If one were to tune down...

a step and a half with a set of 10's, how would one maintain tuning stability?

With a good set of tuners...shouldn't be a problem.

What's a good set of tuners?

I don't think the strings care what they're tuned to. You might have a little instability when you first down tune, but all will be well once they settle in. A good setup is a good setup...

10's are quite slinky at C#. I suggest a light top heavy bottom set to make the most of those deep tones on the lower strings.

Try 11s?

I keep two 25.5" scale guitars permanently tuned down a step. I started with 10s and found that 11s are comfier and less flappy. The increased tension with the thicker strings seems to keep the tuning less vague and I didn't find that I needed to enlarge the existing nut slots.

You might find that it'll take your guitar a little time to acclimatise to the change in tension and you might need a little tweak of the truss rod after a week or so.

I reckon that if your tuners are doing a decent job at stardard tuning, then they'll be fine for what you're planning.

I tune my guitar a whole step down, which makes D-A-F-C-G-D. Been doing this for years. Using 10 - 52 set back then, and now that I have a Tele, 10 - 46. It feels like playing 9s, only a step lower. If you get any tuning problems, use thicker strings. I believe many guitar players tune their axes down to get heavier tone.

I tune my guitar a whole step down, which makes D-A-F-C-G-D. Been doing this for years.

Wouldn't that be D G C F A D? Unless you're looking in a mirror :wink:

I have .10 flatwounds on now. I like them even though (because?) they're really slinky at C#

I'm willing to move up if I need to, just wondering if there is a way to stay with tens.

I used to tune BF#BGBE AND C#F#BGBE and the only way I could find pitch stability is with 11-56 and 12-60. But I played with a very heavy hand. I use 11-50 now and even drop tuned can make it work. No way with 10s

I have a Jackson tuned to C with 12's on it and after doing it initially it felt weird but after playing for a day it felt totally normal. Your finger callouses just need a minute to get used to it. I wouldn't keep 10's for a C# tuning unless bending up 5 intervals is part of your playing style:lol:

If you want to tune 1/2 step down as many famous players do, ie: Hendrix & Stevie Ray and many others, a 10 through 46 will be fine. I like 9 to 46 round wounds on my Strat, 10 to 52 on the Tele. It is easey to accidently bend strings while play cords so don't mistake this as the guitars' fault. As far as flat wound strings I haven't used those since 1966 Not what I would discribe as slinky but to each his own. What are good tuners ? Quality ones that don't mechanically slip. Locking tuners , like Sperzel are among the the best.

I'm willing to move up if I need to, just wondering if there is a way to stay with tens.

For a half step to a full step I've stuck with 10-46's or 10-52's but I would think down a full step and a half you may want to beef up the gauge to 11's.

When I lower the tuning on my bass even a half step I always step up one gauge just to keep the tension firm. I would think 10-46's would feel like rubber bands tuned down to C#.