Known as Hard Truckers Cabinet.

        Cabinet: 15ply or 12 ply Birch plywood 14 1/2" Deep,   42 1/2" High,   19" Wide 1 1/4"    lip on the front 5/8". Dimensions are outside finished dimensions. You    can coat the wood    with a polyurathane or West System marine epoxy which is bullet proof.

       Aluminum speaker holders 1"wide X 2" long X 3/4" thickness. There are 3 steps to the    back of them 1/4" 5/8" and 11/16. With the 1/4 inch lip resting on the speaker and the 11/16    in land resting on the wood. Both the 5/8" land and the 1/4" lip are 3/4" long. That means    that the 11/16 thick part is 1/2 inch wide. Confused yet?  : )  




Specs provided by Erik Larson

JBL D-120
      The D speakers are made with a Alnico   magnet. they don't have a direct recone kit   made   for them, so when they are rebuilt (as I   would   imagine most of them need by now)   you aren't   getting an equivalent of the original   speaker.  Also,   they don't handle as much   power as a K  or E   series speaker. These   speakers are nice  and   bright and great for a   Twin but not  recommended   use with a power   amp.
JBL K-120
     The K speaker is alnico. K and E are   electrically equivalent and should have the   same power rating. Reconing an old K series   speaker gives you the same sound as a brand   new E series speaker in a lighter basket  
                             JBL E-120
     The E speaker is a ciramic magnet (heavy)
Garcia from the 80's on used the E-120's. Their made for power.
Weir was a Gauss man    
Speaker wiring
  The impedance of a speaker is basically a measurement of how hard the amplifier will have to work to drive that speaker. The impedance is measured in Ohms and is usually marked on the back of every speaker. The impedance of the speaker(s) i is essential, particularly in the case of tube (valve) amplifiers that the impedance or ‘load’ presented to the amplifier is correct; otherwise this can damage the amplifier. Many tube amplifiers are set up with multiple ‘taps’, e.g., 8 and 16 Ohms. In such cases, it is important that the impedance of the speaker system matches the impedance value set on the amplifier. Most transistor amplifiers are designed to drive 8 Ohm loads. Although the impedance matching is not as critical as with tube amplifiers, the impedance of the speaker(s) should be at least equal to the minimum impedance of the amplifier.

The way in which multiple speakers are wired (in a 2x 12" cabinet for instance) determines the overall impedance of the speaker system. Hence wiring is critical. There are basically two ways of wiring multiple speakers: series and parallel. Here are diagrams of the most typical wiring configurations.

1 x 12" Example:
1 x 8 Ohm speaker = 8 Ohm load

2 x 12" Series Example:
2 x 4 Ohm speaker = 8 Ohm load
2 x 8 Ohm speaker = 16 Ohm load
2 x 16 Ohm speaker = 32 Ohm load
2 x 12" Parallel Example:
2 x 4 Ohm speaker = 2 Ohm load
2 x 8 Ohm speaker = 4 Ohm load
2 x 16 Ohm speaker = 8 Ohm load