Magnetic material

The most important parts of a pickup are its magnets. The magnetic material determines the dynamics at the first line and the frequency response in terms of the resonance-peak damping. At GAS Pickups, we use the finest magnetic material for all our products. The majority comes from world-known manufacturers in the US (such as Thomas & Skinner, AMT, Adams, etc). The rest comes from EU and UK manufacturers.

The main magnetic material categories that we use at GAS Pickups are Al-Ni-Co and ceramic magnets. Both have clear differences from each other and will behave differently on the same pickup in terms of dynamics and frequency response.
Al-Ni-Co material is an iron (Fe) alloy that contains aluminum (Al), nickel (Ni), and cobalt (Co) in considerable percentages, as well as copper (Cu) and titanium (Ti) in very small percentages (0–2%).

Depending on the Al-Ni-Co distribution inside the alloy, there are many Al-Ni-Co types (A-types), marked with a digit, such as A2, A3, A5, A8, etc. Each type of Al-Ni-Co alloy has different magnetic and electrical characteristics. Depending on their crystal structure and magnetization process, they may show different dynamic behavior and signal levels over the frequency spectrum, and since Al-Ni-Co alloys are electric conductors, they affect the midrange and higher frequencies. All these result in a different tone.

However, it is not possible to describe a certain alloy type (e.g., A5) with a specific tone or dynamic behavior. There are many reasons for this fact.
A first reason is that there is not only ONE A5 alloy composition, but, depending on the specific contain percentage of Al, Ni, and Co, there are over 7 different officially normalized A5 sub-alloys, such as A5-c, A5-7, A5-ab, etc.

A further reason is that Al-Ni-Co alloys can be produced only in an industrial environment, following specific steps such as high heating, casting, magnetizing, cooling at a specific rate (Temperature downgrade per-minute rate), and many others (no need to go deeper in here).

Each manufacturer follows its own steps, so the same suballoy from two different manufacturers will probably sound differently on the same pickup. For example, there are currently five different A5 magnetic bars that we use in GAS humbuckers, from different manufacturers, and they all sound differently to each other (one shows more bass, the other shows more compression in the higher frequencies, the third has more bite in the high midrange, etc.). So, there is actually no "A5 tone" or "A2 tone".

For all the above reasons, at GAS Pickups, we take care and deeply analyze the magnetic material that we intend to use in our products. By cooperating with the Institute of Nanotechnology at the Greek Nuclear Research Center "Democritus," we have analyzed many of our (currently used) magnet bars as well as a few old ones, such as two long bars from a 1959 P90 and a long bar from an early 1960 PAF. We found out that A5 bars from the end 50's used a different alloy composition, containing way more aluminum than the normalized A5 alloy compositions on the 1964 MMPA standards. And that's how we ordered some of our magnet bars.

The magnetic parts that we use at GAS Pickups, especially in humbuckers and P90s, really make the difference in terms of tone and dynamic range.
We spent quite some time on research for this material. By contacting mostly US-based magnetic manufacturers, we had the opportunity to try and analyze magnetic material from all of them.

Currently we use following bars on our humbuckers & G90's models:

- 2,500" long rough cast AlNiCo II (A2) - 1958 specs
- 2,500" long rough cast AlNiCo V (A5) - pre 1964 MMPA specs
- 2,500" long rough cast AlNiCo V-ab (A5) - 1964 MMPA specs
- 2,444" rough cast AlNiCo V-7 (A5) - 1964 MMPA specs
- 2,444" polished cast AlNiCo V-c (A5) - 1964 MMPA specs
- 2,310" "short" rough cast AlNiCo V-c (A5) - 1964 MMPA specs
- 2,600" Ceramic OX bars.

All the Al-Ni-Co bars that are listed above are made from the correct alloys and have different magnetization levels depending on the model used.

In more detail:

• The "long" 2,5" rough-cast A5 (pre 1964 MMPA specs) magnet bars, which are installed on some of our top-line Legend series pickups (such as the '59 PE, the '59 PVA and the '59 Green), come from the US manufacturer Thomas & Skinner, who was a supplier of top US musical instrument brands in the era of the 50's and 60's. These bars are exclusively made for GAS Pickups following an alloy composition as of the end of 50's (that’s before the MMPA standards of 1964 were applied). Therefore, these bars feature the same alloy composition as back then and are also slightly degaussed for more dynamics. T&S bars provide our Legend PAFoid models with the well known open tone and the required sensitivity and dynamic range. 

• Further "long" 2,5" rough cast A5 bars, which are used on our Legends, come from UK manufacturer Eclipse. These also built on old MMPA specs and offer a warmer timbre, combined with high sensitivity, perfect for bright guitars.

• The 2,5" long rough cast A5 bars that we use on our '58 Legends and the KF Signature set come from UK manufacturer Eclipse Magnetics, and also offer a great sensitivity, but with a more enhanced low midrange and bass boost, which fits perfectly to the needs of a more aggressive, overwound set like our Legend '58ers or the KF set.

• 2,500" rough-cast A2 magnet bars are used on GASholder humbucker, but also on our '57 Legend and Night Train Legend sets.

• 2,444" A5 rough cast bars (A5-7 sub-alloy), based on the MMPA 1964 standards, are used on our 60 Legends and our low-output standard TTop Legend models.

• Our regular 2,444" polished A5 (A5-c sub-alloy) magnet bars, also based on the 1964 MMPA standards, are used on our A5 humbuckers of the standard series.

• Short 2,310" A5 bars (A5-c suballoy) are used on our "hot" Legend TTop Plus models.

Of course, we are always in search of better material, so the above specs may change at any time.

Ceramic magnets are made of a totally different material than AlNiCo alloys. OX ceramic ferrites are electric isolators (they don’t affect the frequency spectrum of a pickup in any way), and they show different compression behavior (e.g., more tight bass). We use such material on some of our high-gain humbuckers (Flaming GAS, GASer Plus A, GAS Drax Custom Signature, etc.).

The dynamic behavior of a pickup depends directly on its magnetic material. Since it's a very complex procedure, we'll try to explain it very briefly.

As described in the chapter about the main features of a pickup, the string vibration causes a relevant change in the magnetic flux density B. The magnetic flux density causes a change in the magnetic field strength H inside the magnetic material. The magnetic field strength causes the electric current, which is then led to the pickup's output wires (the guitar's signal).

However, the ratio of these two values, B and H, which is called the magnetic permeability μ, is not constant, neither spatially along the magnet (bar or rod) nor through the frequency spectrum. In some frequencies, small changes in B (which means a light string pluck) cause a larger H value and thus a stronger current. This means that at these frequencies, the pickup shows greater sensitivity (a wider dynamic range). At other frequencies, even large B changes (which mean a stronger string pluck) cause very small H changes (a weaker current). At those frequencies, the pickup shows a more compressed signal.

The general behavior of each magnetic material in the dynamic range is therefore dependent on several parameters such as its construction, dimensions (short bar or long bar), production procedure (casting temperature, cooling rate), crystal structure, etc., and not only on its plain alloy composition. There are A5 bars that show a totally different dynamic behavior than other A5 bars from the same magnet manufacturer. Therefore, it's a highly important issue for a pickup designer to know and understand the dynamic behavior of the magnetic materials that are used in his products.