A carbon fiber shadow flare... very impressive sirReally nice!
I've been lazy, but had my brother milling an aluminium mold to try out the Prepreg carbon fibre stuff I bought almost a year ago...
First attempt.
Looking at the former midrange/tweeter parameters https://www.erinsaudiocorner.com/driveunits/kef-r300-drive-unit/ Displacements limits was 1,5 mm. Assuming Pmax 100 W The SW I use Max Output Level (MOL) starts falling from ~350 Hz and down. Increasing displacement to 2,5 mm MOL starts falling from ~300 Hz. Do you think /know if it is possible to have a x-over below 350 Hz without limiting MOL?Since i intend to put crossover point between 200-400Hz
Can these Shadow flare improve the stock?, the stock shadow flare have a trade because if you use the flare in you got a 1dB of dip in 700hz, but with the flare out the dip its gone, its possible do make a new one for get the best of the flare out and in ?, the response gonna smoth a litlle bit and also its better looking if looks like the referenceIt started like this:
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2mm steel, laser cut ring. Diameter is 150mm, hole diameter is 115mm. Suspension rubber is about 2.3mm thick so it makes flare near suspension sit on the hard rubber part glued to the midrange frame. Since it is not stainless but regular steel, it needed some coating to prevent rust and since i'm confident in my sexuality
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Driver opening in speaker baffle will be as large as the diameter of midrange is. Ring is the medium between the front baffle and the driver chassis. You'll notice that the screw holes aren't lined up. That is not by mistake. If anyone noticed on previous pictures, screw holes on chassis do not line up with the spokes on the basket. Trying to get minimum diffraction, i intend to chamfer the back of the midrange baffle between spokes to allow midrange to breathe, but i will keep extra thickness where mounting screws go in to the MDF. Similar to THIS.
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If you are asking yourself am i exaggerating i'd usually say -probably-. But i noticed that the aluminium frame in midrange has its own chamfer and if at KEF they cared enough to make it, it is probably wise to invest some thinking in to minimum shading of midrange cone. I intend to make the baffle chamfer continue from chamfer molded in frame. I don't know how visible frame chamfer is but here it is:
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Screw heads would get in the way but Magnus (aka Nusse) predicted it in printed version so they align perfectly with small holes on the back of the flare.
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Please do@Nusse I'll send you a drawing of shadow flare how i think would work best with neodimium magnets. If your brother can make a file for 3D printer based on that, we can upload it here for download by anyone interested. Ok
Can these Shadow flare improve the stock?, the stock shadow flare have a trade because if you use the flare in you got a 1dB of dip in 700hz, but with the flare out the dip its gone, its possible do make a new one for get the best of the flare out and in ?, the response gonna smoth a litlle bit and also its better looking if looks like the reference
Thanks to Erin for this graph
.........
Will you measure distorsion at low freq and high SPL?
The best result its the shadow flare pushing in with your fingers, so the shadow flare its flat with the suspension as you saidAs i've understood Erin's measurements, best thing you can do with stock flares is to push them in as much as you can until the suspension is flat with flare. I'm not sure it is worth the effort to rip the flares and modify factory cabinets. If you want it to look as in Reference, take the flares out, lightly sand them with 800-1000 grit sandpaper and spray them with some primer for plastic and paint you like for finish.
I've been thinking about this a little bit... Erin measured distortion for R3 that utilizes this coax at Erin's audio corner website at 86dB/1m and 96dB/1m.
Since it is crossed at 400Hz and 2900Hz with pretty shallow slopes, distortion graph is quite valid to observe. At 96dB/1m up to 1kHz we have 0.3% HD2 while HD3 is at staggeringly low 0.1%. Over 1kHz though HD2 falls to 0.1% while HD3 goes down to -70dB which is equal to 0.03% distortion.
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And as if that isn't enough, Soundstage Network magazine did distortion measurements at 95dB but at 2m and above 200Hz there is no sign of distortion stress.
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I'm wondering is there really any actual need for additional distortion measurements since i'll hardly match Klippel and Bruel & Kjaer equipment regarding distortion accuracy. If we want to compare it, Kef R coax has distortion at 96dB from 300-3000Hz almost as low as any of Purifi 6,5's
To be honest with my R7 if I add 1dB in 700hz make no much difference.. The speaker already sound nice...First thing i'd do (if i was in posession of kef R loudspeaker) is try to make the transition from flare to baffle as mild as i can, with measurements before and after of course. That way i would know for sure if that's the problem.
If it is responsible for that dip, making the flare line up with suspension and baffle might work.
On the other hand, it is dip of just 1dB or so. I probably wouldn't waste my time with correcting that before i check audibility of it by simply adding +1dB eq at that spot.
If you have some try foam and felt, in my own experiments poly wadding had no significant measurable effect on cabinet resonances.Redistributing damping material shown on the pic seemed like a logical thing to do. It was leaking standing wave through the port which was severe enough to influence the woofer response. Red is before damping material redistribution, yellow is after. Sorry for the paint quick sketches but you get the idea. Red is poly wadding and blue is modified - same amount of stuffing in both cases.
Then I must have misunderstood your description of what you did.Poly wadding isn't a great material in its original form but densely rolled and packed in strategic places does wonders - as can be seen from my measurements.
Which is the reason why I like to use it, each to their ownI use foam in some occasions but felt i try to avoid since it is a black hole for sound.
I realised too late what the measurement was of. It would be interesting to see a measurement of what comes out of the port at higher levels with the crossover in place.I see no port leakage worth mentioning.