The TiN is applied to both sides of the diaphragm to stiffen it, but it's titanium suspension is masked from the TiN vapor deposition to allow it to maintain it's original flexibility.
Pretty impressive reduction in decay time.
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The smoothness comes with a sensitivity reduction, reduced power capacity and only 0.1mm Xmax.
Using a LTH142 60x50 tractrix horn (presumably with a 1.4" to 1" throat adapter) it's sensitivity is ~105dB at 1kHz.
Rated at 30 watts (1500Hz-15kHz) ~120dB at 1kHz may be the limit, assuming the diaphragm would not be hammering the phase plug at that level.
By comparison, the 100 watt Faital HF1400 is ~5dB more sensitive at 1kHz on the same horn:
That said, if you don't need the headroom a typical compression driver has, looks like a bargain!
Art
I'm giving the shaping plug a second chance. The 1" Lavoce driver seems to be coherent enough in the top octave for this to work, so there's hope.
For the start, this is still a shorter one to verify the exit wavefront shape. It's simply a Gen2 adapter -
For the start, this is still a shorter one to verify the exit wavefront shape. It's simply a Gen2 adapter -
I often used two-part polyethylene as a damping compound. It never gets hard and damps very well - especially if it is mixed with glass microbeads. I've only ever seen epoxy that gets hard.
Some 4" diaphragm JBL 245x drivers have Ti, Aquaplas coated Ti and Be versions. I think the Aquaplas coated version has also been measured against both on some forums. How it looks like: https://reconingspeakers.com/products-page/jbl-d16r2451sl-diaphragm/ https://www.diyaudio.com/community/...pression-driver-diaphragm.374388/post-6717786
There was a thread on a forum, don't remember which forum, discussing Aquaplas, not sure it's been ever publicly shared what it's made of.
Speaking of aqua and plas, simple PVA wood glue is a water based emulsion, and cures to a plastic film with some elasticity. (Maybe the D3, D4 types more so?) Vinegar should be able to dissolve it, so it wouldn't be nasty to work with, potentially reversible and allowing for multiple tries.
Other option could be to sandwich other layers of materials onto a diaphragm. But before that one could mix PVA with many different things, like fine sawdust (resulting in something with wood fibres), gypsum, sand, baby powder (talc). Lots of possibilities for the ultimate recipe.
There was a thread on a forum, don't remember which forum, discussing Aquaplas, not sure it's been ever publicly shared what it's made of.
Speaking of aqua and plas, simple PVA wood glue is a water based emulsion, and cures to a plastic film with some elasticity. (Maybe the D3, D4 types more so?) Vinegar should be able to dissolve it, so it wouldn't be nasty to work with, potentially reversible and allowing for multiple tries.
Other option could be to sandwich other layers of materials onto a diaphragm. But before that one could mix PVA with many different things, like fine sawdust (resulting in something with wood fibres), gypsum, sand, baby powder (talc). Lots of possibilities for the ultimate recipe.
I get can an epoxy with hardness possible to set between Shore 60A - 75D, depending on the mix ratio. Microbeads sound good, I guess that works by converting shear to heat, more damping with less mass, is that right? Spare titanium diaphragms for the old drivers are not expensive, I'm tempted to try something with the 3" diaphragm of the D3300...
- What I also always wanted to try is to flock the phase plug surface facing the diaphragm. Or just fill the whole compression chamber with some soft wool.
- What I also always wanted to try is to flock the phase plug surface facing the diaphragm. Or just fill the whole compression chamber with some soft wool.
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Just keep enough distance from the diaphragm! You don't want fibers touching the dome (I once tried it with a dome tweeter).
Routine work by now 🙂
(waiting for the last part...)
(0.25 mm nozzle)
(waiting for the last part...)
(0.25 mm nozzle)
Someone should come up with a method how to punch holes into a surround nicely.
The diaphragm of this driver has a patch of fabric sandwiched onto the dome: https://audioxpress.com/article/test-bench-oberton-nd72ct-hb-1-4-compression-driver
For rubbery stuff there are products like this, fairly available in small quantities and low cost, it's natural rubber latex emulsion if I'm not mistaken https://glorex.com/en/latex/112425-latex-moulding-emulsion-200ml.html
I imagine mixing with many different materials would work to adjust the final consistency. Beeswax chewing gum is a thing and latex rubber would be a gum base for that, for an example for a composite gummy stuff. I wonder how comparable pine resin (also available, low cost) is to bitumen when looking for viscoelastic properties. Then mixing in solid particles.
The diaphragm of this driver has a patch of fabric sandwiched onto the dome: https://audioxpress.com/article/test-bench-oberton-nd72ct-hb-1-4-compression-driver
For rubbery stuff there are products like this, fairly available in small quantities and low cost, it's natural rubber latex emulsion if I'm not mistaken https://glorex.com/en/latex/112425-latex-moulding-emulsion-200ml.html
I imagine mixing with many different materials would work to adjust the final consistency. Beeswax chewing gum is a thing and latex rubber would be a gum base for that, for an example for a composite gummy stuff. I wonder how comparable pine resin (also available, low cost) is to bitumen when looking for viscoelastic properties. Then mixing in solid particles.
The shaping plug assembled and measured with the A520G2/DF10.171K.
Could be worse.
This is not so different from the standard matched adapter (which is good):
Now it can be worthwhile trying something a bit longer...
Could be worse.
This is not so different from the standard matched adapter (which is good):
Now it can be worthwhile trying something a bit longer...
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Not bad! It looks pretty consistent on and off axis 🙂
Pretty interesting how it disperses a bit of the peak at 18k
I also have a simulated version with further improved directivity above 6 kHz but that showed a worse stability of the calculation, with some visible impedance issues not possible to get rid of (probably actual resonances). It has the center channel a bit smaller at the exit - it can actually be a form of diffraction that improves the directivity, hard to say. I will surely print and test it as well, the core of the plug is replaceable.
Some news concerning buying options for the Peerless DFM-2535R00-08:
I have possibly found an option for people from EU countries and Switzerland: I contacted a German Tymphany distributor who could still acquire stocked drivers.
Some reviews on the compression driver:
Now to the hard facts:
The condition for the distributor to stock the lot is a collective order of a minimum of 50 pairs / 100 pieces. The price is going to be around 48 Euro per driver plus shipping.
If there is reasonable positive feedback, I might organize the collective order. Please let me know if you are interested and for what amount of drivers you are willing to pay. I will take one pair, 49 still required. 🙂 👍
I have possibly found an option for people from EU countries and Switzerland: I contacted a German Tymphany distributor who could still acquire stocked drivers.
Some reviews on the compression driver:
Now to the hard facts:
The condition for the distributor to stock the lot is a collective order of a minimum of 50 pairs / 100 pieces. The price is going to be around 48 Euro per driver plus shipping.
If there is reasonable positive feedback, I might organize the collective order. Please let me know if you are interested and for what amount of drivers you are willing to pay. I will take one pair, 49 still required. 🙂 👍
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