SP110 DAB Tuner

The SP110 is a DAB tuner (also known as DAB digital radio) firmware version 1.2, manufactured by the Acoustic Solutions Corporation in the People's Republic of China (PRC), in 2002. It was similar to the SP111, which had an additional analogue FM (RDS) tuner. The SP110 was part of the Acoustic Solutions hi-fi system consisting of SP-120 CD player, and SP-100 amplifier, and all three having remote control capability. More information on the SP110 including specifications are in the manual.

Review

The SP110 has one digital tuner for band III (174 MHz to 240 MHz) reception through an F-connector socket for the aerial. There are approximately 41 channels in this range (5A to 13F) and the number of stations you can receive depends upon your location and signal strength. It has very good sensitivity rated at -96 dBm (typically), and sometimes just a single wire is enough to detect a couple of stations from a nearby multiplex.

The LCD display consists of 2 lines of 16 characters with LED backlight. It also conveys the signal strength by the number of bars illuminated. There is also a minimum reference point of the signal strength to inform the user, because any signal below this point will have lower quality sound.

This DAB tuner has two audio outputs, analogue through RCA sockets, and digital through an optical cable. The analogue output is 2.5 V p-p from a 16-bit digital-to-analogue converter (DAC). The digital output is through an optical interface (TOSLINK) providing S/PDIF IEC60958 compliant signal with 24-bit sample resolution. If you want the absolute best in sound quality, then using the digital connection is the better choice of the two. This type of interface can connect with many surround sound amplifiers with an optical-in connection.

The sound quality is excellent providing you use a good quality antenna for digital reception and point it in the correct direction. Using a compatible optical interface also improves the audio quality as well. However, the sound quality is not all dependent upon the tuner hardware. DAB involves compressed audio in the form of lossy compression, and the sound quality can vary a lot depending upon the station because each multiplex is responsible for the compression of their digital streams and the amount of data they send through it. Some stations such as Radio One is heavily compressed due to high listening levels of their popular music, however stations such as Radio 4 use little or no compression and usually sound much better.

A good feature of this tuner is the LCD readout of the Signal Error Rate. This numeric value indicates the level of real-time correction the DSP is applying to maintain audio quality. As the digital signal becomes weaker, the DSP has to apply more corrections and consequently audio quality drops. Many lay people including "professionals" do not realise that to get the best sound quality, you will need the best aerial pointing precisely in the correct direction. Page 7 of the manual provides good information on fixing the antenna.

The built-in headphone amplifier sounds decent providing you use a good pair of headphones. Unfortunately there is no volume normaliser and some stations can be very loud, whilst others almost silent.

The station selector knob is an encoder that works well when surfing for stations. The name of each station usually appears on the LCD display, and you simply push the knob in to select it.

Price/eBay

The SP110 and the SP111 are sometimes for sale on eBay and they are very desirable to audio enthusiasts building their modern hi-fi system. On occasion, I have seen broken ones with faulty LCD display, or broken headphone socket, but generally these units are reliable and provide good sound if you set them up correctly. Back in 2003, you would have paid £79.95 at Richer Sounds for a boxed SP110; however, a pre-used one in mint condition can sell for approximately fifty pounds on eBay.

In the following pages of this multi-page article you can see the inside electronic engineering of this DAB tuner, which might be useful for engineering students, and the enlightened visitor.

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