Zilch's AK Design Collaborative - Econowave Speaker
- Thread starter Zilch
- Start date
skywave-rider
Slumming in Akihabara
Zilch,
What do you mean by "half coated?" One side? The D8R2452H-SLs u show, one is coated, one not. ?
Confused.
But I want those.
What do you mean by "half coated?" One side? The D8R2452H-SLs u show, one is coated, one not. ?
Confused.
But I want those.
Bauhausler
Rational Subjectivist
According to my cheap LCR meter the two ULA woofer chokes that I have are 1.6mh and 1.58mh so I guess the meter is working.
I'm going to figure out how much wire has t obe unwound from these chokes to get them from 1.6mh down to the specified 1.5mh then publish that result in the build thread.
I suppose it would be more useful to tweak the woofer L and C to get the most accurate slope for that particular woofer and the EWG, but I don't think I have accurate enough measurement devices for that purpose. A Radio Shack SLM and freebie sig gen software aren't going to give me enough resolution to dial in the woofer's crossover.
<EDIT> or could I? if anyone is willing to describe a testing process to help me refine the LP section of this network for the ULA woofer I'll do my best to carry it out. I'm not going to buy acoustic testing gear at this time because on my want list that's far below more necessary things like a new distortion analyzer, a bigger bench variac and better transistor tester but I'm willing to do what I can with the gear on hand.
Just an update on my S L O W progress. I received the PCB's for the Xovers form Jack the other day(Thank you Jack:thmbsp
and plan on ordering the drivers and Xover parts this week.
Still working on this but just a bit slow(had to sell something else before I could order parts).
Happy Holidays all.
and plan on ordering the drivers and Xover parts this week.Still working on this but just a bit slow(had to sell something else before I could order parts).
Happy Holidays all.
Bauhausler
Rational Subjectivist
Sorry to excavate this older post but I'm not sure I understand it. Jack, could you explain what the RTA traces illustrate about what you're trying to accomplish? I see more HF rolloff in the lower traces. Is that the 'treated' phragm? I assume the HF rolloff is an undesirable consequence. I don't see any other significant differences.
dnewma04
The Healer
Adding mass to drivers generally has no effect on HF performance, it just lowers the sensitivity. I believe the idea of the treated diaphragm was to damp resonances and potentially make the diaphragm more pistonic. It probably did the former but not the latter in this case being that the aquaplas treatment on the JBLs dries hard, it probably helps make the diaphragm stiffer.
I guessed earlier that the drop in HF extension could be a matter of damping resonances in that range rather than a problem with the additional mass.
This is an area where a true measurement system would be in order. I bet we'd see some differences in distortion measurements and possibly in the FR with a little higher resolution measurement.
I guessed earlier that the drop in HF extension could be a matter of damping resonances in that range rather than a problem with the additional mass.
This is an area where a true measurement system would be in order. I bet we'd see some differences in distortion measurements and possibly in the FR with a little higher resolution measurement.
Bauhausler
Rational Subjectivist
Coating diaphragms reminds me of a tweak for dome tweeters that I had forgotten. A friend used to work for a speaker manufacturer who shall remain nameless. The manufacturer modified fabric dome tweeters for his best models and charged a large premium for the upgrade. The modification process was in three steps:
1) brush on a coat of Varathane Diamond Gloss polyurethane varnish.
2) pour on powdered ceramic abrasive while the varnish is still wet. The ceramic abrasive consists of tiny brittle spheres of material that have almost no mass.
3) after the varnish hardens, blow off the powder that didn't cling and paint another coat of varnish over the ceramic.
This was The Ceramic Tweeter. The effect was to create a coating with three layers and very little mass. I think there are still a few of those around here and maybe I can get a pic of one. I don't know what audible or measurable effect the treatment had, as I never made detailed comparisons. The designer was a VERY sharp guy and must have had his reasons.
1) brush on a coat of Varathane Diamond Gloss polyurethane varnish.
2) pour on powdered ceramic abrasive while the varnish is still wet. The ceramic abrasive consists of tiny brittle spheres of material that have almost no mass.
3) after the varnish hardens, blow off the powder that didn't cling and paint another coat of varnish over the ceramic.
This was The Ceramic Tweeter. The effect was to create a coating with three layers and very little mass. I think there are still a few of those around here and maybe I can get a pic of one. I don't know what audible or measurable effect the treatment had, as I never made detailed comparisons. The designer was a VERY sharp guy and must have had his reasons.
Bauhausler
Rational Subjectivist
If the moving element of a driver is made significantly heavier it should reduce the HF response. Greater mass requires more energy to accelerate it. It's my understanding that as frequency rises mass plays a greater role than suspension stiffness. I don't know how that effect compares to the resonance that you cite, and the data that we have isn't going to resolve the issue.
dnewma04
The Healer
www.diycable.com/main/pdf/WooferSpeed.pdf
This also applies to any driver, not just woofers. Mass does not have an effect on HF performance.
Bauhausler
Rational Subjectivist
That seems reasonable on its surface, but I'll have to read it closely and make certain that the white paper's analysis of a woofer is relevant to the case of a compression driver diaphragm.
But not today. Gotta hit the road to visit family in Lansing for Christmas Eve.
Cheers!
jackgiff
Well-Known Member
Ross, the top FR is the diaphragm before treatment, the middle one is after one coat of dampener, and the bottom FR is after the second coat. I wanted to show the degradation of the response curve with addition of Quiet Kote.
On the left is 2452H, an embossed diaphragm with no coating; the coated 2452H-SL is on the right, having a smooth diaphragm substrate.
On the "SL," the black Aquaplas coating only extends to the center of the diamonds, and it appears thinner in that area, diminishing to more like overspray at its very edge, which likely tells us how it's applied.
Somebody knows something we don't, obviously....
jackgiff
Well-Known Member
I am sure that the photo you showed of the 2452H-SL is the one that I referred to as showing the diamonds coated. Should have studied it some more, but at the time it just wasn't that important, cause coating Seleniums was not part of the picture. It was obvious that the diamonds had Aquaplas on them.
I feel that Dave has hit the nail on the head with his comment about the Quiet Kote maybe killing resonances in the Diaphragm. Something about the addition of Quiet Kote killed the output of the diaphragm across the board, but more so on the top end.
I feel that Dave has hit the nail on the head with his comment about the Quiet Kote maybe killing resonances in the Diaphragm. Something about the addition of Quiet Kote killed the output of the diaphragm across the board, but more so on the top end.
The 3" beryllium 2435HPL is what most are coating over on LHF, including the surround, but that is not diamonds. It's JBL Consumer doing the Aquaplas "enhancement" thing on those, both beryllium and titanium, maybe the aluminum 2431H, also.
I believe the 275nd I showed above to have been the first offering of a damped diaphragm in a JBL commercial product. The technique may have changed since then with others.
Rob has done some small-format diamond-surround titanium 2425Hs; perhaps he can fill us in on the details of what he did, and the results. Giskard knows this stuff, as well.
There may be some pics of what others have done over there.... :yes:
I believe the 275nd I showed above to have been the first offering of a damped diaphragm in a JBL commercial product. The technique may have changed since then with others.
Rob has done some small-format diamond-surround titanium 2425Hs; perhaps he can fill us in on the details of what he did, and the results. Giskard knows this stuff, as well.
There may be some pics of what others have done over there.... :yes:
Hello Zilch
The surrounds are Kapton and they do not get coated. Just the Beo diaphragm. The Ti were at one point and it you look at a stock 275?? it's the Dome only if my memory is correct surrounds are free of coating. You have a pair don't you??
Hey man Happy Holidays!!
Rob
Thanks, Rob!
Your memory is correct:
I never did much with them, because they require different comp than the stock Ti. They are also thinner, I believe, but since they are NLA, I'm not messing with them to make a definitive determination of that....
Last I knew, some LHF members were able to obtain small "sample" quantities from the manufacturer, enough to coat hundreds, if not thousands, of diaphragms. It then gets thinned with water, and possibly also filtered, for painting uniformly on the dome by hand, in multiple thin coats, using a turntable for rotation of the diaphragm.
[It's pink, as I recall....
]