I think I'll start this out by saying for the benefit of those who already know about the afterlength and tuning it, that with fine tuners, 54.5 and 55 mm are not at all meaningful when fine tuners are involved.  At least not according to my own experiments.

This is likely to be a long post (especially with even brief explanations) about violin adjustment, and might be too technical of a matter for most people's interest.  There's the disclaimer.   

Now a word for those who have no idea what I am talking about.. The afterlength is the part of the string between the bridge and the tailpiece.  Some very reputable violin folks say that those should also be in tune, though it is not as simple as them matching the strings because it is a much shorter piece of string.  What I have usually seen said is that if you bow the afterlength of the D string, it should be in tune with the harmonic near finger 4 when your hand is in position 1, but an octave higher.

Now you may wonder why that would be important.  Well, it is supposed to have to do with how musical notes resonate through the bridge and nut and tailpiece and how one string affects the others when you play.  But an easier point to understand would be that that little bit of string does vibrate when you play, and if it is not at any sort of musically related pitch, it may be a very sour note.  It would be a much quieter note than the one you are bowing, but there would always be a little bit of sound from the afterlengths of all 4 strings there in your sound, so some folks tune those by adjusting the position of the tailpiece.

For most people, I would say it is nothing you will want to mess with.  Adjusting it requires many times the amount of work you'd do in say, changing a set of strings, since it likely will have to be done quite a few times to get it right.  The pitches are high enough that some people might have some difficulty hearing them (or even playing them, if you haven't learned to play harmonics yet) and in my opinion most electronic tuners just aren't made to be accurate up in those ranges. 

The process itself isn't that hard and doesn't take any special tools or Harry Potter's magic wand or anything, but with taking the violin partially apart and then reassembling it and re-tuning it over and over, it would probably fall under that list of things most folks will prefer to just leave alone or ask a luthier about.  Some people also say it either doesn't make a difference or that the difference is so slight in most cases that it isn't worth the trouble involved.  It seems to be rather controversial so far as adjustments go.  Just keep all that in mind if you ever decide to go ahead and try it, and don't say I didn't try to warn ye, ok?

So anyway, I decided to tackle adjusting the afterlength of my electric violin.  I had the bridge and 2 of the strings off anyway, because of my "tube elimination" project, and I had been meaning to get around to this adjustment on my electric, so it seemed like a good time.  I ended up spending couple hours getting it even close, and then fussing with it on and off for most of the day and evening before finally getting it right. 

It took me longer than I thought it would because my fist adjustment, I tried adjusting the tailgut length to bring the afterlength to 55 mm, considering it to be the length of the string between the bridge and the ball end of the string in the fine tuners.  That ended up being way too long, the afterlength pitch was several notes low.  But still thinking it should probably be somewhere around 55 mm that I have seen mentioned, I walked it back up slowly.  During all those retunings and etc, it was kind of like my violin was having a case of "multiple personality disorder".  At some of the spots, the sound was very unpleasant.  What string was loudest changed with almost every move, and the timbre of the instrument changed.  Most of the differences were subtle, but some of them were glaringly bad.  I didn't find any "magic" spot in the overly long lengths that actually sounded wonderful.  Some of them were at least playable, even reasonable.  But so far as those folks that don't think it makes a difference, well, it did on this particular violin, anyway.

As I got close, I ran into another problem.  The vibrations through the instrument got pronounced enough that the back plate started to rattle and buzz.  On my electric, the whole back is one plate that is held on with small screws.  After checking the screws to make sure they weren't just loose, I ended up taking the back off and padding the inside of it at spots where it might be buzzing against other parts with some thin craft foam.  That fixed it, and I'll think of it as an upgrade in eliminating possible mechanical vibration where it isn't wanted. 

I finally got it to where the afterlength is in tune.  Now a few days to let things settle and make sure I don't have to touch it up again, and I'll call it good enough.  Since this adjustment does involve talking off the bridge and tailpiece, I'm not at all sure that it won't need another adjustment or two after it has had some settling and "play in" time.

Now, back to that 55 or 54.5 mm that is considered the approximate "usual" measure of the afterlength.  My experiment suggests that the number is not even close to right when using fine tuners.  The distance from bridge to ball end of the string is measuring at about 43 mm.  The distance to the "fret" of the bridge (where the afterlength would have been measured without any fine tuners) is closer to the 54.5 mm measure, being about 52 mm. 

I hypothesize from this that the tuners themselves may vibrate more like a string than they do like the bridge.  55 mm would be about halfway along the length of the "arm" of the tuner, and I see no mechanical pivot point or etc there to account for that. 

I suppose the important part would be whether or not I feel that the effort improved the sound.  I'm hesitant to commit to an opinion on that just now, since I won't be sure the adjustment is exactly right until the instrument has been played for at least a few days  to give a chance for all the parts to settle and to see if that requires more adjustment. 

It sounds *nice*, though.  Nothing harsh or bad.  But some things are a bit different about the sound and feel of the instrument.  Vibration is more noticeable while playing, not only through the collarbone and jaw but also the thumb and fingers of the left hand.  I can feel the vibration in the bones of the left hand and wrist, which I hadn't noticed before.  That's not a bad thing.  My favorite electric guitar (Gibson) does that as well. The instrument also has more of the odd "echo" quality.  Playing it unamplified in a quiet room, at close range (like my ear) it sounds almost like it is being run through a slight reverb.  Bow noise seems to be down a bit, and that only changed right when I got to the last adjustment and the afterlength tuning for the A&D strings got to "dead on". 

However!!  This is an electric instrument.  Even if the adjustment maybe improves the acoustic characteristics a bit, that is no guarantee that it will actually sound better when played as an electric instrument.  Some schools of thought about electric instruments with piezo pickups view the acoustic properties of the instrument as something that should be kept to a minimum, because the very resonances that can sound good on an acoustic instrument can result in problems with desirable frequencies getting messed up by something called phase cancellation, that I won't go into here.  (Not enough electric violin devotees to assume the readership here is likely to have many people interested in such technical points)  But those folks claim that the best thing for an electric violin would be to have no acoustic sound at all, with all vibration just stopping at the base of the bridge where the pickup is and no sound happening in the body or neck of the instrument at all. 

I did this experiment because I don't necessarily agree with that.  In my experience, if you take two acoustic guitars and put piezo pickups on them, the one that sounds best acoustically will usually also sound best through the piezo. In fact, if an acoustic guitar sounds crappy, then putting a piezo pickup on it and amplifying it usually just makes it sound even worse, just louder.  I have yet to see a case where a guitar sounded like crap but was just beautiful through a piezo pickup.  I think it falls under the old maxim, "Garbage in, garbage out".

I can't really evaluate the electric sound yet, because I ran into another little problem.  I made the preamp to work with the pickups at their previous output level.  I adjusted the components in the circuit so that it would just barely edge into clipping/distortion if I played a note quite loud.  Either the change in pressure or the increased vibration from this adjustment has changed the pickup output so that it is putting out enough to overdrive the preamp into clipping with anything but very light bow pressure and gentle bowing.  So I'll need to open up the back and tinker on the electronics a bit before I can tell for sure.  Theoretically, it could be a good change, though, since more output from the pickup would mean a better signal to noise ratio.  But I won't know for sure until I tinker with that preamp a bit and tame down the gain levels to match the pickup's output at present.