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Multidriver BA iems, the benefits?

post #1 of 9
Thread Starter 

Ok, so I saw this video by Westone talking about more drivers will help create more flat FR.

 

 

 

Also was Jerry Harvey the first one to use more than one BA drivers for iems?

 

What's the benefit of the new 12 driver iems by JHA?

post #2 of 9

It would be the same as with speakers... If you have one driver, it has to produce all of the frequencies from 20Hz to 20kHz. That is quite a trick to design for a flat response. If you have multiple drivers, each one can be optimized to cover a smaller section of the audible range and it won't have to work so hard. The trick with multiple drivers is creating a crossover that hands off from one driver to the next without overlapping and doubling up frequencies at the join.

post #3 of 9

If you know headphone, you will know a really flat FR curve will sound terrible. By the time a flat FR speaker produced sound and that sound reached our eardrum, it will no longer be flat (by measurement) anymore. That sound still appear to the listener as flat because because our brain naturally compensate for the change, and we perceive it as flat. Since headphone is so close to our eardrum, a lot of the FR change that natural occurs due to room / environment acoustics and HRTF will no long apply. So in a sense you don't want a truly flat headphone, but you want a headphone with a FR that mimics what is supposed to "sound" flat to your brain.

 

Now every companies has its own 'ideal' FR. While you can try to design a single driver that match that ideal FR, it is however more difficult. So the workaround is to use multiple drivers by only using part of the FR curve in each driver that you want, sort of like a Lego puzzle. In the end, hopefully you will end up with a FR that is closer to your targeted FR curve.

 

I am not sure anyone has claimed to be the first to use multi-driver setup in the IEM world.

post #4 of 9
Quote:
Originally Posted by ClieOS View Post
 

If you know headphone, you will know a really flat FR curve will sound terrible. By the time a flat FR speaker produced sound and that sound reached our eardrum, it will no longer be flat (by measurement) anymore.

 

When I say flat response, I mean AUDIBLY flat... the way it sounds in the ear, not measured flat with a microphone. Audibly flat is the same for speakers as it is for headphones.

 

Audibly flat response is natural response. it's what we hear in everyday life. It's what live music played be real musicians sound like. It's the goal of any accurate playback system.

 

It's really easy to determine whether headphones are audibly flat. You listen to them and calibrate them with tone sweeps.


Edited by bigshot - 4/10/14 at 8:48pm
post #5 of 9
Quote:
Originally Posted by bigshot View Post
 

 

When I say flat response, I mean AUDIBLY flat...

 

Actually I was trying to point out to the OP (and not to you) about the last part of the video where the Westone guy is trying to explain a flat FR using an actual flat line with the whole 'speaker analogy', which obviously is different from how you will actual tune a headphone or IEM.


Edited by ClieOS - 4/11/14 at 12:32am
post #6 of 9
Ah! Sorry bout that.

I wish folks would use the term "flat response" as "perceived flat response" and use "measured response" for sound that doesn't involve ears. I think all the correction curves and technical stuff makes a balanced response seem more unachievable than it actually is.
post #7 of 9

Multiple drivers are used for a variety of reasons:

To extend the frequency response

To balance the frequency response

To give more headroom in loudness before they begin to distort

Paired BAs facing opposite directions can have less distortion than single BAs.

 

 

The 'natural' FR of a BA driver has a rolloff in the bass region, then a fairly flat section, then a peak as it hits the armature's resonant frequency, followed by the harmonic peaks and then another rolloff.

 

If you pick the armature's resonant frequency to match where your target peaks around 3 kHz, use a filter to even out the highs, you have something workable. Which is why Etymotic got it right more than 20 years ago without needing more than 1 BA driver. Not that this is easy. However, don't think you need more than 1 driver for top quality sound. Too many and you start to wonder what went wrong in the design process.

post #8 of 9

Surely Etymotic had it right 20 years ago given what engineers could do with a single driver.   Unfortunately they are lost in a stigma of the 1-driver syndrome as being best.    It is audibly impossible for 1 driver to efficiently represent the entire frequency range in a single square centimeter of an ear cavity.  Having said that ER4 would still be my first choice for mastering or mixing but would probably be my last choice for "listening pleasure" and that's where any argument needs to be distinguished.

 

Etymotic has an undisputible problem of lack of bass "realness".   The ER4 replicates bass "tones" fabulously (it goes down really low) but fails miserably from a tactile standpoint so it lacks "realisim" to the listening experience.  While "added" bass on a driver may seem fake, if it is done right it is absolutely necessary to replicate realism to the listener from a live listening setting.   That is the whole thing in a nutshell.

 

Within about 1 cubic centimeters space in your ear...multi-drivers are better at replicating a more expansive dynamic range response in such a tiny space allowing each driver to powerfully represent a narrow but significant frequency range.  It's necessary.  "Crossover" issues are a myth and probably the last thing to worry about.   Splitting frequencies is basic sound engineering.


Edited by Spyro - 4/12/14 at 3:35pm
post #9 of 9
Quote:
Originally Posted by Spyro View Post
 

 It is audibly impossible for 1 driver to efficiently represent the entire frequency range in a single square centimeter of an ear cavity...almost laughable.

[citation needed]

 

Quote:
but fails miserably from a tactile standpoint so it lacks "realisim" to the listening experience.  While "added" bass on a driver may seem fake, if it is done right it is absolutely necessary to replicate realism to the listener from a live listening setting.

[citation needed]

 

Quote:
Within about 1 cubic centimeters space in your ear...multi-drivers are better at replicating a more expansive dynamic range response in such a tiny space allowing each driver to powerfully represent a narrow but significant frequency range.  It's necessary.  

[citation needed]

 

Quote:
"Crossover" issues are a myth and probably the last thing to worry about or correct in this discussion.

[citation needed]

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