Home | About | Comments | Follow the blog

The Bass Guitar Blog

The Blog for Bass Players – Covering all the basses!

  • Bass Blog
  • Bass Archives
  • Blog Topics
  • Bass Links
  • Subscribe
«Bass Combos · Closed Back Cabinet Design »

Bass Amp Cab Design – Open Back Design

Posted by Benjamin on December 7, 2008 Filed under: bass, bassguitar, Gear tagged: cabs, design, speaker

A little while about Mark Wright of Accugroove shared some excellent advice in:  Choosing a Bass Cab – Part I and Choosing a Bass Cab – Part II. The next couple of posts add a little bit of background about the different designs of cabinet, to take away the mystery of the shapes that you see around, and follow on from the post on Bass Amp Set Ups .

Speakers are a key part of the sound, or rather the speaker(s) and the cabinet they are housed in. Cabinet design has evolved over the history of the bass guitar, and I thought it would be fun to talk about the different types of cabinet design. A kind of bass geekyness, but useful background for using and choosing cabs – if nothing else, you’ll be able to blow away the guitarist with your knowledge of acoustic cabinet design!

Early guitar cabinets, including bass ones, were “open backed” – so called because the back of the cabinet was open. That sounds a little obvious, but it was a revelation to me the first time I noticed. A quick sketch helps to explain the next bit:

You won’t see many (if any) open backed bass cabinets these days. There is a simple reason for that: The speaker in the front pushes the air as it moves. Then it does the opposite, as it goes back: it sucks the air in from the front and pushes it out of the back.

Air is surprisingly smart – it moves from the front of the cabinet to the back, and from the back to the front, running around the sides of the cabinet, trying to get back where it came from. OK, the air isn’t smart at all, it is just a bit of physics, but you get the idea. Most of the air moved by the speaker ends up going nowhere except back where it came from. That means no sound produced.

How does a closed back cabinet produce any sound then? Well, it takes the air a little while to get from the front of the cabinet, round the sides, to the back. If I just had a speaker, not in a cabinet at all, it would produce almost no sound. The air would just be rushing ‘around’ the speaker to the back. However, if I put some wood around the speaker (a “baffle”) then the air has a bit of a way to travel to get round to the back, and air actually doesn’t move that quickly. That means when the speaker is moving fast enough (a high enough frequency) the air can’t get around in time, and so sound gets produced.

The bigger the baffle, i.e. the bigger the cabinet, the longer the air takes to move (or actually the longer it takes for the pressure to equalise between the front and back of the speaker). That means lower frequencies of sound can be produced. A bass is low frequency, so to produce sound effectively the speaker would need a very large baffle, i.e. a very BIG (and very heavy) cabinet. Not so good! How do you fix that? Simple: a closed back design…

 

Share this:

  • Click to share on Facebook (Opens in new window) Facebook
  • Click to share on X (Opens in new window) X
  • Click to share on Reddit (Opens in new window) Reddit
  • More
  • Click to print (Opens in new window) Print
  • Click to email a link to a friend (Opens in new window) Email
  • Click to share on Pinterest (Opens in new window) Pinterest

Like this:

Like Loading...

Like it? Share it!

Add to delicious Stumble it Share on Facebook Tweet it

3 Responses to “Bass Amp Cab Design – Open Back Design”

  1. Closed Back Cabinet Design, on December 9th, 2008 at 12:06 PM Said:

    […] «Bass Amp Cab Design – Open Back Design […]

  2. Antonio, on May 17th, 2010 at 5:53 PM Said:

    Wow! I play guitar, but this is really useful!

  3. Benjamin, on May 17th, 2010 at 6:50 PM Said:

    Same ideas of speaker cabinet design play out there 🙂 – Although closed back’s are rarer, as they come into their own for the low notes – Us bassists don’t want too much back from our thin-stringed friends ;).

Leave a Reply

Subscribe to comments  |  Trackback URI
«Bass Combos · Closed Back Cabinet Design »
  • Follow the blog…

    Love bass? Follow The Bass Guitar Blog on twitter, on Facebook or by RSS
  • Recent Posts

    • Carol Kaye on Bass
    • The 10 Things Professional Bass Players Never Do
    • Tony Levin on Bass and Music Man
    • Electro-Harmonix Battalion Bass Preamp and DI
    • BEAD Tuned Bass
    • What can you do with 12 Strings?
    • 2 String Bass
    • Apollo Jazz Bass Linear Humbucker from Seymour Duncan
    • Solo Bass “O Come All Ye Faithful”
    • A History of The Bass
  • Recent Comments

    • Benjamin on Tony Levin on Bass and Music Man
    • Rob Greco on Tony Levin on Bass and Music Man
    • Benjamin on The 10 Things Professional Bass Players Never Do
    • Doug S on The 10 Things Professional Bass Players Never Do
    • Benjamin on Tony Levin on Bass and Music Man
    • sonicfrog on Tony Levin on Bass and Music Man
    • Justin Levitt on Plectrums – To Pick or Not
  • Categories

%d

    Copyright © 2008, 2009, 2010, 2011 Redcatco Ltd | Got news, views or tips? Something we should know? e-mail us | Be happy, be bass.