amplification focus



Ultra low noise amplification allows our amplifiers to perform well with ultra sensitive headphones and speakers. Focusing on quality, not quantity, enables our amplifiers to deliver high levels of detail and fast transient speeds.



Amplifier Design



Amplifier design focuses on purity of sound, technology, modularity, and hiding complexities.



Purity of sound



The first step towards sonic purity is a low noise power supply. LIPO batteries remove the need for traditional power supply filters, conditioners, and cords. Without transformers and capacitors, power supply sag is eliminated and Electrical Magnetic Interference is drastically reduced. More room is available for processing and amplification of music in a smaller lighter enclosure.


The next step is to design with low noise components. Circuitry resistors are 0402 or 0603 .01% thin film. Where more current is needed, MELF resistors are used. Where possible, capacitors are polymer or COG. In all cases, values are chosen that result in decreased distortion and increased signal bandwidth.


Finally, circuit board layouts must be placed and optimized by hand, not automation. From input to output, the length of the left and right channel tracks are matched to less than .05mm difference. Digital signal and clock tracks are matched to less than .001mm difference. Digital noise is isolated using separate digital and analog ground planes on mother boards and modules.



Technology



The two most valuable emerging technologies are increases in battery and microprocessor performance.


With proper management of the signal and operating points, both vacuum tubes and transistors can deliver great sound. Analog switch chips controlled by microprocessors shorten the signal path while eliminating EMI noise found in traditional approaches. The operating point of a tube changes as the tube ages. The operating points of Class A transistors changes based on power demand. In both cases, microprocessors programmed with rules and algorithms ensure optimal performance.


We use ultra high frequency or the first generation of triodes vacuum tubes. Both work well in preamplifier circuits.


Class A biased transistors are better at providing current drive than vacuum tubes. Transistors eliminate the need for excessively high voltages and output transformers that limit bandwidth and provide unwanted tonality. Other technologies may be more efficient than Class A transistors. However, these technologies have their own distortion problems.



Modularity



All amplification products use the same modules. Modules are placed on mother boards unique to each product. Tube modules have configuration changes but they are the same modules. All modules and motherboards are designed and built in-house. Modules can be categorized as input, preamplification, output, and control.



Input Moldules



USB increases the convenience of the audio experience but at the expense of unwanted noise. All USB inputs are galvanically isolated to filter out the noise from the sending device. The signals are processed by a 24 bit 192 kHz upsampling DAC.


Input selection and input circuitry power is handled by analog switch chips, which are controlled by a microprocessor. Circuitry noise, sending unit noise, and longer battery power is achieved by only powering the parts of the circuitry that are required. In other words, USB input 1 must be selected before it will be powered up and recognized by the sending device.



Preamplification Modules



Preamplification is controlled by a discrete 128 step processor controlled I2V volume control. Because differing gain levels are required for headphones and speakers, the volume control also contains a processor controlled gain stage.


Optimal vacuum tube performance and care is handled via a dedicated processor. This processor monitors and controls all aspects of the vacuum tube and well as balancing the gain of the left and right channels. The processor extends the tube life by 50%.



Amplification Modules



Amplification is controlled by a dedicated microprocessor. Communicating through a series of modules, the microprocessor monitors demand and available voltage, in order to adjust gain and the operating point of the output transistors. The microprocessor extends the battery life by 25% while reducing distortion and transistor heat generation.



Control modules



Microprocessors control the battery monitoring, amplification, tubes, source selection, volume control, and circuitry power.


There are also control modules for each battery. They connect the batteries in series for more voltage or parallel for more current. They also disconnect and charge the batteries.



Preamplifier


Inputs include two galvanically isolated USB inputs, one optical input, and one RCA input. Inputs are only active when selected using the source select touch pad. Digital processing is via a 24 bit 192 kHz upsampling DAC. The volume control is 128 step I2V that is controlled by up down touch pads. Battery life is 16 hours when using the digital inputs and 40 hours when using the RCA inputs.



Integrated Amplifier


The integrated amplifier is created by adding the Class A transistor output and amplification modules to the preamplifier. A switch directs the output to copper banana jacks for the speakers. The headphone jack is always on. Power output is 4 to 6 watts into 8 ohms. Battery life is 9 hours when using headphones and 4 hours at 2 watts when using speakers. Distortion is .14% at 2 watts 8 ohms.



Mono blocks


The mono blocks consist of same the Class A transistor and amplification modules that are used in the integrated amplifier. A gain stage module is added in place of the preamplifier. Increasing the batteries from 10 to 12 amps increases the power output to 11.5 watts while providing 9 hours of run time. Distortion is .039% at 2 watts increasing to .4% at 10 watts into 8 ohms.



swan song audio



Designing and building low noise high performance audio products in America

info@swansongaudio.com