Best Solder??

Rja,
I would be careful with some of the "audiophile" solders. Some have pretty corrosive flux in them. IF you dont clean it all off, will eventually attack the joint.

In one of our audio club meetings, we had one demo where we tried different solders. They do make a very big difference, bigger than I would have thought. The other thing is you need to have a good mechanical connection over time.

we ended up picking Kester 63/37 with a 285 flux as the preferred choice. 63/37 is also eutectic, which most others are not.

Mundorf supreme 9.5%silver 4% Cu, and 0,1% gold- its melts very good with stock soldering iron, with soldering station 460'C even more. it "sounds" smooth comparing comapring with WBT for example. its good or bad depends on system.

This thread reminds me of something that happened in my senior year of engineering school. My room mate's brother was an audiophile. He was having trouble with one of his speakers and asked if I would have a look. He had purchased these speakers 2nd hand and I pulled out the crossover board on the offending speaker and plainly seen that someone had been inside the speaker before and modified the crossover. The modification was a real hack job and I found many cold solder joints. I simply broke out an iron and some trusty Kester lead free and reflowed the bad joints. I reassembled the speaker and gave the speaker back to my room mate to give back to his brother telling him I just had to resolder some joints. I recieved a note from his brother thanking me for the repair and using that special solder. He continued by saying it was a marked improvement over the working speaker and asked if I could use the special solder and resolder the joints on the second speaker for him. I just shook my head, kept my mouth shut and laughed.

I have used Kester 24-7068-7063 for repairs and Diy. Rosin Activated 96.5% Tin 3% Silver 0.5% Copper

Jeff at Sonic Craft (who knows a lot about this stuff) advised me to use Cardas Eutectic solder. He gave me reasons why it was better than the Mundorf and others, but I can't remember what they were. I think it had something to do with the amount of silver content and also long term corrosion. Call him.