Ernie Ball Cobalt Guitar Strings
[B]Pros:[B] Higher output, greater clarity, tuning stability, and longevity
Cons: Higher price, possibly more fret wear, harder on fingers
I've only got about two weeks worth of experience with these strings on my Fender Strat, so I'll update this post as I get more familiar with them should my experiences change. So far, here's what I've noticed.
Cobalt is a harder metal than Nickel, and that's noticeable right off the bat. They feel rougher to your fingers, but the difference isn't huge. If you're an experienced player with some callouses on your fingers, they won't pose any problem, but I could see how they might be a bit tougher on a beginner. This leads to my main worry: fret wear. While I don't think they'd drastically shorten the life of your frets/fretboard, I do think because it is harder, they will have some effect on it. How much, I can't say, and it'll probably be years before anyone can say for sure.
The output is noticeably higher as well. It's not a huge difference over steel or nickel, but it is something that you'll notice without having to A/B them. They also seem to have greater clarity over nickel and steel strings. You will especially notice this with chords, as you can hear the individual strings ring out better. Intonation doesn't seem to be any better or worse between these and nickel or steel. Also, sustain doesn't seem to be effected by these strings. For the record, my Fender Strat has a humbucker, alnico single coil, and a lace sensor pickup, and I've noticed increased output and clarity from all three pickup types.
Another benefit is tuning stability. They seem to stay in tune slightly better than steel or nickel strings. Once again, nothing huge, but it's slightly noticeable. Not as big as a difference in this department as the other two, but it's there none the less.
They also seem to resist corrosion better. This may only be a perception thing. It's hard to say, as I'm not real familiar with them yet. The increased output and clarity from the get go could be skewing my view, but so far, they seem to sound newer longer and haven't yet shown any physical signs of corrosion (changing color) in two weeks of moderate use (about 1-3 hours a day). I usually notice my nickel D'Addario XL's starting to deteriorate in tone after a few days. They'll still sound good for a few weeks, but the first signs of change usually happen after the first three to seven days. With these cobalt strings, I've not noticed any change in almost two weeks. But since I'm not that familiar with them yet, so they may have changed and I just haven't noticed.
In conclusion, these strings are slightly better than any other string I've used before in just about every category. I'd recommend them to anyone trying to maximze their tone, which means these will be my go to strings for recording. Due to their harder metal and the fear of shortening fret life, I not going to use them as my daily strings just yet. I'm going to keep them on my Fender Strat for a year or so to make sure they don't tear it up before switching brands on some of my more expensive guitars. My impressions are that they shouldn't induce any noticeable extra wear, but I want to be certain before I commit to them fully. If my suspicions are correct that they don't wear out my frets any faster, I'll switch them out on all guitars full time. In the mean time, I have no qualms about setting up any guitar with these strings for recording purposes.
So it appear that two weeks is about as much as I can get out of these strings, tone wise. After that, the tone noticeably dulls. With my old nickel strings, I'd get about one week, so these last maybe twice as long? I will typically keep them on a guitar for months, unless I'm going to record or play a gig somewhere, so the slower corrosion is definitely a plus! I also just bought some more, and will probably switch out all my guitars as my current supply of nickel strings gets used up.