Fostex F200A

I bet you do. Looking at Fostex's massively smoothed FR plot, there's a peak centred at 4KHz, and from experience we know that the small bump that appears on their published FE126E FR, is in reality a +8 - 10db spike, which probably explains the metallic sound you're hearing.

Not sure -phase plugs might (might) be possible, which would certainly solve the problem if they could be fitted. Damping the dust-cap with varnish etc., might be an option.

EnABL apparantly makes a big sonic improvement, and I suspect would be worth doing at some point. Only slight problem is that nobody has figured out exactly what it does in a technical sense yet. Ron's certainly established what it doesn't do, so we're in a 'we don't know what it does, but we know what it doesn't' situation at present; this will only improve in the near future though as it's further explored.
 

ronc

Member
2003-03-08 2:22 pm
this will only improve in the near future though as it's further explored.


The physical actions has merit. I can see some very good applications/results ,with the current design/methods, within a limited BW.

Now to tackle the physics outside the limited BW.

I have some time now to investigate as i handed over the ultrasonic edge scanner to production(up to Rev C) and i am not going to invest time in any other work projects till after the holidays.

ron
 
EnABLed drivers that have been measured have not shown significant changes in FR so it is unlikely to kill that problem. Syill worthwhile doing, but it would be better to fix the problem before doing anything else.

The FF125 has what might be a similar colouration, I suspect it is from the metal dustcap. Removing the dustcap would probably fix the problem, but would also, i suspect, reduce HF extension dramatically.

dave
 

OzMikeH

Member
2007-03-18 9:22 am
planet10 said:
EnABLed drivers that have been measured have not shown significant changes in FR so it is unlikely to kill that problem. Syill worthwhile doing, but it would be better to fix the problem before doing anything else.

The FF125 has what might be a similar colouration, I suspect it is from the metal dustcap. Removing the dustcap would probably fix the problem, but would also, i suspect, reduce HF extension dramatically.

dave


....unless that little metal dustcap is ringing like a bell.
Reduced reflections from it's edges would mean less ringing.

Off with it's head! (well, it's dustcap anyway)
 
I have heard, that the versions from currently production of this model is much more better in all respects than older versions.

Are there such observations by user's, that have tested both versions ??

P.S. By the model No FE 166 this is so in real life (especially by the frequency response graph - equalizing in the midrange aera isn't necessary by the newer versions).
 

BHD

diyAudio Member
2004-06-07 8:25 pm
Brooklyn Park, MN
I know it's heresy, but the right thing to do is use a notch filter and cross the driver over to a really good supertweeter. I've heard the driver with and without one and the difference is really night and day. Even with extended break in the peak is just awful sounding. Used with a notch filter and a good (in this case ribbon) supertweeter the F200 is a world class driver.
 

ultrakaz

Member
2004-10-20 11:32 pm
I have a pair that has been enabl'd by Bud. Before enabling there was some kind of hash that made it sound very 2d sounding. After the treatment the sound "opened up", but not quite the 3d effects that can be heard in any competent 4" driver. I'm sure the peak at around 6k-ish is still there-on axis- but does not stand out. Bud recommended that they be run baffleless to understand its full potential, but alas I have not tried it fully implemented and optimized with some type of bass driver. (I did listen to it naked but only as computer speakers.)

In a conventional enclosure the strength of the driver is its bass, very solid and visceral. The weakness is its size which of course limits its treble dispersion. So, again everything is a compromise.
 
Experiment.
Easiest experiment is to listen off axis and see if that works for you.

Or, what I have done in the past is to make a "tripod" out of stiff wire and then place a piece of material in the centre of the tripod to absorb / reflect. Try foam, wood cotton, table tennis ball etc.

You can also of course move the material closer or further away from the metal dustcap.