Interesting details by by Bruno Putzeys and Lars Risbo on Purifi motor inner workings.
Some Speaker Problems That Needed Solving | audioXpress
They are growing more open about the secret sauce, the article and this pic both show the winding details and Neo slug in the motor that were originally more closely guarded.
Some Speaker Problems That Needed Solving | audioXpress
They are growing more open about the secret sauce, the article and this pic both show the winding details and Neo slug in the motor that were originally more closely guarded.
An externally hosted image should be here but it was not working when we last tested it.
Hello Lars,
Very nice to have you here.
what precisely is the thinking behind the alternating double-quadruple voicecoil winding? I could follow the reasoning of going from double to triple or quad layers for parts that are at the far end of the v.c., but this alternating, intrigues me.
Thanx,
Eelco
Very nice to have you here.
what precisely is the thinking behind the alternating double-quadruple voicecoil winding? I could follow the reasoning of going from double to triple or quad layers for parts that are at the far end of the v.c., but this alternating, intrigues me.
Thanx,
Eelco
Thanks. The winding has 4 layers but with typically 2 to 4 gaps where the coil is effectively only 3 layers. These gaps flatten the Bl(x) by reducing Bl around the rest position. This trades some sensitivity for much better linearity (the reduced mass due to the gaps compensate to some degree). the positions and widths of the gaps are found using computer optimisation of a finite element model. I hope that explains it better.
Cheers,
Lars
We use MagNet for the motor. Simulations are controlled from Matlab and data are imported into Matlab that also does the optimisation of the winding profile.
We rely on Comsol for the vibro-acoustic FEA studies. Again, heavily integrated with Matlab and the geometry optimisation is driven by Matlab.
Lars
yes, we have plans for dedicated mid range versions for the 4” basket and coming 5.25” line. I am currently doing studies of geometry optimisation for the 5” version. looks very promising and can have a sensitivity exceeding 95dB (at 4 ohms, paper). An alu version also looks attractive. Anyone seeing a need for smaller mids than a 10cm?
don't know about sizes lower than 10cm, but there is a niche which might be addressed... car audio 
current 4" version is usable as mid/mid-bass (low sensitivity is not a problem), but it has one drawback - big magnet, which makes it hard to mount this driver in pillar
also - overall diameter - if it could be smaller - than it would be perfect!
i know this isn't a request line, but my 2 cents. maybe you can address those two 'thoughts'
current 4" version is usable as mid/mid-bass (low sensitivity is not a problem), but it has one drawback - big magnet, which makes it hard to mount this driver in pillar
also - overall diameter - if it could be smaller - than it would be perfect!
i know this isn't a request line, but my 2 cents. maybe you can address those two 'thoughts'
4” and 5.25” with high sensitivity meets all my needs! Could you talk about subjective differences in sound?
Would be great to see a high sensitivity SPK kit using these.