Tips on soldering Deltron Banan plugs


I've tried soldering Deltron banana plugs to Mogami W3103 (12awg) but failed miserably.
Anyone have experience with these or similar plugs ?

I'm used to soldering RCA plugs where I put a blob on the connector that I reheat and connect the wire to.
On the Deltron plugs, there is no room to put the solder iron once the speaker wire is inserted.

Also, do you tin the speaker wire entirely, or just the tip?

Thanks in advance.
You're going to need to develop better soldering technique.  Solder is not glue.  To properly solder something so large you'll need a 100 watt gun, not an iron.  Insert the cable into the connector, heat the connector sufficiently and the solder will flow into the joint.  There are numerous online tutorials to help you develop better skills.
Well, a good temp controlled iron with broad tip will work too. Also tin the wire first.

For a wire that large it is easiest to use a solder pot. Then follow instructions as above! Insert wire, heat joint, add solder to junction.
quit wasting time soldering these banana plugs. Their terminals are for crimping and there's a screw to lock the wire. If you have proper gauge crimping tool, don't bother soldering, because crimping gives you more genuine contact than soldering.