Sennheiser HD600 - neutral EQ - flat bass (Patreon)

I finally need some rest, because I haven’t really slept a lot the last days. Therefore I wanted to post this before taking some days off together with my family for fall break and make my “neutral EQ” for the HD600 finally public which will allow for listening to my binaural recordings with the correct sound. All my upcoming videos will have my new compensation applied and together with this EQ for the HD600 you should get a mostly uncoloured lifelike sound.

It took me several attempts with lots of setbacks to finally achieve a relatively true sounding EQ setting for the Sennheiser HD600 which is based on my own personal target for headphones and was derived from endless spectrum analysis and listening sessions. My target departs in many ways from the common Harman based targets while definitely offering a way more realistic sound than those at least to me. There will also be variants of this EQ with a more Harman like bass as opposed to a flat measured bass, also dicussing which one is actually the more correct one. There will also be optimised settings particularly for the Qudelix 5K, because the same values result in a different sound when compared to EqualizerAPO which of course is quite annoying. I will also try to finetune this EQ more in future, because having just 10 filters available while trying to achieve the smoothest result will always end in some compromise with further room for improvement. You will find all these “extras” in the dedicated enthusiast level section. After my return I will start working on other headphones but also trying to get closer to the same target for IEMs with some models maybe revealing additional qualities over others. My plan is to come up with a new improved tuning for the Free Pro 2 as soon as possible, although I cannot say how long it may take to get first usable results. Like mentioned before I would like to select some popular headphones maybe also based on some wish-list which ones too choose and then create similar tunings for them, which hopefully should give most of you a significant improvement in sound and allow for a more honest and correct way of listening. I see headphones rather as a working “tool” with some having more potential to offer a true lifelike sound than others after proper equalising. But no single headphone I tried so far regardless of price, was able to really deliver a faithfully neutral sound. It will be interesting to finally discover which headphone model may be the best blank for further adjustment and maybe also the best bargain.

Oratory1990 was so kind to prepare simulated responses of my EQ based on his existing measurements of the HD600 done on a standardised GRAS system with my EQ applied virtually. You can see both variants with flat bass and a more Harman like bass, still kept at a rather neutral level and not boosted as much as Harman suggests:

I would love to hear your opinion on this EQ. It’s definitely optimised for my own ear and I perceive it as way more natural sounding than stock. Overall my EQ is based on rather generalised and heavily smoothened responses of differently measured headphone positions, thus the EQ should remain mostly generic as well and I am wondering how well it might also work for others. I need some feedback in order to know how to proceed and what to change in future. I would welcome any HD600 owner to try this EQ out, and let me know how it sounds to you. If you don’t own a HD600 this would be the best opportunity to finally get one.

Having elaborated a solid workflow this should allow for faster equalising results in future, but it’s still not a one-click solution and needs some effort and listening to find the best possible EQ setting for each headphone. This time it took me so long because I needed to try out several approaches and had to find the best methodology how to achieve a reliable result which comes down to the correct averaging and smoothing of the measured responses. The more strictly you try to EQ one response to another the worse the result may become, which was quite surprising to me. I even tried to auto EQ a setting for both my ears separately hoping that this could improve the result even more, but actually it sounded really scruffy, while averaging over various kinds of headphone placements and smoothing the final response for any further EQ accordingly became the most important factor having the biggest influence on the outcome. Due to the strong averaging the EQ is also rather gentle just trying to match the response of the headphone better towards the target, instead of dealing with every peak which in case of the HD600 worked pretty well, due to the rather neutral character of this headphone to begin with. Lots of time went into optimising the setting in such a way to make the EQ work with 10 filters only making it universally usable on mobile devices like the Qudelix 5K or mobile phones running decent apps which allow for parametric EQs with at least 10 filters. Therefore the limit I set myself is to use just 10 filters in all my upcoming creations and try to squeeze out the most neutral sound out of the given headphone. My current setting for the HD600 may still leave some room for improvement but it will be hard to easily get an even smoother response as I really tweaked the filters manually for hours in order to get a nicely smooth spectrum with decent detail. You can get a rough setting quickly also by simply auto EQ one response towards the other. But the hard part comes when you start fine tuning the result slowly approaching the optimum result bit by bit while adjusting just a single filter will influence the overall result. By adjusting some bass filter, you will notice that it can significantly have an impact on the smoothness of treble at the same time. Sometimes it may sound better by changing 40hz to 41hz or changing the Q-factor from 1 to 1.001 which can have a huge impact how smoothly the final spectrum will be perceived.

If you are satisfied with the current result and are interested in supporting my further work feel free to check the enthusiast level because it’s lots of work, but all my further EQs for other headphones will be only available for the enthusiast level because they are a pain in the ass to create and require lots of listening and optimisation work to make them usable. I am already getting tinnitus from all this by continuously listening to pink noise and trying to find the smallest errors.

Thanks a lot for any support so far!