FE207 -- dustcap removal leads to roughness

[leeoh]

Not sure whether or not this is the appropriate place for my query, but I will try anyway. I have built a set of G Changs with Fostex207Es and have been very impressed with them - a little more so each time I play them. Great effort by Scott and Dave. The initial top end roughness (shout?) has long since gone, so I had two sets of phase plugs made by a woodturning friend. One I passed on to an on - line acquaintance who built Sachikos a year or so ago with 206Es installed. I measured both sets before they were used and they were both identical. My on - line acquaintance has had no problems with his, in fact is very impressed by them. Mine certainly improved the overall sound quality but some of the top end roughness has re-appeared. In particular, the top end of the male voice in my Les Miserables recording and also the upper register of Miles Davis' instrument.
Any one with brilliant ideas about overcoming this problem? I have made sure that I cut all the residue of the centre of each speaker away and the plugs definitely don't touch the perimeter of their space. Thanks.

[Godzilla]

I wonder if the roughness is cone resonance? Maybe damar or enable could resolve this for you? Just a thought. I've never heard the 206/207.

[planet10]

Shout got worse after removing the dust cap? Can you send closeup pictures of the voice coil opening (without the plugs)?

Do not damar. That will stiffen the cone and exacerbate things,

Full treatment should transform them. But before any treatment goes on, dustcap removal should have reduced shout not brought it back. Be a good idea to get to the root of that 1st?

<Coating+phase plugs to FE167>

dave

[Bob Brines]

I put a set of P-10 plugs in a pair of 206's and found that the result was a ~4dB cut between 6-8kHz. I would expect the same results with 207's. The sonic result is a reduction in the sibilance in female voice and a reduction in upper harmonics of various instruments. I.e, they sound smoother. You are applying a rather specific mechanical filter. Whether this is the right approach is in the eyes of the beholder.

I received a pair of EnABLed 167's from P-10. First impression is that they sound smoother. I have not had a chance to A/B these with stock 167's yet. Maybe in a couple of weeks. I can tell you this: I demo'd the 167en's next to DX3's at LSAF and the opinions were split 50/50. Some liked the brighter, airier DX3's, some liked the smoother 167en's. Go figure.

Bob

[leeoh]

Thanks to Bob Brines, Dave (Planet 10) and Godzilla for their help with "shout" after fitting phase plugs to my Fostex 207s in G Changs. However, I think I have found my own answer to the problem. It ocurred to me that I had put only two screws into the back of the plugs, at the 12 and 6 o'clock positions. I thought that it may have caused some instability and also there may have been insufficient grab from the magnet to hold the plug firmly, so I took out one of the screws and drilled two more holes so that I could put in screws at the 6, 10 and 2 o'clock locations. After replacing the plugs and fairly extensive listening, there seems to be no more top end roughness. WAF has greatly increased. We are once more (at least for the immediate future), on good terms. They really are great speakers, aren't they? Again, thanks guys. Robert.

[planet10]

Good to hear it was something simple... all of our FE20x plugs have 3 screws

dave

[Godzilla]

>>> I have not had a chance to A/B these with stock 167's yet. Maybe in a couple of weeks. I can tell you this: I demo'd the 167en's next to DX3's at LSAF and the opinions were split 50/50. Some liked the brighter, airier DX3's, some liked the smoother 167en's.

I have a pair of Enabled P-10 Fostex 165k's i've yet to listen to... (thanks Dave). Should get them loaded up soon tho... maybe this weekend. Will report what i hear when i give them sufficient listening time. Interesting about the comparison between Fostex/Lowther... couple of top shelf drivers!

Godzilla

[Piek]

Listen to rock, is the snare "too much"?
My rough estimation is: Through cutting out the dust cap and using a phase plug the area >6KHz got "better" and now everything below is unaffected and the problem wandered to 3KHz and up as it is (relative to original state) louder now (can be solved with a notch filter, sacrilege! ).

-Micha

[Vix]

Hi,

Upon seeing this thread it came to my mind that I have done a couple of wrong things with my Fostex FE206E drivers:

1. I had applied one coat of dammar
2. Being impatient, I put wrench sockets as phase plugs (like Decware's)

Needless to say, after an initial euphoria, it became apparent that it did not work as it should. Sound became more edgy, and the socket didn't do much justice to it, partly because the metric diameter of the socket is smaller that it should be, and the gap between it and the voice coil too big. Since the magnet holds the socket very firmly, I was afraid to forcefully remove it...

So, what I did? Nothing I bought another speakers, Visaton B200's which I use today in OB's...

Fostexes are sitting in a box for more than two years...

Is it possible to rescue them? Would applying a layer of puzzlecoat help? And what can be done with the socket and that gap...?

Thanks,

Vix

[Vix]

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