Following conventional wisdom, I Mod-Podge'd and phase plugged a pair of Fostex FE166En's. Here are the FR plots:
The white trace is the unmodified FE166En.
The red trace is after doping with Mod Podge.
The blue trace is with P10 phase plugs installed.
The first chart is on axis.
The second chart is 15* off axis.
The third chard is 30* off axis.
The doping sucked the life out of these drivers. They now sound dull and uninteresting.They sound a lot like BOFU's, but without the guts. Yes, any hint of sibilance is gone, but at what price. These modified drivers absolutely required a tweeter.
I doped the whizzer as well as the main cone. My reward is a huge spike just over 10kHz. I am hoping that I can remove most of this by kneading the whizzer to soften it up.
There is a lesson in here somewhere.
For your amusement, the last three charts are off axis comparisons, Stock, Mod Podge, and Mod Podge'd and phase plugged. The traces are
White 0*
Red 15*
Blue 30*
Green 45*
Yellow 60*
Bob
The white trace is the unmodified FE166En.
The red trace is after doping with Mod Podge.
The blue trace is with P10 phase plugs installed.
The first chart is on axis.
The second chart is 15* off axis.
The third chard is 30* off axis.
The doping sucked the life out of these drivers. They now sound dull and uninteresting.They sound a lot like BOFU's, but without the guts. Yes, any hint of sibilance is gone, but at what price. These modified drivers absolutely required a tweeter.
I doped the whizzer as well as the main cone. My reward is a huge spike just over 10kHz. I am hoping that I can remove most of this by kneading the whizzer to soften it up.
There is a lesson in here somewhere.
For your amusement, the last three charts are off axis comparisons, Stock, Mod Podge, and Mod Podge'd and phase plugged. The traces are
White 0*
Red 15*
Blue 30*
Green 45*
Yellow 60*
Bob
Attachments
In my opinion nothing good can be gained by most cone treatments on good drivers. The various treatment processes are just too unpredictable to merit do it in my opinion. If cone treatment were needed, then the original manufacturer would have done it. Cone treatments should be reserved for cheap, throwaway drivers. If you wish to have a better driver, buy one and enjoy it as the manufacturer intended.
Scott,
Please post a picture of your application, it will give people some important context to your results.
dave
What were your expectations? And what didn't you like about the sound of the Fostex?
Don't feel too bad. You may have well destroyed the Fostex, but is worth it. Not only to satisfy your curiousity, but gained knowledge of what this particular mod does. There is no substitute for personally acquired empirical knowledge, especially in matters of taste. "Conventional wisdom" or assumed knowledge is worthless in this regard.
After destroying a pair of Lowther DX55, I've come to the conclusion to just let the driver be itself. There was a temptation in thinking that a different mod or more or less of the same mod would be better, but that is the path to economic ruin and frustration......And even if I had unlimited resources and hundreds of pairs of the same driver, why not just look for a better/different driver that suited my sense of good sound(?).
The only exception is a pair of "enabled" Fostex F200a which unmodded is stinky-compressed/undynamic in mids and treble. However, that mod was done by Bud, himself after he had enabled a previous pair or two, and hundreds of other drivers for years prior.
The Fostex guys have been making drivers for quite a while, so they know what they are doing. Like it or not it is what it is. I would not try to "improve" any well engineered product, unless 100% reversible and proven exactly on this particular product.
Don't feel too bad. You may have well destroyed the Fostex, but is worth it. Not only to satisfy your curiousity, but gained knowledge of what this particular mod does. There is no substitute for personally acquired empirical knowledge, especially in matters of taste. "Conventional wisdom" or assumed knowledge is worthless in this regard.
After destroying a pair of Lowther DX55, I've come to the conclusion to just let the driver be itself. There was a temptation in thinking that a different mod or more or less of the same mod would be better, but that is the path to economic ruin and frustration......And even if I had unlimited resources and hundreds of pairs of the same driver, why not just look for a better/different driver that suited my sense of good sound(?).
The only exception is a pair of "enabled" Fostex F200a which unmodded is stinky-compressed/undynamic in mids and treble. However, that mod was done by Bud, himself after he had enabled a previous pair or two, and hundreds of other drivers for years prior.
The Fostex guys have been making drivers for quite a while, so they know what they are doing. Like it or not it is what it is. I would not try to "improve" any well engineered product, unless 100% reversible and proven exactly on this particular product.
Well my plan is to order some enabled drivers from someone who knows what they're doing (Dave) and some stock drivers and decide for myself. Enabling is a labor intensive process and would add significantly to the cost of any driver and might be a hard sell in a competitive market. Don't know if you consider chr70s "cheap throwaway drivers" but in my opinion it's the end result, not the cost, that determines the worth. Of course cost does play a significant role for a lot of us.
The on axis trace with the phase plug brickwalls at 5k and doesn't recover to the unmodded traces until 9k. THAT's the problem. The spike at 12k isn't extension, it is a resonance that needs notching out.
Bob
I put two coats of Mod Podge, diluted 1:1 with water. Cone and whzzer got the same treatment. Note that problems don't occur until 5K. Also note that the notch is much deeper with the phase plugs. I did a test with the phase plug removed, i.e. without the dustcap. The trace was very similar to the one with the phase plug in place. I know from previous experience that the real effect of a phase plug is to put a notch in the frequency response that corresponds to the sibilance spike of female speakers who swallow the mic. Makes the singers sound smoother. I'm going to check my other speakers with phase plugs. The effect may be primarily due to removing the dust cap.
Bob
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>>> Makes the singers sound smoother. I'm going to check my other speakers with phase plugs. The effect may be primarily due to removing the dust cap.
I just modded a Beta 12lta with great results! Removing the dustcap improved the driver and adding the phase plug smoothed the sound nicely... most notably with female vocals. Sorry about your drivers Bob... that stinks! Thanks for posting your charts.
Zilla
I just modded a Beta 12lta with great results! Removing the dustcap improved the driver and adding the phase plug smoothed the sound nicely... most notably with female vocals. Sorry about your drivers Bob... that stinks! Thanks for posting your charts.
Zilla
Member
Joined 2009
Paid Member
7k being the cone break up mode for the now defunct 127e. I tried the damar / trifoil treatment on a pair of those cones but it didn't really fix the problem. It made a slight improvement but I think I 'lost' a little magic in proportion. Based on my experience with the 127e I'm not so convinced that Fostex always knows what they are doing with their designs. However, I would balance my experience against that of many happy customers of the 127e.
To Bob Brines,
Working on the new fostex as well.
Adjusted my previous blh design for the FE166En.
Did a group build with four people.
Compared the "old"166 to the "new.
New : after break-in 200+ hours the still had some "metal" sound in them.
So we started some reversible tweaks.
long story short:
everybody likes the "open cell tweak" ,
in combination with the FT17H.
See pics.
Working on the new fostex as well.
Adjusted my previous blh design for the FE166En.
Did a group build with four people.
Compared the "old"166 to the "new.
New : after break-in 200+ hours the still had some "metal" sound in them.
So we started some reversible tweaks.
long story short:
everybody likes the "open cell tweak" ,
in combination with the FT17H.See pics.
It's always frustrating when a mod doesn't work in the actual listening. I have done a few Enabl jobs over the past three years and followed much of Ed's (Ed Fontaine) discussion.
As Bob said, and if you allow for some variance in application technique, I've found the result to take the "life" out of speaks as well. The same cannot be said for phase plugs. Phase plugs can make a silk purse out of a Pioneer 4 in. NSB.
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