Increasing bass on floor standing speakers


I have some floor standing speakers that were a Visation kit from 30? years ago. 
The treble and mids are amazing but the bass is a little weak. And suggestions on increasing the bass? 
Concrete floor 
Room 3.5 x 11 meters... Speakers on the long wall. 
Rotel ra-01 amp
Project rpm 4 (I think) 
Currently listing to Stevie wonder hotter than july.
Thanks for any suggestions 
speakerboyz
These look the closest however there is a slit in the bottom at the front. https://impactaudio.co.uk/collections/visaton-loudspeaker-kits-accessories/products/visaton-vib-2000...
I have the ortofon 2m red cartridge (new). 
I also have cd player (nad) and a computer attached. 
I'll try moving the speakers but it's not a practical solution unfortunately and I'll do a test with tilting them. The bass is also light with the cd player. 
Don't know if it's been mentioned, but you could try placing them on soft footers (I usually recommend first trying something from around the house like cutting up an old mouse pad/rubber mat, et cetera).

Does the Rotel's LF boost (6dB @ 100Hz) help?

As far as moving the speakers goes sometimes just a few inches will make a difference.

DeKay
You may find it useful to download a Real Time Analyzer (RTA) to your phone and check your room for bass modes and nulls--then you will see if your listening position is in a null.  I use AudioTools but there are many others.  You can also use a free room mode calculator called Amroc, but that's more helpful for modes rather than nulls.
Not sure about your loudspeakers but a 40WPC Rotel isn't going to have kick ass bass no mater what.