Bookshelf vs diffuser panel. Who wins?

Where is that bookshelf located vis-à-vis your audio system? A bookshelf is definitely better than nothing, but it cannot possibly compare with a properly designed diffuser panel. I used such bookshelves to mimic diffusers early on, but once I tried diffuser panels (GIK Alpha 4a), there was not going back. The 4” Alphas are combination absorber, bass trap, and diffuser. I now have 14 Alpha 4” and 6”.

Here is copy / paste from GIK website:

The key to good diffusion is an even scattering. A quality diffuser should scatter the sound in a complete 180 degrees. GIK treatments like the gotham and alpha series are designed with a mathematical formula to give a perfectly even scattering.

Good diffusion doesn’t happen by accident, the designs are very precise and complex. Some people suggest using a bookcase filled with books as a cheap form of diffusion, but a random assortment of books is extremely unlikely to have the layout precision required to produce good diffusion. It’s probably better than a bare, reflective wall, but it won’t perform like a good diffuser.

full and healthy bookshelves perform a similar function to room treatment and (more importantly, imo) makes a space cozier and more comfortable to be in.

i have nothing against professionally treated rooms - they sound amazing - but i personally prefer a comfortable space surrounded by the things that i love and value to some sterile, professionally treated, Serious Listening lair with a single chair and 50k in electronics on the floor surrounding the obelisks from 2001: a space odyssey. i could hit the lottery tomorrow and would still gladly make that sacrifice (or alleged sacrifice) in sound quality 8 days out of the week 😂

Personally I can't stand bookshelves in rooms. You have to fill them with books or assorted pictures and objects so they will hopefully interest visitors. U are Stuck with them.

Much prefer the blank canvas of a wall that you can decorate much more creatively.

What wins?  Artificial ficus trees win.  Get a few 5' - 6' artificial ficus trees and use them as diffusers.  Much more effective than bookshelves or wasting money or time on diffuser panels.  I have over a dozen in my listening room and they are great.  And have a VERY HIGH Wife Acceptance Factor value.  

Books work well! if you tilt the 3 book forward, DA Scanlon will come down the elevator fireplace!