While some of us are content to listen to portable radios on kitchen worktops while children scream in a far-off room and oven timers buzz, there are those who demand a little more from their hi-fi. If you're one of these more discerning listeners, looking for a DAB component worthy of your existing stereo separates system, then the TU-1800DAB may have a place in your stack.
Denon is no stranger to the radio scene. The company has previously made higher-end FM tuners and its expertise in digital to analogue conversion is in evidence throughout its range of AV amplifiers. It was first to market with consumer THX-EX decoders for movies like Star Wars: Episode I and its DTS surround-sound systems are well regarded.
With DAB receivers the challenge is slightly different though. Not only does the unit need to decode a digital stream, but it has to make what is, at best, a 192Kbps digital audio broadcast sound like something an audiophile would be happy to listen to. Hi-fi radio receiver manufacturers have always fought against the odds in making this equipment sound great. Though their efforts are often impressive, the source medium -- high-frequency airwaves shared by multiple stations -- don't lend themselves well to the transmission of complex, dynamic music. Nonetheless, the range of stations on offer and quality of reception make the technology tempting, even if CD-quality broadcasts are not quite within sight.
The TU-1800DAB is extremely sturdy and, at 3.8kg, heavy. Though it's a crude test for the quality of audio components, there does seem to be an uncanny correlation between the weight of separates and the quality of the sound they produce. A high-quality transformer coil in the PSU will typically be heavy, so there is logic behind this assumption.
We were so mystified by the heavy weight of the TU-1800 that we detached the cover to take a look inside. As expected, there is a large transformer and a sleek black circuit-board that includes the DAB decoders and AM/FM receiver, as well as a pre-amp for the rear left/right phono connectors and a stage for the optical outs. Denon's attention to detail is obvious even inside the case -- somewhere you'd never usually pry. The circuitboards have a handmade look not unlike those of British audiophile posterchild NAD.
The front of the TU-1800DAB is a clean silver with a faint wire-brushed finish. The fascia is fairly uncluttered -- it looks like Denon has anticipated the loss of your remote control at some point and included buttons for all functions, save for the memory recall, on the fascia. Four LEDs on the panel indicate the TU-1800DAB's various status messages. 'Secondary' lets you know when a secondary service is available -- for example, Five Live's coverage of a more minor sporting event alongside its main coverage; 'Stereo' lets you know when a broadcast is stereophonic; 'Tuned' indicates that a station is being received at a strong signal level; and 'RDS' indicates that an FM broadcast is transmitting station information and the tuner can use this to determine the optimum transmitter frequency to receive the broadcast from. This might sound complicated, but it's an invisible process that makes tuning far easier.
The radio is switched on and off using a recessed power button and tuning is done using a simple rotary control. A line of small buttons alongside the tuning dial provide Dimmer, Menu, Display, Band and Auto Tune functions. The LCD screen is bright and readable even at long distances, and it's backlit by an attractive blue light that seems refined in this age of gaudy Dixon's mini-systems. It displays all the usual DAB information, including scrolling text.
Denon has been generous in including digital optical and coaxial outs on the rear of the radio, as well as an RDI optical connector. RDI is little-used, but it allows you to hook the DAB up to other devices like a PC. There are also three different aerial connectors: one for an FM coaxial antenna, one for an AM loop antenna and one for a DAB coaxial antenna. All three aerial types are included in the box. Although reception in our case was excellent, because the aerial sockets all use standardised connectors, you can improve reception in difficult areas by using custom aerial solutions, purchased separately.
Of all the DABs we've tested so far, this radio has the fastest autotune speed. When the Denon TU-1800DAB is first switched on, it tunes itself to all available DAB stations and displays the percentage of the scan complete, along with the number of stations detected at that point. After a few seconds the scan is complete and you're ready to listen to radio.
If the aerial is incorrectly attached, or not attached at all, the radio will indicate that no stations have been detected. Because of the nature of digital transmissions, there is an all-or-nothing behaviour to DAB receivers -- in difficult areas of your home, you may find that a DAB detects and stores multiple station names, but won't actually play radio at all. Repositioning the aerial will solve the problem. In our London labs we were extremely happy with reception once we'd picked a good position for the aerial, but unlike analogue radio, you won't be greeted by static in areas of bad reception -- instead, you'll hear almost nothing at all. This experience is true of all DABs, but may puzzle the first-time user.
DAB reception on the TU-1800DAB covers all Band III and L-Band broadcasts -- meaning there's not a DAB station in the UK this thing can't lock onto. It's possible to set up to 100 DAB presets and 100 AM/FM radio presets. The radio can decode FM RDS transmissions and RadioText as well as converting digital broadcasts to analogue at 192KHz 24 bit -- though the full potential of this is wasted on the kind of DAB bit rates we're seeing from broadcasters in the UK. Trawl the alt.digital.radio newgroups for a while and you'll discover that many audiophiles out there are extremely disappointed with the low resolution of UK digital radio broadcasts, but more on that later.
The analogue and digital optical outs on the TU-1800DAB are easy to connect to an amplifier using standard cables. The remote control includes a numeric pad which lets you recall DAB presets from across the room. Because the radio is sat on 15mm feet, there's enough space between the radio and the ventilation slots of the equipment below to make it suitable for resting directly on top of a fairly hefty amp.
Reception and fidelity on the TU-1800DAB left other tuners for dead -- this much was obvious from the moment we turned it on. Bass was well separated and talk stations like Radio 4 sounded rich and unstrained. Despite this excellent performance, there is one caveat, and it's a big one -- DAB radio broadcasts aren't currently good enough to do justice to even a mid-range hi-fi separates system. Listening to a 256Kbps MP3 on our reference system was immeasurably better than DAB and listening to a CD exposed a dramatic difference between Radio 1's DAB broadcast of a song and the original recording. While FM is no angel, we expected something a little more special from DAB when using a dedicated tuner.
A higher audio fidelity is not one of DAB's strengths, but choice of stations and stability of reception is. The TU-1800DAB is an exceptionally good tuner, let down only by the shortcomings of current DAB broadcasts. Side-by-side comparisons of music on digital radio and then on CD demonstrate just how far the format still has to go before it can begin to match its claims of near-CD quality sound. Though clarity varies from station to station, most music sounds muddied and overcompressed -- but you may well find that the range of station choice compensates for this. If you want to listen to radio, the TU-1800DAB is one of the best tuners out there, but don't expect it to deliver miracles: look to the broadcasters for that.
Edited by Mary Lojkine
Additional editing by Nick Hide