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A series of videos about Sennheiser headphones starting with the tuning of headphones

thewas

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Ever wonder why Sennheiser headphones are tuned the way they are? We sat down with audiophile expert, Jermo and acoustic and signal processing engineer, Werner at our German headquarters and got technical. We fielded questions from our community and discussed the intention behind our audiophile headphones and why we tune our headphones the way we do. Sit back and geek out at the art of Sennheiser headphone tuning!

Chapters:​



Intro​

0:00


Guest Introductions​

0:28


Sennheiser Transducer Lab​

3:16


What is tuning​

4:41


Tuning​

7:27



Tuning Principles​

12:53


The Transducer​

14:44


Open vs Closed​

16:39


How do you accommodate 4 ears​

18:58


DIY tuning tips​

22:17


Whats next for Sennheiser​

26:33
 
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thewas

thewas

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What's the difference between audiophile headphones and everyday headphones? How long does it take from product conception to product launch? How does manufacturing play a role? We sat down with our audiophile product manager, Jermo and acoustic and signal processing engineer, Werner at our German headquarters and and fielded questions from the community, focusing on R&D and manufacturing. Special thanks to @Listener and @undercoverbackup9134 for the excellent quesitons. Curious to know what happens behind the curtains? Drop a question in the comments below and we just might feature it on a future episode!
 

Robbo99999

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Very interesting videos, I watched both all the way the through from the beginning. My own general perspective on Sennheiser before I start talking about the vid: I'd say in overall terms my best headphone is a Sennheiser headphone, the HD560s, so I'm interested in Sennheiser products and I think they really do make some solid headphones, both in terms of sound target, but also in reliability - low unit to unit variation, good channel matching, and can be used for years without failing (got the HD600 too).

I'm gonna list a few points I thought were interesting from the two videos:
  • 90% of headphone tuning is achieved by the design of the transducer, the remaining 10% that contributes to the final sound is shape of the earcups/pads/dampening. They design & make their own transducers, can take years to design a product, did he mention up to 10yrs, but often around 2yrs. I was really surprised to hear that the transducer is what shapes 90% of the frequency response/tuning, I thought it was gonna be considerably less than that.
  • Harman Curve: they basically said HD600+bass shelf, confirming what we already knew back in the 90's. (They did say the Harman Curve research was very important and notable though.) More than just the measured frequency response they mentioned. But they do use measurements rig though in the development process. They didn't mention if they measure in-ear on real humans for frequency response though, to see if there's large variation between people with certain headphone designs for instance - HpTF variability. Perhaps they're more seperating themselves from measurements done on rigs, in terms of being strict about a target frequency response - because they say of course they tune them by ear as well as measurement. My thoughts: I'm less confident that large straying from Harman is beneficial, although I can imagine targetted and/or small'ish tweaks around it to cater for different tastes could be useful, but a fair few of their headphones seem to track Harman well, better than many other manufacturers from that point of view.
  • HD800s. Baffle manufacturing variability (metal mesh) in terms of 150-300 "Sennheiser ohms", therefore they match transducer to the correct category of baffle. Different groups of baffles & different groups of transducers, they know which groups of both they need to match to get the "same" frequency response. How they control the frequency response of the HD800s so that there is minimal unit to unit variation. Perfectly matched channels, imaging, one of the reasons why they think it's done so well. And my thoughts: a good argument for getting a miniDSP to EQ both your channels to perfectly matching through whole frequency response range - for other headphones (I've done this, I think it's worth doing). I thought the length they go to control unit to unit variation & channel matching in the HD800s was pretty cool.
  • HD560s. Started off in Jermo's basement (guy on the right), 6'ish months to develop, very quick, even though they did develop & manufacture a specific driver for it.
I thought it was good that these two significant players in the Sennheiser R&D team were young (good ears for one thing), but also their enthusiasm and energy, but it was also good that they were more on the nerdy side rather than somekind of Youtube influencer or something (lol), which is good because you want them to have a scientific approach backed up behind their enthusiasm. I'm not using "nerdy" as a negative term, because they came across well on the vids and explained stuff with enthusiasm and energy and their own personality which helped make it interesting.
 
Last edited:

isostasy

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What do you think of their approach to IEMs?

What they say about all ears being different, therefore requiring different tunings for IEMs sounds plausible but isn't the case for me in practice. I listen to my Etymotic ER2XRs with a small 3dB reduction at 1.7kHz. With this they sound tonally identical to my HD6XX but with better treble. If I scoop out the midrange to match the Sennheiser IE900 it's an interesting effect but definitely doesn't sound like the HD6XX.

Is this just because I'm extremely lucky that my ear is close to the average represented by the various rigs used to measure these headphones?

Or do their IEMs sound very different to what you'd expect based on measurements because of what they say about the resonance chambers used?

The Etymotic approach of completely removing the internal ear canal resonance as a variable still seems the best starting point to me. I don't see how the resonance chambers in the Sennheiser IEMs would reduce this person-to-person variation.

I'd like to see how this works in practice but don't have $1000 to spend on an IE900 to find out!
 

Robbo99999

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What do you think of their approach to IEMs?

What they say about all ears being different, therefore requiring different tunings for IEMs sounds plausible but isn't the case for me in practice. I listen to my Etymotic ER2XRs with a small 3dB reduction at 1.7kHz. With this they sound tonally identical to my HD6XX but with better treble. If I scoop out the midrange to match the Sennheiser IE900 it's an interesting effect but definitely doesn't sound like the HD6XX.

Is this just because I'm extremely lucky that my ear is close to the average represented by the various rigs used to measure these headphones?

Or do their IEMs sound very different to what you'd expect based on measurements because of what they say about the resonance chambers used?

The Etymotic approach of completely removing the internal ear canal resonance as a variable still seems the best starting point to me. I don't see how the resonance chambers in the Sennheiser IEMs would reduce this person-to-person variation.

I'd like to see how this works in practice but don't have $1000 to spend on an IE900 to find out!
I'm not a big IEM user, in fact I only have one IEM, the Truthear Crincacle X Zero Blue, and after EQ to the Harman 2019 v2 Target Curve (the one Amir uses) then subjectively I found it to be very similar to Harman 2018 Over Ear Target (used on over ear headphones obviously). So to me I think the Harman 2019 v2 IEM Target Curve is done right and mirrors the 2018 Harman Over Ear Target well. One caveat, I don't use IEM's as I hate sticking stuff in my ears, but when I received that Truthear Crincacle X Zero Blue IEM then I really did do some intensive use of them over a couple of days - I thought they were fantastic.
 
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