Discrepancies in sub bass of graphs vs perception

IEMs / In-Ear-Monitors General IEM Discussion
1

I’ve purchased a couple of iems recently which have resulted in a massive discrepancy in the low end between what I see in the measurements and what I hear. Basically some iems sound like someone put a subwoofer into my ear. Tip rolling doesn’t affect this.

For reference (pun intended) the Crinear Reference is a little below my preference for quantity of low end. The Truthear Pure is closer to my preference overall although I wouldn’t mind a little more low end for certain genres of music.

So given the praise I decided to get the Daybreak which in the graphs is not that far off from the Pure. I assumed I would get a little more deep low end and rumble. When I got them the low end was so exaggerated that made them simply unlistenable to me. I got a similar experience with the Thieaudio Hype 4 mk2.

Anyone has any idea what is going on?

BTW I’ve never experienced this with headphones. Typically what I see in the graphs aligns somewhat with what I hear.

From Crin’s 5128 database:

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From the Super Review 711 database:

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Edit:

Another point of reference. The Moondrop Chu 2 sound fine to me in terms of bass quantity and yet in the graphs it’s close to the Daybreak:

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2

Maybe you have alien ears?

3

Maybe :slight_smile:

LLMs mentioned something about some drivers moving more air which isn’t represented in presure measurements (SPL).

I was thinking maybe I have a like a bone closer to the ear canal or something.

4

This is why measurements arn’t everything when it comes to headphones.

5

It’s because the FR at your eardrum is not the same as the FR at the ‘eardrum’ of the measurement fixture. Remember the graph just gives you the picture of the sound in the condition of the device being on (or in) that head and ears, not yours.

Regarding the specific squigs, you’re seeing how acoustic impedance really matters when it comes to understanding how these devices perform. The 5128 (and 4620) will reveal more information about IEM performance, especially at low and high frequencies, than the 711 datasets, because it has the more accurate acoustic impedance.

But even still, there’s more to it than that. With IEMs, there are some very specific challenges to do with in-situ response variation, where the graph becomes less predictable than we’d like. This is why:

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6

Thanks very cool video!

The frustrating aspect is it appears there’s no way for me to predict when this “subwoofer in my ear” effect will happen other than buying the IEM and trying it (no CanJam happening in Mexico).

Obviously the FR is not a good predictor but apparently neither are the drivers.

For the low end, the Hype 4 mk2 has 2x 8mm DD and the Reference has 2x 10mm DD. One triggers this and the other doesn’t. Same with the Pure and the Daybreak. Both have 1x 10mm DD. One triggers the effect and the other doesn’t. There’s probably some spec like travel excursion or something that explains this… but this is not something that anyone publishes.

Anyway, thanks again for the help.

7

It is most likely FR, we just can’t see it with conventional measurements.

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