Tried Eb alternate tuning but guitar intonation is off and I'm unsure how to fix it

Question

I have a fender mexican strat, with 10s. I have never changed string gauge, I only tuned all the strings down half a step to Eb from E.

The issue I am running into is that the low Eb, Ab, Db, and Gb strings are all sharp. I tested the intonation by playing the string open and then checking the 12th fret. These 4 strings seem to be in tune when played open but all of them are sharp when played at the 12th fret. The low Eb is the worst and the rest of them are just slightly sharp. I tested this using consistent attacks on both open and 12th fret.

I tried to fix the issue by adjusting the saddles. I made the saddle adjustments in increments by moving the saddle towards the bridge after loosening the string and it seemed to only make the Eb more sharp. I also got the point where I can't physically turn the screw further as it is very tight and I don't want to strip the screw.

I'm not sure what to do now. I have very little experience with guitar set ups so I wanted to see if I can get any advice on how to proceed without damaging something.

Thanks!

Answer 1

Start by re-setting the neck - with lower pitch comes lower tension, so the strings may be affected by the action. A high action will necessitate the strings having to be pressed harder, sending them sharp. Using the 12th fret harmonic is a time-honoured way to check against the fretted 12 pitch.

That's of course after putting on a new set of strings, as old strings can be difficult to intonate.

Next comes setting the string height, by saddle adjustment, to at least get it playing properly again.

Because the string tension is less, you may want to also adjust the spring tension on the vib.

Then test intonation. It's possible to remove the little springs that are behind the saddle, although I've only ever had to do that on low E.

Changing the string gauge, or string tension shouldn't give problems like this.

Failing all that, search for some shorter saddles that will fit and effectively make the strings longer.

Answer 2

I'm more experienced with Telecasters than Stratocasters, but I see this problem with gauges much higher, such as .013s trying to get into standard-neck baritone territory. I took off the low-Es spring to gain some space, but it seems impossible to have blues-rock post-1982 if you can't intonate a Strat in Eb.

Taking it to a luthier for a setup is a reasonable course, but at this point, depending on the age of the instrument, maybe changing the strings might be an idea. Not necessarily string guages — stick with 10s if you're happy with them — but the current set might be played out, hindering your attempts at intonation.

ETA: An answer to a previous question explaining what a setup entails.

Answer 3

Yeah you need to get a high resolution tuner, one that shows 1 cent up or down increments so you can dial in your intonation a lot more precisely. I think your intonation is off.

Answer 4

You should send guitar to a professional luthier whenever you want to change tune and/or string gauge, even if it is just half step down or a simple Drop D. Strings have tension, and the truss rod is not the only thing that keeps the strings in tune.