So I likes a lot of what these drivers can do, but I hate the way the high frequencies tend to drill through your skull (all of this IMO of course!)
So I tries Daves' Dammar/Puzzlecoat mods along with a perilous but successful dust capectomy and phase plug install, with the result that the drill had got smaller, but was still there.
Then I reads (no, I don't know what's with the esses either!) about Steve Deckerts mods with the DFR-8, and thought "OO. Haven't tried that one, wonder if it'd work with a smaller driver?"
So I bought some 4.5" surrounds off Steve and set to work.
The mod was not actually that tricky to do. The hardest part was levering off the plastic trim without lifting the original surround.
Listening afterwards reveals that the 'drill' seems to have gone away completely - in fact I can now comfortably listen on axis!
The only downside I've noticed so far is there's a mechanical 'buzz' when playing low frequency test tones, possibly where a small portion of the original surround lifted at the inner edge, but so far I've not noticed it with music.
More impressions when I've modded the other driver, bit so far at least, it looks to me that Steve's come up with a bit of a winner! (to my ears at least)
Cheers
Dave
So I tries Daves' Dammar/Puzzlecoat mods along with a perilous but successful dust capectomy and phase plug install, with the result that the drill had got smaller, but was still there.
Then I reads (no, I don't know what's with the esses either!) about Steve Deckerts mods with the DFR-8, and thought "OO. Haven't tried that one, wonder if it'd work with a smaller driver?"
So I bought some 4.5" surrounds off Steve and set to work.
The mod was not actually that tricky to do. The hardest part was levering off the plastic trim without lifting the original surround.
Listening afterwards reveals that the 'drill' seems to have gone away completely - in fact I can now comfortably listen on axis!
The only downside I've noticed so far is there's a mechanical 'buzz' when playing low frequency test tones, possibly where a small portion of the original surround lifted at the inner edge, but so far I've not noticed it with music.
More impressions when I've modded the other driver, bit so far at least, it looks to me that Steve's come up with a bit of a winner! (to my ears at least)
Cheers
Dave
Attachments
Frequency reponse.
Original driver in blue, modified in pink.
Any ideas anyone how to reduce the 7K peak?
Both responses are white noise, 'C' weighted (I was playing with the software and forgot to remove the weighting before taking final measurements, but I think the graphs are still valid for comparison purposes).
Cheers
Dave
Original driver in blue, modified in pink.
Any ideas anyone how to reduce the 7K peak?
Both responses are white noise, 'C' weighted (I was playing with the software and forgot to remove the weighting before taking final measurements, but I think the graphs are still valid for comparison purposes).
Cheers
Dave
Attachments
Most interesting. Especially your measurements.
These measurements indicate that, while giving some clear improvements, none of the mods we have so far tried manage to tame the FE126E's peak around 6.6 KHz .
MarkMcK performed some measurements and analys of the FE126E in the Full-range reference project tread.
His measurements are here, and measurements of his "fixed" drivers are here and here
Unfortunately he did not share with us the details of the mods he performed.
SveinB
These measurements indicate that, while giving some clear improvements, none of the mods we have so far tried manage to tame the FE126E's peak around 6.6 KHz .
MarkMcK performed some measurements and analys of the FE126E in the Full-range reference project tread.
His measurements are here, and measurements of his "fixed" drivers are here and here
Unfortunately he did not share with us the details of the mods he performed.
SveinB
Hi guys,
Fostex drivers are not good candidates for diy projects. Too many problems and too much skill required to implement them.
For example, many of the Fostex transducers have problems with edge holes. Adding mass to the surround will reduce the edge hole problem. Yet you risk the creation of a low frequency buzz in modifying the surrounds. This is not a good thing.
Regardless, if the surround mod adds mass to the system (typically 1/2 of actual mass of surround material), then it will also reduce high end output. It will not, however, address the cone vibration (breakup) problems.
Oh yes, coating a paper or metal cone will have almost no impact on cone vibration modes. Not even when adding many coats. I have before and after testing documentation to support this statement. Generally material vibrations are not simplistic and most diyers try to address them with simplistic solutions
Fostex drivers are not good candidates for diy projects. Too many problems and too much skill required to implement them.
For example, many of the Fostex transducers have problems with edge holes. Adding mass to the surround will reduce the edge hole problem. Yet you risk the creation of a low frequency buzz in modifying the surrounds. This is not a good thing.
Regardless, if the surround mod adds mass to the system (typically 1/2 of actual mass of surround material), then it will also reduce high end output. It will not, however, address the cone vibration (breakup) problems.
Oh yes, coating a paper or metal cone will have almost no impact on cone vibration modes. Not even when adding many coats. I have before and after testing documentation to support this statement. Generally material vibrations are not simplistic and most diyers try to address them with simplistic solutions
Holy cow!
Hey Mark I have no reason to doubt a single word you've said but I'm chuckling cause you're going to start a fire storm if every guy in here who has used a Fostex driver in their project responds to your post.
All that said, what fullrange drivers do you believe lend themselves well to the diy'er?
Rick
Hey Mark I have no reason to doubt a single word you've said but I'm chuckling cause you're going to start a fire storm if every guy in here who has used a Fostex driver in their project responds to your post.
All that said, what fullrange drivers do you believe lend themselves well to the diy'er?
Rick
Rick J. B. said:Holy cow!
Hey Mark I have no reason to doubt a single word you've said but I'm chuckling cause you're going to start a fire storm if every guy in here who has used a Fostex driver in their project responds to your post.
All that said, what fullrange drivers do you believe lend themselves well to the diy'er?
Rick
It would be very interesting to engage Ed S in this conversation.
Mark, of course you're absolutely right on all counts.
A thought that occurs, it would be interesting if someone did/has done a set of responses for the effect of increasing layers of cone coating to see how it compares to the peripheral mass damping that I have done.
I suppose for me (as a comparitive noob in these areas) the aim was to increase the acceptabilty of the sound rather than aiming for perfection; in this I think I've succeeded - to my ears the sound seems more balanced, but then this is a very early days personal opinion of course.
Do you have any useful references for breakup mode theory and strategies for overcoming them? Google as usual so far has been giving me 15000 snippets without anything I can really get my teeth into.
My lack of knowledge in this area frustrates me: I have a Physics background, but when it came to specialising, I chose the wrong "A" - astrophysics rather than acoustics!
Cheers
DAve
A thought that occurs, it would be interesting if someone did/has done a set of responses for the effect of increasing layers of cone coating to see how it compares to the peripheral mass damping that I have done.
I suppose for me (as a comparitive noob in these areas) the aim was to increase the acceptabilty of the sound rather than aiming for perfection; in this I think I've succeeded - to my ears the sound seems more balanced, but then this is a very early days personal opinion of course.
Do you have any useful references for breakup mode theory and strategies for overcoming them? Google as usual so far has been giving me 15000 snippets without anything I can really get my teeth into.
My lack of knowledge in this area frustrates me: I have a Physics background, but when it came to specialising, I chose the wrong "A" - astrophysics rather than acoustics!
Cheers
DAve
I suspect he's refering to Ed Schilling, of Hornshoppe Horn fame (a kind of modified, enlarged Buschorn MK1), owner of a wide variety of personal artillery etc., and 4 - 4 1/2in Fostex driver enthusiast. If memory serves, Ed started out by using the FE108Sigma, moved to the FE108ESigma, and currently uses the FE126E in his cabinets.
Fostex driver's don't lend themselves to modifications. Hmm. Dave's phase-plugs measureable improvements to the FR. Fostex's own brass-rings to mass-load their Sigma drivers have generally proven highly effective for all those who've tried the. Cone damping is not the easiest thing to get right I agree, but it's possible for some people to do it right with correct location and application to break-up points. Witness the damping Dave applies to his FE126E cones, and the basket & magnet. He's done this sort of mod for 25 years or so I believe, and is constantly refining the process> It's done via measurements BTW: it's not just a shot in the dark. I'm not saying it's easy. But nor is impossible to improve these units either if you've the experience and the skill to do so. Not many DIYers have, but some do.
Fostex driver's don't lend themselves to modifications. Hmm. Dave's phase-plugs measureable improvements to the FR. Fostex's own brass-rings to mass-load their Sigma drivers have generally proven highly effective for all those who've tried the. Cone damping is not the easiest thing to get right I agree, but it's possible for some people to do it right with correct location and application to break-up points. Witness the damping Dave applies to his FE126E cones, and the basket & magnet. He's done this sort of mod for 25 years or so I believe, and is constantly refining the process> It's done via measurements BTW: it's not just a shot in the dark. I'm not saying it's easy. But nor is impossible to improve these units either if you've the experience and the skill to do so. Not many DIYers have, but some do.
Scottmoose said:
That's the guy; although he might take exception to the above description of his favorite speaker. Further, he'd most certainly beg for an explanation as to why none of numerous "Horn" owners who've upgraded to the 126E over either version of the 108 haven't gone back.
It's always entertaining to follow his participation in forum threads such as these, discussing his own POV of the loudspeaker design process.
FWIW, Ed has dabbled himself with driver mods over the years, but the last I recall from him on the subject was that "it ain't broke...."
How many DIYer's have had their creations receive Stereophile Class C rating, or repeated accolades at 6Moons?
Both Scott & myself are fortunate enough to heave experienced firsthand the improvements these careful driver modifications can achieve. As well as in my case, the opposite results of "co-ed tweakers gone wild"
The improvements over the stock 126 Dave's mods bring are amazing. And the stock driver is a blinding performer.
Oh I don't know. No criticism implied or intended... (I stress this in case Ed gets the wrong idea and wishes to discover the effect a couple of 9mm Parabellum rounds have on someone from ye olde country)
chrisb said:
Oh I don't know. No criticism implied or intended... (I stress this in case Ed gets the wrong idea and wishes to discover the effect a couple of 9mm Parabellum rounds have on someone from ye olde country) Scottmoose said:The improvements over the stock 126 Dave's mods bring are amazing. And the stock driver is a blinding performer.
Scott, don't worry - he's got thick skin; just don't threaten his business or family. I'm pretty sure he'd never (fatally) shoot an innocent man
But back to subject - I'm sure there are lots of DIYers who've been inspired to try their own concoctions of cone / basket /surround tweaks on Fostex and other driver brands.
Of course it's not likely to hear reports of grotesquely unsuccessful attempts that statistically must have occurred.
chrisb said:
Of course it's not likely to hear reports of grotesquely unsuccessful attempts that statistically must have occurred.
Seems appropriate somehow to post the second driver response at this point - not quite grotesque, but hardly impressive at this point!
Stock driver in blue, modded in pink.
I wish I knew what the mechanism was for the 7K peak.
Cheers
DAve
Attachments
It seems that the resonance peak between 6.5 and 7 Khz is consistent in all measurements.
I wonder if it would be possible to mitigate that with a notch-filter.
Something like 4,7 uF in parallel with 0.11 mH, and a resistor of say 8 ohm (approximate values). Since the peak is rather sharp and narrow, it may be necessary to tweak precise values.
This may seem like just a pain-relief for the symptom instead of curing the disease, but maybe not all that different from accepted medicine ?
Svein.
I wonder if it would be possible to mitigate that with a notch-filter.
Something like 4,7 uF in parallel with 0.11 mH, and a resistor of say 8 ohm (approximate values). Since the peak is rather sharp and narrow, it may be necessary to tweak precise values.
This may seem like just a pain-relief for the symptom instead of curing the disease, but maybe not all that different from accepted medicine ?
Svein.
Knorke
Yes a gated response would be much better, but when I tried using Speaker Workshop I got totally non-reproducible results - probably GIGO on my part, but I got fed up of it!
The charts I've posted are from Realtime Analyzer, integrating over 16s and waiting until results stabilise before taking a screenshot, then overlaying results in Photoshop.
This does get a rather 'warts and all' response, but I'm hoping that the differences are due to the single uncontrolled variable, the driver.
Svein_B
A notch filter may be in my future, but I'm holding off at the moment.
Listening to real music as opposed to tones has shown me that something good seems to have happened. The 'shoutiness' that has bothered me in the past seems to have subsided, to the extent that I've been able to remove all the stuffing from my horns. The drivers are now however sssomewhat more sssibilant, probably as a result of the reduced levels lower down, which toeing in seems to balance quite well.
I think I'm going to let some time (and music) pass and see how they settle down.
Cheers
DAve
Yes a gated response would be much better, but when I tried using Speaker Workshop I got totally non-reproducible results - probably GIGO on my part, but I got fed up of it!
The charts I've posted are from Realtime Analyzer, integrating over 16s and waiting until results stabilise before taking a screenshot, then overlaying results in Photoshop.
This does get a rather 'warts and all' response, but I'm hoping that the differences are due to the single uncontrolled variable, the driver.
Svein_B
A notch filter may be in my future, but I'm holding off at the moment.
Listening to real music as opposed to tones has shown me that something good seems to have happened. The 'shoutiness' that has bothered me in the past seems to have subsided, to the extent that I've been able to remove all the stuffing from my horns. The drivers are now however sssomewhat more sssibilant, probably as a result of the reduced levels lower down, which toeing in seems to balance quite well.
I think I'm going to let some time (and music) pass and see how they settle down.
Cheers
DAve
an interesting 2 way with 126e
Hi everyone,
slightly off topic but I have some FE126e's and found this page to be very interesting.
Regards Philip
http://www.troelsgravesen.dk/FE126E.htm
Hi everyone,
slightly off topic but I have some FE126e's and found this page to be very interesting.
Regards Philip
http://www.troelsgravesen.dk/FE126E.htm
MarkMcK said:
Interesting opinion, and no one is questioning your credentials (particularly those who've enjoyed following your suggestions for cone resonant abatement) , but judging by the satisfaction that many of us DIY hackers have achieved using a variety of Fostex drivers in numerous enclosure designs, there might be a higher collective level of skill in dealing with the "issues" than you supposed.
Care to elaborate on what you mean by "edge holes"? I've installed more than a few of several models of Fostex myself, and if you're talking about physical holes or inadequate adhesion of surround, I've yet to see that.
Agreed that the extra surround mod that Deckert describes is as "out of the box" as the original socket phase plug, and both will no doubt change the sound; subjectively better or worse? - could be a system synergy thing?
Some folks have been inspired by your postings, and continued their own investigations with materials & treatment patterns. For example, as posted on his site, DaveD's own includes both selective radial and overall coatings on smaller full range cones, as well as combinations on larger whizzer coned drivers. Quite a few folks, myself included, have heard the difference these make., and I think the consensus is that while they may not be perfect yet, the change is certainly not in the wrong direction.
Acknowledgment and appreciation must certainly be expressed for the contributions by all members of the DIY community, regardless of credentials.
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