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Can we have review of IEMs with many many drivers?

ReaderZ

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There are so many IEMs with 4,5,6 even 10+ drivers, I wonder how do they get so many of them to work together, so any chance we can have reviews here?
 

stevenswall

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I'd like to see that. I have a JH Audio Lola with a pretty interesting setup: quad tweeter, dual opposed midrange drivers, dual woofer. I'd love to see the Etymotic Evo compared too when it's out.
 

stevenswall

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So send one to Amir to review.

I've offered in a few places. I'd rather send in my 8260 monitor and have it show "The Ones" what wide, even dispersion actually is.
 

Frank Dernie

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There are so many IEMs with 4,5,6 even 10+ drivers, I wonder how do they get so many of them to work together, so any chance we can have reviews here?
That would be interesting.
I have always wondered, given how tiny they are, how they effectively split the bandwidth between so many drivers
 

stevenswall

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That would be interesting.
I have always wondered, given how tiny they are, how they effectively split the bandwidth between so many drivers

5 way crossover instead of a 3 way, or a 3 way crossover and multiple units are to increase SPL and decrease distortion. Not sure what is most difficult, but tiny electronics and crossover circuits aren't new, and I don't think companies like UE or JH audio mess around with first order crossovers and nonsense like that.
 

Frank Dernie

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5 way crossover instead of a 3 way, or a 3 way crossover and multiple units are to increase SPL and decrease distortion. Not sure what is most difficult, but tiny electronics and crossover circuits aren't new, and I don't think companies like UE or JH audio mess around with first order crossovers and nonsense like that.
How would you make a (passive) bass crossover tiny?
My guess is that the only "crossover" is the bandwidth of the individual drivers, and their location and vent shape/length in the blob of plastic they are mounted in, and the crossover "slopes" are whatever mechanical and acoustical limits cause it.
I am afraid I am not seeing anything other than "more is better" and "reassuringly expensive" as reasons why they should have any benefit.
Hence my interest in seeing measurements :)
 

AudioJester

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I recently picked up an IEM with dynamic drivers, BA drivers, electrostatic drivers and bone conduction drivers... gulp...
 

stevenswall

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How would you make a (passive) bass crossover tiny?
My guess is that the only "crossover" is the bandwidth of the individual drivers, and their location and vent shape/length in the blob of plastic they are mounted in, and the crossover "slopes" are whatever mechanical and acoustical limits cause it.
I am afraid I am not seeing anything other than "more is better" and "reassuringly expensive" as reasons why they should have any benefit.
Hence my interest in seeing measurements :)

Put whatever you need on a tiny circuit board? I'm not aware of a hard limit being reached with capacitors, inductors, and resistors that is larger than an earphone. Could be wrong, I figure since computers fit billions of transistors on a tiny chip it's all ancient technology fitting several passive components on a circuit board.

Then you also have acoustic tuning and you can use front chambers, side chambers, and back chambers, resonators, length, width, volume, membranes of varying stiffness, vents, etc.

And I think you're right: the properties of the drivers themselves can be controlled to focus on different areas and have different roll off characteristics.

More is better if they remain accurate and the goal is increased SPL and lower distortion.

All things being equal (including reasonable size), I'll take the audio reproducing unit with a lot more SPL or reduced distortion, whether it has one eighteenth of a driver, or eighteen octillion drivers.

Measurements would be nice though. If something measures well and it is a twelve way, 36 driver system that fits well, it shouldn't be liked any better than a single driver unit capable of the same things.

Also curious if there is a 3 driver system, if you doubled all of the drivers if there are any drawbacks or if it's just an SPL and sensitivity increase with a distortion decrease.
 

Frank Dernie

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Put whatever you need on a tiny circuit board?
Have you seen the size of an inductor used in a bass crossover?

I figure since computers fit billions of transistors on a tiny chip it's all ancient technology fitting several passive components on a circuit board.
These are active circuits, not passive. What you "figure" doesn't have any technical logic as far as I can see, but I could be wrong too.

Then you also have acoustic tuning and you can use front chambers, side chambers, and back chambers, resonators, length, width, volume, membranes of varying stiffness, vents, etc.
For me that, and transducer characteristic, is all you've got, as I put in my post. The problem here will be consistently making them acceptably close to all the same and whether it has any merit, given how good single driver IEMs are.

More is better if they remain accurate and the goal is increased SPL and lower distortion.

All things being equal (including reasonable size), I'll take the audio reproducing unit with a lot more SPL or reduced distortion, whether it has one eighteenth of a driver, or eighteen octillion drivers.
Maximum SPL hasn't been a limit on any IEM I have heard of, including all the single driver ones. Is distortion likely to be less? I am not so sure, given the inevitable complexity.

Measurements would be nice though. If something measures well and it is a twelve way, 36 driver system that fits well, it shouldn't be liked any better than a single driver unit capable of the same things.
Exactly, that is what I want to see, it would also, as ever be interesting to see how consistent they are from earpiece to earpiece if there are a lot of drivers, ducts, resonators and so forth. Can they make the all the same? is always a question with complex devices IME.

Also curious if there is a 3 driver system, if you doubled all of the drivers if there are any drawbacks or if it's just an SPL and sensitivity increase with a distortion decrease
I can see why 3 ways is a gain in loudspeakers for SPL and distortion. Not sure even 3-ways is needed in IEM, never mind more, except for marketing, of course.

I would just like to see measurements. I am an engineer and so far nothing about multi-way IEMs looks convincing to me.
 
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ReaderZ

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I think arguing any further without measurement is likely to be fruitless, so anyone can get Amir test some of these?
 

stevenswall

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Have you seen the size of an inductor used in a bass crossover?


These are active circuits, not passive. What you "figure" doesn't have any technical logic as far as I can see, but I could be wrong too.


For me that, and transducer characteristic, is all you've got, as I put in my post. The problem here will be consistently making them acceptably close to all the same and whether it has any merit, given how good single driver IEMs are.


Maximum SPL hasn't been a limit on any IEM I have heard of, including all the single driver ones. Is distortion likely to be less? I am not so sure, given the inevitable complexity.


Exactly, that is what I want to see, it would also, as ever be interesting to see how consistent they are from earpiece to earpiece if there are a lot of drivers, ducts, resonators and so forth. Can they make the all the same? is always a question with complex devices IME.


I can see why 3 ways is a gain in loudspeakers for SPL and distortion. Not sure even 3-ways is needed in IEM, never mind more, except for marketing, of course.

I would just like to see measurements. I am an engineer and so far nothing about multi-way IEMs looks convincing to me.

1. No, perhaps you could figure out what inductor properties would be necessary for a tiny driver and we could google for small ones that match?

1620888162033.png


2. Passive crossovers = a circuit board with pieces soldered onto it. Having a machine do reflow soldering with tiny componants doesn't make it active, unless they are using an amplification circuit in which case it would need a power source. Tiny components on a circuit board that I'm describing are still passive/subtractive. Here's an example: (Other clear custom IEMs have electrical componants in them not on a board like this that look like resistors and capacitors.)
1620888391073.png


3. I'm glad we agree driver and chamber/port/membrane differences would work to acoustically tune things. Maybe measurements will prove it wrong, but I live with the assumption that different drivers would be best utilized for different frequencies and would optimally operate with different bore sizes, back chambers, ports, side channels, etc. which would be part of my argument for multiple drivers even if there were no such thing as tiny crossover components.

4. Max SPL is something consumers seem to be demanding, and companies are aiming for. JBL, Genelec, Klipsch, and many others make speakers and IEMs that go mind numbingly loud. Doesn't benefit you or I, sure, but we know that distortion increases with volume, so it is a given that if you split the loudness between multiple devices that don't have to handle the SPL alone the distortion goes down. I've only seen measurements ever indicate increasing distortion with increasing SPL, and lower distortion with lower SPL, and adding a subwoofer for example, leading to less distortion in a two way system trying to play deeper bass at higher levels.

5. Tyll at InnerFidelity used to do measurements of multi driver IEMs and single driver IEMs, headphones, etc... Anything decent seems to match the left side to the right side very well, and I haven't noticed a difference with multi vs single driver units. The most famous variance I recall was with the Focal Utopia units not matching well, and perhaps some Campfire Audio stuff that is also measured on SBAF.

6. There are tons of measurements available here:

https://www.stereophile.com/content/innerfidelity-headphone-measurements

I don't think it will prove much besides "some multi driver IEMS and some single driver IEMs are bad, and some multi driver and some single driver IEMs are good." Just like with speakers. Some 3 ways sound better than some 2 ways, some 3 ways sound better than than 4 way systems, some 2 way systems sound better than 4 way systems, etc.

I'll concede that I don't think there is an inherent need for multiple drivers in an IEM, though I don't think that has anything to do with not being able to have them work together, miniaturizing crossover components, being limited to acoustic tuning.

Marketing wise companies will market whatever they have, whether it's and "XWB driver, xtra wideband phase coherent dynamic driver" in a Sennheiser IEM, or "eigh drivers splitting the lows, mids, and highs, time aligned with FreqPhase technology" by JH Audio. Both don't tell us about the measured performance of the unit, so both should be equally scoffed at.

Personally I like multiple drivers with separate signal paths because it opens the door for an active crossover, or a tweakable passive crossover: With JH Audio earphones for example you can boost or lower the bass driver output with an inline "pod" that is permanently attached. You can also get aftermarket stuff to separately adjust the bass, mids, and treble separately. Perhaps there is a way to do that with a single driver too by splitting the frequencies in a small crossover, having potentiometers or switches, and re-combining the signals.
 
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