hookin up a cab to a combo

Discussion in 'Amps and Cabs [BG]' started by deer_tick70, Jun 20, 2001.

  1. I currently have a peavey 112 bassman and found out that you couldnt hook a cab (probably 4 10's) up to it without blowin the 12 inch speaker. I am trading it in to get a peavey combo with a 15 in in it for 150 watts, my friend said his bassist has the same combo and hooked up a 4 "10" cab to it and is now playing about 300 watts. My question is, by hooking up a cab to a combo ,does it actually make it louder or just something extra to play out of?
  2. Comakazi


    May 3, 2001
    Midwest US
    Welcometo Talkbass deertick. In response to your question yes. And, someone correct me if I'm wrong, it will for a couple of resons. First it will drop the ohm load which will make the amp run with a higher wattage. And by adding more speakersyou move more air. And in simple terms,the more air you move the more full and deep your bass will sound - you're simply getting more of it out there.
    Most companies factor this in to their combos. They know that people may want to add an extension speaker and factor the amp to run more power with another speaker added. I have SWR Workingman 15 that I occasionaly add a 4x10 to and it raises the wattage from 160 to 200 by adding it. It makes the low b sound quite nice!
  3. kcm


    Jun 17, 2000
    Woking, Surrey.
    In my experience if the combo has another speaker output then its designed to take another cab. The minimum ohms would be written next to it. What you have to watch out for is not to try to butcher the cab and make an output by running leads from the existing speaker if there are no extra outputs. This would more than likely do the amp and not the speaker some damage as the output would be at optimum with the existing speaker.
  4. i have a peavey combo, but the plug for cabs clearly says " 130 watt 4ohm ", while the amp is 150 watt.. weird eh ?
  5. jcadmus


    Apr 2, 2000
    I also think that one-speaker combos tend to sound a little boxy and one dimensional.

    I've found adding a cab can really add depth, width, harmonics, and will generally open up the sound.
  6. Well you just sold me on buying a new cab for my Combo to add on to the stack. I was thinkin about doin it anyways, but hey, that comment about fuller sound, aww yeah baby!
  7. The Peavey Basic 112(which is what I think you're getting at) pushes 50 Watts at 8 ohms, and 75 Watts at 4 ohms.

    Now, as far as I know, the Basic 112 does not have a line out(this is after playing one and carefully studying the sockets - Peavey.com says otherwise). Therefore, to use a cab with your combo, you need to run the cab out of the headphone socket, as the 'Preamp Out' signal is not enough to drive the cab speakers.

    So, assuming the combo has no line-out, when plugging the cab into the headphone socket you will get a minimum of 50W output. Hopefully, the amp in the combo will realise that it can run at 4 ohms(turning off the combo speaker) and throw 75W at the 4x10.

    If your amp has a line-out then it will definitely do 75W. The 115 you're getting(TNT or TKO?) does have a line out, and will push a lot, around 170W. This is a lot of bass.

    Bear in mind I played a Basic 112 that looked like this:

    And not a Basic 112 that looked like this:

    The Peavey website says that the Basic 112 has an external speaker jack, but has a picture of the second amp shown above. Maybe this is a newer model? I played the first amp, and that had no external speaker sockets.
  8. Good morning guys.

    You can't run a cab from a headphone socket - least ways, you shouldn't be able to do that if the electronics are properly designed. There is usually a resistor of about 100 Ohms in series with the headphone socket feed, inside the amp. This is so you don't deafen yourself when wearing 'phones. It's done in exactly the same way inside your HiFi...or should be if it's done properly.

    Likewise, you can't run a cab from the preamp out or line out socket because they're 'small signal' sockets: the signal levels there are designed to feed (say) another slave which then powers another cab.
    Theoretically, if you halve the load (say going from 8 Ohms to 4 Ohms) you'll get double to power out BUT ONLY IF THE POWER AMP IS DESIGNED TO DO THAT. If not = smoke!!!! If there's no extension speaker output then assume it's NOT SAFE to connect more speakers. Destroying a speaker by adding more speakers is really unheard-of: wrecking your amp by doing the same is very common indeed.

    Hope that helps. :D

    Rockin John