1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

Ac30 speaker wiring negative positive lead..

Discussion in 'Amp Tech Center' started by nirvana, Apr 14, 2014.

  1. nirvana

    nirvana TDPRI Member

    Posts:
    90
    Joined:
    Mar 26, 2013
    Location:
    hawai
    Hi,

    I have an AC30C2 All tube guitar amp, based of the new chinese made 2007 or later models. I was switching out speakers and now want to rewire back in series a pair of celestion speakers. I do not however for the life of me remember which is positive or negative and dont have an impendence meter to check. One wire is black with a RED line and the other is completely black. So which one is positive or negative?

    Thx
     
  2. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

    Posts:
    18,996
    Joined:
    Nov 9, 2011
    Location:
    Philadelphia, PA
    Red is usually positive I think though it shouldnt make a difference as long as the speakers are wired together right
     
  3. nirvana

    nirvana TDPRI Member

    Posts:
    90
    Joined:
    Mar 26, 2013
    Location:
    hawai
    Thanks thats what I thought...
     
  4. steveneddy

    steveneddy Tele-Meister

    Posts:
    235
    Joined:
    Jan 16, 2012
    Location:
    Texas
    Get some masking tape - or some scotch tape with a little piece of paper - and mark the wires BEFORE removing them from the speaker in the future.

    :^)
     
  5. CoolBlueGlow

    CoolBlueGlow Tele-Afflicted

    Posts:
    1,536
    Joined:
    Nov 20, 2011
    Location:
    Arkansas
    It matters that both are in phase to each other AND to any other amps you may use in a simultaneous multi-amp setup. I try to make my amps follow the industry standard positive voltage = forward cone motion (as defined by JBL, EV and others)

    Generally the SLEEVE of the speaker jack (on amps so equipped) is negative and the tip is the positive going signal. On the AC30C2 the red wire is the "end" tap on the output transformer, (either 16 or 8 is available, according to the schematic I saw - you should verify which tap it is on your amp, IMO) The black wire should show continuity to ground of chassis. Easy to check that.

    Generally the speakers themselves are marked with a red dot for the lead which produces forward motion with positive voltage applied. Examine them carefully - the markings are often subtle...but almost always there.

    If they are not (unlikely) then here is how one identifies acoustical polarity. Obtain a 1.5 volt AA battery and two alligator or similar leads. You will just momentarily connect the battery to the speaker terminals. just "touch it" to move the speaker cone. As you do, simply note the cone direction and trace out how you have it connected to the battery. IF you got forward motion, trace the alligator lead from the battery + terminal to the speaker. THAT is your RED speaker terminal. Mark it now. If you got backwards motion, trace the negative battery alligator lead to the speaker terminal and mark THAT terminal as the RED. Perform the same test on both speakers. Now you know which is which on both loudspeakers.

    Series wiring of two loudspeakers.

    1. Connect the red wire of the output transformer (coming from the inside of the amp chassis, along with a black wire) to the red + terminal of the left speaker.
    2. Connect a JUMPER from the NOT RED terminal of the left speaker to the RED + terminal of the RIGHT speaker. Got it? That's NOT RED LEFT to RED RIGHT with a jumper.
    3. Now connect that black wire (which also came from inside the amp chassis) to the NOT RED/NOT POSITIVE terminal of the right speaker.

    That's it. Ready to rock, in phase series wiring. Be aware that your amp now sees an impedance which is double that of each individual loudspeaker.

    Be aware that excessively high Loudspeaker impedance mismatches can cause output transformer damage in certain designs.
     
  6. Johnny Cache

    Johnny Cache Former Member

    Posts:
    1,809
    Joined:
    Mar 6, 2014
    Location:
    Oregon
    3 things.

    Red is positive.

    Most the time speakers are wired in parallel not series.

    You can check to make sure your speakers are in phase by hooking up a 1 1/2 volt battery and note which way the cone moves, forward or backward. They should both move in the same direction.
     
  7. BluesOwl

    BluesOwl Tele-Holic

    Posts:
    848
    Joined:
    Feb 15, 2005
    Location:
    MI
    AC30s spkrs wired in series usually. 2 8 ohm spkrs in series connected to a 16 Ohm output.
     
  8. Wally

    Wally Telefied Ad Free Member

    Posts:
    38,244
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    1) As Blues Owl notes, Johnny, 'in general' does not apply to all specific situations. IF one wired these two 8 ohm speakers in parallel and ran them against a 16 ohm tap, one might be putting the amp in joepardy.

    2) CBG notes that one wants to make a momentary...part of a second...contact with that battery. One does not want to 'hook up' a battery to a speaker. A constant voltage like that to a speaker will burn the voice coil down in a short period of time. I'm not sure that you meant 'hook up' in a literal sense, Johnny...but we have to be careful because someone might take it that way, right? I am clarifying for the benefit of those for whom this procedure is a new thing.
     
  9. Johnny Cache

    Johnny Cache Former Member

    Posts:
    1,809
    Joined:
    Mar 6, 2014
    Location:
    Oregon
    You wouldn't leave the battery hooked up it's only a momentary contact test, I've done it that way for several years and never had a problem.

    I don't see why I have to defend myself when I point out a solution to a problem. WHEW!
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.