Dan Armstrong - The Man and his Guitars

The Dan Armstrong bass guitar features a pickup thats just as ingenious and innovative as the various guitar pickups. While it lacks the interchangeable pickup design of the guitar model, its worth mentioning that the bass can get just as many different sounds eminating from it as the guitar. This amazing feat is accomplished by the simple fact that the bass pickup is actually two totally different pickups in one housing.

Like the guitar pickups, the bass pickup was designed by both Dan and Bill Lawrence who goes on to say "We had actually designed two different types of pickups for the bass instrument but Ampeg decided to only use the one." The one that Ampeg settled on was actually two pickups in one. Two single coil pickups are stacked - one coil on top the other. Because the coils are stacked in this manner the magnets are placed along the sides of the coils, and as usual for Dan Armstrong pickups - the entire unit is then encased in a brown colored resin - thus making the bass pickup much like the guitar pickup - one of the earliest known potted pickups on the market.

According to literature the bass pickup is known as the DB or 'Deep Bass' pickup which, according to Kent Armstrong were wound with 43 gauge wire (AWG) on the top coil with 44 gauge (AWG) on the bottom coil. By turning the tone knob down the signal runs through a capacitor, and as a result, only the larger (bass) coil underneath is activated. This gives the instrument a thick, solid lower bass tone. By turning the knob up, the upper (treble) coil gradually gets blended in to the already low end bass sound. As the tone knob gets turned up more, the treble coil gets more prominent, while the lower bass coil begins to dissipate. With the tone knob full up, the larger bass coil underneath, along with the capacitor, gets faded out altogether, resulting in a very trebly-midrange sound. So by simply adjusting the tone control, the two coils can blend together, or apart, for a wide variety of sounds. The blending of these two pickups, and sounds, is strictly a matter of personal taste and was Dan's way of getting the most out of a single pickup bass guitar.

Unlike the guitar model, the original bass pickup does not connect to the rest of the instruments circuitry by employing banana plugs and jacks. Instead, three spade type lugs protrude from the pickup that anchor to the acrylic body using three machine screws. The wiring to the rest of the instruments electronics are tightened underneath these screws as well as can be seen at left.

Around 1971 the bass pickup took on a new look. While made the same internally they now sported a new outward appearance from those prior to it. Specifically, there was a rise in the center of the pickup that extended the length of the bar pole piece.

The reasons for this rise is unknown and one can only speculate that an internal part or component had changed, such as the bobbin for the top coil. It may have been redesigned to fit flush with the full length bar pole piece.

photo courtesy of Bill Richardson

Seen here is an early Dan Armstrong bass pickup with the resin stripped away. One can easily see the two coils, one on top the other. Notice how the top bobbin is actually secured onto the lower bobbin using a form of glue or epoxy to eliminate any resonant vibration.

The top coil is the treble coil that gets blended in with the bottom bass coil as the tone knob gets turned up. With the tone knob turned down the top coil fades out and only the lower coil is activated, making for a very thick, low end bass sound.

photo courtesy of Bill Richardson

Instantly obvious is the unusual placement of the pickup magnets resting beside each coil. Two huge ceramic magnets were placed alongside the lower coil, one on each side, while the top coil only features one ceramic magnet placed on the north side of the pickup.

Notice how the two wires coming off the top pickup attach to two of the three spade lugs while a single wire coming out of the lower coil gets soldered to the bottom metal plate or "ground".

photo courtesy of Bill Richardson

Notice the extra piece, or shelf - added to the top coil bobbin for the spade lugs to reside on.

Sharp observers may notice that the lower bass coil bobbin has a thin strip of material glued underneath it to help isolate it from the metal plate below.

photo courtesy of Bill Richardson

Seen here is a better angle of the two ceramic magnets on both sides of the lower coil with the single ceramic magnet on the upper coil.

This bass pickup had gone bad and had the resin carefully removed from it. The pickup can be seen on Bill Richardson's web site where he states that he wants "to share the pictures in order to help players understand how these neat sounding pickups work......... and sometimes die."