Magazine article Guitar Player

Speaker Solidarity

Magazine article Guitar Player

Speaker Solidarity

Article excerpt

WELCOME TO GP'S NEW SHOP TALK COLUMN. Tube amp wizard Gerald Weber will field your amplifier related questions, and we'll call on the experts in other fields to kick down the answers to whatever you need to know about guitars, effects, recording, etc. Please send your questions to the attention of GP's general mailbox (

I have several Fender tube amps with extension speaker jacks. What should I be aware of when connecting extension speaker cabinets to these jacks?

--Paul Belvedere, Novato, CA

With Fender amplifiers, an external speaker cabinet can be used if its impedance is the same or greater than the impedance of the on-board speaker load. For example, with a Fender amp such as a Pro Reverb, Bandmaster, or Twin Reverb--all of which have a 4[ohm] speaker load--either a 4[ohm], 8[ohm], or 16[ohm] cabinet could be safely connected. With a 4[ohm] extension cabinet, the power will be split evenly between the internal speaker and the extension speaker cabinet. With an 8[ohm] extension cabinet, the internal speaker(s) would get 2/3 the power, and the extension would only receive 1/3 of the power. Similarly, when you connect a 16[ohm] speaker cabinet, the onboard speaker gets 4/5 of the power, leaving only 1/5 of the power for the external cabinet. Don't connect any extension speaker to a Fender amplifier with a 2[ohm] impedance--such as a Super Reverb--as it will cause the total impedance to drop dangerously low, and possibly lead to premature tube failure.


Also, when using multiple speakers, you need to make sure that every speaker cone is moving the same direction at the same time. …

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