How to Turn Fender Guitar Amps into Bass Rigs

Guitar amps and speaker cabinets are normally built much lighter than typical closed bass-amp cabinets. High-wattage bass amps require dense, robust construction that can handle serious air pressure. They’re often closed cabinets with air intakes called bass reflex systems, which control airflow from the speaker vibration and enhance the lower frequencies. But even without a bass reflex system, some guitar amps can produce a nice bass-guitar tone. Obviously, they’re not capable of doing what an 8x10 Ampeg cabinet can do, but for me, that’s not relevant. The music that I listen to and play (mostly ’60s and ’70s rock, soul, and blues) has a laid-back yet articulate bass tone.

I grew up listening to a lot of Donald “Duck” Dunn’s Jazz and Precision bass-guitar playing on recordings by Otis Redding, Booker T. & the M.G.’s, and other legendary artists from Stax records in the ’60s. For Dunn’s tone—which drives the groove and forms a significant part of the mix—you don’t need an extremely deep or punchy bass. With classic Fender guitar amps, you can get a mellow bass tone with medium-low frequencies that blend in smoothly with a band.

“With classic Fender guitar amps, you can get a mellow bass tone with medium-low frequencies that blend in smoothly with a band.”

Another trick I like to do is jump channels. I dial in a full, relaxed tone on the bass channel, and a brighter tone on the normal channel with the bright switch on. (Sometimes I add some overdriven tones using the mid switch and volume on the normal channel.) If you’re after more volume, consider installing louder, more efficient speakers. The original Oxford, Jensen, or Utah speakers in vintage Fender amps are modest compared to modern ceramic or Neodymium speakers, which can help lighten the heavy speaker cabinet. Plus, you can use other external speaker cabinets with the 4-ohm Bassman head for more punch and different tones. The speaker impedance should be between 2 and 8 ohms, but 4 ohms will give you the most clean headroom.

The Fender Showman and Dual Showman are two other piggy-back amps worth mentioning. Compared to the Bassman, these models have some advantages. They boast almost twice the power for bigger stages and rooms, and the Dual Showman’s flexible impedance allows you to use a variety of speaker cabinets. (I prefer 10" and 12" speakers over the original 15" Showman ones for their faster response and lighter weight.) That said, they lack the Bassman’s deep switch, dedicated bass channel, and ability to jump channels.