Why are cabinets so deep on newer bookshelf speakers?

[babsaldis]

I been shopping for Polk bookshelf speakers and have looked at current RTi models and those going back about 10 years. Noticed that the depth of the cabinets on models with 6 1/2" drivers (RTiA3, RTi6 RTi38, RT35i) became much deeper starting with the RTi6 and RTiA3's. Cabinets on the RTiA3 and RTi6's are 14" deep which is getting really deep for a bookshelf speaker. Previous models with 6 1/2"' drivers, the RTi38 and RT35i, are only about 11-12" deep.

So, my inquiring mind is wondering why there has been a trend to deeper cabinets on the newer bookshelfs models with 6 1/2" drivers. Is it for stronger bass sound?

I'm shopping for bookshelf speakers, but doubt I would buy any with 14" deep cabinets because of placement issues in my limited space, so this is mostly a matter of curiousity for me (am I the only person who's wondered about this?). Can anyone enlighten me?
Babs

[dkg999]

A certain amount of interior space is needed to make the speaker work properly. In a choice of making the cabinet wider or deeper to get the required interior space, current designs are mostly going deeper.

[nguyendot]

Bookshelf speakers are only really bookshelves in terms that they do not sit on the floor. If they don't sit on the floor they're either bookshelf of in wall.

Normally bookshelf speakers sit on stand for optimal listening since a lot of times their ports are also in the back. Take for example the RT-55/i. Those won't fit in any bookshelf, but they are bookshelf speakers. Then again so are the RT-25s, which could probably fit just fine.

[lmacmil]

So, my inquiring mind is wondering why there has been a trend to deeper cabinets on the newer bookshelfs models with 6 1/2" drivers. Is it for stronger bass sound?

As already mentioned, a certain cabinet volume is required for optimum performance. The designers have opted for a minimal front width (typically only 7" wide or so) and height. That leaves only depth to achieve the required volume.

I have 28 year old Polk Monitor 7Bs which were also considered bookshelf speakers in their day. They are about 12" wide, 26" high but only 10" or so deep. No way those babies would fit on a bookshelf. ;)

[babsaldis]

Interesting responses, but check out these cabinet measurements

RT35i 15"H 8 1/4"W 11 1/2" D
RTi38 15 1/4"H 8 1/4"W 12 3/4"D
RTi6 14 3/4"H 7 3/4"

[babsaldis]

Ignore my last post, accidentally sent it before I was ready.
Babs

[Face]

Narrower cabinets generally have a cleaner frequency response from less diffraction and also image better.