Oluv's neutral IEM target - WIP (Patreon)

I was not inactive the last 2 weeks, but too busy to post anything as I had set up my listening solution in the living room again and spent most my time to fine tune my headphone target a bit more. At the same time I tried to achieve a similar result for in IEM, which in my case is the Free Pro 2, based on my previous quick and dirty approach.

It's quite a frustrating experience if you think you managed something decent, just to hear the next day that it's still not right and I didn't want to rush out posting something half baked like before. But I think I managed some significant improvement for both my headphone target and also the IEM target. It takes several approaches and requires regular pauses to reset the hearing again. I noticed that I perceive sound differently in the morning or in the evening particularly for IEMs as the ear canal is the only resonating chamber and can obviously change a lot in overall cubature during the day. Also driving inside a car climbing a hill will change the response slowly until your ears perform a pressure equalisation and the sound becomes normal again. IEMs are very critical in consistent placement, the shape of the ear canal etc therefore it was really not easy for me to achieve something decent that quickly. Sound perception will also depend a lot on what you were hearing before. Listening to pink noise for longer "burns in" some image which will start sounding quite static just like a CRT screen displaying the same image whole the time. I tend to play some music in between after a while and suddenly pink noise will be rendered quite different. Also playing sine notes or doing sine sweeps can be helpful to stri up your hearing again and you will achieve a better overview about the rough sound without concentrating on the fine details too much. But most important is to have a constant reference and try to match the sound to this, not trying to optimise anything just "blind" otherwise it will drift to something completely different.

So after several days of dreary listening I finally came up with an IEM curve which sounds to some degree similar to both the speakers and the overear headphone, although the HD58X started to sound off and I had to readjust this as well, to my surprise I had overheard some important aspects of the perceived spectrum with my previous approaches and had been wondering why my headphone measurements deviate so much from the speaker measurements I did with my ears. But now both are closer, although still different in the 3-4khz region and above, but as hard as I try to match these areas through graphs the more it starts to sound different. Below the new setting for the HD58X compared to the previous one I posted recently in green and grey the measurement of the speakers:

Finally my new setting for the HD58X as well as my latest setting for the Free Pro 2 should give more or less the same perceived spectrum between all 3 sources. They still do not sound exactly the same, but they all resemble each other quite well and any deviation from this response will result in a spectrum which deviates even more. I am still trying to optimise my IEM setting a bit and hope I can match them even better. Here you can see the final response for the Free Pro 2 which I perceive as fairly “neutral” or similar enough to the sound I hear from the KH80 together with some previous versions.

You can notice that they all align quite closely to each other nevertheless each of them sounds significantly different from the optimum curve. My goal was to get the responses as close and realistic sounding as possible to achieve a curve with as few errors as necessary in order to have a valid graph which I can further use as guide for other headphones and IEMs because any user dependent variance, sample variation etc will introduce further errors thus my own curve needs to be as perfect as possible not to carry over any initial errors. Because of this it takes a bit long to achieve perfect results. I usually tweak the settings compare back and forth, then listen the next day and if I am satisfied I start listening with this setting for a while until I notice that something bothers me and start to tweak further. If I can't even manage it for myself properly how can I dare to offer something to you.

One would assume that a headphone and IEM measuring with exactly the same response will also make them appear to sound the same, unfortunately that's not the case. As you remember I let both my HD58X and the Free Pro 2 unit measure on a GRAS system by Oratory1990, below you can see the final responses for both measured on this professional rig (red the Free Pro 2, blue the HD58X):

You can see that they resemble each other to some degree but they are far from equal still I perceive them both as quite similar sounding. The high amount of bass measured for the IEM may be a result of wrong impedance of the measuring system with this shallow insertion depth. 

I want to give me some time for further listening and improvement before posting anything, therefore keep in mind it will always remain a work in progress! I hope I can share a final EQ for the HD58X next week and at least a setting for my current Free Pro 2 and my own ear canal resonance. It will depend a lot on the demand and support to offer further settings for different resonances. Due to the high amount of sample variation for the Free Pro 2, I would need to measure all units and create an average for all of them. This would basically make 12 exact measurements for all common resonances which is a lot of work, not even talking about the propriate equalisings. I would prefer to only cover those who really ask for it otherwise I'd invest too much time into something that nobody will need. I would beg everyone who still didn't do this poll to tell me their ear canal resonance for the Free Pro 2 to have a better statistics about the real life distribution: https://www.patreon.com/posts/whats-my-your-60519720?utm_medium=clipboard_copy&utm_source=copyLink&utm_campaign=postshare_creator&utm_content=join_link