Electrostatic headphones are the undisputed kings of headgear when it comes to sound quality – it is only their price and power consumption which stops everybody wanting them! Some of their mystique can be dispelled by knowing the internal workings, but they’re still going to impress!
They operate on the principal that ‘opposites attract’, although Paula Abdul is not involved here. The technique has a thin membrane of plastic held in place between two electrode plates called ‘stators’. The membrane is coated in a conductive substance which allows a static field to be built upon it, and this in turn reacts with any audio signal which is fed to the stators.
Being statically charged, the membrane is attracted by any positive force held within the stators, and opposed by any negative force within them. Since any similar forces in the stators either side of the membrane will be effectively cancelled out, one of the stators is wired out of phase so that one stator is pulling the membrane whilst the other is pushing it. The effect of this is to double any force acting upon the membrane, much like two sawyers operating each end of a large saw.
This is also happening on the opposite side of the headphones; so along with energy required to build up the static fields on the membranes, more energy is needed to move them.
The combination of ultra-light membrane and powerful moving forces makes for a very accurate sound with great separation; since the membrane is acted on as a whole, it does not bend and this also avoids distortion. Also due to the fact this technology can cover all frequencies well beyond 20kHz, there is no need for the crossovers and multiple drivers which would cause distortion in a dynamic or balanced armature equivalent.
Orthodynamic, AKA Planar Magnetic or Isodynamic Transducers
If you think Orthodynamic headphones are for people recovering from ear operations, you might not be alone as the various names for this driver technology are not that well known. Perhaps due to the relative cost of this type of driver, it has not had the exposure of the ubiquitous dynamic version, for instance.
Orthodynamic: Technical term advanced / popularized by Yamaha Headphones in 1976 to describe their line of headphones at the time using a driver type known generically as isodynamic, planar-magnetic, or magnetostatic incorporating characteristics of both dynamic and electrostatic driver design.
Of all transducer methods, perhaps the most sumptuous-sounding is the electrostatic method, where a large thin membrane is suspended within a magnetic field which is affected by an electric impulse passing through it. The advantages of this is a very fast attack since the membrane can be thin and light with little to no inertia. On the down side, the technology is horrendously expensive and difficult to drive; a portable rig will likely require a backpack to power it!
A decent halfway house however is the planar-magnetic (AKA orthodynamic or Isodynamic) transducer type. Rather than the membrane being suspended between two electromagnets as in the electroststic method, it is suspended between two sets of permanent magnets; the audio information is fed through a thin wire on the membrane (the voice coil) which makes it react with the magnetic field it is suspended in. While this extra weight makes the membrane less reactive, this is a much cheaper and more efficient way to get near the electrostatic sound.
Some advantages of orthodynamic headphones over their dynamic counterparts include the flat driver with the voice coil controlling its entire surface. Since the membrane reacts across the whole surface at once, it does not need to be rigid which cuts down on weight and inertia. The result is a very fast driver which is particularly good at replicating a wide soundstage with great separation.
Balanced armatures are fantastic for detail, but find it hard work to replicate the very low, and very high frequencies. Also their relative lack of power keeps them mainly in the in-ear realm, where a good seal is required for decent bass perception.
My favourite? Just now I’m loving my full size orthodynamic HiFiMAN HE-400s but recent experiences with both dynamic and balanced armature-driven in-ears (such as the Sennheiser IE800 and Westone UM3X for example) tell me that it’s anybody’s game. There is no ‘best’, only what suits the listener at that particular point in time.
Mark from HighEnd Workshop, distributor and maintenance man for some very serious audio brands was kind enough to have a chat with me about headphones. Among others, he looks after HiFiMAN‘s distribution in the UK and is in the know about their exciting new range of planar magnetic headphones. This technology is also known as orthodynamic, or magnetostatic driver technology.
Lauri – Hello Mark, it’s nice to see you. Did you have any trouble getting here?
Mark – We are communicating by email.
Lauri – Of course. Perhaps then, I should ask what led you to be in your current position and what do you like best about it?
Mark – The company I previously worked for closed down, so I started a repair company (HighEnd Workshop). After 7 years I noticed that the repairs were slowing down so I decided to go into small scale distribution (something that is very niche) and offer an over the top service which comes from my background repairing £8000 cd transports and £14,000 amplifiers. Hence I started Electromod. The best thing about my position is it was my hobby (not so much now but i still get some time to listen). Also I run my company as I want and do not need to answer to anyone other than the customers.
Lauri – How does orthodynamic (or planar magnetic) technology work and does it have any advantages over dynamic driver technology in your opinion?
Mark – Orthodynamic headphones have drivers with flexible plastic film diaphragms (like cling film) into which a flat voice coil is imprinted in the shape of an S. It is embedded this way for an even distribution of the drive force. This allows the diaphragm to be driven equally over its surface, so you therefore do not need to make a stiff driver or cone; it is very lightweight and with this you have a faster reacting driver. These drivers or diaphragms are tensioned to supply returning force. The magnets are on one or both sides of the diaphragm and supply the magnetic field against which the flat voice coil reacts. This makes the diaphragm vibrate causing sound, the design of an orthodynamic headphone is somewhat similar to an electrostatic design and produces a similar sound characteristic.
Lauri – There are lengthy threads on headfi.org for instance, which describe how to go about modifying headphones such as the HE-400 in order to change the sound signature/fit etc. Do you feel that this is going against the ‘vision’ of the designers, or do you welcome such tinkering? Would HiFiMAN consider incorporating the ideas of modders into future designs?
Mark – My views are that everyone is entitled to their own expression and music is a very emotion thing. I offer one flavour of sound shall we say, and it is down to you to modify or not. I do not mind which but it is important to get the sound you like, if this means playing with a product to get this then so be it. But I don’t agree with playing about with any product and then trying to claim warranties when it goes wrong; that just goes against us and our policies of honesty. I do not think manufacturers will generally take any modding ideas on.
Lauri – What future do you see for orthodynamic headphones? Are they making an impact on the ubiquitous dynamic versions?
Mark – HiFiMan’s orthodynamic headphones are a very good choice and I hope they will make an impact on the overall market; but we still have a long way to go in educating customers that there are options other than dynamic headphones. People who follow Hifi understand the technology, but outside this bubble we still have work to do. It does help when dealers have them in their shop on show to demo, as normally once a customer hears the HiFiMan headphones it is hard to miss how good they are.
Lauri – How robust is this technology when compared to dynamic drivers? Is it easy for the careless to ‘blow’ a driver like with dynamic drivers sometimes?
Mark – Like all speakers, if you feed a driver with a distorted waveform or sound then you are reducing the life of that driver. I have been distributing HiFiMan since 2010 and up to now we have not had a driver fail! As I would say, it is down to the care that HiFiMan put into these ear speakers, and also you will find the customers who are purchasing these products are not normally the ‘head banging’ type and therefore are more careful of their products too!
Lauri – Why did HiFiMAN decide to include a dynamic-driver technology headphone (the HE-300) in the series?
Mark – This was all to do with efficiency; some customers wanted the Hifi-Man sound on their portable devices and since the orthodynamic headphones are a little hard to drive on these devices, it was thought that we would do a dynamic driver version to solve this issue and also be an entry point into the Hifi-Man brand.
Lauri – I see there are aftermarket cables available, consisting of pure copper and pure silver cores for instance. What do you think of this market?
Mark – Again this is down to personal taste. Getting a cable made to do a job, say XLR to BNC, well then that’s a great thing to offer as we all need cables made for different things.
Lauri – Is the low impedance of the HE- range a deliberate part of the design, or does it come with the orthodynamic technology?
Mark – As we understand how to build better and cheaper diaphragms as in the HE400, then the orthodynamic headphones will come more in line with the normal impedance headphones but the inherent design of orthodynamic headphones makes this a very big learning curve.
Lauri – Would you recommend headphone amplifiers with this range of headphones (for home and portable use)?
Mark – This is also down to personal taste but I would say the HiFiMAN amps go well obviously, then Schiit Audio, Trilogy Audio and I have heard good reports from customers who are also using the following: Icon Audio, Bryston and Epiphany Acoustics. But have a play and listen, as this is what it’s all about and I think some people forget this is supposed to be fun as well!
Lauri – Truer words have never been said. Thanks for the interview, Mark!
