Mike has been a solder-sans-silver sort of guy since he was about 12, but has recently started using solder with a 4% silver content on occasion and has suggested a discussion of the topic on this blog. It should be noted that at least one customer requested a major resoldering of a unit and even provided the boutique solder to accomplish it. On listening this customer found the previously listenable unit rendered unlistenable, so Mike has a bit of a negative bias regarding silver solder.
Here are some pros and cons of silver solder, as suggested by Mike:
- Better conduction,
- A harder bead (which might be beneficial for some high stress connections),
- A higher melting point (which might be beneficial for some high temp situations).
- Faster cooling/setting which can cause imperfect connections,
- Higher melting point makes it more difficult to desolder,
- Fouling of the soldering tip,
- More expensive, sometimes ridiculously so,
- A tendency to bead rather than flow into the connection,
- A tendency to look like a cold solder joint even when properly completed.
Anectdotally, we have at least one example of a consumer of silver solder unhappy with the sonic outcome. But the circumstance was essentially a substantial resoldering of entire boards which is different from what I do. I have used the Dayton 4% silver solder with very positive results, but it is very difficult to distinguish the effect of 40-80 capacitors replaced vs. the solder used. (Not to mention cleaning pots and switches!) In my experience the very popular Radio Shack silver solder, which I believe is 2% silver, is easier to use. So, I have no answers to all this at the moment. I tolerate the slight additional difficulty of using the Dayton product and trust that it is a better product at some level.
At some future time we need to take two vintage components and refurbish them identically with the exception of the solder used. All solder joints in the unit should be redone, one with a high quality conventional solder and another with a 4% silver solder. And then call out the golden ears in the group to see what they hear, so to speak. I think two modestly sized, high quality receivers would be the best targets for this effort since they are relatively cheap to acquire, tend to occupy a sonic sweet spot, and provide a variety of areas to test (e.g. tuner, amp, preamp, tone control.)
This topic is very similar to one that has made the rounds lately at Austin Stereo, the effect of using presumably 'better' capacitors in speaker crossovers. A number of recent examples have resulted in emphasized high frequencies, the dreaded shrill speaker. Better components do not guarantee better sound, ultimately. Look for a more thorough discussion of this topic in the future.