Walco,

Too small meaning the length and width are not sufficient (volume wise
they are almost equal)?

Yes, but the longest dimension is also too short. Both the longest dimension
and the total volume are important.

Do you mean it's almost impossible to get an adequate bass response in
there?

It's a myth that you need a certain minimum length for low frequencies to
"develop" in a room. In truth, what happens is the walls are all so close
that the reflections are strong, and the inevitable series (comb filter) of
peaks and nulls begins at a higher frequency.

Also, have a look at the Acoustics FAQ, second in the list on my Articles
page:

www.ethanwiner.com/articles.html

--Ethan