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ST Audio DSP24 Media 7.1

PC Audio & MIDI Interface
Published January 2003
By Martin Walker

ST Audio's recording interface provides multi-channel, multi-client audio I/O, as well as MIDI In and Out and full 24-bit/96kHz capability, for a highly affordable £230.

ST Audio DSP24 Media 7.1ST Audio is the new name adopted by Korean-based Hoontech, who claim that their DSP24 Media 7.1 is "the world's first true 24-bit/96kHz PCI full-duplex multi-channel audio/media interface with an onboard GM/GS hardware synthesizer". While this is quite a mouthful, it does sum up the approach taken by ST Audio, in offering extremely versatile products that are also good value for money. The Media 7.1 is just £229.99, and as the last part of its name also suggests, it can play back up to 7.1 surround sound through its audio outputs.

Essentially the Media 7.1 is a four-input/eight-output soundcard with both co-axial phono and Toslink optical digital I/O, supporting 24-bit/96kHz operation throughout. All the main inputs and outputs are all to be found on the half-rack-width breakout box, along with a headphone output with its own volume control, plus a balanced mic input with +48 Volt phantom power, a line input with optional RIAA phono preamp, and a single MIDI In and Out. On the soundcard itself there's a lower-quality mic and line input plus a mix output, with 18-bit converters primarily intended for general-purpose Windows duties. Finally, as mentioned previously, the Media 7.1 also features a 48-voice GM/GS hardware synth, whose MIDI output appears as a second device inside Windows.

ST Audio DSP Media 7.1 £230
  • Excellent value for money.
  • Good-quality 24-bit audio on recording.
  • Good ASIO, WDM and GSIF drivers.
  • Integral GM/GS hardware MIDI synth.
  • AC97 codec will compromise breakout box audio playback quality if you plug it in.
  • Improvements in sound quality at 96kHz are marginal.
The ST Audio DSP24 Media 7.1 provides a comprehensive array of features for the price, including both an RIAA preamp and a handy ROM-based synth, and provides good (if not exceptional) audio quality at a very reasonable price.



Given the complexity of this product, I was pleased to find a block diagram of its functions in the well-written 73-page printed manual, which helped to explain how the various devices are plumbed into the system.

On the front panel of the breakout box is a pair of phono inputs at -10dBV consumer line level, with a Phono switch alongside to switch in an RIAA-equalised preamp for direct connection of a record deck. The mic input is a balanced TRS quarter-inch jack, and has both a front-panel gain control and optional switched +48 Volt phantom power. Completing the front panel are two pairs of S/PDIF sockets (a phono and Toslink optical for both input and output), a quarter-inch stereo jack for the headphone output (again with its own level control), and a red LED power indicator.

The back panel has eight phono analogue output sockets, and the first three pairs are duplicated by stereo 3.5mm jack sockets labelled Front, CN/Sub, and Rear for surround duties, while above outputs seven and eight is another 3.5mm jack marked Mix In (more on this in a moment).

There's also a pair of five-pin DIN sockets for MIDI In and Out, and a D-type connector for the umbilical to the soundcard. The main converters are also inside the breakout box, and all eight channels of both A-D and D-A conversion are carried out by a single AK4529 codec chip, as also used in M Audio's Delta 410 and 1010LT soundcards.

The soundcard houses an SAM 9703 hardware synth and a self-contained lo-fi (sorry, I mean "consumer audio") AC97 codec featuring its own internal CD and Aux inputs (a suitable cable for connecting to your CD-ROM drive is supplied), along with a 3.5mm stereo Line In and Mix Out, and a 3.5mm Mic In on the backplate. These all operate at up to 16-bit/48kHz. The umbilical cable joining the soundcard and breakout box is two metres long, while a further two-metre cable with 3.5mm stereo jack at each end is intended for connection between the soundcard's Mix Out and the breakout box's Mix In, allowing the AC97 codec's contribution to be added to physical outputs one and two.

The software bundle includes Emagic's Logic Soundtrack 24 with 24-bit/96kHz capability, Sonic Foundry's Acid Xpress 3.0 and Siren Xpress 2.0, InterVideo WinDVD 3.0, DART CD Recorder 4 Basic and Karaoke Studio. Of particular note is DCart32(Diamond Cut) version 4.0, which includes a range of specialised tools for restoring vinyl and tape recordings.

Drivers & Software Options

Since ST Audio say in their printed manual that their drivers are optimised for Windows XP, this is the operating system I chose for the review. To make sure I got the latest drivers I downloaded them from the ST Audio web site; the ones I got were version 7.2.0806, dated 6th August 2002.

Drivers are also available for Windows 9x, Me, NT 4 and 2000. All support WDM, ASIO 2.0 and GSIF, and provide "ultra-low" latency and/or zero-latency direct monitoring. Installation is made easier because the manual also provides an extremely detailed eight-page Troubleshooting/FAQ section which covers motherboard chipsets, IRQs and Windows 2000/XP system optimisation. ST Audio recommend disabling ACPI and avoiding IRQ sharing, particularly if your motherboard has a VIA chipset, even if you don't get any obvious conflicts, since ultimate performance may be affected.

Once installed, the drivers appear to music applications as five input pairs and seven output pairs. Each has the prefix 'ADSP24' and the suffix either of 'WaveOut' or 'Input' when running under Windows 98/Me, or a blanket 'Audio Device' when running the WDM drivers under Windows 2000/XP. The outputs comprise Int, which is used to play back WAV files through the AC97 codec, Ext 1/2 through to Ext 7/8 to do the same through the main soundcard circuitry, Ext SPDIF, which plays back through both optical and co-axial digital outputs simultaneously, and finally Ext Digital, which is the combined signal from the Media 7.1's internal DSP mixer.

The available inputs are Int, Ext 1/2, Ext 3/4, Ext SPDIF and Ext Digital Device. Ext 1/2 can either be the signal from the line input or the integral RIAA preamp, while the mic input signal overrides these as soon as a plug is pushed in. Ext 3/4 is connected to the output of the internal hardware MIDI synth, so that you can record it directly as a stereo audio track in your audio sequencer, and Ext Digital Device enables you to record the combined output from the soundcard's DSP mixer.

 DSP24 Media 7.1 Brief Specifications 
  • Soundcard internal I/O: CD in, Aux in, via 18-bit AC97 codec, supporting up to 16-bit/48kHz.
  • Soundcard external I/O: stereo line in, mic in, mix output, all via 18-bit AC97 codec and on 3.5mm jack sockets.
  • Breakout box analogue inputs: stereo -10dBV line/RIAA-equalised phono in (switchable), quarter-inch jack balanced mic in with switchable +48 Volt phantom power and front-panel gain control, 3.5mm stereo jack mix input (from card external mix out).
  • Breakout box analogue outputs: eight phono line outputs, duplicated with 3.5mm stereo jacks for Front (1/2), CN/Sub (3/4) and Rear (5/6), plus quarter-inch stereo headphone output with volume control.
  • Breakout box digital I/O: co-axial S/PDIF in and out, Toslink optical S/PDIF in and out, MIDI In and Out (MPU401 compatible).
  • Onboard GM/GS hardware synth: DREAM 4MB ROM with 48-voice polyphony, 16-channel multitimbrality, with reverb and chorus.
  • A-D converters: 24-bit 64x oversampling (part of AK4529 chip).
  • D-A converters: 24-bit 128x oversampling (part of AK4529 chip).
  • Signal-to-noise ratio: >100dB (A-weighted).
  • Total harmonic distortion + noise: not stated.
  • Frequency response: not stated.
  • Supported bit depths: 8, 16 and 24.
  • Supported sample rates: 22.05, 32, 44.1, 48, 88.2 and 96 kHz.
  • Digital I/O: up to 24-bit/96kHz, non-audio mode transmits AC3 streams.

Patchbay & Routing Options

Like most other soundcards, the Media 7.1 is supplied with its own Control Panel utility. This has three pages labelled Patchbay, Mixer and H/W Setting, and by default appears with the Patchbay visible. Both the front and rear panels of the breakout box are displayed in graphic form along with a symbolic version of the soundcard itself, above which are displayed the current clock and sample rate settings.

The graphical patchbay makes the various connections between the soundcard driver devices and physical I/O sockets immediately obvious.The graphical patchbay makes the various connections between the soundcard driver devices and physical I/O sockets immediately obvious.There are five pairs of physical hardware outputs available as possible patchbay destinations: the analogue outputs 1/2, 3/4, 5/6 and 7/8, plus the S/PDIF out. To these you can drag virtual patch cords from the internal soundcard signals and the analogue or digital hardware inputs, providing zero-latency monitoring of the latter. The internal soundcard signals available comprise the four stereo Wave playback pairs, labelled Wave Out 1/2, 3/4, 5/6 and 7/8, along with Wave S/PDIF Out, MIDI Synthesizer (the output of the internal hardware synth) and Mixer (from the internal digital mixer). Each of these displays the current playback level behind its text name as a horizontal peak-reading bar meter, whose colour flashes red when it exceeds -1dBFS.

You can't merge signals, so each physical output can be connected to just one input or internal signal, but there's no restriction on how many destinations each internal signal can be patched to. So, for instance, you could connect the MIDI synth to all five output pairs if you wished, although by default, Wave Outs 3/4, 5/6 and 7/8 are all connected to their equivalent physical output while the Mixer output goes to both physical outputs 1/2 and the S/PDIF output. There are various source/destination restrictions, and only those connections that become highlighted when you grab them are permissible.

Unlike many similar products that use simple text-box source and destination options, the functional graphics and virtual patch cords of the Media 7.1 patchbay make it easy to understand what's going on within the first few seconds. However, unravelling the options and the current settings does end up taking longer, simply because following patch cords and studying the possible options for each source or destination takes longer than reading text boxes — you can't have it both ways.

The Digital Mixer page lets you create a monitor mix of the various possible source signals, which comprise Wave 1/2 through to 7/8, S/PDIF Out, S/PDIF In and Input 1/2 for zero-latency monitoring, and MIDI Syn. Each has its own pre-fade peak-reading meter, fader, pan slider, mute and solo button, while a pair of Master channels with their own meters, faders, and global mute button control overall output level. Four presets can be saved or loaded using the buttons at the top right, which is handy for quick recall.

Hardware Settings

The H/W Setting page displays the driver version information, along with its current latency and resolution, and below this are three buttons that call up extra information about the Clock, Device and other settings. The Clock options include a rather superfluous one that allows you to record and play back at bit depths greater than those supported by the card — perhaps these drivers are also used by other Hoontech products. More useful are the options for internal and external master clock, as well as a display of the current sample rate, which can also be set manually and then locked, rather than being chosen by the music application.

You can allocate each output pair to a different driver format.You can allocate each output pair to a different driver format.The Device Settings let you adjust ASIO buffer size, and eight settings are provided ranging from 1536 down to 64 samples (incorrectly labelled as samples per second). Under the Device Mixing section (which in the printed manual is more correctly referred to as Multiclient Support), you can independently decide which driver format is used by each of the WaveOut and S/PDIF Out devices, by ticking the appropriate button. So, for instance, you could allocate WaveOut 1/2 and 3/4 to ASIO for use within Cubase, WaveOut 5/6 to MME for a stand-alone soft synth, and WaveOut 7/8 and S/PDIF Out to GSIF for GigaStudio.

This works well, although as you might expect, you have to make your selection before launching your music applications. There's a further tick box labelled GSIF Enable, which does exactly what it says, although I'm not sure why you would ever need it. Unfortunately, the allocation also determines the ASIO and GSIF driver numbering within applications: in the example above, after choosing the ASIO drivers inside Cubase SX, you can choose from 'Analog Output (1) 1/2' and 'Analog Output (1) 3/4', while GigaStudio also displays its GSIF output options as 1/2 and 3/4, despite actually using WaveOut 7/8 and S/PDIF Out. Meanwhile, all the MME options will still be available to applications, but only the one labelled 'MME-WDM ADSP24 Ext.5/6 Audio Device' will work, the others giving error messages. Admittedly you won't be changing such settings very often, but this is a source of initial confusion. Having said that, the ability to mix and match driver types is certainly useful, although various other soundcards I've reviewed have managed to perform the same feat in a more transparent manner.

The final page is labelled Etc, and contains a couple of further options. Multi Channel Device Support will primarily be used with software applications like WinDVD or PowerDVD to play multiple audio channels using a single MME device, while S/PDIF Out offers a choice of Consumer or Professional modes. You can also move between the various pages using menu options, while an additional Call Internal Mixer option launches the standard Windows mixer for controlling the AC97 codec playback and recording features, should you decide to use them.

In Use

The Media 7.1 wave playback quality sounded reasonably similar to my Echo Mia, which is hardly surprising considering that the former uses an AK4529 codec and the other an AK4528 codec. However, the Media 7.1 lacked crispness at the top end by comparison, and the Mia obviously has a lower-jitter clock, as its transient detail was noticeably cleaner and its imaging more precise. The AK4529 codec also has slightly higher noise levels, and with 24-bit/44.1kHz recordings the RMS background noise measured a reasonable -98.2dB. This is about the same as Terratec's DMX 6Fire, and about 1dB worse than their EWX 24/96 and M Audio's Audiophile 2496, but some 6dB worse than the Mia. The 24-bit/96kHz figure was -96.6dB RMS, this further rise of a couple of dBs being fairly typical for the doubled bandwidth.

My tests with Rightmark's Audio Analyser 4.0 showed similar background noise levels, but confirmed my listening tests as far as frequency response was concerned. While the Media 7.1's low-frequency response was only -0.4dB down overall at 20Hz, it was -3dB at 15kHz for both 44.1kHz and 96kHz sample rates. I repeated my tests using the Echo Mia as a reference to measure the Media 7.1's A-D and D-A sides separately, and this proved that the A-D recording side was fine at +0.12/-0.79dB between 20Hz and 20kHz. The D-A playback portion was causing the problems, measuring +0.34/-4.69dB over the same range.

Suspecting that I'd received one of several early cards sent out with incorrect capacitor values, ST Audio sent me a second one to test. While both cards had an identical low-end roll-off, the second one was rather better at high frequencies, rolling off to -3dB at 20kHz when using a 44.1kHz sample rate, extending only slightly to 23kHz with a 96kHz sample rate. All other performance aspects of this second Media 7.1 card were identical to the first.

This is much more acceptable for an eight-channel card that retails at £230, and although 96kHz recordings will show little improvement over 44.1kHz or 48kHz ones, I still maintain that at this end of the market these lower sample rates are more suitable anyway. If you really do want to record at 96kHz, two similarly priced cards that I have tested that exhibit a wider frequency response are M Audio's Audiophile and Echo's Mia, both of which are only 1dB down at around 42kHz using a 96kHz rate, but have far fewer channels.

It's extremely handy to have a GM/GS MIDI synth in hardware, since of course it consumes no CPU overhead, but with a 4MB ROM you can hardly expect it to set the world alight. Even so, its sounds are relatively rich and smooth, and sometimes quite powerful, if somewhat lacking in expression given the short length of each sample. The printed manual does help in extracting the last drop of performance from it, with a full list of sounds and bank variations, plus a comprehensive SysEx implementation table for getting deeper into sound and effect editing.

The ASIO drivers worked extremely well in Cubase SX 1.02, with no glitching on my test songs even at the lowest 64-sample setting, which at 44.1kHz gives a 1.45ms buffer latency, while the GSIF drivers gave a faultless performance with GigaStudio160, and the WDM drivers gave me an excellent 5.8ms latency in Sonar 2.0. With Pro 52 in stand-alone mode the DirectSound drivers managed a reasonable 25ms, and only the MME performance with Pro 52 at 45ms was mediocre — not a cause for much concern given the other available options. The S/PDIF I/O also gave an accurate bit-for-bit copy of a DAT transfer.

I would advise against using the AC97 codec at all, since its audio contribution is permanently added to breakout box output 1/2, and as soon as I plugged in the extra 3.5mm jack-to-jack lead from soundcard to breakout box, low-level digital hash appeared in the background, along with crackles each time the display was altered or mouse moved.

Final Thoughts

With its eight outputs and wide variety of input options, the Media 7.1 will obviously appeal to musicians interested in low-cost surround sound, and here a couple of obvious competitors are Creative Labs' Audigy (reviewed in SOS November 2001), and Terratec's DMX 6Fire (SOS April 2002). I still feel that with its fixed 48kHz engine and poor noise performance, the Audigy causes more problems for musicians than it solves, although it does provide SoundFont support and FireWire ports. However, the DMX6Fire is a much stronger competitor, providing similar performance and background noise levels to the Media 7.1, and a similar complement of analogue and digital I/O, including an RIAA preamp. However, for its additional £50, the Media 7.1 also features a built-in hardware MIDI synth whose output can be internally recorded using the Ext 3/4 input, as opposed to a WaveBlaster connector, while its mic input has +48 Volt phantom power.

Overall, despite the AC97 codec features (which can be ignored if you prefer, or pressed into service for Windows sounds and lo-fi audio CD playback), and a subtle roll-off at the top end, the Media 7.1 gives the impression of a fairly rugged, straightforward design for musicians, and will no doubt find plenty of users.

£229.99 including VAT.

Test Spec

  • Soundcard driver version: 7.2.0806.
  • Intel Pentium III 1GHz processor, Asus TUSL2-C motherboard, 512MB Crucial SDRAM, running Windows XP.
  • Tested with: Steinberg Cubase SX v1.02 and Wavelab v4.0d, Tascam GigaStudio 160 v2.50.48, NI Pro 52 v2.5, Cakewalk Sonar v2.0.
Published January 2003