dBu level, eight balanced/unbalanced TRS quarter-inch jacks at -10dBV level, stereo headphone jack with rotary level control.
  • PCI host card digital I/O: word clock in and out, MIDI In and Out, coaxial S/PDIF in and out.
  • EX8000 digital I/O: word clock In, ADAT in and out, four coaxial S/PDIF in and out, four AES-EBU in and out, EDI in and Thru.
  • Dynamic range: input 116dBA, output 118dBA.
  • Frequency response: 20Hz to 20kHz ±0.1dB.
  • THD + noise: <0.0003%.

To The Max

I experienced no problems while using the Maxio XD system, and my Rightmark Audio Analyser measurements supported the manufacturer's spec quite closely. The D-A converters have a dynamic range of 120dBA, and even once the output circuitry has been added this remains close at 118dBA. The A-D converter chips are even better at 123dBA, but the analogue input circuitry reduces this to 116dBA, and my loopback tests that measure both simultaneously were extremely close to this at 115.7dBA with both 96kHz and 192kHz sample rates. Frequency response was a good 0.3dB down at 9Hz and 21kHz at a 44.1kHz sample rate, extending to 43kHz at both 96 and 192 kHz sample rates, while THD was a very low 0.0008 percent, and stereo crosstalk an excellent -115dB.

ESI's Direct Wire utility window is as impressive as ever with the Maxio XD — here I've patched the first two analogue inputs for MME recording, the same MME outputs to a WDM application, and the first two outputs of Gigastudio direct to ASIO inputs 3/4. ESI's Direct Wire utility window is as impressive as ever with the Maxio XD — here I've patched the first two analogue inputs for MME recording, the same MME outputs to a WDM application, and the first two outputs of Gigastudio direct to ASIO inputs 3/4. Photo: Mark Ewing

My double-blind auditions against my own Emu 1820M and Echo Mia interfaces using a variety of music once again proved revealing, although as often happens, the differences between them and the review interface were subtle. The Mia revealed itself as having a slight harshness and less focused sound, while the 1820M and Maxio XD were both rather more revealing of low-level detail, and proved more difficult to tell apart.

I re-shuffled the card outputs and repeated my listening tests at least half a dozen times, and then looked back at my written comments to find that I chose the Emu and ESI fairly equally as providing the best sound, so the fairest conclusion is to declare it a draw on audio quality. The 1820M is considerably cheaper, but the Maxio XD offers far more I/O and other options for its higher price. I also liked the sound of its mic preamps, which were certainly quiet, yet had an extended and natural high end.

Driver Performance

ESI provide multi-channel as well as basic stereo Wave drivers, and in Sonar 's WDM/KS mode I managed the lowest 1.5ms setting at 44.1kHz with no glitching. In ASIO mode I managed the same setting in both Sonar and Cubase SX3. The Direct Sound drivers managed a slightly better than average 30ms Play Ahead setting with NI's Pro 53, with the MME drivers achieving 45ms, while I had no problems using the GSIF drivers with Gigastudio 3. They are only claimed to be GSIF1, but GS3 declared them to be GSIF 2.0, and I could use them to record audio, so GSIF2 they proved to be.

Evert van der Poll's MIDI Test utility proved that like most PCI interfaces, the Maxio XD put in a good performance on the MIDI side, with an average MIDI latency of just 0.81ms (the lowest I've measured to date), average jitter of 0.22ms, and maximum jitter of just 0.48ms. These are all excellent results, two to eight times lower than any USB or Firewire MIDI interface I've measured to date, and even the most discerning drummer should have no issues with the Maxio MIDI timing.


I suspect the Maxio XD will particularly appeal to those who need to cater for the need to interface with whatever other gear comes along, and of course an audio interface with eight mic preamps built in is the perfect spec for many musicians making live band or other ensemble recordings. Until the company's demise, Aardvark's Q10 was very popular for this reason, but there isn't now all that much direct competition for the Maxio XD. The Presonus Firepod retails at about £600, has eight mic preamps, eight-in/eight-out analogue plus S/PDIF digital and MIDI In/Out, and up to three units can be used simultaneously for 24-in/24-out operation, but it doesn't support 192kHz, or feature ADAT, AES-EBU and multiple S/PDIF I/O.

A much closer competitor is MOTU's Firewire-based 896HD, which does support 192kHz, has eight mic/line inputs and 10 analogue outputs plus separate stereo headphone output, and features ADAT optical, stereo AES-EBU digital and word clock I/O, as well as the option of stand-alone use, providing up to 18 ins and 20 outs at 44.1 and 48 kHz. At £995 it is £300 less than the Maxio XD, but doesn't have its inserts, simultaneous +4/-10 analogue outs, multiple AES-EBU or S/PDIF I/O, and using more than two units may not be possible on PCs when running at 192kHz, although four units have been used at this sample rate with some Macs for 32-in/out operation (see 'Why PCI?' box)

Overall, ESI's Maxio XD is certainly an ambitious and impressive system, and with its high-quality audio, well written drivers and incredibly versatile options it ought to find a home in many rigs, especially for those who want plenty of future expansion potential. It's slightly disappointing that with so much analogue and digital I/O on board the EX8000 you have to choose just eight ins and outs at a time to connect to your PC via the host card, but I feel this is largely redeemed by the versatility of the EX8000 and the ability to turn it into a stand-alone converter box. I'm still not personally convinced of the benefits of 192kHz recording, but it's there if you want it, with up to 32 inputs and outputs on a fully expanded system with four EX8000s. Plenty of manufacturers hint that drivers supporting multiple interfaces may be available at some time in the future, but ESI are to be commended for having them from day one. 

Published December 2005