Some KEY points for project context and **choice of speaker drivers**

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I posted this in the “Challenge” thread, but felt it deserved it’s own post. If there’s one thing I can get passionate about designing, it’s headphones!!!

Hi everyone. I was one of the original writers quoted in the first post that kicked off this campaign to design a pair of headphones. I love headphones and audio design. I have a little bit of technical knowledge, as well - and I think I have a broad enough understanding to help everyone here get a bit more knowledge on this subject and reasons why wireless headphones seem to always pale in comparison to wired.

I’ll start off with a couple points.

  1. Wireless headphones need electronics. Wired headphones do not.
  2. There is more than one major technology for speaker drivers. Planar magnetic is one (example at low price-point) that I strongly feel we should consider because it would drastically set us apart in some areas, and there’s not a lot of competition. I was going to put these links at the end,but they really do need to be up front:

CNet reviews HE-400 - “First-rate clarity, detail, and bass impact by way of new driver technology help propel the HiFiMan HE-400 headphones to the top of their price class”
rtings.com - planar explained
Massdrop - HD4xx Planar headphones: “As for quality, once again, at $169? I can’t name another set of headphones at this price point that can beat it in the full-size market. Yet, the headphone is also a Planar too? Okie Dokie!”

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This seems simple on the surface, but there’s really a lot involved here. Why should you read this information? To help us keep perspective.

Electronics add complexity to the question of “good sound”. Lots of complexity. Especially to something as sensitive as audio. I’m all for packing all of the community mentioned features in, but we must be very careful not to sacrifice acoustical design for these features.

It goes from simple wiring to complex electronics as soon as you add Bluetooth. Why? Signals. The source must send a digital signal to the receiver to use Bluetooth. A digital signal now means that the conversion from digital to analog and the amplification step must happen in the headphone. This introduces a lot of complexity, potential for interference, and automatically comes with drawbacks.

Effectively: wired = 3.5mm jack, a headband, ear pads and speaker drivers. Simple. Wireless? You need a 3.5mm jack, a headband, ear pads, speaker drivers, an amplifier, a DAC, EM shielding, a Bluetooth receiver/computer to process the signal, a battery, a charging circuit, as well as any ANC hardware (which is a whole 'nother set: microphones, processing chips, etc). There’s a LOT of complexity here. Once you add all these electronics and a power circuit into the headphone, you need more parts to make sure there is no interference introduced into the sound.

If your budget for PRODUCTION of headphones is $150 USD, all-in, for a 25% profit margin after all expenses, you can put a lot of effort into designing a wired pair of headphones. You can’t just slap expensive drivers with some pads into a headband and call it a day. There’s design involved. Obviously, you could use some incredible drivers and materials with a $150 budget, and still have a good audio design.

If you try to do the same thing wirelessly, well…we need to be careful. A good pair of wireless headphones will need to have an incredibly low noise floor to compete with wired headphones. This is hard to do with all of those electronics packed in so closely together. This takes design time.

To illustrate this point, a very popular DAC/AMP unit is the FiiO E10K. This is a very nice little unit, and really makes any reasonably good pair of headphones sound really good. The DAC chip used in this unit costs pennies. I believe it’s under $2. That’s what makes the unit tick, as well as the amplification hardware. I’d estimate the actual hardware costs $10 at most. It’s the design to make sure there’s no interference and the ouput is clean. No noise. I actually own this amplifier - it blows away the hardware in my phone as well as my desktop PC. Not even remotely comparable. A good amplifier and DAC circuit is very important to quality of sound.

This little amplifier costs $75 USD, and I believe the original MSRP was higher. That’s just the DAC and amplifier, let alone a much more complex system with many more electronics that involves putting all of that hardware right next to the analog outputs (otherwise known as the speaker drivers).

Electronics in headphones make it very difficult to design a pair of headphones for a serious listener, or even someone who just really likes music.

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.2. Planar magnetic drivers. Fairly simple concept, actually. Regular drivers, properly known as dynamic drivers, use a diaphragm that is vibrated by a magnetic coil which is attached at the neck of the diaphragm. This diaphragm is a thin sheet of material, generally cone-shaped. The vibration produces sound. A planar driver is similar - except the diaphragm is vibrated by magnets which run parallel to it. Since it is suspended by the magnetic fields produced by the magnets, it can be extremely thin, and since it is so thin it is much more responsive, especially at bass frequencies.

Planar technology has inherent benefits which surpass what is possible with regular drivers. They come with some drawbacks, but the technology has greater potential than dynamic drivers. One example is when you compare planar headphones to high-end dynamic headphones. An example is headphones that are “hard to drive”, or “high-impedance”. What does this mean? It means that the magnetic coil we mentioned earlier is thinner, which provides more accurate sound. It also means it takes more electricity to produce the same amount of volume. Most high-impedance headphones CANNOT be used on the go with your phone, since they require powerful amplifiers to work properly.

The precision afforded by the diaphragm design in a planar driver allows for lower distortion in the audio signal and improves clarity, similar to a high-impedance dynamic headphone, while not requiring more power. Using planar drivers could also help counter noise introduced by electronic circuits inside the headphone, since we’re going all out on features.

Planar headphones are known for having very powerful bass, while still being very clear. The clarity provided in low frequencies by planar drivers is natural to the technology - you can get powerful yet good quality bass with planar much more easily than dynamic headphones, without making any major sacrifices in clarity and power in the upper frequencies.

An example of high-end Planar headphones is the LCD series by Audeze, with their website linked here.

At the top are a few more sites as reference material, with some real proof that planar technology is the clearly superior choice for an “underdog” product that really wants to shine.

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