This edition of Geek Corner is being brought to you by Brandon Whitt. A few weeks ago Brandon did some sweet work on my Marshall guitar amp. He was able to help give it the tone and feel of a stack. Brandon will walk us through the steps he took to give it the big punchy sound that I was after. Take it away Brandon…
So you want a Marshall Stack…
Unfortunately, either the wife or the landlord or the budget won’t allow you to have your dream rig. Such is life. You, however, are a reasonable man. You’ve learned to make compromises. You scaled down your rock arsenal to just an axe and a combo and you are content. Well, mostly content. Usually, mostly content. You are fairly content but what you really want is that big stack rumble. That punch that hits you in the chest at lets you know that rock-n-roll is serious business. You want a rig that allows you to be the Guitar Gladiator in the Arena of Rock slaying all who would dare listen to Kenny G on their iPod.
Hey man, we’ve all been there. Luckily there is a solution to your sonic quandary. There is a way to get the tone of a Marshall Stack from your environmentally friendly combo amp. Have patience, Grasshopper. First you must learn where the Marshall Stack punch and crunch comes from. What is it about this mystical maven of metal mayhem that sounds so good? Why don’t all amps sound like that?
Part One: Good Mechanics
Stacks derive much of their characteristic sound from the speaker cab. These cabs are what is referred to as ‘closed back’, meaning there is a solid piece of wood covering the entire back of the cabinet. Most combo amps are ‘open back’, meaning the back portion of the cabinet is left partially open and you can see the backside of the speakers. The speakers of a ‘closed back’ cab are in a sealed box that does not allow air to flow. As you begin to play Back in Black, the speakers move in and out and a vacuum is created. Since air can not flow in and fill the vacuum, the speakers movement is dampened and the low-mid frequencies are emphasized. This mechanical dampening is what gives stacks their characteristic low-end punch and tight feel.
Part Two: Power
Speakers need to be pushed in order to produce their sonic nirvana. In the same way that you can not use a stomp box to duplicate the sustain that comes from playing your amp loud enough to resonate your solid-body, you can not coax the stack tone from a preset or an EQ setting. You need power. More importantly, you need power at the right time and the right place. A true Marshall Stack is a big, tube amp. I could go on for page after page talking about tube amps and why a 100 watt tube amp is far more powerful than a 100 watt solid-state amp. However, that is another diatribe for another day. Today we are focused on driving our closed back cab. To get the punch, you need the attack. You need a power supply that has enough reserve energy give your notes a clear, aggressive attack. A cap job should do it.
The power supply contains capacitors that store energy for later use. Just like the huge trunk-thumping mega-bass power cap that Ryan has installed in his classic Mercedes. The larger the caps, the more power you have on tap. Doubling the size of your power reserves will give you the headroom needed to push your speakers into compression.
So that’s it. The secret is mechanics and power. With a little work most any combo can produce a nice “stacked” tone and get you on your way to becoming an Emo rock-god like our friend RMac.
-B
Be sure to check out Brandon’s Marshall Amp Mod Photo Album…
So life is pretty good here in Middle Tennessee. Long sleeved t-shirts, crunchy leaves under foot, and gross candy corn (only the white cap on the corn is actually edible- the rest is just garbage- speaking of garbage- I was never allowed to own Garbage Pail Kids cards as a child and, I think this has contributed to the fact that I can’t clean out the bottom of the kitchen sink after washing dishes-without almost vomiting. I think that, had my folks let me collect the cards, I would have a higher threshold for disgusting stuff and would be able to contribute more to society). 
