Question on Wiring More ThanTwo Speakers Together?.

Discussion in 'Amp Tech Center' started by saltyseadog, Jan 5, 2019.

  1. saltyseadog

    saltyseadog Tele-Meister

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    I am planning on building a finger jointed pine cabinet and then giving it a tweed covering for my 1987 green board Blues Junior amp. As well as the original 12" Eminence 8ohm speaker I have an 8" Eminence 4ohm 820H Patriot I had bought for an other amp I had. I originally intended to build a head and a speaker cab but think I would prefer to stick with it as a combo. To this end I will buy another Patriot 820H.

    Now my idea here is to build the speakers in a triangle with the 12" on top and the two 8" underneath and run separate jacks from the 12" and the two 8" speakers wired in series which would give me two options both at 8ohms. Now I will be happy enough with that if that is how it turns out but would it be possible to wire all three speakers together in parallel and retain the 8ohms. 8+4+4=16 giving 8ohms wired in parallel, I have a feeling I am wrong but thought I would ask anyway?.
     
  2. AAT65

    AAT65 Friend of Leo's

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    If I understand correctly you want to know if there is a way to wire an 8ohm speaker and 2 4ohm speakers for a total impedance of 8ohms?
    No there is not.
    All 3 in series would be 8+4+4 = 16ohms, as you said.
    The 8ohms in parallel with the two 4ohms in series ( 8 || (4 +4) ) would be two 8ohm loads in parallel, which is a total of 4ohms and might be useful.
    All 3 in parallel would be 1.6ohms, which probably isn’t useful...
     
  3. Mexitele Blues

    Mexitele Blues Tele-Holic

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    Putting the pair of 8" in parallel in series with the 12" would yield 10 ohms. Close enough?
     
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  4. SSL9000J

    SSL9000J Tele-Meister

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    This. A difference of 2 ohms in theory is negligible in practice.
    To get exactly 8 ohms (measured) out of all three speakers would require a high-wattage resistor in series, (4 ohms,) or parallel, (16 ohms.) That being said, keep in mind we're talking about impedance and AC, not resistance and DC. Resistors and inductors behave differently, plus you have different tolerances, so the "8 ohm" spec (or whatever) goes out the proverbial window once current starts flowing through it.
     
  5. saltyseadog

    saltyseadog Tele-Meister

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    Thanks for the replies which have confirmed for me it was not so simple. I will just stick with my original plan of having a 1 x 12" option and a 2 x 8" option separately.
     
  6. alathIN

    alathIN Tele-Holic

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    I'd like to politely suggest you keep investigating this.

    I have a 2 x 12 cab that is wired so you can switch the configurations around, and I've had a few different kinds of speakers in it. Right now it's one Celestion G12H30 and one Ted Weber 12F150 (blackface Fender tone).

    But no matter what speakers I've had in there with what combinations of guitars and amps, it always sounds better with both speakers switched on.

    I know it sounds too dumb to be true, but in my experimenting, more = better.

    Also keep in mind you can use spade connectors to easily try different wiring schemes, and only solder it when you're sure what you like best (or never, for that matter).

    Here's from a Ted Weber Q&A:

    I have two 8 Ohm speakers that I can wire either parallel or series to my tube amp for an impedance of either 4 or 16 Ohm. My amp has both 4 and 16 Ohm output taps. Are there any sonic differences or benefits of series over parallel wiring or vice versa?
    GERALD C. LOPEZ
    Gerald, connecting two speakers in parallel is an old trick to smooth out speaker response and enhance the damping of either speaker. HIFI designers took it one step further by connecting two speakers of different sizes in parallel. A speaker has a large impedance increase at its fundamental resonance, and depending on the installation, this can cause the speaker to sound boomy or out of control. By connecting two speakers in parallel, particularly two speakers of different sizes with different resonant frequencies, each speaker will tend to quench or dampen the boominess of the other. Since no two speakers are exactly alike, even two of the same size, that damping will occur, however slight, for any speakers connected in parallel. For speakers connected in series, there appears to be less control, and more of what is called 'back EMF' from the speakers fed back into the output circuit. While that seems rather chaotic, many players prefer the series connection, as it gives them a more textured tone, enhanced breakup, and overall a more desirable tone for guitar work. It's totally subjective, of course, and many factors affect the end result, such as voice coil size, gap energy, closed back/open back, output circuit damping, etc. The best thing to do, in my opinion, is try both arrangements since you have the luxury of impedance tap selection, and go with the configuration you like the best.​
     
  7. saltyseadog

    saltyseadog Tele-Meister

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    Right just so that I get this right. I would wire the two 4ohm Patriots in parallel giving 2 ohms then join the outgoing + & - to the 8ohm Eminence + & - and this would give me 10ohm which should not be a problem?.
     
  8. Mexitele Blues

    Mexitele Blues Tele-Holic

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    What you just described would connect all 3 speakers in parallel.

    Connect the speaker jack positive terminal to both 4 ohm positive terminals. Then connect both 4 ohm negative terminals to the 8 ohm positive terminal. Finally, connect the 8 ohm negative terminal to the speaker jack negative terminal. Now the pair of parallel 4 ohm speakers is in series with the single 8 ohm for a total load of 10 ohms.
     
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  9. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    I would not recommend using multiple ohm speakers in one connection. While you may be able to get the math for the impedance to work, the power to each speaker would be different and is also something to consider.

    With ***so many*** speaker options out there just a click away it should be easy to find something that will do what you want.
     
  10. uriah1

    uriah1 Telefied Gold Supporter

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    I have a kustom 3x15. That is odd.
     
  11. Mexitele Blues

    Mexitele Blues Tele-Holic

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    If I am doing the math correctly, wired at 10 ohms, each 4 ohm speaker will see 40% of the output power and the single 8 ohm sees 20%. The smaller speakers will definitely be working harder in this arrangement.
     
  12. saltyseadog

    saltyseadog Tele-Meister

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    Then it wouldn't be a solution for me as the Eminence 12" is rated at 50W while the 8" Patriots are rated at 30W each?.
     
  13. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    I mean, any of those would be fine for the Blues Junior, but it's just something to think about. If *you* are okay with that then it's fine, but you're likely not going to hear much of that 8Ohm speaker.
     
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  14. saltyseadog

    saltyseadog Tele-Meister

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    Rather than start a new thread I thought I should reopen this one. I found out that I could get an upgraded output transformer made by Hammond the 1760F in the link https://www.hammfg.com/files/parts/pdf/1760F.pdf for my bluesjunior which will give me 4/8/16ohm options. The primary side of the transformer is pretty straightforward and on the secondary side it looks like I should connect the black common to the same point on the amp it is attached to now and the 4ohm yellow to the point on the amp where the present 8ohm green cable is connected. By then joining the 2 x 8" 4ohm speakers wired in series at 8ohm and the original 1 x 12" also 8ohm onto a single 1/4" jack into the amps output jack this would give me a total impedence of 4ohms and be an acceptable solution or am I wrong?. If correct then should I just dead end the remaining green 8 and white 16 ohm wires and tuck them safely out of the way?.
     
  15. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    That all sounds correct.
     
  16. schmee

    schmee Poster Extraordinaire Silver Supporter

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    But the 8" will be a lot louder in that mix. Hard to say how it will sound. I have tried some oddball combos to use speakers I have over the years, none have been that good really. OP: build the cab you want and get speakers you really want .
     
  17. Mexitele Blues

    Mexitele Blues Tele-Holic

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    True. I'm not familiar with the sensitivities of the speakers he is using so I can't speak to the loudness but it sounds like OP is on the proper track with a multi tap OT.
     
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