/admin and relative paths

[eluser]Kunzilla[/eluser]
I work with CI 2.x and i created a backend (/admin) in my application. All works fine! But, i must set the subdir /admin in every method.

for example:

Code:

$this->load->model('admin/user_model');

what i want:

Code:

$this->load->model('user_model');

Can i set the /admin subdir as default url / path for my backend?

Thanks