In response to the latest round of theories.
I have tinnitus in both ears equally (from a well balanced stereo, of course) at a perceived frequency centered around about 7 KHz. This is a common frequency to get tinnitus. Why? It's actually very explainable. The hairs inside the cochlea of the ear hear sound starting at the highest frequecies nearest the point of entry where the stapes bone is connected. The cochlea winds like a Nautilus and as it goes inward the frequencies we perceive on the hair cells go down in frequency. This reaches a limit where the really low frequencies are perceived by the semicircular canals that also help in balance. Now you know why very high SPLs at infrasonic frequencies can make you feel a little ill.
So again, why 6-8 KHz is typical tinnitus frequency of perception? Same reason it is also the most common area of hearing loss: the position of the hair cells where we hear that range of frequencies sits right on the first bend in the cochlea. The sound waves hit this area the hardest by mechanical means. Somewhere in this range also lies our most sensitive hearing range as well, because it receives the most signal, and is well known as in the presence region.
Also, this tinnitus region is also my worst hyperacusis region. My hearing damage has shown no hearing loss as everyone would expect, but has tinnitus and hyperacusis exactly where we would also expect that loss. Why? Because theoretically the damage was not long enough and loud enough to flatten dead the hairs in the cochlea there but was short enough and sharp enough to damage perhaps the function of those hair cells and down the nervous system from there. Hyperacusis is an excessive perception of volume that we think is caused by nerve damage where the nerves aren't good enough to feedback quickly enough the automatic gain control in our hearing system. Tinnitus is also a nervous system disorder in the hearing system where likely the nerve firings don't want to stop. It's very common to have both symptoms.
When I got rid of my first metal dome tweeter speaker, I found I could listen to soft domes. The next speaker choice was a ProAc Response 3. The next was implementing what I learned about frequency range of damage and designed and built my own speaker. It was a little cross between the ProAc Response 3 and the Avalon Ascent, as much as I could imagine the implementation to be correct and use off-the-shelf drivers and crossovers.
The drivers were a Scanspeak D2907 fabric dome tweeter from 6 KHz on up, 24 dB/octave acoustically Linkwitz-Reilly, similar to ProAc's tweeter with less frequency coverage for smoother performance from this otherwise slightly rough tweeter. The other crossovers were all the same type of filter. The midranges were two MB Quart 2" titanium domes, the driver that was modified and used in the Ascent. They operated from 700 Hz - 6 KHz. The woofer was an Eton 8" Nomex-Kevlar design that is still around and popular to this day.
The result with a pair of titanium domes in there? No problem with hardness whatsoever. The peaking that occurred in-band in the tweeter region was filtered way down. The hardness was not perceived because A) it was not stressed by overcoverage of low frequencies and B) it was not overstressed by the fact I used two of them for more output from less excursion from each. The 8" Eton had no problem reaching 700 Hz.
That speaker sounded pretty good I thought. My friend heard them too and wanted to buy them. When I decided to go flea power SET and horns I did sell them to him and bought the smoothest horn I have heard - the Avantgarde DUOs. Those do not shout and play plenty loud without any harshness. I thought this was perfect, until the day I heard the Oris 150 horn. It will shout at very high SPLs but it wasn't terribly harsh either. It was simply more articulate and detailed and got rid of that plastic-like sound that was always there in the DUOs.
Then I heard about everyone abandoning Oris horns for Orphean horns because of a leap in articulation and detail and dynamics, and at 112 dB/1W/1m from 250 Hz on up it took only a 1/4 watt amp to play loud. But it had a fatal flaw for me. There was a resonant peak at 6.5 KHz and it was harsh when excited in that region. Nothing I could do could change that, it was inherent to the coaxial compression driver in the mid driver, but not the tweeter driver. Funny thing was, the 2" throat it used has a major acoustic modal point at exactly 6.5 KHz. And the crossover between midrange and tweeter compression drivers inside was also at 6 KHz. I tried changing the crossover but some acoustic crosstalk between the drivers kept that 6.5 KHz peak going. Yikes! Finally I gave up, sold them, gave up on horns altogether and since I heard many metal domes that controlled harshness, I figured the well reviewed Focal Utopia speakers couldn't mess it up.
Maybe I still have the wrong amp, but I can't imagine that a super low output impedance amp is really going to fix everything. Quite the opposite seems true to me - the high impedance amp reduces harshness, or even adding series resistance to the speaker reduces harshness.
As to my source, my Sennheiser HD-595 headphones don't perceive anything wrong even at the very loudest settings where I have to move them off my ears.
The only thing I need to check out further is if the 30W/ch amp is actually clipping every time I hear a resonant assault on my ears. It might be, and then I need to surely back off on the volume controls like I'm doing already out of necessity.
I did go to see Indiana Jones this weekend and it was a very clean horn system without harsh digital artifacts either. It was louder than I ever play my system these days and I walked out with no pain. I want those speakers I think. But those are way too big.
Kurt
