Pure Science. Pure Audio™
|
|
Pure Science. Pure Audio™ |
HOME PRODUCTS ZUS AUDIO ENGINE TECHNOLOGY TESTIMONIALS SEARCH CONTACT US ORDER NEWSLETTERS
Overview
Bandwidth
Harmonics
% Total Harmonic Distortion
(%THD+Noise)
vs. Frequency
%THD+Noise
vs. Output Power Levels
Noise and Hum
Symmetrical
Soft Clipping
Discrete Circuitry
Reliability
Design Criteria
Electrical
Specifications
The ZUS Audio Engine™ is what drives all our amplifiers and pre-amplifiers. The ZUS Audio Engine™ is the heart and soul of our design philosophy and topology. The ZUS Audio Engine™ sets new standards for audio and pushes technology to the highest level. A no-compromise approach to audio.
The ZUS Audio Engine™ allows all the music to be reproduced at an extraordinarily high level of sonic perfection. The listener is surrounded by audio that is harmonically rich in content and alive in presence. The music is more realistic than ever thought possible. Subtle tones and nuances that may have previously been lost, are once again present. The sheer impact and emotion of the music's presentation is reclaimed. There is a complete sense of involvement as the listener is fully immersed in the dynamics of the music. With an "inky-black" soundstage and near perfect sonic specifications, you will hear music presented in a virtual holographic 3D format. Hear all the music...perhaps for the very first time.
Liquid, smooth, delicate, powerful, dynamic, clear, silent, present, real, brilliant, subtle, expansive, sensational, complete, stunning, effortless, alive, magnificent.
Perfect.
There is no "sound" to the ZUS Audio Engine™. In fact, you have no awareness of an audio amplification and control process whatsoever. To the human senses, the ZUS Audio Engine™ does not exist. Only the music is present. Nothing is missing and nothing has been added. The ZUS Audio Engine™ unleashes the highest sonic performance from both Digital and Analogue sources. SACD and DVD Audio with their ultra-sonic bandwidths are complemented by the ZUS Audio Engine™. Analogue sources like vinyl LPs are unmatched in their presentation.
The ZUS Audio Engine™ has been based and developed using specific design criteria and parameters. Through our research and experience in the audio field, we realized that the current specifications for audio equipment was far out-dated. The current specifications do not identify what is needed from a test and measurement perspective to reproduce audio with near total and practical perfection. At ZUS Audio we have established a new audio specification. When this specification is met, the audio equipment will process and amplify the music as intended. There will be no audible distortion nor coloration of the sound.
You hear the whole performance. Every instrument, every note, every detail. Designed for the Human Auditory senses. The ultimate goal is then achieved - a straight wire with gain.
The human auditory senses are capable of hearing sounds in the range typically from 20Hz to 20kHz. We also recognize that the human auditory senses are capable of perceiving Subsonic and Ultrasonic frequencies, although one may not actually hear these frequencies. Additionally, many musical instruments generate harmonics in the Subsonic and Ultrasonic region.
The new digital SACD and DVD-Audio formats were established in an effort to re-create music as close to the analogue domain as possible. Traditional CDs lack warmth and detail due in part to their limited upper bandwidth of 22kHz. With a frequency response of 20Hz - 100kHz and a dynamic range up to 120dB across the audible frequency range, SACD and DVD-Audio promises to provide the next generation of enhanced sound quality. However, this new digital specification places very high demands on power amplifiers and pre-amplifiers. In order to complement SACD and DVD-Audio, the bandwidth of amplifiers and pre-amplifiers must be at least equal to the bandwidth of these formats.
The ZUS Audio Engine™ embraces and supports the new digital audio formats. Our amplifiers have bandwidths from 3Hz to 120kHz, and our pre-amplifiers have bandwidths from 3Hz to 250kHz.
When a bow is drawn across the strings of a Stradivarius violin, the exquisite sound you hear is made possible due to the rich and complex harmonic content contained in each note. The Stradivarius has a unique sonic signature. Experts can actually hear the differences in the types of wood used in the construction of the violin itself.
The piano is said to be one of the most difficult musical instruments to reproduce faithfully in an audio system. For some it is the ultimate test for audio purity. Not surprisingly, the piano has a tremendous amount of harmonics present in each note.
As well, the infinite variations of harmonics make each singer's voice unique - just like our DNA is totally unique to us.
It all comes down to harmonics.
Scientists and engineers use advanced mathematical algorithms called Fast Fourier Transforms (FFTs) to de-construct a sound back into its fundamental frequencies. This allows one to examine with great precision, the unique harmonic signature or sonogram of any sound. The FFT reveals the number of harmonics, the placement of the harmonics in the frequency and time domain, and the amplitude or strength of each harmonic.
In order to retain the sonic signature of the original music source (and such melodious instruments like the Stradivarius or piano), the audio system must therefore:
The ZUS Audio Engine™ has been carefully engineered to ensure the above criteria are met.
It is imperative the amplifier and/or pre-amplifier minimize or eliminate harmonic distortion artifacts. We suggest that THD+N levels in the audible frequency band of 20Hz - 20kHz remain equal to or below 0.01% THD+N. It is quite a task for audio power amplifiers to reproduce Subsonic and Ultrasonic frequencies with:
For most audio power amplifiers, the greatest challenge is the reproduction of the Ultrasonic frequencies.
In trying to determine what exactly makes an amplifier and/or pre-amplifier "sound perfect" we found that one of the most critical elements was the ability to reproduce Ultrasonic frequencies (higher than 20kHz) with inaudible distortion and doing so at high output power levels.
We found most audio equipment was either:
Enter the ZUS Audio Engine™.
Our first Ultrasonic test on one of our prototype amplifiers showed us clearly why our ZUS Audio Engine™ gave such a total audio experience to the listener. We first tested a very popular high-end amplifier at the standard 1kHz @ 1Watt RMS. This amplifier was rated at 300 Watts RMS into 8 ohms. We'll call it AMPx.
AMPx tested out extremely well with %THD+N readings around 0.005%. We auditioned AMPx and found it "sounded" quite decent - as we expected it to. We then hooked up our prototype ZUS OPTI-MOS amplifier rated at 400 Watts RMS and did an A-B comparison. The results were very revealing.
The ZUS amplifier reproduced sound that was much more detailed and was very natural. At bench tests done at 1kHz @ 1Watt RMS, the ZUS amplifier actually produced higher %THD+N readings than AMPx at around 0.008% THD+N. We thought it strange that although the ZUS amplifier tested "worse" on the bench, it definitely sounded superior than AMPx. We then decided to perform %THD+N tests at 20kHz and above. (Please note that this is an extremely brutal test for any audio power amplifier.)
We set the input signal to 20kHz, and powered AMPx to 1 Watt RMS output. Not surprisingly, AMPx showed huge amounts of %THD+N. We then slowly raised the power output and at only 6 Watts RMS, AMPx's heatsinks got dangerously hot. At that instant all the rails fuses blew. AMPx, although rated at 300 Watts RMS, was unable to output 6 Watts RMS at 20kHz.
We then set the ZUS amplifier on the bench and subjected it to the same brutal test. At 20kHz and 1 Watt RMS the %THD+N readings were less than 0.01%. We then started to raise the power output. We were able to achieve a power level of 400 Watts RMS (0dB) while still maintaining less than 0.01% THD+N at 20kHz. This was truly remarkable. In fact, we then raised the input signal to 40khz and were still able to output 400 Watts RMS and less than 0.01% THD+N.
At this point we realized we had a true breakthrough in audio power amplifier design and performance. No wonder the soundstage from the ZUS amplifier was so encompassing and fulfilling. That revelation anchored our design mandate to enable us to build the ZUS Audio Engine™ to a high level of audio performance. We also continued with the same type of test but at the Subsonic frequencies of 10Hz and below. The conclusions were synonymous with those made at the Ultrasonic testing: ability to reproduce Subsonic frequencies at inaudible distortion levels and at full output power (0dB).
Another interesting piece of the audio-puzzle is research has showed that humans are more tolerant to distortion if it generates an even-order harmonic content. It seems we humans find odd-order harmonic distortion very irritating, whereby we are less objectionable to even-order harmonic distortion. Should any harmonic distortions occur at all, the ZUS Audio Engine™ ensures that only even-order harmonics are generated.
Another revealing specification is the %THD+N versus the output power level of an audio power amplifier. Much emphasis has been placed on reducing %THD+N at the highest output levels (0dB) of the power amplifier. Indeed, this is a critical parameter as it is necessary to amplify the signal to realistic output level volumes without audible distortion. However, all music is dynamic. That is, it can get very loud one second and get very quiet the next. As well, the harmonics being reproduced are also of varying levels of amplitude (loudness).
It therefore becomes obvious that %THD+N levels are equally important at the lowest power output levels as they are at the highest power output levels.
Many power amplifiers actually have more distortion at power levels less than 1 Watt RMS compared to their full output (0dB) power levels.
With high distortion levels at very low power levels, there is a distinct loss of realism and tonal integrity of the music. A Stradivarius violin just doesn't sound quite right. A violin is heard, but the sonic signature of a Stradivarius violin is blurred and smeared. As the musical notes decay and the harmonics fade in intensity, there are distortion artifacts being introduced that were not there in the original source.
Ensuring the power amplifier produces inaudible distortion at high power levels as well as levels less than 1 Watt RMS, preserves the realism and tonal integrity of the music.
The ZUS Audio Engine™ allows for a very high-resolution and highly detailed audio soundstage by ensuring there is no audible distortion whatsoever in the entire output power range. From the very quietest note to the very loudest, the listener enjoys a near perfect reproduction of the original sonic source. Indeed, it is a most captivating and immersive experience.
Music is inherently dynamic. There are loud passages and completely silent ones. It goes without saying that the audio system must not generate any audible types of noise and/or hum. Not only is this annoying to the listener, but certain types of noise and hum can introduce distortion artifacts into the original source. This is of course undesirable in all respects.
The power supply rejection ratio or PSRR denotes the immunity level of an amplifier or pre-amplifier to ripple content and signal components that may be superimposed on the power supply rails. Poor PSRR performance will manifest itself in the forms of hum, crosstalk and distortion. ZUS audio equipment naturally has superior PSRR performance.
The ZUS Audio Engine™ has been described as having an "inky-black" background, totally free of any types of perceptible noise or hum.
Clipping is the distortion that occurs when an amplifier or pre-amplifier is overdriven. This can be seen visually on an oscilloscope as the peaks of a waveform are flattened or "clipped off" at the signal's ceiling. When this occurs a) the signal is flattened at the peak values, b) the signal approaches the shape of a square wave, and c) high frequency harmonic components are introduced. Clipping may be hard, as is the case when the signal is strictly limited at some level; or it may be soft, in which case the clipping signal continues to follow the input at some reduced gain. Hard Clipping is not only undesirable to listen to, it has the potential to severely damage or destroy loudspeaker components.
The ideal amplifier or pre-amplifier would clip in a perfectly symmetrical fashion when overdriven, and the clipping characteristics would be "soft". Interestingly, the clipping characteristics of vacuum tube (valve) amplifiers tend to be very soft. Soft clip action is very rare amongst solid-state amplifiers and pre-amplifiers. The harsh sonics created by hard clipping is one of the major objections that some audiophiles have toward solid-state amplifiers and pre-amplifiers.
The ZUS Audio Engine™ incorporates symmetrical as well as soft clipping in all amplifiers and pre-amplifiers. We are not surprised to hear feedback from listeners that our solid-state audio equipment outperforms the best that vacuum tubes offer with none of the drawbacks.
Many "high-end" audio products are incorporating Integrated Circuits (ICs) in their designs rather than attempting to construct a solution from the ground-up using discrete components. The reason is, there are few if any, engineers today with the understanding and knowledge-base of how to build discrete, non-IC high-performance analogue audio equipment.
Most audio equipment manufacturers are forced to rely on incorporating off-the-shelf ICs in their products. It is common now to see Operational Amplifiers (OP-AMPs) being used in virtually every piece of audio equipment. The performance of an audio ICs is sonically inferior to a properly designed discrete topology. However, with virtually no one available to design a high-performance discrete audio amplifier or pre-amplifier, the manufacturer is stuck using ICs. The result is most IC-based audio equipment can never fully deliver true High Definition Audio.
When we embarked on designing a Pre-Amplifier, we initially took the route of using "high-performance" OP-AMPs from industry standard components that most every other audio equipment manufacturer was using. The completed Pre-Amplifier was then tested out on the bench, and showed low %THD+Noise and decent specifications otherwise. We then auditioned the unit and were completely disappointed. The soundstage was flat and 2-dimensional. There was no sense of realism. The subtle harmonic content was completely absent. The music was lifeless and dull. It sounded horrible, despite having decent electrical specifications.
At that point we undertook the tedious and difficult task of coming up with a fully discrete (no IC's whatsoever) topology that would complement our line of amplifiers. After many months we had a breakthrough. The result was a gain section (the heart of all pre-amplifiers) that amazed us all. The electrical specifications tested out nothing short of extraordinary. In fact, it was almost impossible to test the gain section as it was virtually invisible to our test equipment. Our Pre-Amplifier had better performance than our test equipment.
We were very eager then to audition the unit. Upon first turning up the volume we immediately knew that we had achieved our goals. (Actually, we ended up far surpassing our goals.) The music once again came alive. The openness and realism was stunning. Never had we heard such rich and harmonically filled sound. We were speechless.
Upon further testing and studying, we concluded that Op-AMPs had higher noise content, limited bandwidth, higher %THD+Noise, lower slew rate, lower dynamic range, clipped with "hard clipping" and generated odd-order harmonic content (the most objectionable).
The ZUS Audio Engine™ uses only fully discrete components and does not use any OP-AMPs nor any other IC-based circuitry in the audio path whatsoever.
Audio equipment is only as reliable as its weakest component. A five cent resistor can potentially disable a $5,000 amplifier. Fortunately, most electronic components have very high reliability or Mean Time Between Failures (MTBF) rating. One of the most destructive elements is heat. It is not uncommon therefore to see most failures occurring with power amplifiers.
It takes excellent engineering practices and design topologies to ensure heat, for example, is properly dissipated from a power amplifier. This is done mostly through large heatsinks attached to the output devices. However, careful attention must also be paid to the selection of all components to ensure reliability is not compromised.
The ZUS Audio Engine™ incorporates over-sized heatsinks and uses components that have a proven reliability track record. The exclusive use of Lateral MOSFETs in the output power stages of our audio amplifiers provides an unprecedented level of inherent reliability.
Backing up our engineering in providing a high level of reliability, ZUS Audio offers an unheard-of 20 Year Warranty on Parts and Labour; Unconditional and Fully-Transferable for all our products.
The
ZUS Audio
Engine™ is your assurance of experiencing the ultimate in audio sound
reproduction.
Potential for Several Patents
ZUS Audio Inc. Penticton, BC Canada
Tel: 1-250-770-2022, Fax: 1-250-770-1999
Copyright (C) 2007, ZUS Audio Inc.