[DanWiggins]

Hello Dan,

If cost is not an issue, what would be the ideal housing material for IEM drivers in terms of performance? Polymers, or metals, etc? Thank you!

For me, I am a HUGE fan of polymers, for a variety of reasons:

1. Weight. The NUMBER ONE source of ear fatigue for IEMs is weight. It's something that is heavily optimized with hearing aids, since those wearers tend to use them for 12+ hours a day. Weight is the killer of your ear; given that most polymers are less than 1.2 g/cc - less than half that of aluminum, and nearly 1/4 that of titanium - a polymer is a great choice.

2. Acoustics. I love materials that are rigid to resist flexing and having energy put into them - but then dissipate that energy when it happens. Metals are stiff, but to keep weight down you make them thin. Stiffness goes with the cube of thickness, so you lose a lot of stiffness when you cut the weight in half (stiffness drops by a factor of 8 for a weight reduction of a factor of 2). And then metals are REALLY BAD at internally damping energy. That is the reason there is a big push towards beryllium, it has really high internal damping relative to other metals.

But all metals fall FAR short of polymers when it comes to dissipating energy internally. Polymers just "damp it out". And that means it doesn't ring. You make bells and cymbals out of metal; you don't make them out of plastic for a reason! It's not because of a lack of strength (bullet-proof glass and fighter jet canopies are made from polycarbonate, after all), it's because they are really dead. So WHEN you get energy into the body (which will happen - regardless of the material used) it doesn't ring and send it all right back out.

This is also the reason that Baltic birch is so prized in most high-end speaker assemblies, or laminations of multiple layers of wood materials. They have very high internal damping and really don't ring. They kill the internal energy really well.

3. Comfort - temperature based. Hot or cold, metal is a great conductor of heat. Cold days, who wants to put ice cubes in your ears? Plastics/polymers are usually thermal insulators (you have to do special stuff to them to make them otherwise) meaning they take on your own body temperature. They won't be cold or hot - they just are. That adds to the comfort when wearing outside - and I see that as a the big strength of IEMs over cans - you can use them conveniently when outside and on the go. Easy to tuck away, easy to store, still sound good - and if properly designed, they are great at noise isolation (what some call "passive noise cancellation" which is, in reality, a non-sensical statement).

4. Cost. Tooling for precision injection molding is NOT cheap, but once it's done, you can replicate injection molded parts quite affordably! Metal is either machined (best, high tolerance that approaches injection molding, but very expensive and slow), injection molded (even more expensive tooling AND the per-unit cost is much higher than polymers, but still lower cost than machining), die-cast (affordable tooling, lower tolerance, only suitable for some alloys), or stamped (affordable tooling, decent precision, low cost to reproduce - but really low fidelity in what you can realize). Yeah, we COULD do machined titanium bodies and have them heavier, more acoustically resonant, less comfortable, but the cost would easily shoot up a factor of 20 or more, and that Be would no longer be a $299 unit but a $799 - and do we need Yet Another $800 IEM?

So, overall, I like polymers. And we use them, exclusively. We use polycarbonate for the bodies of our IEMs because it's low density, very strong, high internal damping, and really easy to mold, as well as allow for affordable IEMs. What's not to like?

 

[SCBob]

For me, I am a HUGE fan of polymers, for a variety of reasons:

1. Weight. The NUMBER ONE source of ear fatigue for IEMs is weight. It's something that is heavily optimized with hearing aids, since those wearers tend to use them for 12+ hours a day. Weight is the killer of your ear; given that most polymers are less than 1.2 g/cc - less than half that of aluminum, and nearly 1/4 that of titanium - a polymer is a great choice.

2. Acoustics. I love materials that are rigid to resist flexing and having energy put into them - but then dissipate that energy when it happens. Metals are stiff, but to keep weight down you make them thin. Stiffness goes with the cube of thickness, so you lose a lot of stiffness when you cut the weight in half (stiffness drops by a factor of 8 for a weight reduction of a factor of 2). And then metals are REALLY BAD at internally damping energy. That is the reason there is a big push towards beryllium, it has really high internal damping relative to other metals.
It's nice to read more about the Periodic Audio IEM design. I have the Be and continue to be impressed by how good it sounds with a variety of music genres. Hard to believe it's $299, a great value. Thanks.

But all metals fall FAR short of polymers when it comes to dissipating energy internally. Polymers just "damp it out". And that means it doesn't ring. You make bells and cymbals out of metal; you don't make them out of plastic for a reason! It's not because of a lack of strength (bullet-proof glass and fighter jet canopies are made from polycarbonate, after all), it's because they are really dead. So WHEN you get energy into the body (which will happen - regardless of the material used) it doesn't ring and send it all right back out.

This is also the reason that Baltic birch is so prized in most high-end speaker assemblies, or laminations of multiple layers of wood materials. They have very high internal damping and really don't ring. They kill the internal energy really well.

3. Comfort - temperature based. Hot or cold, metal is a great conductor of heat. Cold days, who wants to put ice cubes in your ears? Plastics/polymers are usually thermal insulators (you have to do special stuff to them to make them otherwise) meaning they take on your own body temperature. They won't be cold or hot - they just are. That adds to the comfort when wearing outside - and I see that as a the big strength of IEMs over cans - you can use them conveniently when outside and on the go. Easy to tuck away, easy to store, still sound good - and if properly designed, they are great at noise isolation (what some call "passive noise cancellation" which is, in reality, a non-sensical statement).

4. Cost. Tooling for precision injection molding is NOT cheap, but once it's done, you can replicate injection molded parts quite affordably! Metal is either machined (best, high tolerance that approaches injection molding, but very expensive and slow), injection molded (even more expensive tooling AND the per-unit cost is much higher than polymers, but still lower cost than machining), die-cast (affordable tooling, lower tolerance, only suitable for some alloys), or stamped (affordable tooling, decent precision, low cost to reproduce - but really low fidelity in what you can realize). Yeah, we COULD do machined titanium bodies and have them heavier, more acoustically resonant, less comfortable, but the cost would easily shoot up a factor of 20 or more, and that Be would no longer be a $299 unit but a $799 - and do we need Yet Another $800 IEM?

So, overall, I like polymers. And we use them, exclusively. We use polycarbonate for the bodies of our IEMs because it's low density, very strong, high internal damping, and really easy to mold, as well as allow for affordable IEMs. What's not to like?

 

[sludgeogre]

For me, I am a HUGE fan of polymers, for a variety of reasons:

I won't quote the whole post for the sake of brevity, but man do I LOVE this post and I'm super glad that I bought the Be. I'm a chemical engineer at a wood/paper resins facility, so material properties are a thing that I'm very familiar with, but in relation to chemical attack and mechanical stress, not to sound properties.

I always thought it was very strange that there are so many IEM's that are machined from metal, since metals are so insanely resonant. It makes no sense to try to overcome that factor when you can use materials that are engineered to better handle it. The popularity of Beryllium really makes sense because of all of its properties that make it such a champ for putting out sound waves, but all of these exotic metal housings make no sense from an engineering standpoint to me other than to make the IEM look pretty and be able to have a truck drive over it. We often talk so much about how things sound that we don't bother to examine the engineering choices that got a product there.

 

[Rick T.]

For me, I am a HUGE fan of polymers, for a variety of reasons:

1. Weight. The NUMBER ONE source of ear fatigue for IEMs is weight. It's something that is heavily optimized with hearing aids, since those wearers tend to use them for 12+ hours a day. Weight is the killer of your ear; given that most polymers are less than 1.2 g/cc - less than half that of aluminum, and nearly 1/4 that of titanium - a polymer is a great choice.

2. Acoustics. I love materials that are rigid to resist flexing and having energy put into them - but then dissipate that energy when it happens. Metals are stiff, but to keep weight down you make them thin. Stiffness goes with the cube of thickness, so you lose a lot of stiffness when you cut the weight in half (stiffness drops by a factor of 8 for a weight reduction of a factor of 2). And then metals are REALLY BAD at internally damping energy. That is the reason there is a big push towards beryllium, it has really high internal damping relative to other metals.

But all metals fall FAR short of polymers when it comes to dissipating energy internally. Polymers just "damp it out". And that means it doesn't ring. You make bells and cymbals out of metal; you don't make them out of plastic for a reason! It's not because of a lack of strength (bullet-proof glass and fighter jet canopies are made from polycarbonate, after all), it's because they are really dead. So WHEN you get energy into the body (which will happen - regardless of the material used) it doesn't ring and send it all right back out.

This is also the reason that Baltic birch is so prized in most high-end speaker assemblies, or laminations of multiple layers of wood materials. They have very high internal damping and really don't ring. They kill the internal energy really well.

3. Comfort - temperature based. Hot or cold, metal is a great conductor of heat. Cold days, who wants to put ice cubes in your ears? Plastics/polymers are usually thermal insulators (you have to do special stuff to them to make them otherwise) meaning they take on your own body temperature. They won't be cold or hot - they just are. That adds to the comfort when wearing outside - and I see that as a the big strength of IEMs over cans - you can use them conveniently when outside and on the go. Easy to tuck away, easy to store, still sound good - and if properly designed, they are great at noise isolation (what some call "passive noise cancellation" which is, in reality, a non-sensical statement).

4. Cost. Tooling for precision injection molding is NOT cheap, but once it's done, you can replicate injection molded parts quite affordably! Metal is either machined (best, high tolerance that approaches injection molding, but very expensive and slow), injection molded (even more expensive tooling AND the per-unit cost is much higher than polymers, but still lower cost than machining), die-cast (affordable tooling, lower tolerance, only suitable for some alloys), or stamped (affordable tooling, decent precision, low cost to reproduce - but really low fidelity in what you can realize). Yeah, we COULD do machined titanium bodies and have them heavier, more acoustically resonant, less comfortable, but the cost would easily shoot up a factor of 20 or more, and that Be would no longer be a $299 unit but a $799 - and do we need Yet Another $800 IEM?

So, overall, I like polymers. And we use them, exclusively. We use polycarbonate for the bodies of our IEMs because it's low density, very strong, high internal damping, and really easy to mold, as well as allow for affordable IEMs. What's not to like?

Wow, thanks Dan. Very much appreciated. That was an exhaustive and illuminating reply.

Yeah, select BB Ply and/or HDF, etc., and elaborate bracing for loudspeakers. But that’s usually reserved for higher end speakers, most still use unbraced MDF..

If ever you plan on coming out with over-the-ear headphones sporting true Be foil drivers, I’d be exteremely interested if the price is right.

 

[DanWiggins]

Thanks all! We try to do things because it's the right way from a product standpoint, not a marketing standpoint. If we were about marketing, we'd have something other than black-and-white cardboard boxes for our IEMs!

All that said, we're not stopping at all in terms of research of development. We'll continue to search to find better materials and approaches, and when we do find them and figure out how to properly use them - reliably and repeatably - then we'll roll those changes across the board.

 

[HiFlight]

Thanks all! We try to do things because it's the right way from a product standpoint, not a marketing standpoint. If we were about marketing, we'd have something other than black-and-white cardboard boxes for our IEMs!

All that said, we're not stopping at all in terms of research of development. We'll continue to search to find better materials and approaches, and when we do find them and figure out how to properly use them - reliably and repeatably - then we'll roll those changes across the board.

What a welcome and refreshing approach to marketing and development!
Dan, I think I can speak for all of us in thanking you for your very informative participation on the thread.

 

[SCBob]

Thanks all! We try to do things because it's the right way from a product standpoint, not a marketing standpoint. If we were about marketing, we'd have something other than black-and-white cardboard boxes for our IEMs!

All that said, we're not stopping at all in terms of research of development. We'll continue to search to find better materials and approaches, and when we do find them and figure out how to properly use them - reliably and repeatably - then we'll roll those changes across the board.

I like the approach to the box. Put the value where it counts. Spent an hour at the dentist today and the Be sound was great and masked those less great sounds.

 

[czy6412]

Just wonder if the Be can be recabled to the 2.5mm balanced plug

 

[DanWiggins]

Just wonder if the Be can be recabled to the 2.5mm balanced plug

With a full recabling, yes. The splitter is where the grounds are joined - there are effectively three wires coming from the splitter down to the 3.5mm jack. The ground is twice as thick as the others.

Why balanced? In general, balanced amps have worse THD and noise performance than single-ended designs. I know many want balanced because they have inefficient headphones, and so need the voltage headroom of a balanced (essentially, bridged) amplifier design, but we get freaky loud with very little power (100 dB SPL @ 1mW - max allowed by law in Europe). So unless you need more than ~700 mV RMS to the IEM (which would be peaks around 112 dB SPL), balanced/bridged won't really gain you anything other than a higher noise floor and more THD. Well, it DOES halve your damping factor too...

 

[tgx78]

Dan any plans for graphene composite diaphragm?

 

[DanWiggins]

Dan any plans for graphene composite diaphragm?

Nope.

 

[shootthemoon18]

Still absolutely loving the BEs but still felt that the upper bass is too much would like more subbass maybe.

I'm looking to for an upgrade in source. Does anyone have any recommendation? I'm looking at mojo, micro iDSD, maybe the new Mytek clef and xDSD. Fiio Q5 looks good but i'm not convinced about balanced amp in a portable device. I had the dragonfly RED before. While it has good amount of details, the volume control is not suitable for IEMs and it's too thin sounding for me.

 

[mgunin]

Still absolutely loving the BEs but still felt that the upper bass is too much would like more subbass maybe.

I'm looking to for an upgrade in source. Does anyone have any recommendation? I'm looking at mojo, micro iDSD, maybe the new Mytek clef and xDSD. Fiio Q5 looks good but i'm not convinced about balanced amp in a portable device. I had the dragonfly RED before. While it has good amount of details, the volume control is not suitable for IEMs and it's too thin sounding for me.

I've read some good testimonials on pairing well with both DACPortable and BlueDAC which are both on the neutral side of sound.

 

[SCBob]

Still absolutely loving the BEs but still felt that the upper bass is too much would like more subbass maybe.

I'm looking to for an upgrade in source. Does anyone have any recommendation? I'm looking at mojo, micro iDSD, maybe the new Mytek clef and xDSD. Fiio Q5 looks good but i'm not convinced about balanced amp in a portable device. I had the dragonfly RED before. While it has good amount of details, the volume control is not suitable for IEMs and it's too thin sounding for me.

Does burn in affect the bass of the Be? If so, how long a burn in is advised? Thanks.

 

[DanWiggins]

Does burn in affect the bass of the Be? If so, how long a burn in is advised? Thanks.

IMHO, no. I've "experienced" burn-in, but measurements show no discernable change in frequency response, CSD, THD, etc. So I think it's more a case of your ears burning-in and getting used to the sound.

For those who think it has a touch too much midbass, try different tips. Foam tips can - and will - collapse and attenuate the mids and highs, which will make the perceived midbass/bass that much more weighty. There is an audible - and measurable - difference between silicone and foam tips! I personally prefer the feel of the foam tips, and the isolation I get with them when traveling is fantastic. But I use silicone tips at the desk/home/office because they just sound a bit more open and neutral.