[marcan]

Another problem is that the phase relation between frequencies below the cross point and above it is compromised, and this is not just at the cross point (I don’t talk about the phase cancelation but phase relation here). And it’s particularly audible on voices, drums, natural instruments, …

 

[ClieOS]

Sound tube tuned multi-driver earpiece
United States Patent 7317806

Inventors:
Harvey, Jerry J. (Newport Beach, CA, US)
Dyer, Medford Alan (San Diego, CA, US)

Assignee:
Ultimate Ears, LLC (Irvine, CA, US)

Publication Date:
01/08/2008

Filing Date:
01/17/2006

Abstract:
A method of optimizing the audio performance of an earpiece and the resultant device are provided. The disclosed earpiece combines at least two drivers within a single earpiece. If a pair of drivers is used, each driver has a discrete sound delivery tube. If more than two drivers are used, preferably the outputs from the two lower frequency drivers are merged into a single sound delivery tube while the output from the third driver is maintained in a separate, discrete sound tube. To compensate for the inherent phase shift of the earpiece the lengths of the sound delivery tubes, and thus driver offset, are regulated. Further audio performance optimization can be achieved through an iterative process of measuring the performance of the earpiece and making further, minor adjustments to the sound delivery tube lengths. The sound delivery tubes can include transition regions. The earpiece is configured to use removable/replaceable eartips. Acoustic filters can be interposed between one or both driver outputs and the earpiece output.

 

[marcan]

Thank you CljeOS.
It's interesting. I read the patent and UE website.
However they talked about a way to minimize the phase shift inherent to the earpice, not the electric crossover. Moreover they introduce a time delay in order to acheive this optimization...

 

[ClieOS]

Quote:

Originally Posted by marcan /img/forum/go_quote.gif Thank you CljeOS. It's interesting. I read the patent and UE website. However they talked about a way to minimize the phase shift inherent to the earpice, not the electric crossover. Moreover they introduce a time delay in order to acheive this optimization...

In the patent, they already state that the phase shift as an overall side-effect caused by the x-over circuit as well as all other factors (column 6 line 12 and forward) and time delay by offsetting some of the driver (column 6 line 47 and forward) is just a way to fix the phase swift. After all, offsetting driver to introduce delay and reflection/reverberation in big can is nothing new. The important thing is that it exits the nozzle in the correct phase.

 

[james444]

Don't understand much of the tech speak here, but from extensive listening and A/Bing among my IEMs I've concluded (and posted), that IMO those based on single driver designs sound more coherent. The observed difference is so significant to my ears, that I'm strongly considering not to acquire any more multi-driver based phones.

 

[Napilopez]

I wil admit I've never heard a multi-driver headphone, and that I know very little of the soound science, but I don't quite see how the argument being presented is totally valid. These are of course solid issues, but it is assumed the manufacturer has thought about and worked through this. It complicates things, but it doesn't seem to me like a particularly huge obstacle. I think price and quality also come into play. It seems to me that outside of the custom area, more and more dynamic driver IEMs(and dynamic BA hybrids like the EQ7 and GR8) which only use one speaker are starting to gain top tier status for universals. However, it also seems clear that the more expensive you get, the more compensated for these issues are.

The JH13 pro has 6 drivers, and is often acclaimed for being pretty much the best IEM there is, which is now being challenged by its 8 driver sibling, the JH16pro. Actually there was a poll here recently about the JH13pro vs the HD800, and last time I checked, the 13 was winning by a wide margin. I also don't see the huge levels problem and damaging your hearings as BA drivers(and subsequently those with more than one driver) are typically acknowledged for being better at low volume listening than dynamic drivers. While I get the feeling I'd be more of a dynamic guy, I feel like this issue that is being brought up is more of a hurdle manufacturers need to overcome that is inherent to the technology, and the better they are at it, the less noticeable the hurdle is. Dynamic drivers certainly don't sound perfect either.

 

[Anaxilus]

Quote:

Originally Posted by Napilopez /img/forum/go_quote.gif I wil admit I've never heard a multi-driver headphone, and that I know very little of the soound science, but I don't quite see how the argument being presented is totally valid. These are of course solid issues, but it is assumed the manufacturer has thought about and worked through this. It complicates things, but it doesn't seem to me like a particularly huge obstacle. I think price and quality also come into play. It seems to me that outside of the custom area, more and more dynamic driver IEMs(and dynamic BA hybrids like the EQ7 and GR8) which only use one speaker are starting to gain top tier status for universals. However, it also seems clear that the more expensive you get, the more compensated for these issues are. The JH13 pro has 6 drivers, and is often acclaimed for being pretty much the best IEM there is, which is now being challenged by its 8 driver sibling, the JH16pro. Actually there was a poll here recently about the JH13pro vs the HD800, and last time I checked, the 13 was winning by a wide margin. I also don't see the huge levels problem and damaging your hearings as BA drivers(and subsequently those with more than one driver) are typically acknowledged for being better at low volume listening than dynamic drivers. While I get the feeling I'd be more of a dynamic guy, I feel like this issue that is being brought up is more of a hurdle manufacturers need to overcome that is inherent to the technology, and the better they are at it, the less noticeable the hurdle is. Dynamic drivers certainly don't sound perfect either.

I'm gonna have to disagree with the notion that a manufacturer knows what they are doing because, well, they are a manufacturer. A lot of it is marketing among other things. I won't give examples because I might take a swipe at somebody's favorite headphones.

As for hearing loss, I've been told repeatedly by many that this is a result of extended periods of high decibel listening and nothing more or less related to sound waves and pressure. Not sure I believe them but it seems to be the consensus. Therefore, I'm not sure that phase shifts in sound would matter....if the pundits are correct.

 

[justanut]

So... from the patent it seems that the TF10 is designed with the technologies considered. Does this also mean that by remolding them by Fisher or UM etc, you are losing the phase modulation controls built into the original design of the TF10s?

 

[amnsiac]

Quote:

Originally Posted by justanut /img/forum/go_quote.gif So... from the patent it seems that the TF10 is designed with the technologies considered. Does this also mean that by remolding them by Fisher or UM etc, you are losing the phase modulation controls built into the original design of the TF10s?

Exactly, and that's why threads are popping up lately discussing how the remoulds are actually worse sounding than the originals, which is something I always suspected might happen.

As for Anaxilus' comment on manufacturers, I'll have to disagree with you a bit there. The case in point is the Audio Technica CK10, for me anyway. How did they get it so right? Multiple BA was hardly a new concept when they came out. The answer is design R&D. Plenty of manufacturers had lobbed a few BAs into a housing before, but AT (a company with huge experience) outdid them without doing anything different, just doing it right.

It boils down to, universals will generally have their design such a way for a good reason (if their worth their salt) and remolding them might (probably will imo) ruin this. If you want assured quality in a custom shell, you pay the big bucks to the guys who will put all the theory into effect, at great effort, for your bespoke application.


Edit; AKG != Audio Technica

 

[weili]

Quote:

Originally Posted by amnsiac /img/forum/go_quote.gif Exactly, and that's why threads are popping up lately discussing how the remoulds are actually worse sounding than the originals, which is something I always suspected might happen. As for Anaxilus' comment on manufacturers, I'll have to disagree with you a bit there. The case in point is the AKG CK10, for me anyway. How did they get it so right? Multiple BA was hardly a new concept when they came out. The answer is design R&D. Plenty of manufacturers had lobbed a few BAs into a housing before, but AKG (a company with huge experience) outdid them without doing anything different, just doing it right. It boils down to, universals will generally have their design such a way for a good reason (if their worth their salt) and remolding them might (probably will imo) ruin this. If you want assured quality in a custom shell, you pay the big bucks to the guys who will put all the theory into effect, at great effort, for your bespoke application.

AKG ? Didn't you mean Audio Technica/A-T ?

 

[amnsiac]

Quote:

Originally Posted by weili /img/forum/go_quote.gif AKG ? Didn't you mean Audio Technica/A-T ?

Palmface.

I blame the hangover

 

[kostalex]

I agree with the OP. The best IEMs I listened were single driver and surprisingly the best overall has dynamic driver, not balanced armature - http://www.head-fi.org/forums/f103/r...4s-re0-468941/.

 

[Young Spade]

@amnsiac: *walks over and shakes hand*
Thanks for clearing that up for me; well providing some insight on the whole situation. I always wondered why and partially attributed it to the acrylic remoulds (no sound absorption from the universal tips, hence the sibilance (which might be part of the problem)) but never knew that the internals being changed could actually be the problem.

 

[amnsiac]

Quote:

Originally Posted by Young Spade /img/forum/go_quote.gif @amnsiac: *walks over and shakes hand* Thanks for clearing that up for me; well providing some insight on the whole situation. I always wondered why and partially attributed it to the acrylic remoulds (no sound absorption from the universal tips, hence the sibilance (which might be part of the problem)) but never knew that the internals being changed could actually be the problem.

No problem, but it's only my two cents, I'm no expert.

 

[marcan]

Quote:

Originally Posted by ClieOS /img/forum/go_quote.gif In the patent, they already state that the phase shift as an overall side-effect caused by the x-over circuit as well as all other factors (column 6 line 12 and forward) and time delay by offsetting some of the driver (column 6 line 47 and forward) is just a way to fix the phase swift. After all, offsetting driver to introduce delay and reflection/reverberation in big can is nothing new. The important thing is that it exits the nozzle in the correct phase.

You are right about the x-over circuit being taken into account. However, it won't be possible to completely overcome the phase issue inherent to the system, it will just minimize it. Moreover, using delays will degrade the sonic coherence, so it’s a tradeoff between phase and time coherence.

So my point is: Why introduce a complexity that has a price (sonically and financially) when headphones are probably the best way to have this phase and time coherence because it can be done by one single driver for a decent acoustic level. Right now it isn’t possible for loudspeakers but for headphones, why sacrifice one of their great benefits: a wonderful coherence.
I’m advocating it because this coherence is important for the realism and the emotion of the music.