Technology





The Davone loudspeakers are not made to look high tech. There is a lot more than meets the eye though. A very large part of our time is spend on developing innovative technologies for our loudspeakers and some are highlighted below.


The Davone Module in Detail


The Davone module is a so called mixed signal PCB design, meaning it has both analog circuits and digital circuits on a single board. Through a careful lay out of components and multipoint high frequency grounding, the mixing of analog and digital signals is avoided while retaining the shortest signal paths. The main components are highlighted below:

  1. The microcontroller is the brain of the Davone module. It's large memory contains the entire DSP and functional program, also called the firmware, written by Davone. This way the often used separate EEPROM memory is avoided and replaced with the internal memory of a microcontroller. This is much better protected against unpredictable power supply swings and therefore more reliable as long term memory storage. During normal operation, when a music signal is detected, it programs the DSP and checks if it is functioning well. If the temperature is within the set limits, it will program the DAC and unmute the amplifier. It will continuously monitor the presence of the mains power and the status of the input signal and act accordingly to ensure stable and noise free operation and reduce power consumption whenever possible.

  2. Quartz Crystal Oscillator for low jitter, packaged in ceramics with metal lid for high precision and reliability. The oscillator signal is used to generate a clock signal which is fed into the DSP's dejitter circuits to guarantee that jitter related clocking errors are avoided. The master clock output of the DSP is fed directly into the DAC with a jitter less than 100ps rms.

  3. Within the 32 bit Digital Signal Processor, the wireless received signal is first routed into the Asynchronous Sampling Rate Converter (ASRC) to minimise jitter. Then the signal is filtered with a FIR filter into the high and low bands and also small imperfections of the drivers are removed.

  4. The high performance 32 bit Velvet Sound AKM Delta Sigma DAC is handling the conversion to analog. The power is supplied through ultralow noise linear regulators and ample capacitance of different types for a virtual battery like performance.

  5. The fully balanced output stage minimises noise and is connected directly to the balanced input of the ICE power amplifier.

  6. The multipoint high frequency ground ensures lowest impedance returns paths to ground for high frequency noise and effectively prevents ground loop noise.





Davone Module High Frequency Design


High frequency digital signals above 1 MHz, like for example the master clock, need to be routed carefully to maintain high signal integrity. Ideally the connections should be short and direct, but often this is not possible because another signal line crosses it’s path. Textbook four layer print design would divert the trace through a so called via to the bottom layer to cross the obstacle. The second and third layer are used for the ground and power supply planes and therefore already occupied.

However, in high frequency circuit design it is vital to keep the distance between the forward and return current traces at a minimum (the path of least inductance). It is therefore much better to route the forward current through the third layer instead of the fourth. That way the return current only has to switch sides on the second layer instead of also jumping planes through one extra via with possible added ground plane noise as a consequence. The improved high frequency current flow is shown in the image above and explained below.

  1. Trace on top layer of Printed Circuit Board (PCB). High frequency forward current shown in red flows at underside of trace.

  2. A small copper tube, or so called "via", connects the top and third layer. The via's are visible at the top of the PCB as tiny holes. The forward current flows at the outside of the via.

  3. Trace on third PCB layer. The high frequency forward current in red now flows at top of trace.

  4. The Second PCB layer is a continuous plane at ground potential. The return current in blue flows at the bottom of the plane nearest the forward current on the third layer, following the path of least inductance.

  5. Around the via, the return current now simply switches sides of the ground plane. The distance between the forward and return current is minimal at all times and signal integrity is optimal.

  6. Bottom layer of PCB. This is where normally the forward current trace would be routed to.






the Magnetic Motor


All loudspeakers may look alike for the untrained eye. But to reduce cost, usually chassis are made from plastic, the magnet and voice coil are too small and the magnetic motor will be from simple, unoptimized geometry, to name a few. In contrast, take a look at the woofer that is used in some of the Davone loudspeakers that has been optimized for quality instead of cost:

  1. The magnetic structure is optimised using advanced Finite Element Analysis software. The result is a magnetic field with a better than 95% symmetry within the voice coil travel range of +/-12 mm. Compared to traditional designs, the harmonic distortion is greatly reduced, especially at higher loudness levels

  2. Large magnet structure with 39 mm heavy-duty fiber glass vented voice coil for better control, power handling, dynamic performance and low-level details

  3. Copper cap on center pole to reduce voice coil inductance and to minimize variations in voice coil inductance as a function of voice coil position

  4. Cone made of a paper/glass fiber mix with improved stability

  5. Rigid die cast alu chassis with extensive venting for lower air flow speed reducing audible distortion





High Density bend Plywood


Our loudspeaker cabinet material of choice is Scndinavian bend plywood. When it comes to acoustical damping properties, bend plywood clearly displays superior spectral homogeneity and resonance suppression compared to aluminium. It has a higher density and stiffness compared to natural wood or MDF and last but not least it has a unique appearance. Our 15 years of experience with bending wood enables us to create truly unique and functional designs.

  1. First a special glue, vital for the superior damping properties, is applied to the individual veneer layers. Then they are stacked and most are oriented with the wood fibers at 90 degrees relative to each other. The stack is then inserted into the mould.

  2. The heavy duty inner mould with the desired final shape. The typical pressure during moulding is 100 Tons, equal to the weight of about 70 cars, Due to this immense pressure the density of the bend plywood is increased.

  3. The heavy duty outer mould with the desired shape.

  4. The outside of the inner mould is covered with a thin metal sheet which is connected to a 20-100kW microwave frequency power source that heats and cures the applied glue in 2-3 minutes. During this time, the full 100 Tons of pressure are applied, pushing the heated glue into the wood layers for perfect adhesion. After cooling the wood will now maintain this shape indefinitely.

  5. Thin metal sheet on outer mould for conducting the applied power.





Meander Room Filling Sound


The Meander drivers, cross over and baffle angle have been chosen cafefully to deliver a room filling sound with minimal changes in the frequancy response with listening position:

  1. The tweeter that is used in the Meander is a so called dome tweeter. This type of tweeter does not beam the sound as much as other tweeter constructions like ribbon or horn tweeters do. Also, it is made of aluminium which has better off-axes response than other popular materials like silk, beryllium or even diamond for the same size. At 60 degrees and 10 kHz, the sound level is only -6dB (red line, tweeter mounted on infinite baffle) which is excellent compared to most other tweeters. This small drop in level is easily compensated for with the digital cross-over. All this means that despite the upward pointed baffle you will still hear the direct radiated high frequencies when sitting in front of the Meander, like you would with a normal forward pointing loudspeaker. But the Meander does generate a larger portion indirect sound in comparison, giving an ambiance rich, life-like sound when sitting in front and a more well balanced sound elsewhere in the room.

  2. The 2 cones represent the left and right channel and indicate that the direct sound is not only travelling perpendicular to the baffle, but also forward, backward, left and right, thanks to the excellent sound spreading drivers and digital cross-over. In comparison, with lower quality drivers the cone would be more narrow, indicating less direct sound travelling to a seated position. For an optimal result the Meander needs to be placed close to hard walls such that the reflected sound can support the direct sound for quality listening elsewhere in the room.