Some technical enlightenment this week as we present the new products selected from the brands Monitor Audio (Monitor Audio Gold range) and Avantgarde Acoustic (Uno, Duo and Trio XD ranges), i.e. hi-fi and home cinema speakers and in particular, new technologies implemented by the British and German manufacturers to deliver high frequencies.
Ribbon tweeter
If you are interested in acoustic speakers, you will probably know that each driver plays a well-defined role in the delivery of sound. Large drivers are essential for reproducing low frequencies, whereas smaller ones are used for high frequencies. These particular drivers, known as tweeters, are small as their reduced size is necessary for reproducing high frequencies. The cone of tweeters must be thin and light in order to swing thousands of times/every second. Their shape enables a wide placement of sound. Hi-fi and home cinema speakers are therefore mostly fitted with alloy (titanium, gold, silver, etc.) or silk dome tweeters.
Despite its powerful nature, the dome tweeter isn’t the best possible type of high frequency driver. There once was a time when the hi-fi world swore by ribbon tweeters. This is obviously a time Monitor Audio remembers fondly as all the speakers in their new Gold range are fitted with such a model of tweeter.
A ribbon tweeter operates in much the same way as a standard dome tweeter but its shape is completely different as it has an extremely thin cone positioned vertically, thus enabling a significant rise in frequency. It is, however, less dynamic in mid-range frequencies. Monitor Audio use an aluminium and magnesium ribbon, coated with a fine ceramic layer (C-CAM technology).
The size of the ribbon tweeter allows it to increase in frequency up to 60 kHz (60 000 movements per second) in order to convey the harmonic frequencies of all instruments, thus adding to the consistency of the sound.
The sound produced by the ribbon tweeter is therefore exceptionally smooth. However, its reduced performance in the mid-range entails the use of high-performance medium/bass or medium drivers which can take over in this frequency range.
Certain manufacturers, such as Dali, use both a ribbon and dome tweeter, as featured in the Dali Opticon (Dali Opticon LCR) and Dali Rubicon (Dali Rubicon 5). Monitor Audio has opted for extremely solid but damping RST cone drivers to improve the reproduction of mid-range frequencies.
The new Monitor Audio Gold range ? positive aspects
Monitor Audio has pulled out all the stops. As well as its famous C-CAM ribbon tweeter, Gold range speakers benefit from particular care and close attention to detail. The 28 mm thick structure is strengthened and each driver is coupled with the baffle using a threaded rod. Each filter is placed in a sealed compartment wired with silver-plated copper conductors. The Monitor Audio Gold range features two compact speakers-Monitor Audio Gold 50 and Monitor Audio Gold 100, two floor-standing-Monitor Audio Gold 200 and Monitor Audio Gold 300, two centre speakers-Monitor Audio Gold C150 and Monitor Audio Gold C350, a surround-Monitor Audio Gold FX and a subwoofer-Monitor Audio Gold W15. Note: the subwoofer has an integrated 15″ driver. 
Horn-loaded tweeter
The German manufacturer, Avantgarde, is an eminent specialist in the field of acoustic horns, as is Klipsch. A horn-loaded driver allows the sensitivity on a specific frequency range to be heightened, the aim being to reduce cone excursion and obtain a low-distortion sound signal.
In addition, the driver/horn combination requires less power from the amplifier, meaning less distortion.
The only restrictive factor is that the size of a horn increases significantly as frequencies go down. The tweeter fitted in Avantgarde speakers has a very stiff diaphragm, placed on a rear compression chamber, thus increasing efficiency. Highly sensitive, this tweeter produces a volume of 104 to 107dB (depending on the model) for 1 W applied. This is amazing! Most standard speakers require 200 to 100 W to produce the same volume level. The difficulty of implementing the compression tweeter is due to the shape and dimensions of the horn.
Avantgarde Uno XD, Duo XD and Trio XD …with Basshorn XD
Avantgarde has updated its entire range of speakers and introduced new XD amplification. If its tweeters and mid-range drivers are passive and therefore require an amplifier, its bass drivers are powered by a dedicated amplifier. This is a 2×500 W Class D model which powers the 10″ and 12″ drivers. It integrates a DSP (digital signal processor) which constantly checks the transducer in order to optimise its functions. The Avantgarde range includes the Avantgarde Zero 1 XD White. The Avantgarde Uno XD and Avantgarde Duo XD models are fitted with large acoustic horns (50 and 67 cm diameter) for mediums and use a standard subwoofer, while the Avantgarde Duo Mezzo XD uses a horn-loaded subwoofer. The Avantgarde Trio 2 Basshorn XD features even more imposing horns and runs with a horn-loaded subwoofer called BassHorn. The musical performances of Avantgarde speakers are quite simply phenomenal.
