Tascam US1641

Put simply, if you want to send lots of audio inputs into your computer simultaneously, but don't want to pay too much for the privilege, the US1641 could be exactly what you're looking for...

The Tascam US1641 is a flexible, 16-input, 24-bit/96kHz audio interface, with basic MIDI I/O and the connection to the host computer provided via USB. The unit is housed within a solidly constructed 1U, 19-inch rackmount case and enjoys its own built-in power supply — something of a rarity in 1U rack interfaces at this price point. Supplied with the US1641 is a standard 'kettle' lead, a USB cable and a CD-ROM containing drivers and documentation. A printed copy of the manual is also provided, along with another CD, containing a copy of Tascam's CV Piano plug-in instrument and a DVD-ROM including Steinberg's Cubase LE 4 (see the 'Bundled Software' box for more details).

Installation

Setting up the US1641 is simple enough — the first step is to install the device drivers. Windows XP and Vista are supported (although only the 32-bit versions so far), as is Mac OS X (Tiger and Leopard, on both Intel and Power PC architectures). The manual recommends checking the Tascam web site for updates to both the device drivers and the device's firmware, and this was the first thing I did.

Installing the device drivers also installs the Control Panel software, which allows access to a few basic settings, such as Audio Performance (basic latency adjustments can be made between 'lowest' and 'highest'), Sample Clock Source ('automatic' means that the device will follow an external clock signal if one is connected, while 'internal' means that external clocks are ignored), Digital Output Channels (the US1641's digital output can have 'line out 1&2' or 'line out 3&4' routed to it), and Digital Output Format (S/PDIF or AES/EBU). Apparently the 'Audio Performance' option is not provided in the Mac Control Panel — although most audio applications provide their own buffer settings with which to adjust latency.

The Control Panel also displays the device's current firmware version. The review unit arrived with firmware version 1.0, so I decided to download the update to version 1.02. This takes the form of a small self-contained updater program and the update process is as simple as running it, clicking a button, and unplugging the device when prompted. When the device is plugged back in, the Control Panel reports the new firmware version. This worked perfectly for me, the whole process taking little more than a minute to complete.

Two Point Oh

It's important to note that the 1641 supports USB version 2.0 only — so although it is physically possible to connect the device to a computer with an older USB 1.1 port, you shouldn't do so and expect it to work. Tascam point out that the USB 2.0 protocol supports data transfer rates of up to 480 million bits per second, allowing greater bandwidth than either Firewire (400 mbps) or USB 1.1 (12 mbps).

The US1641 interacts with your computer's operating system as a 'multi-client' device. What this means is that it can handle audio output streams provided via different protocols — for example, ASIO and WDM — simultaneously. This means that on a Windows machine it would be possible to monitor the output of an ASIO application such as Ableton Live, a WDM application such as Sonar, and Gigastudio (which uses its own GSIF2 driver protocol), at the same time.

Connections

The US1641 provides a total of 14 analogue inputs and two digital channels. These can be used simultaneously, for a total of 16 input channels. Ten of the analogue inputs are located on the front panel: eight on balanced XLR mic inputs and two on quarter-inch jack sockets. The latter are switchable, operating as either unbalanced guitar inputs or balanced line inputs. The XLRs can supply +48v phantom power, which must be switched on or off in two groups of inputs 1-4 and 5-8 — so it isn't possible to switch phantom power on and off for an individual mic.

The US1641's Control Panel software is particularly simple, offering just four variable controls.Photo: Mike CameronTen small knobs allow the input gain for each of the front panel sockets to be adjusted — from -2dBu to -58dBu for the eight XLRs and from +4dBu to -42dBu for the jacks. Each one has an accompanying LED, which lights green when the signal reaches -30dBFS and then red as a clip warning at -2dBFS.

Keeping our attention on the front panel, there's a standard quarter-inch headphone socket with an accompanying level knob, and a separate monitor level knob. There's also a mix knob, which controls the balance of signals sent to the headphone outs. With the knob all the way to the left, a mix of the analogue inputs is heard. With the knob all the way to the right, the signal output from the computer via USB is heard. In intermediate positions a mix of the two can be heard, allowing for hardware 'zero-latency' monitoring of the inputs.

Four further analogue inputs are available on the back panel. These are balanced line-level inputs on TRS (Tip, Ring, Sleeve) quarter-inch jack sockets. The input level for these is switchable between -10dBv and +4dBu. The remaining two input channels are digital, in stereo S/PDIF format, on the usual RCA socket.

Outputs are less numerous, but there's still a fair selection: a stereo S/PDIF digital output, to go with the input; four quarter-inch TRS jack sockets, configured as two stereo pairs, and another pair that serve as dedicated monitor outputs. Finally, there's a standard USB port, and two MIDI sockets (one In and one Out).

The number and variety of inputs available make the US1641 a good bet for basic home studio applications. Recording 'live' takes of a band, for example, you might have four mics on the drum kit, two more on guitar amps, with bass and keyboards DI'd, and perhaps another mic for a guide vocal — and still have some inputs to spare.

One thing the US1641 lacks is serious multi-channel digital capabilities. The S/PDIF pair is certainly useful, but would be no substitute for, say, the eight channels available via an ADAT interface. MIDI I/O could also be more flexible than the basic one In and one Out provided. If your studio has a lot of external MIDI hardware, the US1641 may not be your first choice for that reason.

In Use

Sixteen inputs notwithstanding, the number of tracks it's possible to record simultaneously depends upon your computer's capabilities, in terms of hard disk performance, processor speed and available RAM. Tascam's specified minimum system requirements for Windows are a Pentium 4, AMD Athlon or equivalent processor at 1.4GHz or faster, at least 512MB of RAM (more would be better) and 1GB or more of free hard disk space. For Mac users the recommendations are much the same; a 1GHz G4 or 1.5GHz Core Solo processor is the minimum, and Mac OS 10.4 or later is required. In both cases a DVD-ROM drive and an internet connection are required to install and activate Cubase LE (see the 'Bundled Software' box).

I tested the US1641 on my 1.8GHz dual-core Pentium machine with 1GB of RAM; not enormously powerful by current standards. Even so, the US1641 performed well. Input latencies of under four milliseconds were easily achieved (by selecting the 'lowest' latency setting in the Control Panel software), making ASIO input monitoring quite feasible.

As you can see, the rear of the US1641 is a pretty straightforward affair, as a good deal of the connections are found on the front. But what's that there on the far right? Yes — it's got an internal power supply!Photo: Mike CameronSetting up multiple recording buses in Cubase LE is easy, and in no time I was able to route signals from any or all of the US1641's inputs to different tracks as required. With all 14 analogue channels in use, a tiny bit of cumulative hiss was sometimes detectable. Nothing excessive, and more noticeable when listening on headphones than via monitors. Turning down the front-panel gain knobs for any unused channels helped reduce this.

With Cubase configured for 16-bit, 44.1kHz operation, recording all 16 inputs to separate tracks simultaneously posed no problems. Adding effects gradually increased the load, but not problematically. Switching to 24-bit, 96kHz operation naturally made more demands of the system, and although there were no serious problems, I did start having to think in terms of larger buffer settings and fewer real-time effects.

In general, I found that recording and playback via the US1641 was clean and trouble-free. The only minor glitch is that activating, and particularly deactivating, phantom power for the mic inputs seems to produce an unpleasant crackle over the monitors — not loud enough to do any damage, but still noticeable.

Overall, the US1641 is easy to get along with. Connecting and swapping mics and other sources is easy, thanks to the front-panel sockets. Even if you are not likely to be using all the inputs simultaneously, you can treat the device as a basic patchbay, leaving different sound sources connected and switching between them as recording sources in your software as required.

One final grumble, though: the front-panel knobs are made of chrome-effect plastic, which is smooth and in fact slightly slippery to the touch. They're also quite closely-spaced (although this is all but unavoidable in a 1U device) and as a consequence can sometimes feel a bit awkward and fiddly.

Summing Up

The US1641 fits plenty of features into a small and sturdy box, and rivals some more expensive audio interfaces for flexibility. If you need multiple analogue input channels, and mic inputs with phantom power, the US1641 could be just what you're looking for; it's a very straightforward, workable package that's good value for money. While the 1641 is not entirely unique, there aren't many competitors in this price bracket, and Tascam's long experience in the field should certainly count for something.