Earfun Free Pro 2 - newtral revision (Patreon)

Having achieved a smoother neutral kind of headphone sound with my new HD600 EQ, I continued approaching the same kind of sound for the Free Pro 2 using the recent "newtral" as base for further tweaking. I may still try to improve some things, but after some hours of tweaking I am already way closer to the timbre of the neutralised HD600 than I was before, although I had to readjust the overall balance again slightly. I noticed some were not satisfied with the latest approach due to lacking body etc, I think this new iteration may improve some things. It's definitely more bassy than the tunings before, but it doesn't appear boomy to me, as upper mids increased as well, the overall balance is now closer to the sound of the speaker. Unfortunately this tuning lost some further dB in loudness, comparing this setting to the previous tuning will require about 2-3dB loudness boost. For me it's not such a problem as I am  just losing 1 volume step and listen mostly at step 9 out of 16 now, but many seem to have issues with lacking volume, maybe the same curve can be approximated with other settings, I may try to achieve this when I am really satified with the final sound and have a final curve that I can use for adjustments. This setting was purely approached by listening and comparing the equalized HD600 to the Free Pro 2 and a speaker at the same time. It's way easier to compare an IEM to a headphone, therefore it helped me a lot to have a better reference with the new HD600 EQ but even that was not quite easy, therefore all the hassle. 

I didn't have much time to listen to the new setting yet. I finished it at 5 o'clock in the morning and immediately started listening after waking up. I think the sound is really smooth and natural now, although there is still some slight edigness to the sound which is mostly noticeable with pink noise, with music it's not such a problem. It will be hard to make the spectrum completely smooth with the limited filters. For the HD600 I used nearly 30 filters, although I may manage to bring them down to 10 as well with some work. I prepared a measurement to see what changed, and although the changes appear minimal from the graphs, the difference in perceived sound is actually quite big, again a proof that judging a sound purely from looking at some graphs won't tell you anything. The amount of upper mids will affect the perceived amound of bass, although bass may measure with a stronger amplitude, it may be perceived as being less if upper frequencies change as well. 

If you want to compare some settings directly I would recommend doing it with some external EQ like EqualizerAPO and simply load all my settings as configuration files, this will allow for way more precise listening, remember to revert the Free Pro 2 to an "empty" EQ to really have the raw-sound putting your EQ on top of this. I would also advise using pink noise for testing to really hear the changes properly:

Blue was the previous "newtral" while green was the original "neutral", in grey also the Harman target overlaid. The bass appears higher from the measurement than in reality due to too much front volume from the measuring microphone. It's interesting that it's getting even closer to the Harman target now, although without the added dips it would sound off. The correct frequency and amount of dip is quite crucial for the final result to sound "correct". Depending on your own HRTFs you may want to experiment by moving both the dips at around 7.4khz and 9.4khz to better match your own expected response. 

For this particular setting I got a spare filter left, the "air"-filter which I used to adjust the highest frequencies is not needed in this case, but it will be probably needed for the other resonance frequencies, therefore I just kept it inside with 0dB, the Preamp is there to allow you a better direct comparison with previous setting:

I would again welcome anyone with a resonance frequency close to 6000 to give this setting a try. I hope the overall balance is more satisfing now with enought thump  to the bass to also satisfy some bassheads, still with the bass being kept at a reasonable level. I probably will try to tone down bass a little bit more as for being regarded as "neutral" it's definitely slightly too elevated. I also want to smoothen out upper mids and treble a bit more to bring it even closer to my reference, although it's already quite decent right now there is still some "Hhhhhh" formant out of place that I want to get rid of. 

Some words about sample variation as I just got another brand new unit hich I ordered for a friend of mine which I wanted to prepare for him. With my original values this unit sounded way more muddy and bassy at the same time, a measurement in blue shows the new unit with my original settings, grey would be the current  reference, while green is the new unit with updated settings to get at least a very similar response (it won't be 100% the same anyhow).

This would be the necessary correction delta for the new unit to sound the same as my reference unit:

I would also like to post the necessary settings for this particular unit just for your information, which means it will be impossible for me to guarantee the same sound for everyone, your unit may be more bassheavy than others. My new settings for this particular unit would be way too bright for all my previous units. I am not sure if this variation comes from different production runs as all my other units I had are way more similar, but I bought them right in the beginning. 

I may even need a bit more time to figure out the right way how to deal with this, as creating an average won't make much sense, because then both units won't sound decent with exactly the same settings, I will also need to improve the bass filter as it's already a bit too heavy with my reference unit which is not as bassheavy to begin with. Once finished I will start to work on preparing all the other resonance frequencies. I hope I will manage until the end of this month to have all my current Patrons covered with hopefully the best tuning so far. 

Update: I think I managed to improve my personal setting in the meantime, and wanted to post the update. This version is final release candidate (RC1). Personally I think it's the best sound approximation towards a frontally placed speaker I managed from the Free Pro 2, at least with my reference unit. I managed to hide the edginess into the response slightly, it's simply impossible to make the spectrum completely smooth, but the overall sound appears still smoother now and also sounds more natural to me. I left a bit more air on purpose, although the tuning resembles my equalized HD600, I think the Earfun sounds still more detailed and sparkling, I was afraid it could appear too dark otherwise, especially with the other new unit I tried, but you can reduce the upper most frequenices with the last filter if needed, which is not active in this case, or use the 11K filter for a more global clarity adjustment, although already small changes of this filter will have a big impact on the overall balance. I also think that bass is more natural than before, while still not sounding really thin. Keep in mind this setting should only give decent results for ear canal resonances around 6000hz, but I somehow managed to hide the upper peak into the response, so that I can also wear them more shallow while still getting a sound which is not that off, this didn't work with my previous settings, I had to wear them at an exact depth, and the sound became considerably worse when they started to slip out on their own after a while or if pushed them in too deep.

Update 2: due to the feedback about too low volume, I remodelled the filter and added some kind of fake gain control with one of the filters. At the same time I tried to smoothen the response even more, after fighting the whole day and jumping back and forth between dozens of versions again, I think this will be the final release candiate and would like to share it with you before working on all the other resonances. 

I prepared some measurements, although actually not much has changed compared to RC1, except a bit less upper mids and lower treble, and a bit of additional bass reduction. I think now the bass is really neutral, black is RC2, purple RC1 and green was the original neutral tuning: 

The 3rd filter is the "gain-control" which you can use indirectly to adjust bass level like some slight balance tilt, it acts in a very broad range and is boosted by 3dB. The frequency defines the mid-point  of the boost which right now is at 5000Hz. Here also shown with frequency set at 1000Hz and at 10000Hz: 

The last 16K filter should be used to adjust "air" depending on the unit and taste. I currently have it set to 0 on one unit and -1 on the other one, but some may even prefer -2 or lower. If there are no objections I will continue listening with this setting a bit although so far I like it most over all previous versions especially as we are back at normal gain and the sound appears again a little bit smoother than before. I prepared a short playlist for you to listen to some great recordings I discovered recently which are also included in my upcoming audiophile collections:

https://music.apple.com/at/playlist/newtral/pl.u-DdAN0YeTaMKYpd

https://open.spotify.com/playlist/4TwQYs7hYOdUmmV2jJ9I0I?si=JRFF6chpSaeZlNdkCqJM7g

I hope I will manage to finish all other tunings by end of this week. I will try to cover the entire possible range from 5-8K like I did with the original neutral tuning. Not sure if I should drop that one or rename it, as this new "newtral" sounds definitely more neutral, what a mess!