GFI hysteresis? Reply to Curt Langston

Brint Hannay · Post by **Brint Hannay** » 19 May 2006 12:27 pm

I'm posting this as a new topic, but it's a continuation of a dialogue from the thread about defining hysteresis. I didn't want to take that thread any further off topic.

Curt, I don't claim to KNOW where the hysteresis is coming from. I think everybody discussing hysteresis, including you and me, is speculating and trying to reason it out. I would ask, though, where is it written that it matters how much LENGTH of string there is above the nut? You stated it correctly, there is VIRTUALLY no string above the nut. But there is string, and it bends over two places, the nut and the top of the tuning finger, before it gets to the attachment screw.
My theory is that the deflection of the string over the nut (and, in this case, the top of the tuning finger) impedes the even distribution of tension change along the whole length of the string, including the non-playing length. I suppose the string lying against the changer finger between the contact point and the attachment point could possibly be implicated as well; there's no reason to think that curving over the top of the finger completely isolates that part of the string from participation in the string's tension, and changes thereof.
I haven't done anything to the changer itself; why would it be a source of hysteresis?

Curt Langston · Post by **Curt Langston** » 19 May 2006 4:51 pm

Hi Brint!

Without looking at your guitar, it would only be speculation. Perhaps there may be a pull rod that is not allowing the string to return. Or maybe there is debris inside of the changer, causing an obstruction. I assume you have looked to see that there is some free play in the pull rods.

Here is the heart of my "keyless guitars do not have hysteresis originating from the keyhead" point.

Take a NEW .011 string and cut it into two lengths. One will be 6 inches long, the other will be 1 inch long.

Take two pairs of pliers, and grasp the long string at each end. Now pull. Notice how far it stretches and relaxes. Try the same thing on the 1 inch piece. Notice the results. Of course, the 1 inch piece will NOT stretch as far.(if any)
With 6 inches or more of string in a KEYED guitar, you will have noticeably MORE travel over the roller nut.

More travel over the nut = increased tendency for hysteresis, caused by roller nut drag(resistance)

Hope this helps.

[This message was edited by Curt Langston on 19 May 2006 at 05:54 PM.]

Bobbe Seymour · Post by **Bobbe Seymour** » 19 May 2006 4:54 pm

My wife used to get hysteresis if I didn't come directly home after a night time playing job.

Curt Langston · Post by **Curt Langston** » 20 May 2006 2:13 am

Well, did you try it Brint?

Brint Hannay · Post by **Brint Hannay** » 20 May 2006 9:18 am

Curt, I didn't try your exact experiment--I don't feel it would be possible to get a firm enough grip on a .011 string to be sure of it not slipping--but I performed the equivalent experiment with a rubber band; since it's an issue of elasticity that you are raising, it seems rubber is a lot easier to work with. I cut the rubber band into two pieces, one 5" and one 2". On each, I made two marks in the middle 1/4" apart. I stretched each until it felt that it would stretch no more. In both cases the marks at maximum stretch were 1 and 3/8" inch apart.

Curt Langston · Post by **Curt Langston** » 20 May 2006 9:39 am

Thats good Brint
Yet, remember that the experiment is to be used with an .011 guage steel string.

It takes at LOT more tension to stretch 1 inch of string than it does 4-6 inches of string.

You can feel the stretching on the 4-6 inch piece, but not on the 1 inch piece.

I have tried this little experiment, before posting it here.

Point is: The hysteresis on your guitar cannot be from the keyhead, it must be from someplace else. OR, a faulty string.

[This message was edited by Curt Langston on 20 May 2006 at 10:40 AM.]

Jody Sanders · Post by **Jody Sanders** » 20 May 2006 9:55 pm

Curt, Contact Gene Fields. He is an expert on GFI Steel Guitars and has been involved in desighning, playing, and building steel guitars for a lot of years. Jody.

Curt Langston · Post by **Curt Langston** » 21 May 2006 6:05 am

Hi Jody,

Yes, I have spoken with the folks at GFI. That is why I am certain that Brint's "hysteresis" or "over return" is not coming from his keyless head.

It is not physically possible.

I have owned a GFI keyless, and played MANY others. None of which had ANY of these issues.

Gene knows his keyless technology, and has built a very fine guitar.

I have nothing but praise for them.

[This message was edited by Curt Langston on 21 May 2006 at 07:19 AM.]