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View Full Version : Set-up Qs: zero frets and tensioners



Saxon Moreno
Dec-19-2013, 2:47pm
Hi all, Having just read Rob Meldrum's excellent eBook on DIY setting up, and also having just ordered a compensated bridge for my mandola from Dave Hynds, I have a couple of questions:

Rob goes into detail about nut set-up in his book, but how does having a zero fret, as my mandola does, affect things like how the strings should sit in the nut grooves? Is the nut set-up less crucial with a zero fret?

Now the tensioner question: my 'dola is a flat top and so, to get a nice low action, I'm going to want my saddle height pretty low. This is going to mean that the angle of the strings from saddle to tailpiece is going to be very shallow. (The distance from bridge t tailpiece is about 5 3/8"). I know nothing about tensioners, but I saw from a photo of a restored mandola on Dave's website (http://www.mandolinluthier.com/mandolins_for_sale_5.htm) that he has fitted a tensioner "to improve the string angle at the bridge". What difference does the string angle from the bridge make? Why would one fit a tensioner in order to "improve" this angle?

I realise fitting a tensioner is a bit of an operation, and I'm unlikely to do this, but I'd like to know why one would. my 'dola is a Troubadour Gervaise, and I'm trying to get as good a sound as possible from this very handsome budget instrument.

Richard

sebastiaan56
Dec-19-2013, 4:24pm
Hi Richard,

The easiest way to think of a zero fret is to imagine the instrument with a permanent capo because thats pretty much what it is. The job of the nut in a Zero fret set up is to position the strings laterally only. With a more "normal" setup the nut also sets the vertical alignment.

I cant help with the tensioner, sorry, ask David and then post his reply. Im curious as well.

Tommcgtx
Dec-19-2013, 6:09pm
What difference does the string angle from the bridge make? Why would one fit a tensioner in order to "improve" this angle?

I realise fitting a tensioner is a bit of an operation, and I'm unlikely to do this, but I'd like to know why one would.
Richard

Here's an article from A. Lawrence Smart's website from a lecture. It gets into the string angle and why it matters, among other topics.

Bertram Henze
Dec-20-2013, 2:59am
Is the nut set-up less crucial with a zero fret?

That's exactly right.

About the angle at the bridge: the steeper the angle formed by the strings over the bridge, the higher the force pressing the bridge on the top, the better the contact of bridge and top, the better the sound conduction, the louder the instrument.

Tavy
Dec-20-2013, 4:22am
The zero fret is a fret, you don't set it up at all, unless it wasn't leveled with the other frets when the instrument was made :(

The tensioner is an interesting question - with a greater break angle over the strings you get more definition, less "twang", and are able to hit the strings harder before "bad stuff happens". You can get a similar effect by using a two-footed bridge if the current one is straight across. I've restored a number of instruments with tensioners, and I can say that the effect is quite subtle, and is unlikely to change the underlying tone much. If you're playing quietly you probably won't even notice the effect of having it on there - it really starts to kick in when you're putting more energy into the strings and they start wiggling on the bridge a bit more.

BTW vintage instruments that have tensioners, usually have small square reinforcing plates under the top where the screws go in, without these the screws will pull out eventually. Here's a repair I did on one where the original reinforcing plates had been put in the wrong place entirely resulting in the tensioner pulling out and being lost:

111355

Saxon Moreno
Dec-20-2013, 6:12pm
Hi Tomm, thanks for the reply but are you sure you linked that article? It's not coming up on my device and I'd like to read it.

Saxon Moreno
Dec-20-2013, 6:17pm
Thanks too everyone else. The explanations about the tensioner are interesting - not sure how I'd tell if the bridge needed more downward pressure than it's getting anyway. And it makes sense that the nut plays a less crucial role in the tone when there's a zero fret. Always good to learn more!

Tommcgtx
Dec-20-2013, 6:44pm
Hi Tomm, thanks for the reply but are you sure you linked that article? It's not coming up on my device and I'd like to read it.

Sorry, I guess I didn't! Here it is: http://smart-instruments.com/amluth95.html