westlake bbsm 4
 

I'm looking for a new pair of nearfields and a friend has a pair of westlake bbsm 4's for sale. my current monitors are tannoy pbm 6.5's.
the westlakes have two 4" drivers in each cabinet...my question is how comparable are a pair of 4" drivers to a single 6"?

I used to love these monitors back in the late 80's/early 90's. They sounded similar in tone to the Urei 809's that people in Miami loved so much. Lower bottom than any of the standard 6" single woofer stuff - nice balance of high/mid/low.

Take this with a grain of salt because it's been 15 years or so since I last heard them.

As far as driver area goes (which is a main factor in bass response), the 6in has about 28 sq in whereas 2 4in drivers will cover about 24 sq in.

Though you have multiple voice coils moving air, so that may very well account for any difference through the additional power they can handle.

Another thing to keep in mind is that tuning has a lot to do with low end response - your tannoys are probably tuned at around 50hz. Smaller drivers will have a more difficult time with frequencies below that no matter how the enclosure is tuned though - something to consider if sub-bass is something you're concerned about hearing.

though having never heard either system, i'm not sure how accurate I am...

(BTW, how much would you be selling the tannoys for? I'm in the area and might be interested.)

thanks for the info.

I'm going to hold on to the tannoys. I do have a pair of jbl 4430's for sale though.

Not to split hairs, but the correlation between driver diameter & low frequency cutoff is not entirely accurate. It's quite possible to tune box resonance below 50Hz & get low frequency extension from a tiny driver. What you don't (or rarely) get from a single 4" woofer is enough SPL to make that low end usable. All things being equal (which they never are), the only difference between a 6" driver & a 4" driver is the larger speaker will move more air...which means it will play louder, not lower.