- Dan_C
-
Custom Total utilisateur
kleuck a écrit :
Je n'ai pas retrouvé la doc technique, mais un texte de Bill Lawrence : Citation:
Ceramics vs AlnicoWhen I read that ceramic magnets sound harsh and alnico magnets sound sweet, I ask myself, " Who the hell preaches such nonsense?" There are harsh-sounding pickups with alnico magnets and sweet-sounding pickups with ceramic magnets and vice-versa! A magnet by itself has no sound, and as a part of a pickup, the magnet is simply the source to provide the magnetic field for the strings. The important factor is the design of a magnetic circuit which establishes what magnet to use.
Though ceramic magnets cost less than alnico magnets of equal size, a well-designed magnetic circuit using ceramic magnets costs much more than the six Alnico 5 magnets of a traditional single coil pickup!
Aging
Before the introduction of alnico magnets in 1935, permanent magnets were not quite that permanent. During a certain time, they lost a good amount of magnetism till they finally reached a stable condition. The process to accelerate this decay was called in the industry, "magnetic aging." In modern science, it is called "stabilizing." Since the ‘50's, we use Alnico 5 magnets which lose, under normal conditions, less then half a percent per 100 years.
How do we achieve normal conditions?
Alnico magnets are shipped by the manufacturer in a non-magnetized condition and will not be magnetized until a pickup is completed.
How to maintain normal conditions?
After magnetization, avoid any close contact with other pickups or magnets facing either north to north or south to south with their magnetic poles. Don't ever throw pickups random in a drawer; you may either use a keeper on each side of the magnetic poles or carefully place them with the north facing the south pole of the other magnet. ( For tele players, remember that the iron backplate of a traditional tele pickup functions as a keeper which increases the stability of the magnets.)
Once pickups are in a guitar, there is very little to worry about. That your pickups lose some of their magnetism when you lean your guitar against an amp is nothing but a fairy tale. Or, that pickups lose some of their magnetism when you drop them on a concrete floor is just another fairy tale -- alnicos and ferrites will break before they have any measurable losses. Magnets are sensitive to heat, but so is your guitar. However, heat can be a severe problem when an Alnico 5 magnet is exposed to temperatures above 1000 F, approaching its Curie temperature of 1634 F. At these temperatures, Alnico 5 undergoes structural changes and cannot be re-magnetized. Why do I mention this? Because it happens quite often, when someone doesn't like the unbalance in output of a pickup with staggered magnets and goes to a bench grinder or a belt sander to grind a magnet down. You take a chance that a magnet gets too hot and becomes damaged.
Développe, c'est pas clair
Sinon, à mon avis (qui ne vaut rien, c'est pour ça que je le donne quand même), une guitare se bonifie ou pas avec le temps, qu'elle soit acoustique ou électrique. Pour preuve, j'ai une basse Yamaha RBX170 (donc en agathis) qui, lorsque je l'ai achetée sonnait mieux que lorsque j'ai payé mon Ibanez SR-600. Parce qu'elle était restée en magasin 1 an et demi, que des personnes avaient joué dessus, qu'elle avait pris des vibrations de la part des amplis, etc. Donc quand j'ai acheté l'Ibanez, toute neuve de quelques mois sortie d'usine pas jouée, elle n'était pas ouverte, elle commence seulement à s'ouvrir au bout de 5 mois.
Pour une acoustique, c'est plus flagrant, mais c'est la même chose.
Le mental, c'est quand ça vous arrange.
La conscience, c'est ce qu'il faut faire.
La conscience, c'est ce qu'il faut faire.
