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FDP Forum / Fender Amps: 1985 - Current / Twin Reverb aux speaker (Ohms?)



Mar 8th, 2017 01:53 AM   Edit   Profile  

I have a Fender Twin Reverb (two E120 JBL inside). What Ohmage may an externally connected ppeaker box have?


Would like to add: Are the internal speakers switched off when connecting the external speaker?

(This message was last edited by ChristophK at 04:03 AM, Mar 8th, 2017)

Te 52

Laws of Physics

strictly enforced
Mar 8th, 2017 10:48 AM   Edit   Profile  

The Twin ideally likes to see a 4 ohm load. But as with most Fender tube amps, from 50% to 200% of ideal is acceptable as long as you don't play at full volume with heavy distortion. So total load on the Twin can be from 2 ohms to 8 ohms.

If you plug an external cabinet into the EXT. SPKR jack (with the internal speaker still connected), the internal and external speakers are connected in parallel. The internal speaker is *not* turned off. So the external speaker should ideally be 4 ohms. That will give a 2 ohm total load and the volume coming out of the internal and external speakers will be approximately equal.

You can use a larger than 4 ohm external speaker (e.g., 8 ohms), but then the volume of the internal and external speakers will be imbalanced.



Mar 10th, 2017 03:38 AM   Edit   Profile  

@lawsofphysics: Thanks. In my case I'm a bit afraid to connect a Hammond organ with its deep 32Hz bass to the Twins internal speakers. The player would like to have a bass boost for the organ. I guess the player will not use more than 50 watts (for the room situation), and the external speaker box is a JBL equipped with two D140 F in parallel, each having 16 Ohms (yes) giving a total of 8 Ohms.

Can the internal speakers be taken off easily? Isn't the a 1/4" plug coming from the internal speakers? I'm not with the amp at the moment but will be there later today.


Te 52

Laws of Physics

strictly enforced
Mar 10th, 2017 10:43 AM   Edit   Profile  

Guitar speakers are not designed to handle the very large cone movement (xmax) required for low bass notes. They can easily be damaged.

So if you want to use the Twin for low bass notes, you should disconnect the internal speakers by pulling the plug at the INT. SPKR. jack. Then plug in a true bass speaker at that same jack. Don't use the EXT. SPKR. jack.

And never operate the amp with no speaker connected, that can easily damage the output transformer.

Contributing Member


Hoarder of instruments
Mar 14th, 2017 05:11 PM   Edit   Profile  

I used to run my big cabinet Bassman 2 x 12 with my Twin without problems. Using them together for bass beat the crap out of my Twin's internal speakers.

The Twin's open back cabinet and guitar-specific speakers were not designed to reproduce low frequencies.



Mar 21st, 2017 11:17 AM   Edit   Profile  

Thanks to all. I found that 1/4" that connected the internal speakers and ran the organ with the two cabinets connected and it all worked fine.


FDP Forum / Fender Amps: 1985 - Current / Twin Reverb aux speaker (Ohms?)

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