kevalin Posted December 3, 2020 Share Posted December 3, 2020 View Classified Waversa Systems Incorporated Amp 2.5 MKII class D digital integrated amplifier Waversa Systems has taken a unique approach to music reproduction by producing a mix of high-quality analog tube amplification and phono preamps harmoniously complimenting pure digital streamers, D/A converters, and dedicated Roon Core servers. While we have examined Waversa's unique digital signal processing above in Appendix 25, this technology is also implemented through a different and equally novel approach to amplification, culminating in its PBTL (Para Bridge-Tied Load) output stage. This fully digital amplification technology percolates throughout the entire Waversa solid-state amplifier line, including the WAMP 2.5 MK2, WSlimLITE, WSlimPRO, WMiniHPA, and WMiniAMP. The WAMP 2.5 MK2 is at the heart of the Waversa portfolio as an integrated digital amplifier with enormously high output power. However, if you cringe at the thought of "digital amplifiers," you should now read on especially carefully to understand the Waversa difference. For a summary of this amp offers please read about them under: What's Best Forum Digression: To understand the difference between a Class D amplifier and a "digital amplifier," it is necessary to distinguish the terms PCM and PWM. PCM (Pulse Code Modulation) PCM is a process that converts analog signals into digital signals. It assigns numeric values to the analog signal, the famous ones and zeros that digitally represent the analog signal. The two variables, "word width" and "sampling rate" are decisive for the quality of conversion in the PCM process. The best way to grasp this is to imagine a coordinate system: the horizontal, i.e., the x-axis describes the time course (sampling rate), the vertical, i.e., the y-axis, the amplitude (word width). The sample rate determines the frequency of sampling within a specific time - in the audio sector, this interval is traditionally 1 second. The finer the grid on the x-axis (the higher the sample rate), the more precisely an analog waveform manifests in the x and y coordinates. The second significant quantity to be digitally recorded is the volume of the analog signal. The so called word width defines volume and is expressed in bits. Specifically, the word width determines how many digits the number generated during digitization can have. Usually for audio, 16 or 24 bits are used - rarely 32 or 64 bits. The more digits a sample has, i.e., the higher the number of bits, the more dynamics can be reproduced. So PCM creates a certain number of reading values, each with a certain amount of information. For example, CDs contain digital PCM data with an information amount of 16 bits (either 1 or 0) in each of the 44,100 read values per second (44.1 kHz). An analog signal of 1 second is represented in PCM as a series of 44,100 "read values" (horizontal axis in the coordinate system), each with different "heights" of 16 bits maximum (vertical axis in the coordinate system). PWM (Pulse Width Modulation) PWM is also a method for converting analog signals into digital signals. PWM also represents the analog signal through numeric values. Unlike PCM, however, PWM expresses the analog signal by the width of a pulse and not the extent of a real value. While PCM represents the analog signal's amplitude by the different heights of the read values, PWM varies the pulse width. The ones of each PWM pulse represent the 0 ~ 180 degree part of the sine wave of the analog signal, and the zeros of the PWM pulse represent the 180 ~ 360 degree part of the sine wave. The higher the amplitude of the analog signal, the wider the PWM pulse becomes. Class D The "D" in "Class D" does not refer to "digital," but solely to the order of Class A, Class B, Class AB, and Class C. Class D works with PWM. After direct conversion to PWM, the analog signal is usually amplified by a switching regulator and an output stage (instead of analog amplifying elements such as transistors or vacuum tubes) using a delta generator. The amplification is achieved by varying the switching time; it depends on the width of the PWM signal (see above). The amplitude and frequency of the PWM signal are constant; the music information is exclusively in the pulse width. Therefore, Class D amplifiers are also called switching amplifiers. Finally, the amplified PWM signal is "smoothed" by a low-pass filter in the output stage, i.e., converted back into an analog signal and passed on to the loudspeaker. The Waversa WAMP 2.5 MK2 has an entirely digital signal processing path before the actual class D amplifier. The WAMP 2.5 MK2 converts all analog input signals into PCM format via a high-performance 32-bit A/D converter and an FPGA-based (Field Programmable Gate Array, a programmable digital device) WAP (Waversa Audio Processor) chip, which then converts the PCM signals into PWM format. PWM conversion is only one of many tasks of the WAP, which is also used in Waversa’s D/A converters and streamers. In the course of signal processing, WAP and the WAP/X algorithms improve the sound quality, ensure a linear frequency response, and increase the resolution by mathematical calculations directly on the chip instead of using lossy analog methods like resistors and coupling capacitors. So how does the Waversa WAMP 2.5 differ from "normal" amps? 1. Higher resolution: The analog signal is converted by A/D conversion into a digital PCM signal with high resolution (32 bit / 384 kHz). This is the most crucial difference from other Class D amplifiers, which convert the analog signal directly to PWM. The Waversa audio processor then samples the PCM signal up to 1.5 MHz, a critical step in maximizing resolution before further processing. The extremely broadband frequency response of the Wamp 2.5 MK2 from 0Hz to 160kHz is one of the upsampling results. 2. Transfer of the PCM clock to PWM via WAP: PWM has the inherent disadvantage of not having a digital clock signal. However, the WAP chip evaluates the PCM time interval and then passes this information on during the conversion to PWM. 3. Improved frequency response linearity through WAP: The WAP chip's mathematical calculations guarantee a considerably higher resolution and a linear frequency response. All algorithms are executed in real-time directly on the WAP chip. The amplitude boosting problem in the medium frequency range, one of the most significant disadvantages of analog amplifiers, is entirely solved by the WAP chip. 4. Further digital corrections are made on the WAP chip to improve the detail and the spatial representation regardless of the volume. Analog amplifiers cannot achieve this, so here is a unique advantage of WAP technology. The two most essential corrections based on WAP are: a. WUS (Waversa Ultra Sound): With the help of the unique signal processing of the WAP chip, resolution, spatial impression, and airiness can be varied. The user can choose between three modes creating varying high frequency extension. b. WAP/X: Audio tubes have a distinctive, pleasant sound signature, particularly good at conveying delicate information about even-numbered harmonics. These harmonics are lost to a great extent during digitalization. WAP/X is an algorithm based on the overtone behavior of audio tubes, which reconstructs the 2nd, 4th, and 8th harmonics of real music lost during digital recording or the digitization of analog recordings. Thus, digital music also sounds touchingly real, vividly spatial, and natural. 5. PBTL (Para-Bridge-Tied Load): The WAMP 2.5 MK2's enormous output power of 400 Watts into 4 Ohms is made possible by a parallel structure of four "normal, inverse, normal and inverse" phase output amplifier modules per channel (the WAMP 2.5 MK2 has an authentic dual-mono design). In this way, the gain factor in each of the individual output amplifiers can be reduced, thus reducing by multiples the conventional artifacts (a hardened not very subtle sound in bridge mode), which can result from a (too) high gain factor. We hope this explanation has succeeded in making it clear that the WAMP 2.5 MK2 is not just a generically designed 'digital' amplifier looking to extract performance through quality componentry or good execution, as is the norm among its competitors, but something radically different: it harnesses the full power of the Waversa Audio Processor (WAP) to create a pure digital amplification product. The WAMP2.5 MK2 goes to the heart of the goal of Waversa to fully utilise its unique digital technology, with its design percolating throughout the entire Waversa amplifier line, including the WSlimLITE, WMiniHPA, and WMiniAMP This is a used unit but at full current manufacture specifications version MKII and certainly capable of driving any speaker. Please note two light scratches at the top corner of the chassis on each side - likely from the footers of another component placed on top. I would rate this an 8/10 condition. Retail is around $7500. MAIN FEATURES • Digital Integrated Amplifier • Monorail Construction EXCLUSIVE TECHNOLOGIES • High-precision 32 bit / 384 kHz A/D converter • WAP - Waversa System Processor 32bit 1.5MHz PHYSICAL CHARACTERISTICS • Chassis: Aluminium • Colour: Silver • Inputs: 2 x Balanced XLR, 3 x Single Ended RCA, 1 x Coaxial Digital • Outputs: 2 x 5 Way Binding Post • Dimension: W 440 x L 330 x H 145 mm • Weight: 13 kg / 28.6 lbs. • Power supply: Built in 180~240 VAC @ 50~60Hz S SUPPORTED AUDIO/VIDEO FORMATS •COAX: up to 24/192KHz SPECIFICATIONS •LinuxHigh precision 32bit ADC and PWM processing •FPGA based Waversa Audio Processor (WAP) type 2 applied with built-in 768KHz high-end upsampler •Ultra Low Power Universal Serial Bus Audio Class 2.0 with High Precision Clock •Digital PWM based class D amplifier with PBTL 200W per channel 8 Ohm •8 Level Display Brightness Control Seller kevalin Date 12/02/20 Price 4,500.00 USD Category Amplifiers Link to comment
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