You might consider checking out some YouTube courses on how to use and care for and clean your soldering equipment. If you have stuff built up on the soldering tip you are not caring for it properly and it will not do the job it was designed to do to an adequate extent.
If you look at the picture below you will see the soldering iron that I have been using for the past four years. I have built three tube amplifiers and a FET microphone with that tip.
At a minimum, use the sponge when you solder and quickly wipe the soldering iron tip on the wet sponge after each application of solder to a component. So during the course of a work session you will be wiping that tip many many many times . Make sure the tip is tinned and that it is nice and shiny after each wipe and it will last a very long time and do a great job for you.
Finally if you're going to be doing any kind of work like this it pays to spend a little extra money to get a variable temperature soldering station. The one I have below is a Weller wesd51. It didn't cost much more than $100 and it's a fantastic tool that will allow you to do consistently high-quality work for a long time.
Edit: I learned to solder at a weeks-long soldering school when I was in the US Navy. That school taught soldering techniques that met NASA-specifications for workmanship and was probably the most intense training I've ever had. Those specs cover every conceivable soldering scenario as you might well imagine. Check out https://hackaday.com/2016/11/03/specifications-you-should-read-the-nasa-workmanship-standards/ for an entertaining read on this subject as well as an extremely useful link to the specs themselves.
Now, I'm not saying you need to use NASA standards to make XLR cables, but the standards are very practical and easy to understand, and after a little practice, using those techniques makes things much easier and faster and your work will stand the test of time. Besides, to paraphrase the Hackaday site, it doesn’t hurt the ego to build something trivial to the same standards as a spaceship.