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Pono's mission is to provide the best possible listening experience of your favorite digital music.
Pono's mission is to provide the best possible listening experience of your favorite digital music.
18,220 backers pledged $6,225,354 to help bring this project to life.

More about the PonoPlayer Design


Many of the more technically inclined have asked for more details about what is so special about the PonoPlayer 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 begin 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 cannot publish “specs” on an unfinished product. We belive our backers understand this idea. 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 PonoPlayer, 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 PonoPlayer to drive any headphone on the market with minimal frequency response errors.


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    1. Missing avatar

      Jose Lopez Martinez on April 25, 2014

      Damping factor????
      Eaerphones 16 ohm??

    2. Missing avatar

      JohnW on April 14, 2014

      So I was thinking - who expected Neil Young to be associated with a "zero-feedback" device?

      Yes, I was listening to "Arc" over the weekend. Why do you ask?

    3. Peter Beck on April 12, 2014

      Does a lower output impedance mean that it plays louder, and a higher output impedance mean that it plays quieter? I know that a louder headphone impedance level means that it plays quieter ...

    4. Jonathan Gorman
      on April 12, 2014

      In one breath we are being told this will bring the soul of music, but the specs of the player is undetermined and 50 units with the same specs can sound different. Different good or bad?

      For a product that's been kicking around for some time, there seems to be a lot up in the air. Based on the people posting, I think they will be using lower imped phones.

    5. Missing avatar

      Ahmad Shahrin Bin Ramli on April 11, 2014

      Hm,use just released ess9018,2channel?it 9018K2M,most probably the lower version of the original 9018,8channel.Please clarify

    6. the PonoMusic Team Creator on April 11, 2014

      @Lyle C. Gayne
      Lyle we agree. The digital audio field is in large part science, but it's also part art. Not all audio engineers agree on everything. But that's when you have to pick one superstar and trust them to take you to promise land. That's exactly what Charlie has done for us.

    7. Missing avatar

      Lyle C. Gayne on April 11, 2014

      We shouldn't be too concerned about measurable specs, as every serious listener know that you can take 50 products with similar (and impressive) secs, and they can sound surprisingly different. There is a great deal going on in music reproduction that hasn't yet been figured out or represented in current audio measurements - for example, why tube gear can sound so much more appealing, or real, than solid state gear which appears to be more accurate if measurements alone are one's guide. there is no substitute for a trained ear, or for experience in audio design, to produce results. It is at least as much art, as science. Just like music itself!

    8. the PonoMusic Team Creator on April 11, 2014


      John posted the clarifications as Update #24. Please review when you can. Here's some feedback from a top audio engineer who is a friend of the company, but not affiliated with Ayre:

      "I think 5 ohms is a good number here. Lower will not necessarily be better. I would agree with Charlie on this one. ... . Some real impedance will insure stability also and perhaps less sensitivity to RFI."

    9. Missing avatar

      JohnW on April 11, 2014

      Looking forward to the clarification. As I mentioned on the main comments page, 5 ohms may be a dealbreaker for me.

    10. the PonoMusic Team Creator on April 11, 2014

      We will provide a clarification on the output impedance shortly.

    11. the PonoMusic Team Creator on April 11, 2014

      Yes indeed. We're very much opposed to upsampling and will make sure everything we sell is truly the resolution it is sold as.

    12. Missing avatar

      Bastian on April 11, 2014

      Hi @Pono team

      A spec I would like to ask you about is whether you can include the functionality of controlling the PonoPlayer with the iPhone controls that many headphones have?

      I was looking at the sennheiser momentum the other day, and noticed that it includes a corded control for volume and play/ pause, and couldn't help but think that it would be cool to control the PonoPlayer with those buttons.

      I don't know if you have to pay some sort of license to Apple, but if you don't it would be cool.

    13. MobiusEngine on April 11, 2014

      Now say that again for the less technically inclined...

    14. Levvy on April 11, 2014

      @Seb Riou
      For a portable DAP, 5 ohms is not freaking low

    15. Stephen on April 11, 2014

      So will the site actually validate the files on offer are actual "hi-res" audio files and not just upconverts missing signal above 44 Khz? HD Tracks has taken a ton of flack for their presentation of music as "HD" but in reality just being upsampled from CD sources.

      And therein lies the problem - Pono will rely on music delivered by the music industry. If what we are given are improperly mastered audio from the improperly mastered CD versions, which are then used to create the crappy MP3 versions, what's the difference w/ the Pono? The only difference is the player (which will be phenomenal). So I can just rip crappy mastered music from my own CDs and dump them on the player.

      I really hope the Pono team sticks with integrity. Ensure the files they offer are truly better than CD. It's pretty easy to see when a file is just an upconvert, so I hope someone sits in as a middle man between the what the record companies deliver and what Pono sells, with Pono stopping crap from filtering into its music store.

    16. Missing avatar

      joey192 on April 11, 2014

      Could the PonoPlayer support 384khz ?

    17. Missing avatar

      Seb Riou on April 11, 2014

      For Guys who want to lower the output impedance : 5 Ohm is already freaking low.

    18. Missing avatar

      John Ivan Greilick on April 11, 2014

      Please do not include an EQ in the user interface. Thanks.

    19. Ryan Litwin
      on April 11, 2014

      David, good point as there is more than just the output that can affect things. That is the danger of "internet engineers" like myself, lol. But I agree, it is fun to experiment. My advice is to enjoy this ride and read up and learn things, I enjoy that part!

    20. Missing avatar

      robert hake on April 11, 2014

      "no overshoot & no undershoot ..." is a nice quote for the l.e. t shirt you could celebrate each and every kick with.

    21. Missing avatar

      John Ivan Greilick on April 11, 2014

      Nice man. I'll bet it'll sound great. I don't really care whether I can read the specs until after I hear it. I'm the same way with audio gear that I print with. If someone I trust tells me a piece sounds great, I'll listen to it and then read the specs later. This can be a lot of fun and surprising sometimes.

    22. Ryan Litwin
      on April 11, 2014

      Another good read and food for thought.... or just to stir it up!

    23. Levvy on April 11, 2014

      Usually the impedance won't affect headphones that much. Even the ak100 with 22ohm impedance had little effect on the Sennheiser momentum which is around 16ohms.
      The high output impedance affects multi balanced armature drivers type more.

    24. Paul Haggerty on April 11, 2014

      I appreciate going into some of the engineering details and how they chose the different parts. It still would've been cool to see the specs of your prototype, since that's what all the testimonials you've been showing us are really about.

    25. Kjell Ims on April 11, 2014

      @Lawrence I'm no expert, but 55 Ohms should be fine. There should be a pretty wide "good to optimal" range of headphone impedance. Basically you want your headphone impedance to be roughly 8 times or HIGHER than the amp output impedance, but within reason. I wouldn't expect trouble until you started hitting a couple 100 ohms on your headphones, but again, I'm no expert.

    26. Missing avatar

      Michael Keeley on April 11, 2014

      Will the Pono team discuss audio mastering at any point in these updates, specifically whether there will be any push by Pono to restore dynamic range/avoid "brickwalling" and unnecessary loudness that is prevalent in modern masters? There is conversation that high resolution files won't make much difference if the mastering is too loud.

    27. Ryan Litwin
      on April 11, 2014

      Kjell, many people think Fiio works to keep it low just to take the "fight" out of people who track it and for whom it would be a deal breaker. I tend to think that Ayre will do fine so I am not worried. I just wanted to post a pretty good article so people have a general idea. But, by no means am I jumping in to "yay" or "nay" this for anyone but myself! I am keeping mine because I have trust in Ayre to make a quality product.

    28. Ryan Litwin
      on April 11, 2014

      But to keep it interesting, many people say as long at it less than 7 it is fine. So, just putting out info. Like everything in hi-fi there never seems to be one answer. iPods can be as high as 7 (so many versions, but take a look in google). I wonder if they meant 5 or .5 only because it could technically be either of those.

    29. Kjell Ims on April 11, 2014

      @Ryan I was wondering the same thing. 5 ohms is rather high it would seem. My Grado SR80 are around 32 Ohms, so I have more or less the ~8 times difference, but not quite.. Still, my thoughts are to stick with Pono, then if I don't like it, I could sell it (possibly at a loss) and get a Fiios device instead. :)

    30. Ron H
      on April 11, 2014

      Will there be a digital out along with the analog out?

    31. Missing avatar

      Lawrence Engel on April 11, 2014

      I use some inexpensive studio monitors by AKG (K-240). They have a Rated Impedance of 55 Ohms. That seems like a BIG difference from the PonoPlayer: "output impedance is roughly 5 ohms." Will I need to purchase special headphones for my new Pono?

    32. Ryan Litwin
      on April 11, 2014

      I do wonder if they meant .5 instead of 5 actually. For example, Fiio X3 is .3

    33. Missing avatar

      Man Hin Cheung on April 11, 2014

      +1. Output impedance needs to be lowered. It is marketed as a portable player, after all.

      Plus no one has answered my question about EQ and Crossfeed. These are basic features, so there's no excuse of not including them.

    34. Ryan Litwin
      on April 11, 2014

      From Head-Fi on impedance. Remember headphone impedance and amp output impedance are not the same. Generally lower amp output impedance is better overall for a wider range of headphones.
      What is Headphone Impedance?

      Headphone Impedance is the electrical characteristic of the headphone voice coil and magnetic field coupling of the voice coil & magnet inside the headphone.

      Impedance is an electrical unit which expresses the combined Resistance, Inductance and Capacitance of the headphone's voice coil.

      In terms of matching to an amplifier, the headphone impedance is the "Load Impedance".

      An amplifier drives a headphone with voltage, the current drawn by the headphone is proportional to the headphone's impedance.

      As a rule of thumb, the load impedance (headphone) should be at least eight times higher than the amplifier output impedance.

      This allows the amplifier to exert more control over the headphone, i.e. the lower the output impedance of the amp, the higher the damping factor and the higher the efficiency of the amplifier/headphone interface (See note 1 for additional detail).

      Some basic electrical theory:

      •Voltage = Current x Impedance, in AC circuits, i.e. music, power lines, etc.
      •short form for voltage is "V" and is expressed in Volts
      •short form for current is "I" and is expressed in Amps
      •Power = Voltage x Current,
      •short form for power is "P" and is expressed as "Watts"
      •Impedance = Voltage/Current, short form for impedance is "Z"
      •Resistance = Voltage/Current, short form for resistance is "R", this is for DC circuits, i.e. power supplies, batteries
      •see note 2 for definition of Voltage and current, see note 3 for definition of resistance, inductance and capacitance.

      Here's an example:

      For a headphone to receive 2 watts of electrical power (this is almost never the case, just a simple example) it can be driven by:
      1.1 Amp @ 2 Volts , or
      2.2 Amps @ 1 Volt.

      therefore if 1 Volt draws 2 Amps of current the headphone has an impedance of:

      Impedance = Voltage/Current (or Z = V/I)

      therefore Z =1/2 Ohm.

      Based on Z=V/I, we can deduce that Case 1 will have an impedance of 2 Ohms, and Case 2 will have an impedance of 0.5 Ohms (see note 4).

      Again, this is just an example, headphone impedances are actually much higher.

      Headphone power levels are almost always much lower, for example: 1 - 10 milliWatts.

      1 milliWatt (mW) is 1/1000 of a Watt.

      If a 600 Ohm headphone draws 10 mW, Voltage = 2.44 V, current = 4.1 milliAmps (mA)

      If a 32 Ohm headphone draws 10 mW, Voltage = 0.56 V, current = 18 mA

      Pros and cons of high impedance headphones:
      1.Headphone impedance is usually increased by thinner wire and most importantly more turns of wire in the voice coil. More turns or loops creates a larger field (area of magnetic influence). In layman's terms more magnetic force for the coil to move the diaphragm. Thinner wire usually works out to a lighter, more responsive diaphragm. Depending on the headphone design, this may lead to more accurate response.
      2.The displacement (amount of movement) of the diaphragm (the part that vibrates to produce sound) can be better controlled via a more accurate flux (magnetic field to pull and push the diaphragm).
      3.Difficult to drive for small headphone amps with low output voltage and low gain.
      4.Most high impedance headphones need an amplifier with higher voltage gain and higher output voltage, e.g. the 600 ohm Beyer DT770/880/990 series.
      5.Allow Solid State Op Amps to work more efficiently with less distortion. Have a look at Op Amp data sheets and a graph of distortion vs. output impedance for most audio Op-Amps and you'll get the idea. This is a very complex subject, but most Op Amps are designed to output (typically) up to 10 Volts into 600 ohm loads or higher.

      Pros and Cons of low impedance headphones:
      1. Headphone impedance is usually decreased by thicker wire and less turns of wire in the voice coil. The magnetic field is built up by more current.
      2.Easier for small and/or portable headphone amps to drive. For example: an iPod or MP3 player headphone jack. Many small and/or portable headphone amplifiers are designed to output a volt or two into low impedance, high efficiency headphones, e.g. Grado headphones.
      3.Low impedance, low efficiency headphones usually sound better when driven by a desktop amplifier, e.g. Audeze LCD-2 or AKG K70X.
      4.Low impedance headphones usually sound better when driven by a solid state or a transformer coupled vacuum tube amplifier. Low impedance headphone do not usually work well with Output Transformerless vacuum tube amps.

      Generally, a properly designed desktop headphone amplifer can drive high and low impedance headphones and can drive headphones of any efficiency.

      Do high impedance headphones sound better than low impedance ones?

      No, there are many very good low impedance headphones available and many very good high impedance headphones available.

      In headphones, the sound also depends upon the following:
      1.Frequency response, this is a representation of volume decreasing or increasing with frequency, this is actually the magnetic field pulling and pushing with different amount of force at different frequencies, impedance affects this in complex ways.
      2.Distortion, represents the amount of "change" from the actual signal to the real signal (i.e. input signal to output signal).
      3.Build and design, i.e. sealed vs. open, etc.
      4.Diaphragm design, voice coil design

      To conclude:

      High impedance headphone: requires more voltage but less current

      Low impedance headphone: requires less voltage but more current

      Amplfier output impedance: the lower the better for any impedance headphone

      higher efficiency (for example: 102 dB/1 mW) less power required

      ​lower efficiency: (for example: 91 dB/mW) more power required

      How they effect sound is dependent on the magnetic field generated and diaphragm construction (physical response of diaphragm).

      We hope this clears the air.

      A few notes:

      1.Some people prefer the sound of vacuum tube headphone amplifiers which usually have higher output impedance relative to solid state (transistor) amplifiers, and therefore have poorer damping factor and hence, fuller bass.
      2.Voltage is electrical pressure, current is flow of electrons
      3.Resistance is constant with frequency, capacitance creates lower impedance at higher frequencies, inductance creates higher impedance at higher frequencies
      4.Headphone impedance is actually quite complex and different driver designs have different impedances at different frequencies and (to a lesser extent) voltage amplitude
      5.Assumes diaphragm construction to be similar and magnetic field to be similar
      6.Assumes linear response at all frequencies (not possible for dynamic driver headphones)
      7.Assumes that impedance increases with change in coil characteristics only.
      8.Assumes speed of electrons in an electrical circuit is constant, it does not change with voltage or current or power.
      9.Other headphone types which do not have a voice coil (for example, those sold by Hi Fi Man, Audeze and Stax) can also characterized by their electrical impedance.

    35. Levvy on April 11, 2014

      @Puhn, a high chance it will, unless you're lucky and the synergy pairs of well.
      But that limits the choices of multi BA type IEMs we get to use with the player

    36. Puhn Chaturaphit on April 11, 2014

      My Shure SE846 has a 9 ohm impedance. That'd affect the frequency response, wouldn't it?

    37. Missing avatar

      Elizabeth Van Pelt on April 11, 2014

      Thanks creator and Charlie for the detailed update!

      I saw some "prototype" pics that were posted and would love to see more if you have them. Any interesting abandoned designs?

      Thanks again; can't wait for Oct/Dec!

    38. Levvy on April 11, 2014

      5 OHMS!!!?? That's the output impedance?
      Have you guys thought about the people who uses IEMs which are usually at around 15-16 Ohms?
      Looks like i'll be dropping my backing soon..