Kef LF drivers: Reference vs R Series (pics)

[exm]

I have some pictures of Kef 6.5” Reference LF drivers and R Meta LF drivers. Curious about people’s thoughts purely based on optics. The R driver weights 4.4lbs and the Reference 5.11lbs for what it’s worth. I think it’s obvious which one is which, but ask me if you are unsure. The impedance difference is interesting I have to say between these two.

 

[Mario Sanchez]

I once took a look inside my 2-driver R-series, which had woofers rated at 8 Ohm, so I postulate it might have to do with how many drivers KEF needs to wire for the LF part. Would I be correct in supposing that the 4 Ohm driver came from a R3 (Meta/Non M), and the 16 Ohm driver come from a Reference 5 (Meta/Non M)?

 

[Beave]

I agree. The 4 Ohm driver probably came from an R3, which has only a single woofer, while the 16 Ohm driver probably came from a Reference 5, which has 4 bass drivers in parallel.

Interesting how the Reference woofer almost has a basket inside the basket.

 

[Mario Sanchez]

I agree. The 4 Ohm driver probably came from an R3, which has only a single woofer, while the 16 Ohm driver probably came from a Reference 5, which has 4 bass drivers in parallel.

Interesting how the Reference woofer almost has a basket inside the basket.

According to their white paper, this inside basket is an apparent evolution of the usual "punctured cone" approach to connecting the VC former to the cone itself for when the cone profile doesn't permit a direct connection. There's basically unhampered air flow between the part of cone inside and outside the connecting element, presumably without sacrificing much on the element's own rigidity, which bodes well in terms of compression...

 

[NTK]

These are the sectioned views of the R Series and Reference LF drivers from their respective white papers. The Reference driver has a much wider spider, longer voice-coil, larger inverted surround, and larger magnet, indicating that it is designed for a significantly longer throw. The design of inside pole piece of the Reference driver is also very different from the R Series (much taller/longer along the voice-coil travel). The support structure between the voice-coil former and the cone is also much beefier in the Reference.

 

[exm]

I once took a look inside my 2-driver R-series, which had woofers rated at 8 Ohm, so I postulate it might have to do with how many drivers KEF needs to wire for the LF part. Would I be correct in supposing that the 4 Ohm driver came from a R3 (Meta/Non M), and the 16 Ohm driver come from a Reference 5 (Meta/Non M)?

Correct. R3 Meta and Reference 5 non-Meta.