Thứ Ba, 22 tháng 3, 2011

Terratec Producer Phase 28 & Phase 26 USB PCI & USB Audio & MIDI Interfaces

It seems as though every audio card manufacturer is keen to promote high sample-rate audio formats. Terratec's Phase 28 and Phase 26 attempt to do this in PCI and USB formats respectively.
John Walden
Regular SOS readers will be familiar with Terratec's product range, which has in the past been dominated by PC audio cards such as the EWS 88MT and EWX 24/96, both reviewed by Martin Walker (in the October 1999 and April 2001 issues respectively). More recently, the company's higher-end soundcards have been joined by a range of more general studio hardware under the Terratec Producer brand, and Hugh Robjohns reviewed the EWS Mic 2 and Mic 8 multi-channel, 24-bit/96kHz, rackmounted mic/line preamps in May 2003.
Like many audio card manufacturers, Terratec have been keen to introduce higher sample rates into their product range. The Phase 28 is a 24-bit, 192kHz PCI-format audio card which, via a breakout cable bundle that attaches to the rear plate of the card, provides a two-in/eight-out analogue system on balanced quarter-inch jacks, MIDI I/O, and S/PDIF digital I/O on RCA connectors. In contrast, the USB-based Phase 26 USB offers 24-bit/96kHz audio in an unbalanced two-in/six-out configuration, MIDI I/O, digital I/O on either RCA or optical connectors, and a headphone output. Both units support Windows and Mac, and a range of driver types is supplied (see the Specifications & Drivers box for more details). I reviewed both under Windows.
Of course, multi-channel in/out audio devices offering high sample rates now come at a range of prices to suit almost any pocket, and Terratec have plenty of competition. It is also true that many home or project studio owners (and SOSreviewers!) are perhaps somewhat sceptical about how 'essential' ultra-high sampling rates are, given the context in which they produce their own music. For many such users 16-bit or 24-bit, 44.1kHz audio can produce perfectly acceptable results if used with due care and attention. So how do the Phase 28 and Phase 26 USB stand up in a soundcard arena awash with 24-bit, high sample rate-capable audio devices?
The Phase 28
Installation of the Phase 28 proved straightforward. Once it was mounted in an empty PCI slot, the cable bundle was attached to the 'D' connector on the card's backplate. This needs to be done fairly securely as, while the breakout cables are quite short, their number means there is a considerable weight involved. On rebooting under both Windows XP and 98SE, I was prompted for the driver installation, which proceeded without a hitch. The supplied CD also includes the Control Panel and ASIO drivers, which require separate installation. In addition to the 'D' connector, the backplate of the card also features gain controls for the two analogue inputs. These can be adjusted with a small flat-headed screwdriver, and provide an adjustment range between -19 and +12 dB. After experimenting with these, I was left wondering a little about the wisdom of their inclusion. Aside from a comment to the effect that they can be used to accommodate a wide range of input signal levels, the manual offers very little in the way of advice as to how the hardware gain and software gain (in the Control Panel described below) interact. Also, since they will be located on the back of the computer, most users are going to want to 'set and forget' rather than make regular adjustments by scrambling about in the spaghetti that usually resides behind a computer within a studio environment.
Under Control
The Phase 28 Control Panel.
The Phase 28 Control Panel software (see screen shot, below) shares many similarities to that supplied with Terratec's earlier EWS audio devices. The upper portion is dominated by a range of faders and buttons that control the levels and so on for the various analogue ins and outs. For each of the output pairs, this includes a drop-down menu to choose between Wave, Analog In or Digital In as the playback source. The Analog In or Digital In settings could be used for direct monitoring of incoming audio via a second stereo output if your audio sequencer does not support direct monitoring or only does so with a significant latency.
The lower portion of the Control Panel provides clock, digital output and audio input sources to be selected. Most of these do exactly as you'd expect, although it should be pointed out that the Wave Record Select is an either/or option — you can not enable both the analogue and digital inputs for simultaneous four-track recording. The ASIO button brings up a further set of options (see screen shot overleaf) that allow the ASIO and GSIF driver combinations to be configured. ASIO buffer settings between 64 and 2048 samples provide plenty of flexibility for those with more or less CPU grunt. In multi-client mode, the four output pairs can be allocated to either ASIO or GSIF use as required.
The Phase 28 In Use
With one minor quirk, testing the Phase 28 within Cubase SX was unproblematic. Both 16-bit and 24-bit recording functioned as expected and, as well as stereo projects, 5.1 surround sound monitoring was easy to configure using three of the stereo output pairs — obviously 7.1 projects would be possible if your software is able to support that format. I was comfortably able to get down to a buffer size of 128 samples (2.9ms latency at 44.1kHz) while running a 16-track audio mix, plenty of effects plug-ins, a couple of software instruments and monitoring a stereo input signal in real time by engaging the Monitor button on the record active track within SX.
The ASIO settings for the Phase 28, including configuration of the multi-client ASIO/GSIF drivers.
The only quirk was that I had to quit Cubase before I could adjust the ASIO buffer size from within the Phase 28 Control Panel. This is only a minor irritation and, to be fair, it is clearly stated within the manual — it is also something that is found in products from some other audio card manufacturers.
Testing with other applications proved equally straightforward. I was able to get down to the same 3ms latency using Reason with no obvious audio glitching even in a fairly busy mix. Acid Pro also performed well, both in stereo and surround projects.
SOS reviewers have commented on problems with Terratec documentation on previous occasions and I must say that the Phase 28 manual is not the most helpful document I've ever seen supplied with a 'professional' audio product. Features such as the hardware gain controls could be more fully explained and it would be useful to have some guidance on configuring the card for use with some of the more popular sequencer/sampler software combinations. Novice users, in particular, might find themselves floundering.
The documentation quotes noise figures of 106 and 102 dBA respectively for the Phase 28's 24-bit/192kHz A-D and D-A converters, although these are the technical specifications of the converters themselves. Testing their audio performance within the Phase 28 using the loopback test in Rightmark's Audio Analyser 5.1 produced very good results for 16-bit, 44 kHz mode. The noise level was -94dBA, total harmonic distortion measured 0.004 percent and stereo crosstalk was an excellent -94dB. Given these encouraging results, I was expecting to see similarly good figures for 24-bit recording but, try as I might, I could not get the Phase 28 to function in 24-bit mode with RMAA at any sample rate. This said, tests usingWavelab and Cubase SX proved that 24-bit recording was perfectly possible and experimentation in Wavelab showed that for 24-bit, 44.1kHz recording, the noise floor was a couple of dBs lower than in 16-bit/44.1kHz mode.
Subjective listening tests with a variety of sources at different bit depths and sample rates suggested that the playback quality of the Phase 28 was perfectly respectable. Reproduction was clear and detailed and the stereo imaging appeared to be good. While there was a subtle, but noticeable, improvement in going from 16- to 24-bit (at 44.1kHz), frankly I could not perceive any significant improvement at either 96 or 192 kHz — but at least the option is there for those who want to explore it. The MIDI I/O operated entirely as expected and I had no problems with either recording or playback via the S/PDIF digital I/O from my Yamaha 01V mixer. My overall impression would be of very respectable audio performance that's not greatly different from a number of other 24-bit, 96/192kHz-capable audio cards that SOS has reviewed over the last couple of years.
Specifications & Drivers
Phase 28
Recommended PC: Pentium III 1GHz or above with 256MB RAM, Windows 98SE, Me, 2000 or XP. Drivers support MME, Direct Sound, ASIO 2.0 and GSIF, with an ASIO/GSIF multi-client mode. WDM kernel streaming for Sonar and other suitable applications is supported.
Recommended Mac: any G4 running Mac OS X.
Phase 26 USB
Recommended PC: Pentium III 1GHz or above with 256MB RAM, USB port, Windows XP. Drivers support MME, Direct Sound and ASIO 2.0. WDM kernel streaming for Sonar and other suitable applications is supported.
Recommended Mac: G4, USB port, Mac OS X (OS 9 drivers don't support the MIDI I/O).
The Phase 26 USB
The Phase 26 USB ASIO Control Panel.
As can be seen from the product photographs, the right-front of the Phase 26 features a series of small LEDs with buttons that allow the user to select from its various operating modes. While the Phase 26 is 24-bit/96kHz capable, the USB bandwidth imposes some obvious limitations. The four operating modes provide 24-bit stereo recording at 88.2 or 96 kHz (without playback), 24-bit playback at 88.2 or 96 kHz (without recording), 24-bit stereo playback/recording at 44.1 or 48 kHz, or two-in/six-out at 16-bit/44.1kHz or 48kHz. The left-hand set of LEDs indicates the selected bit depth and sample rate and also whether ASIO mode is selected or not. The front-panel buttons can only be used to change these settings when the unit is not in use by an application. The right-hand set indicates which input is currently selected, and the choices here are between front or rear line in, the front-mounted phono socket intended for connecting a turntable, the front-mounted quarter-inch mono mic input, and the co-axial and optical S/PDIF digital inputs. Only one input can be used at any time, so the Phase 26 is only capable of stereo recording. The rear panel features eight RCA connectors — two line ins (switched with those on the front) and six line outs, with the 1/2 output pair also switched with those on the front — plus MIDI In and Out connectors.
Installation of the Phase 26 USB required close attention to the manual, and again, Terratec could perhaps have done a better job for the novice user here. Driver files have to be copied from the install CD prior to connecting the unit. Once connected, the Phase 26 can draw its power from a USB 1.1 port and, although it includes a socket for an external 9V DC power supply, no wall-wart is actually provided. The unit then has to be switched between its various modes and the usual Windows driver install process followed for each mode. Completing the ASIO driver install required a visit to the Windows Control Panel to 'update drivers' but, once done, everything seemed to be in order.
Using The Phase 26 USB
I tested the Phase 26 USB using the same range of applications as the Phase 28, and in all respects the results were similar. In particular, on both the desktop and laptop PCs used, I was able to get down to latencies under 5ms, without either PC or laptop seeming too stressed out. This made for very responsive real-time use of software instruments in bothCubase SX and Reason.
The Phase 26 USB provides stereo input, switchable between analogue, co-axial and optical, and six-channel output.
My only real complaint would be the somewhat confusing relationship between the settings in the Phase 26 Control Panel (which is very similar to that of the Phase 28) and the ASIO Control Panel (see screen shot, below). The latter is only accessible from within an ASIO host application and, as well as allowing you to set buffer sizes, also has controls that influence direct monitoring of audio arriving at the Phase 26 inputs. The description in the manual of how these should be configured left me reaching for a stiff drink. Fortunately, given the low latencies available on a suitably specified system, the Monitor button on the required Cubase SX Audio Track produced perfectly acceptable results, but again, new users could do with much clearer guidance on this aspect of the Phase 26.
For the Phase 26 USB, noise figures of 98 and 106 dBA are given for the 24-bit/96kHz A-D and D-A converters respectively. However, the overall audio performance of the Phase 26 itself was a little disappointing in comparison with the Phase 28. Tested using both a desktop and laptop PC, Rightmark's Audio Analyser5.1 produced noise levels at about -80dBA whatever bit depth/sample rate mode was selected, and similar figures were reproduced in Wavelab. However, RMAA's frequency response, total harmonic distortion and stereo crosstalk figures for the Phase 26 were all very good.
In subjective recording and listening tests with a variety of sources (including solo voice, acoustic guitar and orchestral, rock and dance mixes), despite the noise figures quoted above, and so as long as the input signal level is kept reasonably healthy, perfectly acceptable results could be obtained with the Phase 26. There were no noticeably unpleasant frequency response issues and, as with the Phase 28, the stereo separation was good.
Personally, I'm still unconvinced by the arguments for 192kHz sample rates in all but the most esoteric of recording environments. Given this, those who are not driven by a desire for the highest sampling rates will find the Phase 28 and Phase 26 alongside plenty of other very capable, 24-bit, stereo-in/multi-out contenders. Indeed, if you are happy to work with unbalanced connectors (which can still produce high-quality results if used carefully) there are some competing products at well under £200.
This said, the audio performance of the Phase 28 seems very respectable — it certainly will not get in the way within the average home or small project studio provided the usual care and attention is paid to other parts of the signal chain — so if a balanced two-in/eight-out interface with MIDI and digital connectivity fits your particular needs, the Phase 28 is worthy of consideration. While the audio performance of the Phase 26 is not, perhaps, up to quite the same standard, as a stereo-in/six-out-plus-MIDI solution for the mobile musician, it works well enough. And as with the Phase 28, if paired with a suitably specified computer, the low-latency drivers give good results when used with software instruments.