define $wpdb without prefix

It might be an amateuristic question, but whatever.

I have 2 wordpress installations in one database. One with database table prefix “en_” (english) and one “nl_” (dutch version of the website).

For photogallery I use the WP Photo Album plugin.
I only want to update one gallery and make the other wordpress installation (with prefix “nl_”) get his data from the installation with “en_”.
These are the global settings for the gallery plugin.

/* GLOBAL SETTINGS */
global $wpdb;
define('ALBUM_TABLE', $wpdb->prefix . 'wppa_albums');
define('PHOTO_TABLE', $wpdb->prefix . 'wppa_photos');
define('PLUGIN_PATH', 'wp-photo-album');

But it should not use prefix while that makes it go to its own prefix. It should go the the other prefix (en_ instead of its own nl_)

what not works:
define('ALBUM_TABLE', $wpdb->'en_wppa_albums');