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iems/ciems with multiple bore outputs

post #1 of 7
Thread Starter 

So, there are iems/ciems with multiple bore per multiple way cross-over designs.  Most I've run across is the Spiral Ears 5-way pictured below.  How do multiple bore design that has separate bore per it's separate frequency range per set of drivers it's dedicated for benefit?  What do they do to the sound outputted?  To me it sounds to me like there are better separation, and clarity.  

 

 

 

 

 

 

 

 

 

 

post #2 of 7

it's more a choice than THE ultimate solution.

sennheiser always believed that one driver was the best solution because it was better to work on frequency response than to try solve phase and crossover problems.

obviously in multi BA drivers the other choice was made, for easier work on frequencies and to get a better range than just one BA (but still usually less than one dynamic driver).

 

the purpose of several bores as you can guess is to keep each range of frequency separated until the very last moment to avoid possible interference. usually the trebles suffer the most in multi BA IEMs(that's why Suyama san tried the metal tube for the treble driver on the 334).

 

my take on all this is:

+ you get a 2, 3, or 5ways almost up to your brain so each driver can output a clean sound with reduced interference from the others

+ each bore being physically at a different place creates an artificial positioning that will help telling instruments apart in space.

+ it also helps(with the FR) to create an original headstage making the IEM kind of unique (for better or worse).

+ some trebles might end up having a slower roll off.

+ the tubes when using several bores might be used to control the phase between drivers(longer or shorter tubes), it might not be needed, and there are other ways, but it looks like a simple way to do it if needed.

 

- each crossover will either have 2drivers overlapping the same frequencies, or there will be a hole in the FR graph. it's pretty much impossible to hope for perfect filters that will make one driver stop exactly when the other one starts. (but that is a problem in all multi drivers, not just those with multi bores.

- some instruments will make sounds that will need 2 or 3 drivers to be transmitted, if there is a very noticeable spacial positioning effect due to the bores, it might seem unnatural.

- same with sounds going up or down in frequency(let's say guitar of piano playing some notes at 200hz then steadily going up to 2khz), it might seem as if the instrument is moving or jumping. can be fun, or disturbing. and for spacial sound effects (someone walking, a plane passing... that kind of stuff) if you pay attention, you might notice the plane jumping from a place to another at one point in the doppler effect. so not realistic. with several crossover and a single bore, chances are that the spacial cues will work better because the sounds will mostly come from the same area. you might still be able to notice a small jump from one point to another but obviously one bore per driver adds in panning precision, again for better or worse.

 

I usually find that tremendously fun, to me headphones don't create a realistic soundstage anyway(180degree intead of 60 for speakers or even less for a real band). but someone looking for the "real perfect sound and imaging of headphones" should simply avoid multi drivers.

if you like multi BAs then multi bores always sounded better/funnier to me(didn't try 5bores, 4crossovers seem a bit overkill to me for what is actually needed, but maybe it's the ultimate fun...).

post #3 of 7
Thread Starter 

Well, there are those that own CIEMs talk of 3D, and this isn't some BS from what I hear.  I do hear imaging.  It's interesting how the CIEMs are molded to your canals and the acrylic creates a tunnel creating a very deep insertion, but yet, it can create a locational sound depending on the recording.  I don't have good sampled experience to be conclusive on the correlation, but I say there is a correlation between crossovers and the imaging and separation.  

 

Lets not forget the CIEMs are based on hearing aids, and some hearing aids have imaging simulators to help those of hearing disabled locate sound source.

 

What I like to know is how the multiple bores create a separation of sounds and possibly imaging.  This is quite intriguing.  :etysmile:

post #4 of 7

Multi-bore (on universal) is actually a patent of UE / Logitech, IIRC. Find and read the paper.

post #5 of 7
Thread Starter 
Quote:
Originally Posted by castleofargh View Post
 

it's more a choice than THE ultimate solution.

sennheiser always believed that one driver was the best solution because it was better to work on frequency response than to try solve phase and crossover problems.

obviously in multi BA drivers the other choice was made, for easier work on frequencies and to get a better range than just one BA (but still usually less than one dynamic driver).

 

the purpose of several bores as you can guess is to keep each range of frequency separated until the very last moment to avoid possible interference. usually the trebles suffer the most in multi BA IEMs(that's why Suyama san tried the metal tube for the treble driver on the 334).

 

my take on all this is:

+ you get a 2, 3, or 5ways almost up to your brain so each driver can output a clean sound with reduced interference from the others

+ each bore being physically at a different place creates an artificial positioning that will help telling instruments apart in space.

+ it also helps(with the FR) to create an original headstage making the IEM kind of unique (for better or worse).

+ some trebles might end up having a slower roll off.

+ the tubes when using several bores might be used to control the phase between drivers(longer or shorter tubes), it might not be needed, and there are other ways, but it looks like a simple way to do it if needed.

 

- each crossover will either have 2drivers overlapping the same frequencies, or there will be a hole in the FR graph. it's pretty much impossible to hope for perfect filters that will make one driver stop exactly when the other one starts. (but that is a problem in all multi drivers, not just those with multi bores.

- some instruments will make sounds that will need 2 or 3 drivers to be transmitted, if there is a very noticeable spacial positioning effect due to the bores, it might seem unnatural.

- same with sounds going up or down in frequency(let's say guitar of piano playing some notes at 200hz then steadily going up to 2khz), it might seem as if the instrument is moving or jumping. can be fun, or disturbing. and for spacial sound effects (someone walking, a plane passing... that kind of stuff) if you pay attention, you might notice the plane jumping from a place to another at one point in the doppler effect. so not realistic. with several crossover and a single bore, chances are that the spacial cues will work better because the sounds will mostly come from the same area. you might still be able to notice a small jump from one point to another but obviously one bore per driver adds in panning precision, again for better or worse.

 

I usually find that tremendously fun, to me headphones don't create a realistic soundstage anyway(180degree intead of 60 for speakers or even less for a real band). but someone looking for the "real perfect sound and imaging of headphones" should simply avoid multi drivers.

if you like multi BAs then multi bores always sounded better/funnier to me(didn't try 5bores, 4crossovers seem a bit overkill to me for what is actually needed, but maybe it's the ultimate fun...).

Ha! Thanks for the detailed analysis.  It makes lots of sense.  

 

It would be interesting to compare with speakers.  It's odd how different instruments separate.  The imaging is also like there is depth or dimention to the sound.  I've heard flat phones, or just in one plane.  

 

What would be awesome is using the 5 way, 5 bore as positional sound system with sophisticated surround sound DSP.  Would be awsome, and hope it's coming out way.

post #6 of 7

I think it is a very complicated thing to do.

 

they already have a real hard time doing realistic dsp surround for headphones, so there is not much hope for IEM where the sound has to work the same magic + compensate for how the shape of our ears would have changed the sound (up and down is directly deduced from how the sound is changed by the head and on what part of the ear it is bounced back from). each ears being different makes for a complicated answer. maybe one day the mold will take the entire ear and be used to calculate the dsp correction? ^_^ could be fun.

 

to me customs should focus on getting the best crossovers/phase, stop being so picky on impedance and sensitivity(or maybe the other way around and actually have all sources for IEMs really outputting under 1ohm and reduce hissing levels). and try to solve the treble getting crippled by the other drivers, because most customs suck when it comes to trebles. sad thing when positioning cues work best with high frequencies.

post #7 of 7
Thread Starter 
Quote:
Originally Posted by castleofargh View Post
 

I think it is a very complicated thing to do.

 

they already have a real hard time doing realistic dsp surround for headphones, so there is not much hope for IEM where the sound has to work the same magic + compensate for how the shape of our ears would have changed the sound (up and down is directly deduced from how the sound is changed by the head and on what part of the ear it is bounced back from). each ears being different makes for a complicated answer. maybe one day the mold will take the entire ear and be used to calculate the dsp correction? ^_^ could be fun.

 

to me customs should focus on getting the best crossovers/phase, stop being so picky on impedance and sensitivity(or maybe the other way around and actually have all sources for IEMs really outputting under 1ohm and reduce hissing levels). and try to solve the treble getting crippled by the other drivers, because most customs suck when it comes to trebles. sad thing when positioning cues work best with high frequencies.

Yes, I agree.  Have you heard about the customs by Noble that you can switch between a set of drivers in the monitor?  Anyhow, they have put in a BA driver that has impedance close to Sennheisers(~300ohms).  The Dr. told me there are all kinds of BAs out there and high impedance ones exist and I bet of the ones of various sensitivities.  The UERM is close to 40ohms with only 3 drivers.  It's all out there, and it all depends on what the designer is going for I guess.

 

Also possibly the specs for customs are geared toward stage performers, and some are starting to pop up that is being tuned as reference monitors such as UERM.


Edited by SilverEars - 6/28/14 at 11:27am
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