[AstralStorm]

Hell
I've been abusing Electri-Q a lot and derived some really interesting curve for Sleek Audio SA6
with Bass+ and Treble= filters:

 
Exported preset for your listening pleasure (no guarantee it matches you):
http://ompldr.org/vODV4aA/SA6flat.e-q
 
I've used *many* sine tones at -6 dB straight out of Foobar2000's generator, started equalizing at volume picked so that 1kHz tone would sound slightly annoying. Equalized in many pair "octave" and "neighbor" comparisons so that loudness matched.
 
What I find weird is that it ended up sounding like a brighter, less muddy, slightly less punchy, precise variant of Sennheiser IE7 I'm very familiar with... a "3m distance" experience, holographic. It's not like my ears are calibrated for that older IEM or something...
 
Is it normal to derive such a weird-looking equalization curve this way?
Any actual headphones that would sound like it? (list wanted, esp. cheap and possible to drive from portable equipment, mind the wallet)
 
Please also share your own eq experiences...

 

[mvw2]

Earphones are not super flat.  The single drivers being used are not flat.  There are curves to the response.  I'll pull one random example from Knowles website:
http://www.knowles.com/search/prods_pdf/BK-21669-000.pdf
 
A copy of a very expensive but not so great response earphone, the Final Audio FI-DC1601SB in red.  It's not exactly something I'd call good.  The gray is the ER4P, again a single driver but much more balanced.  I will note that perceived balance isn't the same as frequency response balance.  Our ears don't quite hear flat.  However, variations in presentation also influence sound.  A thin note, even if loud, will sound weak and quiet in lower frequencies.  The roll off of the ER4 on the treble is largely perceived as flat, as is the bump in the midrange due to how our ear works.  I also added Phonak's PFE, a relative copy of the ER4's response.  Again you can see the ragged top end before rolling off.  The bottom pick shows some Audio Technica models.  Multi-drivers tend to improve the balance and extension of the response.  The CK90Pro sounds pretty much ruler flat to my ears for example.  I can't really add or remove 1dB anywhere and not mess up the balance.  This is an average adjustment though.  The minor fluctuations could be tuned if you wanted to get detailed enough, but from a broad spectrum, the slight variation is hardly perceivable.
 


 

 
Here's one example of me doing a little EQing to the SA6.  This is showing the result after using a pink noise track and also using the Electri-Q software.  The graph represents the frequency response I ended up with.  This is with the treble ++ port (no filter) and no rear filter (simply removed).  I will say that the treble doesn't sound hot simply because it's so smooth.  It actually sounds rolled off from normal listening, but with EQing, I don't see that shortcoming.
 

 

[AstralStorm]

Thanks for input.
I don't really believe in pink noise equalization myself, it's very hard to properly equalize higher frequencies this way by ear.
(and any other eq is likely flawed) Weird that you bump high frequencies and not even the highest end on these.
It almost seems to me like you've "fixed" pink noise frequency response to almost white noise-like.
Pink noise is 10 dB/octave rolled off, your equalization is almost the inverse.

 
Also, removing the filter changes nothing or next to nothing from the one that is labeled as Bass+.
 
Does anyone happen to have an actual chart of frequency response of SA6 in its various configurations?
Headroom has one measurement, but they don't provide the response of the head itself,
making it useless for the purpose of separating my ear response and frequency response of the IEM itself.
 
Edit: Also, I've "simplified" my EQ, it is actually more precise now:
Edit2: Corrected a few minor mistakes and I'm finally done.
http://ompldr.org/vODYxYw/SA6-flat.e-q
Edit3: Whoops, posted wrong file, here you go with the actual final version. Spot the mistakes in the previous one:
http://ompldr.org/vODY1Ng/SA6-flat.e-q

 

[AstralStorm]

Interesting, adding an adapter and compensating for a difference in volume changed the signature somewhat.
But after retuning the eq the end result is even better... The change is quite dramatic actually, even 6 dB at places and some humps are moved slightly.
Especially at 6-7kHz. Bass got a bit more kick as well.
The eq file: http://ompldr.org/vODY3NQ/SA6-flat-adapter.e-q
 
This is with the Ultimate Ears adapter, I'm not sure, but I think it's 100 Ohm. Will measure it later.
I'm driving those out of headphone amp jack of Presonus FP10 at the moment.
Edit: Mistakes were made, retuned to flatness.

 

[mvw2]

Pink noise is about intensity.  It's different between listening to a tone and noise.  With a tone, you are comparing loudness of points.  This means you want the sensitivity the same.  With noise, you do not.  Noise is area rather than a point and area increases as frequencies go up.  500-1000Hz has twice the area as 250-500Hz.  To compensate for doubling the area per octave, the loudness has to be cut in half.  The low pass filter over the entire spectrum does this.  The end result is a noise track that sounds equal in intensity throughout if the device playing it is tuned to a flat response.  You're still tuning points, but you're never working with a specific point but rather a curve, and this curve still exists over a spectrum of frequencies.  The goal is to shape the end response so the whole spectrum sounds equally loud with no frequency really popping out from another.  Everything is of equal loudness.
 
I started out playing with a bunch of tone tracks, per octave, parts of octave, even adding in warble to the tones to try to help make tuning easier.  In the end, I found pink noise to be so much easier to work with.
 
Since we are all tuning with our own ears, we all will get different results from each other.  Nobody hears the same.  As well, things like loudness reshape the perception of sound.  Tip choices will change the sound from the SA6 quite a bit.  The filters used will affect the sound a bit.  Even the same person over time will hear differently day to day, month to month, year to year.  There's lots of things going on.  In the end, the goal is to tune to your own liking, whatever that may be.

 

[kkl10]

My experiences with equalization have been very rewarding!
 
Note that I usually prefer to cut more than boost.
That's why the midrange has the biggest cut on both of the following graphs. (It just so happens that I perceive it as the loudest part of the frequency spectrum on both IEMs)
 
I'm using foobar2000 - Electri-Q parametric equalizer, sinus sweeps generator, pink noise and not much more...
 
Here is my current EQ curve for the Head Direct RE0 with the stock medium black silicone eartipsmaybe still improvable)
 
 

 
Settings:
 
Freq. - 150Hz
Gain - -7db
Bandwidth - 6,5
 
Freq. - 1400Hz
Gain - -8,5db
Bandwidth - 1,2
 
Freq. - 4700Hz
Gain - -2,5db
Bandwidth - 0,3
 
Freq. - 8250Hz
Gain - -5db
Bandwidth - 0,2
 
Freq. - 13000Hz
Gain - -3db
Bandwidth - 0,1
 
Freq. - 15000Hz
Gain - 3db
Bandwidth - 0,4
 
And for the Soundmagic PL-50 with the same eartips used on the RE0: (still improvable)
 

 
Freq. - 150Hz
Gain - -4,5db
Bandwidth - 2,8
 
Freq. - 1000Hz
Gain - -8db
Bandwidth - 3
 
Freq. - 2400Hz
Gain - -7,2db
Bandwidth - 0,7
 
Freq. - 6800Hz
Gain - -10db
Bandwidth - 0,3
 
Freq. - 11000Hz
Gain - -2,5db
Bandwidth - 0,4
 
The Head Direct RE0, as everybody knows, has a relatively flat, uncolored, and accurate sound signature to begin with so it was the easiest to EQ to flat to my ears.
It might seem strange that I'm boosting the treble and not the bass, but that's what I have to do to hear a flat sinus sweep and it actually doesn't make the RE0 much brighter.
 
I believe that this is due to the fact that before EQ the midrange was very upfront and narrow (the slight lack of low end and some peaks on the treble made me perceive it as somewhat lean and bright) and after EQ it's more in line with the rest of the spectrum and any boost on the treble (as long as it is made so that it sounds flat and in line with the rest of the spectrum, of course) won't make it sound brighter but instead airy and spacious.
The improvements are amazing, spatial and bass resolution improved the most. It's like hearing a higher tier IEM.
 
The biggest improvement however came with the Soundmagic PL-50, since it is less linear than the RE0 in stock form.
The stock PL-50 has a very recessed low end and very prominent higher midrange to my ears thus creating a very unnatural listening experience.
Once EQed it transforms into a completelly different IEM, there's just no comparison.
Probably one of the biggest, if not the biggest, bang for the buck IEM, the low end comes to life with astounishing power and resolution, tone and timbre improve dramatically just like spatial resolution. The overall sonic signature improves incredibly.
Before EQ it was very good for the price I paid for it, but after EQ it is definitelly a steal!
 
Both RE0 and PL-50, once EQed to my ears, have a naturally identical sonic signatures, the only thing that puts them apart is the driver type used and the perceivable (not so much as one might expect) higher resolution capability of the RE0. I believe that this is a very flattering thing to say about both.
 
 

 

[AstralStorm]

Boost and cut are dual (inverse, symmetric) operations in most EQs, specifically in Electri-Q. They're *not* inverse in FIR equalizers, as the synthesized filter will likely have different pre/post-echo characteristics.
As long as you don't get into clipping, your eq is fine either way - my previous ones (after even more slight tuning, now I'm completely happy with it) had some -8 dB gain and VSTHost has a peak tracker, so it's easy to find clipping with it.
I always set the eq so that 1 kHz is at 0 dB - this gives a lot of dynamic range to play with.
 
At least now I know I shouldn't even consider RE0 and PL-50 for the next buy.

I'm looking for something closer to the desired sound signature for use without eq in really adverse conditions, such as cellphone, mp3 player and other unknown systems. (amping is fine, I have one)
 
Here, SA6 lost some of their metallic feeling and gained a lot of intimacy in vocals. Also sound like an anechoic room or a well dampened studio monitors at about 3m distance. The only thing that doesn't match is the bass - it lacks the same directionality as in reality - sounds more like a separate good subwoofer. I suspect I could rectify that by changing the crossover design...
 
Oh, and the final EQ is:

 

[AstralStorm]

Interesting.
Today I've received my Comply T-100 tips.
First of all, the response is... different enough to warrant a separate eq in high frequencies.
Also, the bass goes down a few Hz lower and impact got... smoother, rounder, more dynamic driver-like, still impacting.
The sound is altogether smoother. They still reach 16 kHz easily though, and now I can actually equalize them for the really high end to match loudness without awful ringing.

 
Edit: My theory for this change is that the foam dampens case ringing somewhat, reducing spurious harmonics. The other changes are probably due to better fit and slightly different placement in the ear canal - probably a bit deeper.
 
The current eq curve is: (Edit: pasted wrong picture)

 
Edit: Once I've rechecked low frequencies, it became apparent that SA6 actually boost lower and upper mids a bit, about 3 dB. Correcting this made them seem more precise.

 

[goodvibes]

Guys, I'm not sure that we should be talking about resonance on IEMs. Think about the 1/2 wave of 10 khz. It's it's about 2/3". It's posibble that some minor noise is coming back through the back of a diaphram but if you hear a difference as described, it's much more likely that the foam tip is working directly as a filter. The only point that I could imagine a tip actually directly affecting resonance in an IEM would be the entire IEM moving on a lossey tip connection from lower band excitement which could cause a number of artifacts. I'm constantly amazed at how different tips sound but I doubt that mid and upper freq. case resonance is the mechanism.
 
When I had pl50s I played with some EQ and pulled a few DB around 3k. The rest was pretty flat except I added a hair at 15 or 16k and I didn't need to do much with the bass as one pair I had were vented. Touchy to do but I reall only needed to add a couple DB at 30hz after.  Think I used olives with them. That pair broke and I'm not a big fan of EQ in general so when I got a second pair, I left them stock and eventually just moved them along.

 

[AstralStorm]

Nah, if foam acted as a "simple" filter, it'd directly cut high frequencies a lot, like material used for speaker grill covers. It doesn't, so the effect is different in nature.
The change doesn't sound like something possible to simulate with an equalizer either way.
Note that I'm probably talking about third harmonic, which is quite harsh sounding, so anything in the mids could still be audible as ringing.
This effect is quite subtle, but there. (Caveat emptor: Not a blind test, just A/B) I'd rate it as 20% change in harshness.
 
Edit: Come to think of it, the foam might be absorbing intra-ear canal reflection that shouldn't be there - ear canal is an open space. That would change intermodulation distortion properties.

 

[dadab12]

Why don't you use a better equalizer? I suggest, brainworx, nomad, solid state, nugen, Fabfilter, actually there are alot better equalizers and limiters to deal with.. I'd try dynamic EQ's with spectrum analyzers for beginners 

 

[AstralStorm]

Uhm? Electri-Q is already a parametric equalizer, shows the frequency response and also provides other interesting analog prototype filters to toy with. I've managed to simplify the equalization curve to only 11 biquads, which is entirely reasonable to implement in hardware - which is the actual goal.
The only way I could improve on it is to tune the response at various volume levels and interpolate between those - is that the "dynamic" EQ part you're suggesting?
 
Brainworx mid-side equalization sounds quite interesting, but simple 2x mono eq should be enough. Or a mid-side splitter then eq. (Yes, I can do separate channel eq with 2 instances of Electri-Q, haven't gotten to that yet, doesn't "sound" necessary)
All you've mentioned have only a few controls and they're the horrible dials that don't work well with mouse.
 
Bauer crossfeed already handles positioning really well, not much improvement possible there for me.
The only possible thing I'd add is a room eq and signature, probably by convolution reverb... but this misses the true goal of hardware implementation.
 
Latest simplified setup: