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FDP Forum / Fender Amps: Vintage (before 1985) / Altec Lansing polarity?

Contributing Member

Vacaville CA

Runs with scissors !!
Oct 10th, 2017 12:40 PM   Edit   Profile  

I've ordered replacement Jensen C12N's for my newly acquired '65 Pro Reverb. It currently has '67 Altec Lansings Model 417B in it. Will I have to reverse the wires to retain the correct polarity? I know some JBL's are reverse polarity, not sure about the Altecs.

The tube chart is stamped AA165 Production #1 and "OG" stamped

(This message was last edited by kart24 at 02:59 PM, Oct 10th, 2017)



you want me to play where?
Oct 10th, 2017 01:20 PM   Edit   Profile  

I don't know- I just check them before installation just to be sure.

Contributing Member

So. Cal. USA

Oct 10th, 2017 01:35 PM   Edit   Profile  

Altec is the same polarity as the Jensen. Black is - and white or red is +. The Pro Reverb should be the same as well as long as the speaker wire was properly wired.

In a an amp with two speakers, the main thing is that the speakers are wired in parallel and in phase. 180 out would make no real difference as long as the speakers are in phase with each other.

You can test speakers with a 9 volt battery, making a quick connection to see which was the cone moves.

Contributing Member

Vacaville CA

Runs with scissors !!
Oct 10th, 2017 11:02 PM   Edit   Profile  

Thx. I should get the speakers tomorrow.

Contributing Member


the downtime
Oct 13th, 2017 05:31 PM   Edit   Profile  

When you tap the 9v battery against the speaker terminals, watch the speaker cone to see which way it jumps when energized.

If the cone jumps forward, the + battery terminal is on the + terminal of the speaker.

If the cone jumps rearward, the + battery terminal is on the - speaker terminal.

Easy peasy!

Testing a speaker like this is perfectly safe--so long as you don't hold the battery on the speaker terminals for more than a second. You can cook the voice coil if you keep it on there. DC current will fry a speaker in short order.

(This message was last edited by Peegoo at 07:34 PM, Oct 13th, 2017)

FDP Forum / Fender Amps: Vintage (before 1985) / Altec Lansing polarity?

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