With paper cones you can use quite a few different products to stiffen the cone.
In the past, I used 2 part 5 minute epoxy glue > you just need to work thoughtfully & quickly. VERY STIFF 🙂
In the past, I used 2 part 5 minute epoxy glue > you just need to work thoughtfully & quickly. VERY STIFF 🙂
Is just an topic, i know manufacturers know how to make better cones than just adding a damping material. This can be a mod but i cant find a and b testing showing the cone break up. If this just tames the resonance if the driver, the ringing, then is not worth the added mass
Rigidity and damping needs to work together. At least this is how i see it
The RS500’s driver is made of a three-layer sandwich with a aluminum cone between two treated paper layers. This “retains the transient benefits of cellulose cones with the torsional rigidity of aluminum.”
B139 is a completely solid polystyrene foam cone (not hollow) about 3 inches thick with flat aluminum sheet on the front and PVC sheet at the back. This thing is very stiff and very light, hardly a sandwich. The whole piston is damped. The front, if dented remain dented, it does not return top it original shape. I have preserved the rubber roll surround and over the past 60 years became more and more compliant in the Fs is now 15Hz. Two are used in an H frame that Siegfried and I built, one of the first attempt.
@Mister Audio
In the alu paper alu material mix the paper itself has the damping properties.
Different than using hard foam (Kef B139, Podzus-Görlich) or honeycomb cores (Eton) which are resonant a reinforced soft paper core gets better wirh alu foils in the end.
I made measurements before / after:
This is a 10 inch fullrange driver DSPed to linearity using thick alu foil 3x thicker than household foil:
In the alu paper alu material mix the paper itself has the damping properties.
Different than using hard foam (Kef B139, Podzus-Görlich) or honeycomb cores (Eton) which are resonant a reinforced soft paper core gets better wirh alu foils in the end.
I made measurements before / after:
This is a 10 inch fullrange driver DSPed to linearity using thick alu foil 3x thicker than household foil:
Next you can try to replace the magnet with neodium, and add a shorting right if has none.
In a way, perhaps a bit before their time > the B139's have been quite revered & little criticized > except perhaps their maximum SPL output.
Very interesting note regarding the lowering of Fs over time 🙂
Powerful Neodymium 'motors' have revolutionized the performance of higher mass cones + efficiency in general >
creating drivers with quite astonishingly low QTS.
Why? They have served me well and sound is great. I would not even dream of messing with them. They fill in the low and very deep bass nicely from under the desk supporting a pair of original Rogers LS3/5 (had since new) on either side of my 37" PC screen on my desk.
I don't think you could have anything better sounding for near field listening. No DSP at all, exactly as developed by BBC. The H frame was built by hand, all perfect 45 deg angles, no table saw or routers, by an old carpenter/shop fitter in Santa Carla using solid maple on the outside box glued to MDF on inner box and soft board, often called sound board on the inner, inner cabinet in the late 70s. I have no idea how it measures, but it sounds right.
The two woofers are mounted face to face and crosses over to the LS3/5 at 70 Hz. This has been my personal entertainment system since I can recall. Most recent changes (about 30 years ago) I replaced the passive cross-over to the subs for a 70Hz 2nd order Butterworth active to the H frame. The LS3/5 is driven by JLH 69 and the woofer by JLH 69s bridged. All class A. Yes they are hot and I have the air-con running at 24/7 winter and summer.
I have grown very attached to its sound and really prefer listening near-field than to my main system in the lounge which I hardly use anymore. In the distant past I used Creative sound card on my PC, but the brother bought me a Topping D50 for Xmas a few years ago and that was a marked improvement over the sound card. Late at night when the wife goes to bed, I listen to my HD800 and a small headphone amp that I posted on DIY a while ago. That is my desktop set-up.
I knew I should have used a winky.
Because of the shiny surface, the wave is propagated away from the cone at such a velocity, it creates a lower pressure on the front, thereby increasing the transient response.
And because the wave is no longer being shovelled by the cone due to its increased velocity, the cone itself is less hindered therefore simulating a lighter cone.
See? Simple.
Never mind the science, they got it all wrong.
I have never considered using aluminum foil as I do not think it will add stiffness, I believe the adhesive is likely add the benefit in that case. I have however painted and sprayed many a cone. Some with good effects, others not so much.
Freedom666 is decidedly the most experienced with foils.
i use puzzlekoat/modPodge to try to achieve the same benefits. It adds negligable mass unlike foil. https://www.t-linespeakers.org/design/tweeks.html
dave
i use puzzlekoat/modPodge to try to achieve the same benefits. It adds negligable mass unlike foil. https://www.t-linespeakers.org/design/tweeks.html
dave
Sandwiches bring benefits. Most Al cone drivers i have sampled benefit from puzzlekoat/modPodge oran acrylic for those that bare FRs.
dave
The pva glue is just the damper, the foil doesn't recover shape after being bents, i think these 2 works the best. Shock and spring. Yeah this is nothing new
Many years ago now a shop in Australia called Altronics were selling/clearing a batch of 8" aluminum cone woofers at a ridiculous low price.
I still regret not buying four of them for future projects where two would have surly involved experimentation with damping > like this thread.
I imagine the rubber spray that I now see advertised on TV would probably be an ideal single coat direct onto a aluminum cone 🙂
I still regret not buying four of them for future projects where two would have surly involved experimentation with damping > like this thread.
I imagine the rubber spray that I now see advertised on TV would probably be an ideal single coat direct onto a aluminum cone 🙂
@Mister Audio
I tried on full metal alu cones damping glue with no or little effect concerning the resonances.
Reckhorn has some segmented metal cones. Never tried these.
I always search for fullrange drivers with copper faraday ring and long stroke what is difficult enough, a stroke of more than +-3mm is already rare.
I use then alu foil tweaking and ideally dsp to linearize. Or just current driven amps and some easy smartfone EQ.
My inspiration is the Pfleid FRS20 loudspeaker, the only fullrange I know from loudspeaker history using consequently EQ while sacrificing bandwidth of the driver for good damping of the loudspeaker cone.
I tried on full metal alu cones damping glue with no or little effect concerning the resonances.
Reckhorn has some segmented metal cones. Never tried these.
I always search for fullrange drivers with copper faraday ring and long stroke what is difficult enough, a stroke of more than +-3mm is already rare.
I use then alu foil tweaking and ideally dsp to linearize. Or just current driven amps and some easy smartfone EQ.
My inspiration is the Pfleid FRS20 loudspeaker, the only fullrange I know from loudspeaker history using consequently EQ while sacrificing bandwidth of the driver for good damping of the loudspeaker cone.
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