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The Port Hole Deliberation

Article by Sean Mitchell // October 23 2014
The Port Hole Deliberation

The kick drum port hole is a modern invention that came about in the ‘60s when multi- track recording and close micing techniques became commonplace. Mass market appeal materialized when the studio technique of cutting a hole in the front head began to be utilized for live sound reinforcement. Sound technicians began to use the technique on big name tours with big name drummers and the port hole phenomenon was born.   

While a port hole is incredibly popular today, it isn’t drummers who benefit most from them. The design and function of a port hole is primarily for the benefit of a sound engineer. And while many modern drummers cut holes in the resonant head, the benefit to drummers is largely a tactile one. 

TO PORT OR NOT TO PORT

As you impact the batter head with your kick beater, the concussion sends a shockwave of air pressure hurtling toward the resonant head; if there is no hole (or port) in the front head for the pressure to escape, you will hear the complete tone of the resonant head vibrating from the impact of the air pressure slamming against it. You will also notice that the batter head has a bouncy feel. This is because that air pressure has nowhere to go and remains in the drum causing resistance against the batter head. 

From a sound technician’s standpoint, this gives the drum a very open, resonant sound. The resonant head would be the primary sound heard. 

A hole in the front head creates an avenue for the air pressure to escape. As the beater strikes the batter head the air rushes toward the resonant head and a percentage of the air escapes through the port. From a drummer’s standpoint, this creates less resistance (less rebound) on the batter head and gives that nice firm feeling when the drum is struck. 

From a sound standpoint this allows the mic to be placed inside the drum thereby capturing the frequencies created by the batter head. These frequencies are generally the more focused thud that audiences have grown accustomed to only in recent years. Remember that back in the days of Tommy Dorsey, The Beatles, and even Led Zeppelin, the kick drum sound was always a more resonant, open sounding drum. 

CENTERED OR OFFSET?

If you are looking for a dry thud from your kick, place the hole dead center. As your kick beater contacts the batter head, the air pressure is forced into the resonant head. If the hole is dead center, air rushes out of its middle rather than vibrating the reso head causing little resonance. The bigger the hole, the weaker the resonant sound.

Alternately, if you are looking to get a nice mix of resonant and batter sounds, offset the hole to the bottom left or right corner as this will allow for easier mic placement. From a sound standpoint, as your kick beater makes contact the air pressure slams against the resonant head it disperses and spreads out over the drum causing the resonant head to vibrate, thusly giving you a resonant tone. The offset hole allows for a little air pressure to escape allowing the batter head to maintain that nice big “thwack.”  

With the advent of tools like port hole cutters and customizable hole protectors from company’s like Holz and Gibraltar, drummers are now able to be a little more creative with their port hole cutting techniques. Here are some quick tips to help you decide what size to cut (if at all). Keep in mind that any kick drum padding (i.e. pillow, bass drum pad) will also play a large part in the sound you achieve. 

7-inch hole or larger       

  • Easy access to kick drum dampening (i.e. pillows etc) and microphone
  • Allows for a dry, very punchy attack
  • No overtone (great in studio settings)
  • No resonant tone at all. Will sound the same if you removed the front head altogether.

6- to 4-inch hole

  • Easy access to kick drum dampening (i.e. pillows etc) and microphone
  • Allows for some resonant tone
  • Allows you to mic the drum inside as well as mic the resonant head giving you a well-rounded mix of punch and tone. If you choose to dual mic the kick, make sure to study up on phase cancellation.

Multiple holes (two inches or less)

  • Best resonant sound can be accomplished this way
  • Still allows for a punchy batter head sound
  • No access inside the kick drum
  • Batter head mic would have to be mounted inside the kick drum

YOU MAY ALSO ENJOY:

http://www.theblackpage.net/technique/seating-a-drumhead

http://www.theblackpage.net/articles/setting-up-for-success




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About the Author
Sean Mitchell

Sean Mitchell has been an active participant in the drumming industry for over 20 years. He has studied under Crash Test Dummies drummer Mitch Dorge and Drumming's Global Ambassador Dom Famularo. Sean is also a songwriter and regularly performs with his wife (and singer) Jill Mitchell. Sean proudly endorses Aquarian Drumheads.



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