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Need help understanding planar cans like LCD-2 and HE-5

post #1 of 13
3/1/11 at 1:27am
Thread Starter 
So, I've been doing some preliminary research and its conflicting with what I'm reading here. Need some help understanding planar headphones. Background - my father used to do speaker installations and when I asked him about planar magnet headphones/speakers he said that the diaphragm doesn't move very far and thus creates a very flat sound that lacks a lot of bass response.

"Never cared for them all that much because they had an inherent problem with deep bass. Generally paired with a decent woofer for the lows. Have the advantage in that they are flat, have very little depth and can be wall mounted or embedded in furniture more easily than with conventional Cone Speakers. "

So what makes the LCD-2 and He-5 different than regular planar-magnetic speakers:
http://electronics.howstuffworks.com/speaker11.htm - looks like they function similarly to electrostatics.

How are they able to produce a decent amount of bass guitars and cellos aren't left lacking in recordings, much less deep percussion instruments?
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post #2 of 13
3/1/11 at 2:32am
Thread Starter 

Edit:

Talked with my father again, he clarified for me that stereo speakers play by different rules than headphones.

 

Quote:
What works in miniature often doesn't scale up. Headphones have the problem of small dimensions and limited space for creating sound waves.
 
It is quite possible that planar speakers are a better solution than coil and cone speakers when used in headphones. I know my Sony Headphones (Digital) have great sound and use electrostatic and planar elements. At $400, the electronics and sound are far superior to convoluted mylar cone speakers in other headphones I have owned. Even if I can't hear a lot of the differences anymore.
 
In headphones, the ability to produce a flat waveform over the entire audible spectrum is a plus, whereas it is very difficult to produce similar sound in a large room with planar elements. That's why I never cared much for planar speakers for a stereo system.

 

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post #3 of 13
3/1/11 at 2:58pm

Simply put, the planar diaphrams are very closely coupled to the ear.  They do not have to project sound across a large space as is the case with speakers.  While my Maggies do not reach the bottom octave of bass, the overall SQ, imaging, and sense of realism makes them a very enjoyable listen, and hence relegated my box speakers to storage.  

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post #4 of 13
3/2/11 at 12:32pm

Just for grins, consider also, that Maggies would easily plumb the depths of the bottom octave if they were mounted in infinite baffles.  I've done it and while it greatly troubles the neighborhood, it sounds stupendous as far as LFR.

 

Virgil Fox and the 32' pipes at two blocks away, well, actually, one block away.

 

I did this a lot as a kid and the neighbors hated it then too.  ;)

 

It's all a matter of acoustic impedance matching, and properly dealing with rear wave radiation.

 

When I was in college, 100 years ago, I did a few custom in home installations for sound systems and used planar speakers mounted in wall.  I used the space behind the speaker for a baffle, and hung the client's art (acoustically transparent) over the speakers for aesthetics. Invisible wall of sound, with great LF along with everything else. 

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post #5 of 13
3/5/11 at 12:23pm
My HE-6's, properly driven, have the best bass I've ever heard. That goes for headphones and speakers.
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post #6 of 13
3/5/11 at 6:40pm

I had Apogee Scintilla ribbon speakers. I also listened to Apogee Divas. Both are planars. They had bass. Lots of bass. It just depends on the dimension of the bass panel, the larger the better. They are very inefficient and needed amp with lots of current. They have amazing soundstage depth, dimensionality and palpability specially with Jazz.

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post #7 of 13
3/6/11 at 2:25pm
Thread Starter 

What do ya'll mean by 'inefficiency' in headphones?  I don't really understand electricity beyond the very basics.  Something I hope to change, but regardless.  I keep getting confused between the terms. 

 

Do planar speakers/cans need lots of amperage?

Are they low or high impedance and how is that related to resistance?

Other than the wiring, where is the part that needs so much current? 

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post #8 of 13
3/6/11 at 3:38pm

Read this.

 

Efficiency in headphones is (I believe) just that: the power input required to produce a given sound pressure level. Power is voltage times current.

 

Resistence is the real part of the impedance. Resistance doesn't change across the frequency spectrum, impedance does. Impedance is voltage divided by current (both in the frequency domain in this case).

 

The volume control knob controls voltage. Hence, the power that goes in (and the sound level produced) depends on the impedance. The higher the impedance, the lower the current drawn for a given power.

 

Planar magnetics are low impedance and low efficiency, hence they need both high currents and high voltage swings, but amps usually have no problems providing voltage, it's the current that hurts.

 

The part that needs current is the voice coil, usually a copper track. I think they require the higher currents in order to generate enough of a magnetic field to move the diaphragm (since they are planar and the field is spread over a large area, unlike the windings on cone dynamics, where the field is concentrated in a small volume).

 

 


Edited by Wildstar - 3/6/11 at 4:16pm
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post #9 of 13
3/7/11 at 12:10am

I need to clarify things a bit.

Quote from Scornergy:
What do ya'll mean by 'inefficiency' in headphones?  I don't really understand electricity beyond the very basics.  
Something I hope to change, but regardless. I keep getting confused between the terms.  
 
Do planar speakers/cans need lots of amperage?  Are they low or high impedance and how is that related to resistance?  Other than the wiring, where is the part that needs so much current? 

 

Headphone efficiency is measured and specified by sound pressure level in dB (deciBels) produced by an amount of input power in mW (milliwatt).  It is expressed as a ratio xxmW/dB.  The efficiency of a few planars is quite reasonable and better than some dynamics, there are also dynamics that have much lower efficiency, so, a planar design does NOT necessarily mean low efficiency.  Two examples of relatively high efficiency planars are Fostex T50RP @ 98dB/mW and the Audeze LCD-2 @ 91dB/mW.

  • The efficiency of planars varies a great deal from can to can just as it does with any other technology based headphone.  Historically, they have been more power hungry than the higher efficiency dynamics, but there were and are exceptions to any rule.  The best planar headphones do requite a good and powerful amp to sound their best.  The same is true for the best dynamic cans as well.

 

  • Conventional dynamic headphone impedance ranges from about 16 ohms to 600 ohms.  The impedance of a typical planar magnetic headphone is usually around 50 ohms and almost purely resistive, having almost no inductive or capacitive components to their impedance, unlike typical dynamic cans whose impedance can vary from 80 to 300 ohms in one can, depending upon the frequency of the sound being reproduced.  This purely resistive nature makes the planar magnetic headphone a relatively easy and stable load for an amplifier to drive.  
     
  • There is nothing that consumes current other than the traces on the diaphragm of a planar magnetic headphone, just as the voice coil of a conventional dynamic headphone.
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post #10 of 13
3/7/11 at 3:25pm
Quote:
Originally Posted by Scornergy View Post
"Never cared for them all that much because they had an inherent problem with deep bass. Generally paired with a decent woofer for the lows. Have the advantage in that they are flat, have very little depth and can be wall mounted or embedded in furniture more easily than with conventional Cone Speakers. "?

a planar dipole spkr such as a Maggie, or electrostatic spkrs, need breathing room around them (ie. they need to away from the wall behind them by a fair amount) to properly 'breathe' and produce a spacious sound. it's hard to imagine them exhibiting their best sound placed up against a wall! actually most speakers sound better pulled out into the room, but it's even more important when their backwave is part of the sound vs it being deliberately absorbed/blocked. it really helps their imaging and can help with the spectral balance.
 

 

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post #11 of 13
3/11/11 at 10:15am
Quote:
Originally Posted by daveDerek View Post

a planar dipole spkr such as a Maggie, or electrostatic spkrs, need breathing room around them (ie. they need to away from the wall behind them by a fair amount) to properly 'breathe' and produce a spacious sound. it's hard to imagine them exhibiting their best sound placed up against a wall! actually most speakers sound better pulled out into the room, but it's even more important when their backwave is part of the sound vs it being deliberately absorbed/blocked. it really helps their imaging and can help with the spectral balance.


True enough Dave, but how do we apply this understanding to headphones?

 

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post #12 of 13
3/11/11 at 9:45pm
Quote:
Originally Posted by kwkarth View Post

True enough Dave, but how do we apply this understanding to headphones?

don't sit in the corner but rather have your listening chair well out into the room.  tongue.gif
 

 

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post #13 of 13
3/11/11 at 11:40pm
Quote:
Originally Posted by daveDerek View Post

don't sit in the corner but rather have your listening chair well out into the room.  tongue.gif



Got it! L3000.gif  ksc75smile.gif

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