I ordered one as well (just the standard blacl). I do a lot of travelling, this will be a welcome replacement for my iPod. I'm excited to hear what it can do. My travel headphones are the shure se535 which sound great, and provide really good isolation on the plane.
They sent me some further info on the technical design details:
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Project Update #23: More about the PonoPlayer Design
Many of the more technically inclined have asked for more details about what is so special about the Pono Player design. Charlie Hansen, founder of Ayre Acoustics, and one of the major contributors to the technical audio circuit design of the PonoPlayer that will ship in October, provided the information in this memo to share with you.
But first, let’s be clear that we have no publishable measured “specifications” for the PonoPlayer as of our Kickstarter campaign. While we have a basic design that is a working prototype, and it sounds great today, we have been evolving the design of the Player throughout the last year, and will continue to make changes through the next month or so, as we approach our handoff to manufacturing for October shipments.
When we have stabilized the design of the Player and built a sufficient number of test units, we will being to measure the audio specifications of the Player, and will have those “specs” available at shipment.
One of the primary reasons we chose a crowdfunding platform was to raise the necessary funds to completely finish the design of the PonoPlayer. So, obviously, we can publish “specs” on an unfinished product. We belive our backers understand this idea. So, now, on to the design of the Player.
For the best audio experience, we begin by getting the highest resolution audio recording available from the labels. Our goal is to deliver to the consumer the file that is the closest possible representation of what the artist heard in the studio when the album was being made.
Our singular aim during the development of the Ponoplayer was to build a device with one purpose: the playback of music at the highest possible level of performance given the boundaries of the design. This design called for a small, portable structure capable of storing high-resolution digital files and converting them to analog music, thereby providing a more-than-fulfilling experience for the listener. This product wouldn’t function as a phone, WiFi router, Bluetooth transceiver, portable gaming platform or GPS widget. Any additional features would only detract from the resolution of music in its fullest dimension, and thus, the enjoyment we know possible when music is reproduced with this level of fidelity.
The music is downloaded and stored in a format called FLAC (Free Lossless Audio Codec), a widely accepted, robust, industry standard. It allows for the compression and subsequent storage of large audio files without the loss of critical data. All information stored on the original file can be retrieved with zero loss once the FLAC algorithm decompresses the file. This provides the best of both worlds: compact storage and high potential fidelity. Founded by Charles (Charlie) Hansen (chief engineer and product designer), Ayre has been designing and building high-performance, award-winning home audio electronics for more than 20 years. With their feet firmly planted in both the digital and analog domains, we felt they were the perfect choice for a partner that could design an audio circuit capable of championing the difficult and delicate challenges of high-resolution audio playback.
Everything Ayre has ever made has had fully balanced, all-discrete, zero-feedback analog circuitry. Even Ayre’s digital products employ custom digital filters. The reasoning behind the use and implementation of every one of these technologies is to fortify the presence of the signal and defeat noise in the path of that same signal. Without this, the rendering of high-resolution music would be a futile task, as the listener wouldn’t be able to hear the actual benefits of high-resolution audio.
In the Pono Player, Ayre began their work by designing the circuitry after the main processor retrieves the audio data from the memory and presents it in "3-wire" form - audio data, bit clock, and word clock. They chose the just-released version of ESS's top-of-the-line ES9018. It has two channels, comes in a very small package (5 mm square), and is extremely customizable, able to tackle the rigors of sensitive, low-level signal path design.
The filter generally favored by Ayre is a minimum-phase digital filter (to eliminate pre-ringing), with a "slow" roll-off, to minimize the overall amount of ringing (ringing can be thought of as an oscillation in the digital signal, causing all sorts of errors if misconstrued as actual signal to be converted to analog, which is engineer-speak for music). For the Pono Player’s D/A (digital-to-analog) converter Charlie went a step further and used a moving average filter for both the double and quad sampling rates because it has no pre-ringing, no post-ringing, no overshoot, and no undershoot (these create inaccuracies in the rendering of digital signal and sacrifice fidelity). In other words, it has none of the digital artifacts (digital artifacts also add to distortion and occlude signal) at all.
The DAC chip’s output comes in the form of current, so Ayre designed a proprietary, fully discrete, fully- balanced, zero-feedback current-to-voltage stage. This then goes to a fully discrete, zero-feedback buffer stage to drive both the headphone output and the line stage output. The output impedance is roughly 5 ohms, allowing the Pono Player to drive any headphone on the market with minimal frequency response errors.
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Clarification about the PonoPlayer Output Impedance
Some have expressed concerns about the output impedance of the PonoPlayer being 5 ohms. It is important to note that it is trivial to make the output impedance arbitrarily low -- simply add more and more and more feedback. The problem is that this will make the player sound worse, not better!
All products designed by Ayre (since its inception 21 years ago) have no negative feedback. This results in a more natural sound because feedback can only attempt to correct for an error after it has occurred -- clearly an impossibility. If negative feedback actually worked as people claim, then all products would sound the same because the negative feedback would eliminate the errors. But not all amplifiers sound the same, so feedback is clearly not the answer!
The reason that output impedance is somewhat important is that the impedance of headphones almost always vary with frequency. If the output impedance of the headphone driver circuit is too high, then there will be a voltage divider action between the impedance of the headphone and the output impedance of the headphone amplifier that results in audible frequency response errors.
Now, to some extent this is meaningless as all headphones have inherent frequency response errors anyway. It may be that some headphones (through sheer luck) may produce an overall flatter frequency response with an amplifier that has a high output impedance. But luck and hope are not good ways to design things.
Instead, the goal it to reduce the output impedance to a point that is low enough that there are no meaningful frequency response errors with almost any headphone on the market. In the real world this means that the output impedance of a headphone amplifier should be less than about 10 ohms or so. Lower impedances will result in lower frequency response errors due to the interaction between the output impedance of the headphone amplifier and the headphone impedance itself. But lowering the output impedance through the use of feedback will introduce new sonic problems that are much worse than the original problem.
The only other way to reduce the output impedance of the headphone amplifier is to increase the idle current in the amplifier circuit. This is fine for a home stereo where there is virtually unlimited power available from any wall socket. But a portable player is a different animal altogether. Increasing the idle current of the amplifier will obviously shorten the battery life of the device. The art of engineering is the art of compromise. And when you have a chance to listen to the PonoPlayer, we promise that you will be more than happy with the choices we have made.
The 5 ohm output impedance of the PonoPlayer is the best overall compromise which minimizes interactions between the headphone amplifier and the headphone while maintaining good battery life, and completely avoiding the sonic problems created by the use of negative feedback. Thanks for reading this, and thanks for your questions.
Correction about Converters
The Ayre QA-9 ANALOG-TO-DIGITAL converter uses a moving average design with no undershoot, overshoot, and ringing but not the digital-to-analog converter in Ayre products.
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03-22-2014, 09:34 PM
Linear Mode
