[Jazmanaut]

Your assumption is generally correct.

There are few different approaches you might consider.
The most common is multiplying the same type of driver - often times seen as dual CI (lows), dual Sonion 3300/3800/DTEC (lows) or dual/triple TWFK (highs)
2x CI will decrease THD - as both drivers are typically stack up together so their vertical vibrations from motors will cancel each other out. You can have two configurations parallel or series - each will impact impedance and SPL output differently - depends on what designer wants to achieve.
Sonion 33-37-3800 or KA DTECs are already duals so there's no extra advantage on mechanical THD reduction, but if you divide power between say two 3300 then you decrease load on each of those drivers and you get reduction in THD as well. Still you can wire both in series or parallel adjusting SPL and impedance as well as other factors which impact how driver behaves in whole design.
n X TWFK - same concepts as above (SPL, THD) but since those are used as tweeters typically the point is to reduce overall HF impedance (metioned by @castleofargh ) as with standard BA driver impedance increases dramatically with frequency so in order to match output of the tweeters to LF drivers you need to multiply HF drivers.
Generally speaking multiplying same drivers gives you increase in headroom (volume before distortions) so the IEM sounds overall louder and "bigger"

There's also another way you can go - by adding different types of drivers for the same fr range - for example combining CI and 3300 for lows only - this gives you all above benefits but with changes to sound signature as CI and 3300 have completely two different sounds and definitions of low frequency - with CI being "slow" with long decay and 3300 (considering non-vented option) being fast and precise. So it's kind of like mixing flavors to achieve desired texture or sound signature or definition etc.


Marketing is sort of factor too. But I think also depends on philosophy of company, there are those who don't even bother with selling 1 or 2 BA IEMs.
Impedance - as for the purpose mentioned above.
I don't think I would agree fully with the last point. Drivers coming from factory have typically very tight matching, adding drivers typically can make the circuit very prone to acoustic phase problems meaning it's actually harder to match L/R channel with higher driver count.

Thank you for very informative post. Everyday something new! Can you open a bit more about that vertical vibration?

 

[piotrus-g]

Thank you for very informative post. Everyday something new! Can you open a bit more about that vertical vibration?

Well the concept is pretty much straight forward.
If you join two single drivers with diaphragms facing each other, the mechanical vibration created by motors cancel each other. Not completely (obviously) but greatly.

Another way of reducing mechanical vibration is encasing the driver - for example according to my measurements silicone material reduces THD dramatically (even for single driver) because the soft material acts as suspension of the driver.

 

[b0ck3n]

Well the concept is pretty much straight forward.
If you join two single drivers with diaphragms facing each other, the mechanical vibration created by motors cancel each other. Not completely (obviously) but greatly.

Another way of reducing mechanical vibration is encasing the driver - for example according to my measurements silicone material reduces THD dramatically (even for single driver) because the soft material acts as suspension of the driver.

If you would indulge me piotrus-g, I'm interested to know why you (Custom Art) opted to go the 'FIBAE' route (for anyone interested read more here), and also why you're not, as of yet, offering CIEMs with more than 8 drivers per ear?

 

[piotrus-g]

If you would indulge me piotrus-g, I'm interested to know why you (Custom Art) opted to go the 'FIBAE' route (for anyone interested read more here), and also why you're not, as of yet, offering CIEMs with more than 8 drivers per ear?

Well FIBAE is our in-house development and I believe it's technology that solves some major issues for our customers - that's why reshaping our line up to accommodate for FIBAE tech was pretty easy and natural decision.

I think I try to maintain healthy relationship with IEM driver count. So far I don't find that more is simply needed. That said if I find justification and reason to use higher driver count in our IEMs in order to make them sound better, we will go that way.

 

[b0ck3n]

Well FIBAE is our in-house development and I believe it's technology that solves some major issues for our customers - that's why reshaping our line up to accommodate for FIBAE tech was pretty easy and natural decision.

I think I try to maintain healthy relationship with IEM driver count. So far I don't find that more is simply needed. That said if I find justification and reason to use higher driver count in our IEMs in order to make them sound better, we will go that way.

I see a lot of "in-house development" in CIEM offerings (JH Audio's FreqPhase and 64 Audio's tia drivers to name a few) and to be blunt I figured, without knowing for a fact I'll humbly add, that they're just marketing words to distinguish their products from the competition. I mean, everyone's really just using different means to the same end, yes? FIBAE seems like it has some real world use for listeners who enjoy using a wide array of sources with significant differences in properties, though I can't say that I fall into that category.

 

[piotrus-g]

Thank you for your acknowledgement.

I'm not going to speak for other brands, but it's fair to say that there have been numbers of developments in past years - these with catchy marketing names and these that go unnoticed - but more or less it's all about pushing IEM industry further and giving customer different choices and options. Sometime those are small tip-toe steps sometimes big leaps, ultimately I think all that matters is how it benefits customers and how they are able to use this technology to their needs (be it improving your skills as an artist or get more joy from listening to music as an audio enthusiast)

 

[b0ck3n]

Thank you for your acknowledgement.

I'm not going to speak for other brands, but it's fair to say that there have been numbers of developments in past years - these with catchy marketing names and these that go unnoticed - but more or less it's all about pushing IEM industry further and giving customer different choices and options. Sometime those are small tip-toe steps sometimes big leaps, ultimately I think all that matters is how it benefits customers and how they are able to use this technology to their needs (be it improving your skills as an artist or get more joy from listening to music as an audio enthusiast)

The one thing that keeps getting pushed further above all else is the price. It's refreshing to see that you've chosen to provide options that are useful, and pricing that isn't out of this world. I also very much appreciate how you've answered all my questions.

 

[FullCircle]

The one thing that keeps getting pushed further above all else is the price. It's refreshing to see that you've chosen to provide options that are useful, and pricing that isn't out of this world. I also very much appreciate how you've answered all my questions.

Price

Not really

For example Noble has the EDC line that is just opening up. Starting price is $120 & I wouldn't be surprised to see other companies start looking into more pratcal and efficient ways to build monitors while maintaining sound quality as a priority.

 

[Niouke]

publishing the impedance curves of the IEM's is a step in the right way. The IEM jungle is difficult to navigate, the driver count and subjective reviews are often the only tools people have to evaluate an IEM.

 

[FullCircle]

Ok but what does driver count = in the evaluation process

 

[castleofargh]

it's clearly explained here:


^_^

 

[FullCircle]

That is pure GOLD

 

[Niouke]

Ok but what does driver count = in the evaluation process

There is an old audiophile saying that more is better And more expensive is best

 

[b0ck3n]

There is an old audiophile saying that more is better And more expensive is best

And that is exactly what I take issue with.

 

[b0ck3n]

Ok but what does driver count = in the evaluation process

You tell me. That was one of the questions I hoped to see answered when I posted this thread.