Earfun Free Pro - final neutral tunings (12/2021)

For all newcomers, please start here to know how to apply the EQ values for your own unit: https://www.patreon.com/posts/57711555

Please find all final tunings for the Earfun Free Pro attached as text file. I tried to get an as neutral as possibe target, although the bass area can remain a bit "vague", therefore you may need to adjust it to your own taste and preference. I didn't try to make the sound "better" in any way, these tunings are meant to offer you a mostly natural and uncolored sound reproduction. Keep in mind all tunings were created based on a single unit which I had bought recently. My original tuning is based on a resonance frequency of 6200Hz which was also used for creating my own neutral target, all other tunings are manually adjusted towards this target by performing additional measurements at different resonance frequencies. 

All EQs have the same structure, although some even have a spare filter left which you can use for additional adjustments in case needed. The first and last filters can be used as some kind of bass/treble adjustment without affecting the overall balance too much. Increase or decrease the gain to get more or less bass/treble. -With some settings I already had to use the treble-filter for a global correction, but most settings have this filter set at 0 gain:

I cannot estimate how well my method will work for all other resonance frequencies as they are just extrapolated based on measurements and will heavily depend on how precise the couplers can simulate a human ear-canal, therefore I will need your feedback to know how these values will work for you. Another problem may be sample variation, I noticed that all units I own would give different results with exactly the same values, thus it may be impossible to offer you a perfectly neutral result which I get from my own reference unit.

One option would be to measure all my units with the final tuning, creating an average out of these and using this as a new target, which of course would need lots of additional effort as I need to adjust all tunings again towards this new target. In this case you would probably still get slightly different results than what I had intended, but they may be closer than the current tunings now. 

The most reliable option would be to tune each unit manually which would require most effort, but it could be the only way to really offer you a tuning which is as neutral as possible  as long as I know towards which resonance frequency I need to tune. I could offer that "service" for those interested. Either by getting your unit and sending it back, which will probably cause too much shipping costs, or by selling already tuned units on my own. I may think about this for the Earfun Free Pro 2, as I think hardwarewise it's definitely more solid. I cannot offer this for free of course as the whole procedure is quite time consuming.

How to check your own resonance frequency quickly: just apply an "empty EQ" (choose one of the unused EQ-indexes and hit realtime update) which will result in the raw-tuning, then perform a sine swipe using this great site: https://www.szynalski.com/tone-generator/

Caution: before starting reduce volume to a fairly low level as pure sine tones can be quite invasive at higher frequencies and will compromise your hearing for some minutes. Start at 5000Hz and slowly raise the frequency monitoring when you will get the highest amplitude. You should hear a distinct peak appear between 5000-7000Hz. The amplitute should noticeably start dropping again after you found your peak to both lower and higher frequencies. The frequency where you think you hear it loudest should be your ear canal resonance with the given unit/tip combination. Use the tuning which is closest to your value and try if it sounds OK to you. The result shouldn't sound too different compared to a neutral speaker or headphone. You can perform another sweep with the selected tuning but now the amplitute should remain more or less constant over the entire frequency range. (The perceived raise from 2-3khz is normal and is probably related to the ear-gain.) You shouldn't hear any stronger raises anymore if you chose the correct tuning for your ear canal resonance assumed that my tunings are not off. Keep in mind this is still all just theory, I have no proof how well this approach really works for others and the result will be heavily dependent on the precision of the measuring couplers I am using, but from my own experience so far I seem to be getting quite reliable results.

Please let me know your thoughts as I may need to fine tune my target even more for all future work, but sample variation will make everything a bit complicated. I will try to create an average target out of all my units, maybe even getting 2 further units to have even more variation. This will of course require further time and effort and I am dependent on all your support to get this as solid as possible. Thanks to everyone so far!