Forum Posts

Admin
Mar 22, 2020
In General Discussion
I emailed the forum members about Covid-19 & some people thought it was spam This is just to assure you it was not spam - I encourage people to participate in a collaborative worldwide effort to find a drug which may tackle the virus. It's simply a matter of downloading an application which uses your computer's processing power (when idle or always in the background) to work on analysing the virus to find how a drug that can attack it. Download it here
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Admin
Mar 03, 2018
In Press & Tour Reviews
I thought I would start a thread to report on latest Press reviews. This one just went on-line from TNT Audio Some conclusions: As I said, it is difficult to say much more about such an excellent piece of hi-fi. Once again, I am left wondering how much more performance can be extracted from these computer audio playback devices. I felt that the early USB DACs sounded as good as a mid-range turntable. Now DACs like the ISO-DAC have (IMHO) equaled, or maybe surpassed the best turntables, and without the disadvantage of dealing with the clicks and pops of vinyl. So, with or without, the isolating hub function, I very strongly recommend the ISO-DAC, and thanks to Ciúnas Audio's 'home trial' policy, you can try one yourself for 30 days and then return it if you don't want to keep it. So, if you are looking for a USB DAC, or want to upgrade, I highly recommend the ISO-DAC!
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Sep 10, 2017
In Auditory Perception
​ I recently came across this phrase "dynamic noise floor" here on MonoandStereo.com Then there is “Dynamic Noise Floor” as coined by Robert Koda – DNF. Not so much a noise but rather a gritty and shifting ghostly shadow, a clogging mush that is changing in a continuous and dynamic way yet somehow related to the music in a sickly fashion. It stems from the music its self when passed thru a piece of electronics or system. It is the ultimate corrupter and its nature is a direct result of a multi fold of complex interactions occurring within the make up of the circuitry. It may manifest its self in transients, or perhaps decay. Specifically in every event and every moment of music. It is our opinion that DNF is the single greatest contributor to the inferior sound of a components that otherwise “measure” so well. DNF is perhaps the Achilles heal of modern electronics. ​ Much, if not all of the DNFs make up is spread across the time domain – An occurrence in the past effects the result of the near future. As you can imagine, the effect has catastrophic consequences on music replay! Robert Koda realized the existence of a musically modulated and ever changing Dynamic Noise Floor decades ago. ​ He states in another interview The measurement of a "dynamic noise floor" matters more but this is not easy to measure.
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Aug 30, 2017
In Auditory Perception
3) Can you tell us about how you test finished designs, and about your reference system, along with your musical preferences? Throughout my product design I measure and test components, modules & sub-assemblies. All finished products are tested for their specific functionality and battery functionality — charging is tested. Finally, listening tests for all products, are performed before shipping. I found that with low noise, highly stable battery power to crucial areas of digital audio devices, (like USB receiver chips, low jitter clocks, D/A converter chips), great improvements in sound could be achieved but this wasn’t showing up in my measurements. For instance, early on while I was experimenting on the ESS DAC chip I found it sounded much better when run in synchronous clock mode rather than asynchronous mode where it used it’s inbuilt & well regarded ASRC (Asynchronous Sample Rate Converter). But nothing I could measure showed why this sounded better. And although I use an analogue 100Mhz scope & digital signal analyzer to aid in testing and fault-finding individual components, I remain committed to evaluating my designs using audition — by me, and by a local group of audiophiles in Ireland. Just to say something about measurements here. I find noise which fluctuates because dynamic music signals are being processed is particularly difficult to measure. I haven’t yet discovered, or seen anybody describe, a technique for measuring this  dynamically fluctuating noise. For testing of DACs, I use headphones directly from the RCA outputs which gives me the best forensic insight into the sound. At other times, I use a Naska amplifier and some amplifiers of my own design outputting to Jordan JX92S fullrange speakers in speaker cabinet of DIY design — a 3D spiral horn design. My prototypes are also trialled in the local audiophile community who have a variety of audio equipment. Quad ESL 57s & 63s, Raidho & many other speakers; AirTight & a variety of solid state amplifiers and very heavily modified computers as source. DACs such as Lampizator, Meitner, Eximus and many others are used in auditions. We meet up via a local audio forum Tirnahifi My music listening is varied, Swing Jazz, rock, some classical and some folk & country. Any music which I can connect to emotionally is my preference and I find good music systems make this far easier to achieve. 4) Can you explain, your view, how USB audio has evolved, issues that have been brought to light, and what the current state of the USB protocol for audio is? USB audio came of age when Gordon Rankin introduced asynchronous USB protocol where the clock in the receiving audio device is the master clock timing the USB packets rather than the lower quality clock in the PC. This advance took USB audio out of the realm of an audio toy and into consideration for serious listening. It opened up computer audio to many and certainly began to appeal to audiophiles, particularly with the convenience offered by a music database, tagging and search functionality available. There was great progress in USB audio and many subscribed to the belief that jitter was now under control with asynchronous USB and this meant the audio quality must be optimal. But many reported that their CD playback sounded more dynamic, alive and interesting — computer audio wasn’t matching this for some reason. My path down the road of ultra low and stable power supply noise opened my mind to the psycho-acoustic repercussions of modulating noise. I had already premised that ultra low noise is one thing but stability of this noise is the more important characteristic. We can tolerate and even become unaware of noise which is stationary, not fluctuating — this is easily explained in ASA. Noise which modulates, irregularly, is much more intrusive in our auditory perception and captures our attention because it is not being treated as background. The linked Youtube MP3 demonstration gives an example of this — what is happening here is that quantization noise is generated in MP3, but we cannot hear this fluctuating noise itself, we can only perceive it by its effect on the perceived blurring of the transients. I believe a more subtle form of this, low level noise, is at the heart of why digital audio can sound uninteresting, lacking in perceived dynamics, unmusical, unnatural. One major problem, in all this, is that measuring this low level fluctuating noise is a very difficult task & has not been fully resolved yet — glimpses are seen, however. My audio devices, running directly from battery, do not suffer from this issue of delivering uninteresting audio playback, lacking in dynamics — it’s always been one of the main characteristics that users mention when they first hear my devices. Computer audio now matched and often surpassed even the best CD playback. From my discussion with a few customers in which we resolved why my audio devices weren’t providing the sound I know they can, I was reinforced in my conclusion that noise intrusion can deaden the sound, make it uninteresting to listen to, rob it of life. My direct battery power is addressing the main cause of fluctuating noise but it wasn’t until I heard the Intona USB isolator with my Ciúnas DAC that I could appreciate the audible effect of removing another source of noise coming from the USB connection itself. I had already experimented with this, trying to block common mode (CM) noise using CM chokes on the USB signal lines — no effect; using ferrite rings on USB cable — dulling of sound; using a USB cable ferrous sheath covering — a significant reduction in hiss but some drop off in sparkle (this one will be revisited when time allows). But the USB isolation of the Intona affected the sound in a different way — it solidified the soundstage, made the interplay of the musicians more understandable, making the whole presentation more believable and musical. I knew this was a different type of improvement in sound and decided to investigate further and find a way to use USB isolation with and in my existing Ciúnas audio devices. Again, in this case my premise is that the USB receiver chip is generating some self-noise within the chip & ultimately on the ground plane connected to this chip. This may be due to USB processing itself or, more likely, some overshoot/ringing on the very fast USB signal waveform (USB high speed 500pS is the rise time spec). I believe this is where the digital design requirements & analogue design requirements clash. A Reasonable amount of noise at the digital receiver does not cause bits to be misread but sensitive analogue circuitry like clocks are affected by ground plane noise. We can see a USB signal overshoot in the following measurement as the spikes at the top of the rising edge of USB waveforms in the plot (even though this is a plot of the slower full-speed USB & may be due to the scope probe used. USB isolation of the USB signal lines removes any fluctuating noise, usually called common mode noise (CM noise), which is arriving at the USB receiver. Using a USB hub to regenerate the USB signals after this isolator is required to remove the jitter that all isolators add to the signal. It took some time in testing, listening and ironing out the bugs but I eventually achieved success. My testing also revealed that USB reformatting/reclocking is needed after all isolation devices as they introduce jitter into the signal. My Battery powered ISO Hub was better sounding than the Intona when the group auditioned it side by side. I recently released a number of products incorporating this technology: ISO-HUB — a new device which offers 1 USB input and 4 isolated/reclocked high speed USB 2.0 outputs. Use before any USB audio device to obtain audible benefits of more sonic realism. ISO-SPDIF — A world first — an isolated USB SPDIF converter. The Ciúnas USB SPDIF converter is integrated with the ISO-HUB technology providing a USB signal with optimal signal integrity to the USB/SPDIF converter. ISO-DAC — Another world first — isolated USB DAC. The Ciúnas DAC again with integrated ISO-HUB providing an isolated and reclocked USB signal, internally, to the USB DAC.And lastly a product that many have been asking me to release, so they could avail of this battery power for non Ciúnas devices — a self-contained isolated battery supply which can be used to power many audio devices, not just my Ciúnas devices. ISO-PS — an external battery power supply giving isolated, selectable voltages of 3.V and 6.V outputs and other voltages available on request 5) What do you for enjoyment when not designing digital audio devices and running your business? I’m in the enviable position that one of my passions is actually my audio business. I believe most audio designers are similar and do this because of their passion and it’s no different in my case. When I am forced to unplug my soldering iron and scope, I relax with painting. It’s similar to audio design in the way that one can get lost in doing a painting but it comes from a totally different part of the brain — the creative, intuitive part and yet the joy in a finished painting is similar to the joy in testing an intuitive design change & hearing the results. Some paintings of mine…!
My Interview - Part 3 content media
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Admin
Aug 30, 2017
In Auditory Perception
2) What about John Kenny designs, philosophy, business model, and customer relationships make it unique in the marketplace? Early on, I decided to specialize in computer audio and USB input in my devices as I felt that it was capable of truly excellent sound and it was becoming a serious platform for audiophiles. I reasoned that designing a single input excellently (USB) was much better than designing a number of inputs adequately such as SPDIF, Toslink, I2S, HDMI. USB was often an afterthought input on many audio devices, at the time. I found that with low noise, highly stable battery power to crucial areas of digital audio devices, (like USB receiver chips, low jitter clocks, D/A converter chips), great improvements in sound could be achieved. The reasons for these improvements only became clear when I found answers in the workings of auditory perception and ASA.  Auditory Scene Analysis (ASA). research, instigated by Al Bregman, arose from trying to understand the well-known “cocktail party effect” which is our ability to focus on a particular conversation in a noisy room full of other conversations. This is achieved by the brain’s processing of the auditory signals from the ear, not by the ear, itself. The significance of this research to me is this — audio playback is attempting to achieve an audio illusion — an illusion that the listener can believe is ‘natural’ sounding. The more natural sounding, the more believable and engaging is the playback. But ‘natural sounding’ isn’t just ‘preference’, it’s explainable by ASA’s research findings. From infancy, we absorb how sound behaves in the world & this teaches our fledgling auditory perception as to what is natural. ASA is the study of exactly how auditory perception creates an auditory scene from the nerve signals on the auditory nerve — much the same as visual perception creates a visual scene from the signals arriving from the optic nerve. My clarity about how power supply stability affects auditory perception is explained by ASA. Low levels of power fluctuation are ground noise fluctuations which ultimately affect sensitive circuitry in DACs, for instance. (We even see new ways of hacking what is being typed on computers by sensing ground leakage fluctuations on power outlets powering the computer).  Now these noise fluctuations on the DAC are not random, like the hiss we hear from analogue tape–they are correlated with signal processing. Random noise is categorized by ASA as background & easily ignored – it doesn’t intrude into our perception of the foreground sound. Fluctuating noise is analyzed differently – it has pattern characteristics (temporal, amplitude, spectral) which ASA tries to make sense of – group into any of the auditory objects it has already identified. If it can’t make sense of this signal, it is confusing to our perception & leads to a perception of a less clear auditory scene, less believable, less natural. When this source of fluctuating noise is removed by using stable power from batteries, the whole auditory scene becomes clear, more realistic, more natural – the scene falls into place & makes sense. It’s a system-wide effect, not a change in certain frequencies or amplitude — all of which makes it difficult for some to understand. Just to be clear – the concept of fluctuation of the PS during processing is well established in engineering and it is now one of the well established techniques for hacking called side channel analysis where unintended side channels give an indication of the signal processing activity and can be used to hack it . In Simple Power Analysis (SPA) key bits are seen directly in the power consumption of a chip using it in a multiplication operation. There’s one important point to understand about the whole area of auditory perception and it is exemplified in this phrase, borrowed from linguistics, “poverty of the stimulus”. The meaning here is that there isn’t enough data in the signals coming from the eardrum to create an auditory scene we are sure of. Our perception has to use all sorts of other information to try to resolve this dilemma — the dilemma of achieving, in real time, a stable auditory scene which is trustworthy and useful for our interaction with the physical world. To resolve this we have to draw on other data, data from sight being a primary one but also our prior knowledge and experience of how sound objects behave in the world — for instance a lot of natural sounds have a fast attack and slow decay — the reverse, (slow attack and fast decay) is unnatural sounding. We know that a sound which has a slow decay & then abruptly stops that it is being damped. Through experience we have built a library of such ‘sound pattern information’ which we draw on to make inferences and predictions about the sounds we are perceiving. How does ASA inform my designs? I realised that what I was focused on in my designs was having an audible effect on the whole presentation, not just better bass or better treble. Other aspects that listeners commented on were a perception of increases in depth of soundstage, solidity of the individual auditory objects in the scene, naturalness — in essence a more realistic auditory scene. My current working premise is that, below a certain low noise floor, what is crucial is the stability of this noise. If this noise is fluctuating, it affects how we perceive sound but isn’t heard as an entity in itself. An exaggerated example of this is pre-echo in some low quality MP3s which blur transients but the pre-echoes themselves are not heard, just their effects (here’s a Youtube video of this effect). ASA research, even though started in 1990, is still at a relatively early stage of investigation — 27 years is a short time in perceptual research. This makes for a difficult task in uncovering the exact ASA mechanisms in operation during auditory perception of complex signals such as music. ASA is still at the stage of using relatively simple audio signals for testing and is only now beginning to consider more complex signals. Until there are advances in this aspect, all we can rely on is intuition, experiments and knowledge of ASA to guide us. My philosophy … Doesn’t just apply in the scientific arena but in all of life. Remaining open-minded and inquisitive is a struggle but one worth trying to pursue. Having established a relationship with those people who engaged me to modify their Hiface products, I have stayed loyal to this type of customer relationship — a personal interest in ensuring that they are getting the most from any product of mine. That includes giving advice about the surrounding equipment being used with my audio devices. In the past this has uncovered ground loop issues & sub-optimal playback settings in customer’s systems. My direct sales business model allows me to stay in touch with my customer base and also ensure the best value for money that my products have been renowned for.
My Interview - Part 2 content media
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Admin
Aug 30, 2017
In Auditory Perception
This interview was posted on Fair Hedon I'll try & add the images John Kenny, based out of Dublin, Ireland, has been producing audiophile grade computer audio products that are affordable, feature proprietary power schemes, and sold direct to consumer. In this interview, we discuss many topics including his design philosophy, his new line of ISO products, and USB audio. 1) Can you tell us a bit about your background and how Ciúnas Audio came to be? At an early age I was building crystal radio sets, taking transistor radios apart and building/improving amplifiers, constructing new types of kites, model rockets and model hovercraft. Later, at University, I completed a science degree but at the same time, computers captivated my interest and I eventually set up a computer company specializing in bespoke software. Returning to my electronics hobby in later life I found a trove of information on the web regarding building & designing audio electronic devices and forums dedicated to DIY which I avidly digested. My growing interest in the impact of power supply noise in DACs led me to an investigation into the use of a relatively new battery chemistry. I premised that this battery had characteristics which were important for powering digital audio devices. Apart from ultra low noise, they offered huge current output (120Amps instantaneous) which I believed would make them a very stable PS. I considered the latter hugely important, particularly in the sensitive circuitry of digital audio devices, even though they represent a light load albeit at high frequencies. Another appealing aspect was that their 3.3V voltage output held up during their discharge cycle. Normally batteries drop in voltage as they discharge but these batteries remain close to their 3.3V output until near their fully discharged state. In 2009, I tested the batteries by modifying two popular digital audio devices at the time; Musiland 01US DAC and the original Hiface USB/SPDIF converter. The results exceeded my expectations and I posted details of the modifications on DIYAudio. A number of people took up the challenge and reported great success. However, not everybody wanted to do the modifications themselves and I was inundated with private messages requesting that I make the modifications for them — a business was born. At that time my products were referred to as JKDAC or JKSPDIF and JKDAC32 but I eventually settled on a name which I felt encompassed what I was about — Ciúnas Audio. Ciúnas is the Gaelic word for calm, stillness, serenity and, as my design focus is on noise reduction and stability, I felt it represented this as well as introducing some Gaelic words into the audio world.
My Interview - Part 1 content media
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Admin
Aug 28, 2017
In ISO-DAC
Discussion about this isolated USB DAC - it's not just isolating the I2S output signal lines after the USB receiver - it isolates & reforms the incoming USB signals before the USB receiver. This is the optimal configuration!
World First USB isolated DAC content media
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Aug 28, 2017
In ISO-SPDIF
Discussion about this isolated USB to SPDIF converter - it's not just isolating the I2S output signal lines after the USB receiver - it isolates & reforms the incoming USB signals before the USB receiver. This is the optimal configuration!
World first USB isolated USB-SPDIF content media
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Aug 28, 2017
In ISO-HUB
Discussion about ISO-HUB - isolated USB HUB
ISO-HUB - isolated USB device content media
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Aug 28, 2017
In ISO-PS
Discussion about a battery or supercapacitor powered PS that is ultra low noise & ultra stable.
ISO-PS - Battery/Supercapacitor power supply content media
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Aug 28, 2017
In Auditory Perception
I recently did an interview with Andre Marc who has set up a webzine, Fair Hedon, with a similar ethos to what I'm trying to achieve here. It might be a good starting point for discussions about Audio Innovations as what I touch on in that interview is about how research into auditory perception is revealing aspects of how the brain makes the nerve signals coming from the ear into meaningful information - in other words how we make sense of the auditory world around us. This is highly relevant to this audio hobby as what we are involved in is listening to reproduced audio which hopefully conveys a richer experience than just hearing the right notes. What I believe is happening in audio reproduction, at the moment, is a realisation that when audio reproduction better satisfies the principles that govern how auditory processing works, then we achieve far more realistic, natural sounding & believable reproduction. We begin to be able to connect with reproduction in the same way as we do with the real event. The problem is that the full understanding of the principle working of auditory perception are not yet teased out so there are a number of people in this hobby who are discovering elements of this but yet not knowing the auditory principles behind the discovery - only knowing that it does result in improved sound. This intuitive space where there are no sure answers, only our perceptions, is not a comfortable place for some to inhabit.
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Aug 28, 2017
In Auditory Perception
This area is designated for discussion of all things audio which improve our listening experience. Who needs another audio forum? I do. I find most audio forums don't satisfy my desire for open-minded, sensible discussions of reasonably priced but excellent sounding reproduction equipment. I'm hoping that people can share their thoughts & views as well as advice here in a friendly & reasonable area where posers, of every kind, are excluded. Neither extremes will be tolerated for too long - neither magical thinkers nor measureist, pseudo-scientists will last long in here. It is recognised that auditory perception is the final judge of audio quality but it's not a magic black box. It is recognised that measurements do not define how we perceive audio but they are often very useful to guide our way. What I'm hoping will be achieved in this forum is a balance between these two aspects. This section is meant for those who are pissed off with those who insist that measurements define what is heard and who are equally pissed off with magical-thinkers? Who are pissed off with seeing every thread degenerate into a battle. In other words, we are hoping that this division between these two extremes can be straddled by attracting readers/posters who want a sensible & open-minded approach to this hobby. Those who want reasonable, sensible, open-minded discussions & information about audio. Let me repeat, this is not a forum for posers showing off what they can spend on audio equipment or measuring equipment, it's for sensible people who enjoy this audio hobby & want to find like-minded sensible hobbyists to share views & information. I'm also hoping to post interesting audio articles here To be continued....
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Aug 28, 2017
In Ciúnas Audio Devices
This area is reserved for support & discussions on any Ciúnas Audio device - problems, usage, setups, features, wishlists & of course, reviews should be posted here
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Aug 28, 2017
In Support
How does ISO-Hub work with asynchronous USB? USB sends data in packets, not a continuous flow. Inside the receiving device, the packet data is continually stored in a small buffer & converted to a continuous stream by using the local clock to time the data out of the buffer (it's this timing that is critical & the advantage that asynch provides - the timing out of this data is done from the clock in the audio device rather than a clock derived from the PC's USB packet stream). Asynch tells the computer how much data to send in each USB packet in order to keep the buffer about half full. All USB hubs do the same as the above - they are simply an intermediate station along the way between computer & final USB device However, in this case, it is being used to receive USB packets & at the same time isolate/eliminate any noise on the data signal lines (D+ & D-) as well as the ground or 5V line - this is the isolation part. It also allows, by using ultra low noise & stable battery power, to provide a clean & optimally formed USB signal as output for transmission to the final USB audio device. This is what an ISO-HUB does as a stand-alone device That same technology is incorporated into my ISO-DAC & ISO-SPDIF thus avoiding the cables, different PS, etc. These are the first DACs & SPDIF converters that has incorporated such technology. Other DACs may say they have galvanic isolation but this is only a band aid partial solution as it doesn't isolate & clean the incoming USB signal - it isolates after the USB receiver - it's a case of the horse has already bolted. Why are there 4 USB ports & how can they be used? There are 4 USB ports on all ISO devices - ISO-HUB, ISO-DAC, ISO-SPDIF. Apart from the main function of the device (DAC or USB-SPDIF converter) there is an ISO-HUB built into all ISO devices. These USB ports are exactly the same as the ISO-HUB ports which provide isolated & reformatted USB signals. Any USB audio device can be connected into any of the ports (except in the case of the ISO-DAC & ISO-SPDIF where the USB port on the right is used by the DAC or SPDIF function). Other USB devices may be USB devices holding music files, USB sticks or USB SSDs or HDDs. Playing back audio files from these storage devices plugged into the isolated & cleaned USB ports provides better sound quality than the same files on computer HDD, SSD or USB sticks. For any plugged in USB devices that require 5V USB power this power can be injected into the rightmost USB port. See FAQ question "Is 5V power on the USB ports?" Why is USB isolation needed - is battery power not low noise? I once thought that battery power isolated my Ciunas audio devices from any electrical noise intrusion. I was wrong. When I tried the Intona, the first USB high speed isolator, I could hear a definite audible improvement. So the USB connection is another conduit for electrical noise intrusion. Battery power breaks the ground loop pathway that often exists between computer & attached audio device which can be a conduit for electrical noise that affects sensitive audio devices. Why is USB reforming needed after USB isolation ? All isolation devices add timing variations in the signals being blocked - this is called jitter. USB jitter is audible & reforming/regeneration of the USB signal removes this jitter & results in better sound. Is 5V power available on the 4 USB ports? 5V power can be injected into the rightmost USB port which then becomes available on the 3 other USB ports. This allows the user to control the quality & current capability of this power, 500mA, 1Amp, 2Amps. A USB cable for this power injection can be supplied. Does this power injection introduce a 'dirty' ground into the output? I have found that the major noise contributor affecting audio is the noise on the USB signal lines themselves, not the USB 5V or ground. What are the advantages of battery power? Batteries are a stable, low noise source of power And aren’t sources of leakage currents or suffer from ground loops as mains rectified power can. This cuts out one source of electrical noise that can plague audio systems. Some people state that batteries are noisy under load but this criticism is based on older sealed lead acid (SLA) battery technology where the chemical reaction needed to produce current is noisy. Modern battery technology, such as LiFePO4, which are used in all my products, is ultra silent under load.. What about the problem of battery charging? The charging scheme uses isolated chargers which continually trickle charge the batteries. This allows the user to experience all the sonic benefits of batteries without any of the concerns about charging - it is plug & forget. There is no audible downside from this charging arrangement. Are these batteries safe? Unlike other Lithium Ion batteries these batteries use a different, stable formulation (Lithium Ferrous Phosphate, LiFePO4) which doesn't go on fire due to overcharging or shorting. How do batteries compare to supercapacitors? Supercapacitors are capable of delivering very high currents at low noise but they have some drawbacks. The main one is that they are found mostly in 2.5 voltage versions. To output 3.3V, two supercapacitors in series are required plus baancing circuitry & a voltage regulator needed on the output. Our experience is that balancing circuits & voltage regulators are inferior sounding compared to direct battery power. What about the chemical noise of batteries? Modern battery chemistry is far superior to lead acid (SLA) batteries where chemical reaction noise was an issue when a significant current was being drawn by the load. The design of these batteries use nano particles as anode which means that their reactive surface area is far greater than a lead plate in an SLA. This results in an internal impedance of 6mOhm (lower than almost all capacitors) which means an ability to deliver instant current of 120Amps pulse for 10 secs & 50Amp continuous output. When supplying 3.3V at very low currents the load on the battery is minimal & one can safely say that there is immeasurable battery noise. Old NIST paper (1995) on battery chemical noise - before LiFePO4 batteries were available & Ni-Cd is -205dB @ 10KHz What noise is USB isolation blocking? There are a number of different sources of noise on the USB connection - the 5V wire, the ground wire, both USB signal wires The 5V USB power should never be used for powering sensitive audio devices - it just hasn’t got the stability or low noise requirements for this role - it’s has the opposite characteristics - variable quality, instability & noisy The ground wire has similar variable quality & noise issues Once the above two areas of noise have been dealt with (using battery power, for instance), the USB signal wires are the main source of noise intrusion. This is usually leakage current noise or common mode noise which the differential USB circuitry does not deal with. What does this noise sound like? It doesn’t sound of itself - it’s only it’s removal that is noticeable as greater dynamics, better insight into the interplay of the music - in two words more musicality & realism 0AdminWrite a comment...
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