The centering of the voice coil on lowther need patience and using a sine tone of 50hz will help you on this. So I don't see much of an issue.
Normally if you still encounter rubbing, it is mostly because there are still debris still trap in the magnetic gap
Normally if you still encounter rubbing, it is mostly because there are still debris still trap in the magnetic gap
My latest update on my Lowther OEM build recone kit
Latest work on the cone and whizzer cone. Using pine sap varnish.
Very impressive work!
Another area of available customization is the phase plug. Using my son's 3D printer, we made about a dozen different shapes based on both the Lowther offerings over the years plus other shapes from other manufacturers. For DX4s in a medium-sized listening room, our clear favorite for listening was a pointed plug with elliptical sides. ...the "opposite" profile of a bullet. The pointed plugs also measured best around the frequency of 4X the wavelength of the plug mounting diameter. IIRC, that was ~3kHz. That was a fun little experiment! Super easy to swap the different shapes...
Cheers,
Frank
Another area of available customization is the phase plug. Using my son's 3D printer, we made about a dozen different shapes based on both the Lowther offerings over the years plus other shapes from other manufacturers. For DX4s in a medium-sized listening room, our clear favorite for listening was a pointed plug with elliptical sides. ...the "opposite" profile of a bullet. The pointed plugs also measured best around the frequency of 4X the wavelength of the plug mounting diameter. IIRC, that was ~3kHz. That was a fun little experiment! Super easy to swap the different shapes...
Cheers,
Frank
The 'filled horn' description is very good. I don't have the drivers available now for a photo, but this little "forever spin" top is the closest thing I could find for a photo. The thin portion of the phase plug was longer with sharper point, and the taper was more gradual down to the base. I don't think the mathematical details of the elipse are too important. Just think of a trumpet...
Cheers,
Frank
Cheers,
Frank
Attachments
@ghemmi, I have used acoustic damping material on the portion of the frame that faces the cones, and while the effects were not dramatic, some improvement in clarity was noticeable. I used wool felt with pressure sensitive adhesive, and its placement was fairly tricky on intact drivers. In your case, it would be trivial to treat the frame before adding the cone. Unfortunately, I see that the felt product that I have used is no longer available from the vendor and I cannot suggest another source. But you would have many alternatives working with individual parts during assembly.
Cheers,
Frank
Edit: The best acoustic absorption properties are obtained with 100% wool felt. Perhaps this site would be worth checking. https://thefeltstore.eu
Cheers,
Frank
Edit: The best acoustic absorption properties are obtained with 100% wool felt. Perhaps this site would be worth checking. https://thefeltstore.eu
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