Length of speaker cable effect bass response?

Maybe the design of the cable is different since its 2 companies that you are mentioning.

I bought some BlueJeans Cable a few years ago, but it was going to be used for rear surrounds where I knew it would be over 30 ft, and bought it because it was affordable...and wasnt expecting great sound .

How long have you had the Blue Jean Cables in the system ?

A lot depends on the output resistance of the power amplifier and the guage of the speaker wire. In other words, it can have an effect for the worse. A tube amp with 30 feet of 18 guage wire is a worse case scenario; a Krell amp with 6 guage wire will have much less of an effect.

I have 22ft runs without any loss of bass. I use 12ga ccc Vampire Wire.