[MJK]

I did not hear any objectional peak at 7 kHz from my drivers. If a peak at 7 kHz can be heard in your drivers, I would use a notch filter to adjust the response, this can be easily tweaked or removed later.

I am not a big fan of permanently altering drivers by applying coatings or treatments to the cones. Altering the driver is a permanent change that cannot be reversed and the results are not predictable. In most cases I believe these treatments degrade a driver's performance. I have heard a few of these recipes, including Enable, and in all cases felt that an unaltered driver sounded better. It is interesting to note that the proponents of these changes always hear a large positive result no matter what they do, I have never seen them report that they ruined a driver with a treatment or that it had no effect. It is always a huge improvement. The treatments I have heard produced very subtle changes and it could be debated if it was an improvement or not, I did not believe it was an improvement in every case. The measurements I have made of treated versus untreated drivers did not show any significant results beyond what would be expected from adding a small amount of distributed mass to the cone. There are a lot of claims and BS being spread in the DIY community and in particular among single driver users, a lot of it is driven by commercial interests.

There is nothing wrong with good iron core inductors. The trade-off is the higher DC resistance, size, and cost of an air core versus a smaller lower cost iron core, I use ERSE Super Q inductors all the time.

I do not believe the FF125WK needs a Zoble, you should be fine with just a BSC filter in series with the driver, probably 3 to 4 dB of correction is all that is needed.

[kinku]

Thanks Martin.So it is another snakeoil deal in DIY audio.It also make sense,if a manufacturer spends "some" money to make those speakers, it is hard to believe that they can not incorporate such small treatments to make their product better.Perhaps it does not ,that is why they are not doing it.
You might have seen that peak in my plots too.I do not know wheather it is audible. I have a notch filter in my rockbox player. What should I set my Q value as?I tried to read about it but very confusing, the Q concept.

[MJK]

So it is another snakeoil deal in DIY audio.

In my opinion and experience, yes it is snake oil. Key words "my opinion and experience", others will swear up and down it has significant positive acoustic impact.

You might have seen that peak in my plots too.I do not know wheather it is audible. I have a notch filter in my rockbox player. What should I set my Q value as?I tried to read about it but very confusing, the Q concept.

I don't know how your rockbox works, why not set the filter frequency and adjust the Q setting by ear until you are happy with the result?

[kinku]

Once again REW came to help.It has a built in EQ function compatible with selected devices.But you can put the measured plot in REW EQ analyzer and add peak filters and select attenuation and Q values to see how the plot changes( even can see it in waterfall plots).No need to worry about the concept of Q anymore. I did attenuate the peak ( actually 2 peaks on 1/12 octave smoothing)of 6600 Hz and6100Hz  to about -4dB.i COULD NOT PERCEIVE  anything on listening (Human ear hardly sensitive to changes more than 1/6octave). But may be some what smooth( sorry I can not come up with anything better).
I  am going to call my friend who apparently said he is perceiving shrillness when I first asked him to listen and he turned it off after few minutes saying it aches his ear AND nO BASS( he do not know anything about speakers and peaks and stuff,,and it surprised me).
I guess many self proclaimed audiophiles including me, are challenged in hearing from repeated trauma to the sensitive sound-sensing organ from their experiments. That is why we are after all these stuff and never get satisfied from what we have.....

[planet10]

It is interesting to note that the proponents of these changes always hear a large positive result no matter what they do,

Some of the experiments decidedly turn out bad. I don't talkmuch about those, but do learn from them.

dave