I think the point is that badman already owns a pair of FF85Ks, so whether or not anyone else considers another driver to be superior (whatever that means) is a matter of complete indifference to him. All he was doing was asking what mods Dave or anyone else has used successfully on the '85K rather than recommendations for other drivers, or enclosures, be they good, bad or ugly. 
<<Off topic and harsh>>
It goes back a ways. I constantly see HM posting about his horns, out of context, and not infrequently putting down other designs in relation to his own pseudo-commercial offerings. I leave it to others (or the moderators) to deal with in "Their" threads, but when it's a post directed to me, I called BS. If you're behaving unethically (flooding the forum hawking your cheesy wares?) you're not my kind of person, and when appropo (and I honestly think it was, here) you'll get called on it.
<</Off topic and harsh>>
I'm looking at doing pretty much Dave (planet10)'s mod set, but would love to get some more feedback on these or other mods. I may well go to a standardized setup, and do proper tests (within my means) of the results of the mods.
Some others that people have liked (with other drivers):
Cutting 'extra' legs out of the frame for less backwave resistance
Bucking magnets and/or shielding the magnet
Grounding the frame
So just thinking about how to best treat these itty bitty drivers.
It goes back a ways. I constantly see HM posting about his horns, out of context, and not infrequently putting down other designs in relation to his own pseudo-commercial offerings. I leave it to others (or the moderators) to deal with in "Their" threads, but when it's a post directed to me, I called BS. If you're behaving unethically (flooding the forum hawking your cheesy wares?) you're not my kind of person, and when appropo (and I honestly think it was, here) you'll get called on it.
<</Off topic and harsh>>
I'm looking at doing pretty much Dave (planet10)'s mod set, but would love to get some more feedback on these or other mods. I may well go to a standardized setup, and do proper tests (within my means) of the results of the mods.
Some others that people have liked (with other drivers):
Cutting 'extra' legs out of the frame for less backwave resistance
Bucking magnets and/or shielding the magnet
Grounding the frame
So just thinking about how to best treat these itty bitty drivers.
badman said:
Let me pipe in here
Horst does sometimes present as rather condescending and self-promoting, and in spite of numerous reminders of same, doesn't quite seem to get the message. This particular post was less offensive than some, and let's just let it go?
I've heard Dave's modded FF85K, and this already pretty interesting driver is definitely improved. I've posted before about how well it works as a wideband mid-range/tweeter - when we first fired them up before the treatment, it was on a small OB.
For very nearfield listening ( e.g. PC monitor ), bass augmentation might be "optional" rather than essential.
For a full-range (2 channel) audio set-up, powered woofers (XO circa 250/ 300Hz? ) would definitely be required.
The truly crazy man might want to try an OB line array
As for modifying the basket frame itself, I'd take a good look at the driver first. This piece has probably the highest ratio of magnet size/ weight to cone mass/Sd of any of the Fostex drivers. The diameter of the magnet assembly is such that removing legs of the basket frame would not likely gain much advantage in terms of early reflections, and would definitely weaken its integrity.
Now if Fostex was to incorporate a 3 legged machined or cast frame like on the FX1250 or the Sigma series (from which this driver almost looks orphaned), and/or utilize narrow diameter NEO /Alnico motors....
edit:
or shaped motor housings like the new ScanSpeak Illuminators,
...
I think I just specified another "dream" driver
I'm not Dave (obviously).
What I usually do to begin with is a fillet of epoxy (JB Weld is my brand of choice) between the frame and motor. Use the regular JB and not the 5 minute or the "waterweld" version.
Carpet felt "sock" on the motor.
I don't know if you would have space on so small a driver but a wrapping of carpet felt on the legs or on the internal surface of the legs, this is all is to aid kill the reflections back through the cone.
I have used felt in the past but do not detect any difference with it, ymmv.
On the surface of the enclosure itself around the perimeter of the driver a cork facing ~ 1/4" thick, you will not need a rebate for the driver if you do this.
If you build an enclosure and its not for OB usage, try a non box shape, as little damping material as possible, I have success with the damping material rolled into a cylindrical shape, its diameter as least as wide as the drivers and centered behind the motor.
Shellac the interior of the enclosure (keep glue lines free of same).
Give the driver lots of play time.
What I usually do to begin with is a fillet of epoxy (JB Weld is my brand of choice) between the frame and motor. Use the regular JB and not the 5 minute or the "waterweld" version.
Carpet felt "sock" on the motor.
I don't know if you would have space on so small a driver but a wrapping of carpet felt on the legs or on the internal surface of the legs, this is all is to aid kill the reflections back through the cone.
I have used felt in the past but do not detect any difference with it, ymmv.
On the surface of the enclosure itself around the perimeter of the driver a cork facing ~ 1/4" thick, you will not need a rebate for the driver if you do this.
If you build an enclosure and its not for OB usage, try a non box shape, as little damping material as possible, I have success with the damping material rolled into a cylindrical shape, its diameter as least as wide as the drivers and centered behind the motor.
Shellac the interior of the enclosure (keep glue lines free of same).
Give the driver lots of play time.
Gone.chrisb said:
chrisb said:I've heard Dave's modded FF85K, and this already pretty interesting driver is definitely improved. I've posted before about how well it works as a wideband mid-range/tweeter - when we first fired them up before the treatment, it was on a small OB.
As for modifying the basket frame itself, I'd take a good look at the driver first. This piece has probably the highest ratio of magnet size/ weight to cone mass/Sd of any of the Fostex drivers. The diameter of the magnet assembly is such that removing legs of the basket frame would not likely gain much advantage in terms of early reflections, and would definitely weaken its integrity.
Now if Fostex was to incorporate a 3 legged machined or cast frame like on the FX1250 or the Sigma series (from which this driver almost looks orphaned), and/or utilize narrow diameter NEO /Alnico motors....
edit:
or shaped motor housings like the new ScanSpeak Illuminators,
...
I think I just specified another "dream" driver
That you did mate, I'd love to see an 'all out' version of a 3" (though tang band is getting pretty slick with their smaller fullrangers)
I'm currently using the FF85k with a vintage 12" (JBL 123A, alnico) in OB. I've used felt to some success around and about the mounting (not least of all to bring the baffle plane flush with the driver frame) and did some pretty extensive work to let the rearwave flow freely.Cutting out the magnet legs is definitely an iffy thing with this driver, but I wonder if it couldn't be done..... perhaps by reinforcing 3 of them, the other three could be removed.
Andrewbee said:
Do you mean that you've used carpet underlayment for this application with success, but when you did the same with felt it didn't seem to affect anything?
Andrewbee said:
I'm currently doing this with felt rather than cork. Cork may indeed be the better option here though. I'll think about giving it a shot!
Andrewbee said:
It is indeed an OB, but your suggestions about box shape and damping are well-advised. Something else I've found to be effective is using bracing at angles to make interior reflectors within a rectangular enclosure, so as to break up any internal reflections and whatnot (not to mention, if you just cut a bunch of 45 degree angles on either end of various sized pieces, this is both easy and effective as an additive to other bracing).
Run-in is definitely a must!
This thread is rather useless without pics, is it not? I'm awaiting a truck with all my worldly posessions (close enough anyway), after which, I can start posting pics of my progress. I probably should order a couple more FF85ks anyway for comparison purposes (and backups if this lovely little driver is ever disco'd)
2 coats thinned puzzlekoat
EnABL
Strengthen basket (SR500 to fill the bezel, and in the basket magnet juncture (same purpose as Andrew's epoxy)).
Ductseal to shape the exit of the driver.
Felt pad on the back
If you are going to take out legs you will have to mount with both the magnet & the bezel.
Felt inside legs never hurts
dave
EnABL
Strengthen basket (SR500 to fill the bezel, and in the basket magnet juncture (same purpose as Andrew's epoxy)).
Ductseal to shape the exit of the driver.
Felt pad on the back
If you are going to take out legs you will have to mount with both the magnet & the bezel.
Felt inside legs never hurts
dave
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