|11-30-2011, 11:46 AM||#2 (permalink)|
Join Date: Jun 2010
Location: Tucson, AZ
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Re: Alnico 2 vs Alnico V's
Vintage Gibson Humbucker Specs
Article taken from: Musical Illuninism website
Vintage Gibson Humbuckers Specs:
1956 – 1957 (“PAF”): Long (2.5”) Alnico 2, 3, 4 and 5 magnets used randomly, brushed stainless steel cover, *no* PAF sticker, automatic traverse wound with manual-stop (until bobbin was “full”), #42 plain enamel wire (purple), individual coil ohm differences, black leads on coils, ohms vary from low 7k to high 9k, black PAF-style bobbins (”square in circle” with holes). PAFs first installed on Gibson lap-steels in ‘56 and then guitars in ‘57.
1957 – 1961 (“PAF”): Long Alnico 2, 3, 4 and 5 used randomly (A2 most common), nickel cover, “Patent Applied For” sticker, automatic traverse-wound with manual-stop, #42 plain enamel wire (purple), individual coil ohm differences, black leads on both coils, ohms vary greatly – generally between 7k and 10k, black and cream (early-’59 thru mid-‘60), all bobbins black again by late ’60, PAF-style pickup bobbins.
1961 – 1962 (Late “PAF”): Smaller (2.37”) Alnico 5 magnet used for remaining production (all transitioned by July ’61), nickel cover, PAF sticker, automatic traverse-wound with manual-stop, #42 plain enamel wire (purple), black leads on both coils, individual coil ohm differences, ohms averaged 8.0k by ‘62, PAF-style bobbins.
1962 – 1964 (“Patent no.”): Alnico 5, nickel cover, “patent no.” sticker (mid-’62), polyurethane wire (starting ‘63), black/white lead wires, “auto-stop” winding starts circa-’62, PAF-style bobbins, usually 7.6k – 8.0k ohm.
1965 – 1967 (Late “Patent no.”): Alnico 5, polyurethane wire, “patent no.” sticker, bobbin wires white, Chrome cover (starts mid-’65), more durable and flatter bobbins with no “square in circle” hole circa-‘65, ohms usually between 7.4k – 8.0k. Gold-plated PAFs used in arch-top electrics as late as 1965 – “Varitone” guitars had gold-plated pickups with one pickup having a reversed magnet. This pickup style was used far less than nickel-plated pickups, thus inventory lasted thru 1965.
1967 – 1980 (“T-top”): “T” on bobbin top, Chrome cover, Alnico 5, polyurethane wire, automated winding begins ‘65 – ‘68, some ’69 – ’73 pickup covers embossed “Gibson”, “patent no.” sticker on baseplate ‘67 – ‘74, (patent number metal-stamped beginning 1974), ink stamp with date ‘77 – ‘80, ohms average 7.5k – consistently reading between 7.3k – 8.0k.
General Pickup Tech:
The following pickup article is based on years of pickup related research, experience and experimentation. It’s written to be accessible to both the average guitarist and those who appreciate technical description. If you’re interested in pickup tech and tone, you will get a lot out of it after careful reading.
Alnico Magnet Types and Gauss
The II thru V Alnico numbering system is used to indicate the specific alloy each type of Alnico magnet is composed of. Alnico stands for ALuminum, NIckel, and CObalt. Other than iron (which comprises about 50% of all Alnico magnets), these are the main metals used in Alnico magnets – plus all grades but Alnico IV have a bit of copper in them too. And, interestingly, Alnico III contains no cobalt. So, we see the recipe for each Alnico grade is different, with the ratio of metals in each alloy varying quite a bit.
Magnetic flux is measured in Gauss – this is an indication of how strong a magnet is capable of being. Magnetic field intensity is measured in Oersteds. Technically speaking, the strength of a magnet is best measured as an approximate combined product of the Gauss and Oersteds. This is somewhat analogous to how electrical power in Watts is the product of Volts and Amps (Volts x mA = Watts). For instance, 40 mA at 250 volts (40 x .250) produces 10 watts per tube, and the same 40 mA at 500 volts (40 x .500) produces 20 watts. So, when considering magnetic strength, ultimately, both gauss and oersteds are factors. Yet, I’ll keep the scope of this article to follow to the more commonly used measurement gauss.
Alnico III actually possesses the weakest gauss of all commonly used Alnico magnets – less than Alnico II, IV and V. That said, you can still have an Alnico V magnet that’s weaker than an Alnico II magnet, because magnets aren’t always fully charged. Yet, Alnico V has the capacity to hold a stronger magnetic charge than Alnico II, III or IV. A weaker a magnet lowers the resonant peak and a stronger magnet will increase the resonant peak and brightness audible to the ear.
Following is some data regarding accurate gauss meter readings on approx 80 Alnico magnets. The magnets checked were Alnico II, IV and V – both polished and rough cast had the following readings:
New Alnico II magnets measured at gauss levels ranging from 22 to a high of 35, with most in the 25 to 30 range. Alnico IV magnets ranged from 22 to a high of 36, with most in the 32 to 35 range. The Alnico V magnets tested were all from older Gibson “T-top” pickups – 20+ years old, and these all measured in the 25 to 30 gauss range, with most reading 25 to 27 gauss. So, interestingly, older “T-top” pickups show moderate gauss level readings for Alnico V. Gibson pickup magnet gauss readings, on both Alnico II and V magnets, consistently averaged 25 to 30 gauss on the late-‘50s thru the early-‘70s guitars.
A Burstbucker Alnico II rough cast magnet had the most consistent reading along it’s edges than all the other magnets tested, with a gauss level of 25. I was expecting to see a gauss range that defined the different grades, but there were some unexpected results. Alnico V magnets of the “T-top” era had notably lower than expected readings. And, except for the Burstbucker magnet, all the magnets were stronger towards one end of the magnet. This could possibly have tonal implication on magnet orientation in the pickup. Conversely, newly recharged Alnico II magnets in testing spiked out higher towards the center of the magnet.
The type of magnet in a pickup can have more impact on tone than winding resistance when dealing with modest ohm variations of 1 – 2k. You can have a humbucker reading 9k with an output approaching a single-coil. And, conversely have a Humbucker reading 7.5k that sounds like a typical “hotter” wound pickup, as we see with some of the Alnico V magnet pickups of the Gibson “T-top” era. Output and tone depends as much on magnets as winding types, not to mention everything else in the chain like pots, caps, etc.
So, the actual pickup tone type is highly dependant on the magnet and the resistance/windings, as a pickup with a dead magnet will produce 0% output! Additionally, long magnets (PAF-style) are a bit punchier and have better definition than the short magnets, which can sometimes produce a slightly “smeared” sound. Though magnet type can compensate for this, as Alnico V’s additional output, punch and brightness balanced out the shorter magnet size Gibson used beginning 1961.
Additionally, the stud side of the coil actually has slightly more output than the adjustable side on a traditional humbucker. There is a direct connection to the magnet inside the pickup on the stud side, while the adjustable pole extends out the bottom of the pickup. And, there is a slight loss of magnetic field and energy out the bottom of the pickup.
Here's the full page;
|11-30-2011, 01:18 PM||#3 (permalink)|
Join Date: Nov 2011
Location: Cave of Caerbannog
Thanked 14 Times in 9 Posts
Re: Alnico 2 vs Alnico V's
Everything depends on the gear you're using; amp, etc... one type of pickup magnet
may not sound as good with your guitar+rig as another. It's up to you to experiment
AlNiCo-2s are "squishy/blurry"... have "note bloom"... are "warm and soft"
AlNiCo-5s are "harder" and seem to have slightly scooped mids comparatively.
If someone digs classic rock tone, I always point 'em in the direction of AlNiCo-2s for humbuckers.
Last edited by Superlizard; 11-30-2011 at 04:42 PM.