Axign chips at the heart of Harman Kardon’s beat

Harman Kardon’s new Citation Amp boasts 200 watts of Class D amplifi cation

per channel, enabled by Axign’s digital feedback audio chip. Nieke Roos Credit: Harman Kardon A udio control specialist Axign has announced its rst A-brand design- win. American home entertainment Highly digital Axign’s AX5689 digital Class D ampli er controller compares the analog signal after controller compares the analog signal after powerhouse Harman Kardon has integrat- the output lter, at the speaker terminals, the output lter, at the speaker terminals, ed the scale-up’s AX5689 chip into its new with the digital input signal. All disturbances with the digital input signal. All disturbances stereo streaming ampli er. e latest ad- in the loop, such as power stage dead times, in the loop, such as power stage dead times, dition to the Citation product line boasts power supply ripple and non-linearity from power supply ripple and non-linearity from 200 watts of Class D ampli cation per the output lter, are directly suppressed the output lter, are directly suppressed channel into 4 ohms, controlled by the lit- thanks to the high digital loop gain. e anthanks to the high digital loop gain. e antle piece of silicon from Enschede. alog signal at the speaker is converted using alog signal at the speaker is converted using

“ is is a major milestone for us, a break- a high-performance feedback ADC, which Thanks to its small footprint – 215 mm wide, through even,” states Richard Langezaal, combines a low latency of several nanosec- 75 mm high and 230 mm deep – the Citation Axign’s sales & marketing director. “ ree onds, for loop stability, with a high dynamic Amp can be unobtrusively and fl exibly placed years ago, we had our own mask set made, range up to 120 dB on set level for consumer around homes, restaurants, shopping centers taking the big step from prototypes and audio solutions like streaming ampli ers, and stadiums. proofs-of-concept to a design that can be smart speakers and TV soundbars. sold. It then takes a while to convince po- With only the converter’s input stage in ers to create a multi-channel wireless surtential customers and get on their short- the analog domain, the AX5689 is high- round sound system. list. And once you nally get selected, it ly digital and consequently has all the ac- “ e Citation Amp is a stand-alone amtakes them another year to make the prod- companying features like programmability, pli er that connects to a wide range of uct and market it. Going to mass produc- self-learning and robustness. Being highly passive loudspeakers,” explains Langezaal. tion requires a lot of e ort and persistence, digital, the chip is insensitive to compo- “It can be used in home entertainment sysbut we made it.” nent tolerances. is allows for high-order tems, but it’s also targeted at custom inloop lters, up to 7th order, enabling a high stallations in homes, restaurants, shopping

Credit: Axign open-loop gain and steep ltering. e ability to program the transfer function loop makes it easy to change lter characteriscenters and stadiums, for example. is is a very big market, especially in the US.” tics, for example noise shaping from 20 to Other big names 40 kHz and vice versa. “ e result is a Class e design-win with Harmon Kardon, a A audio performance at Class D e ciency, Samsung subsidiary, is all the more importsize and cost,” summarizes Langezaal. ant as it proves that Axign can deliver on its promise. “Customers are all waiting for Custom installations someone else to take the rst step. ey Powered by the AX5689, the Citation Amp all want market evidence,” says Langezaal. features Harman Kardon’s digital loop am- “ is shows we’re not a one-day y.” pli cation. By correcting the natural er- With its team of 25, Axign is currently rors and distortion anomalies that occur planning to expand its relationship with in digital ampli cation, this technology Harman Kardon. In parallel, the Enschede claims to restore audio quality to the way scale-up is gearing up to conquer other top it was meant to be heard. Providing ac- audio brands, leveraging its local represencess to over 300 music streaming services, tatives in the US and China. Langezaal is the device can be connected to bookshelf, con dent: “With Harman Kardon on board, oor-standing, in-wall or in-ceiling speak- other big names are sure to follow.”