Pushing three cabs?

Discussion in 'Amps and Cabs [BG]' started by RumbleBot, Apr 16, 2003.

  1. Has anybody else done this? I'm trying out a new setup. I'm running an Aguilar GS112 in parallel with another Aguilar GS112 and a Yorkville 1x15 cab.

    By my figuring, I've got this worked out to a 4.8 Ohm load. How's my math?

    I'm driving these off of a GK 1001RB with a 4 Ohm minimum load. I should be safe, but I just wanted to put it out there for some opinions.
  2. If all three cabs are 8-ohm, and all three are in parallel, you've made a slight mistake. You've now got a 2.67 ohm load on your amp. Not good if it's rated for no less than 4-ohms.

    I've run three cabs and as many as four into my Peavey Firebass-II, but it's rated for 2-ohms and they never equal less than that.

    Equal impedances in parallel are real easy to calculate. Simply divide the impedance of one cab by the number of cabs. 2 8's = 4. 3 8's = 2.67. 4 8's = 2.

    If, by chance, the 1x15 cab is a 16-ohm, then you've got a 3.2 ohm load on your amp. Still to low.

    Stop before you cause some damage.
  3. Petebass


    Dec 22, 2002
    QLD Australia
    Actually if I interpret the jpg correctly, 2 speakers are 8 ohm and one is 4. I'm interpreting the diagram like this, but I'm not 100%:-

    Seems the 8 and the 4 are connected in series which gives these 2 speakers a 12 ohm load. then the third 8 ohm speaker is parallel.

    So (12*8)/(12+8) = 4.8 ohms.

    Anyone else????????
  4. Petebass


    Dec 22, 2002
    QLD Australia
    Scrap that - I just realised they're 3 seperate cabs. Thich means they're all linked in parallel.

    (4*4)/(4+4) = 2 ohms..........

    Don't do it!!!!!!!!
  5. OOPS! I missed the schematic. Petebass is right. Sorry about that.
  6. Let's try this one more time. Petebass is right, if all you've done is hook up the cables to the jacks on the back of the cabinets. You will get all three in parallel, no matter what you do.

    However, it you opened the cabs up and did some rewiring to actually have what you showed in the schematic, then you're alright.

    However, I suspect that you just used the existing jacks.

    So, as I said, Petebass is correct.

  7. Wes Whitmore

    Wes Whitmore Supporting Member

    Mar 10, 2003
    Columbus, OH
    The picture is confusing me (easy to do), so I am probably interpreting it wrong,but:

    1) You could probably get away with running the 8ohm 12s in series for a 16 ohm load, then parallel down the 4 ohm 15to get the 3.2 Ohm total. It's close enought to 4 ohm that you will probably be ok. I would contact GK for make sure, and keep an eye on how hot the air is coming out of the Gk1001. I have the same amp, but haven't really tried anything below 4 ohms. This might technically work for you, but it will send 75% of your power to the 15, and split the rest to the two 12s. It may or may not sound good, and your 15 might take a beating, and you will have to create some custom speaker cables. This is where biamping would come in handy. The amp won't disinagrate apon plugging in an ohm load that is too low, so keep an eye on it.
    I really don't see any other way to get it all up and running and not being at 20 Ohm.
    I guess the next question is do you really need the 15? It would make life a lot simpler.
  8. Just for clarification, I've rewired the 1x15 with two inputs wired in series. I'm running the amp out into the first 8 ohm Aguilar, then running from the parallel out of that cab into the 4 ohm 1x15 which is wired in series with the other 8 ohm Aguilar. Kind of a weird setup, but it sounds great.
  9. Again to clarify the wiring modification id did on the 1x15, I installed two inputs. I wired the + of input #1 to the + for the 1x15 speaker. I wired the - of the 1x15 speaker to the - on input #2. Then I connected the - from input #1 to the + on input #2. So the 1x15 won't run on it's own anymore. Only in series.
  10. If you've actually wired it like that, you will have 4.8 Ohms. If all 3 are actually in parallel you'll have 2.67 Ohms. If you're using the default wiring in the cabs/amps and running regular cables all three cabs will be parallel and will have a nominal load of 2.67 Ohms.
    Ok, I just saw your clarification post, you're good to go! If you have a meter handy, you can check the DC resistance of the combination. If it reads anything above about 3 Ohms the nominal impedance will be above 4 Ohms.
  11. Petebass


    Dec 22, 2002
    QLD Australia
    Interesting. I wonder if anyone else has thrown together an way to link cabs in series. Well done.

    The multimeter is a good idea.
  12. There's a few reasons I came up with this cab setup. It's scalable. I can use one Aguilar for practice, 2 Aguilars for small, medium gigs, or all three for more speaker area for larger gigs. Plus, the 1x15 is from my first bass amp. Sentimental value. The 1x15 is only rated at 200W, so it should be safe in this setup, as a bit more power will go to the single GS112, probably around 275 W, and around 190 to the serial 1x15 and GS112. Plus, it's kinda cool having a stack that's as tall as me, but can be lugged around in four seperate pieces.
  13. #%R@#^%#%!#%$#!%$@#^%%*&(*&*Y

    My head's totally spinning guys. I'll have to run this by Alvin in the morning.
  14. geshel


    Oct 2, 2001
    Hmm, yup - 60% of the power (12/(12+8)) will go to the single GS112. The other 40% will go to the series pair. Of that, 2/3 (8/12) (27% of the total) will go to the GS112 there, and the remaining 13% will go to the 1x15.

    Looks like a pretty good way to use what you've got. Oops, one small problem though,

    This puts the 15 and whatever speaker it's in series with out of phase. A correct series arrangement would be:

    + 1 to + speaker
    - speaker to + 2
    - 2 to - 1

    So the + to - signal path is into the + of input one, through the 15, into the + of speaker two, back from that speaker to the - of input 2 to the - of input 1 and back to the - on the amp.
  15. Ahhh... Gotcha. I missed that little phase wiring problem. Thanks.
  16. Yes the ohms are high enough, but, the 8 ohm AG will be much louder than the AG you have in series with the 1x15. As to how loud the 1x15 will be is another story. I don't think it will help your tone or volume very much. jmho