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Heads and cabinets

Discussion in 'Amps and Cabs [BG]' started by Bushfire, Jul 9, 2005.


  1. Before you all kill me, I've checked the faq, and done a search, and most topics assumed some knowledge on the subject. I have none.

    Now I need to upgrade my amp (badly) and well, combo's are simple and maybe something like the fender rumble 100 will do me.

    But that's beside the point, I'm looking at head units and cabinets and have some questions about them:
    • when you get xxx watts on x ohms on a bass head, what does that mean in terms of the speaker size and power ratings I can attach?
    • How do you connect a head unit to a cabinet, and where would I get one, and for how much?
    • What kind of power would you need for a medium sized rock gig?

    Thank you very much to anyone that answers rather than flaming me.
     
  2. Mental Octopus

    Mental Octopus

    May 24, 2003
    ill try answering your ?'s in order:

    1. say you get a 300 watt head at 4 ohms. that means you could get any one 4 ohm cabinet that can handle more than 300 watts. but then say you get an 800 watt head at 4 ohms and want more than one cabinet....so then you would get 2 8 ohm (because 2 8 ohm cabs = a 4 ohm load. in your situation... i would just stick with one cab.

    2. you connect a speaker cabinet to a head unit with a speaker cable. these can range from really cheap to really expensive.

    3. for a medium sized rock gig...maybe 300 - 400 watts? how many watts of power does your guitarist use? - my rule of thumb is that for 1 watt of guitar there should be 4 or 5 watts of bass.

    hope i helped.
     
  3. Thank you very much, I think I understand.

    And seeing as my guitarist just blew his amp, I guess I'll have to wait and see

    Waitaminute, does that mean If I got a 300w 4ohm head, and connected with a 600w speaker, does that mean that speaker would run at half it's 'potential power?'
     
  4. TheChariot

    TheChariot

    Jul 6, 2004
    Boston, MA
    There's really no such thing as underpowering a speaker cab, really. You can overpower them, but even that takes some effort.

    The main way that speakers get damaged, is by something called power amp clipping. This is when you drive your amp so hard that it sends clipped signals to your speakers, creating a horrifying distortion that often causes damage. A way to help avoid this, is by getting a more powerful amp... which means you wont have to push it as hard. Most cabs will handle this just fine.

    For example, a common rock setup for major label punk bands is an Ampeg SVT 4Pro through an Ampeg 810 cab. The 4Pro puts out about 1200Watts, but the Ampeg 810 is rated at about 800RMS.
     
  5. Iruleonbass

    Iruleonbass

    May 29, 2005
    New York
    I will try my best at explaining what I know seeing as im fairly new to this too, maybe you can understand my primitive means a little better than these complex peoples.

    Ok so, ohms is resistance, so the more ohms you have, the less power the amp can get through. Bassicly like a fuacet, the less close the valve the more water can come through, Well the less ohms you have the more power can come through.

    So lets take a 300w (at 4ohms) and than we'll run it trough a 2ohm cabinet, you'll get maybe 400w (im guessing) Now through an 8ohm cabinet you'll get 200w (guessing again)

    Regarding connecting the head to the cabinet, a normal 1/4" guitar cable can plug into the back of the head and than into the back of the cabinet, if your running at near or full power, a speakon cable is recomended becuase it allows the electrical current to travel more freely. If you go to a guitar store, and ask for a speakon cable, they'll point one out to you, its just a diffrent style of cable.

    While I was at GC the other day, I was recomened to buy an Ampeg 410HLF Cabinet and an Ampeg SVT-350h head. I was a little skeptical about how loud it would be, he turned it up to 4 and it started shaking the ceiling. So It'll be loud enough for a medium sized group. I personally am going with an SVT-CL and SVT-810 just becuase im a moron and think I need that big of an amp. :)

    Hope that helped.
     
  6. It did help, but there's no rush I'm gonna wait till I have some decent money.

    But I want some more specifics on the amp I'm using now, and the info it gives me on the panel on the back doesn't tell me a heck of a lot, so here's all the information I can give you on it, and I'll hope some of you smart TBers can help me out in finding information like resistance and the watts its pumping out (ie not a heck of a lot.):

    Manufacturer: Vantage
    Model number: Vb-10
    Power Source: 240 Vac 50/60 hz
    Power Consumption: 24 VA
    Primary Fuse: 250V 0.25A
    Serial Number: 12961051
    Made in Korea
     
  7. BurningSkies

    BurningSkies CRAZY BALDHEAD

    Feb 20, 2005
    Seweracuse, NY

    Your amp is made by Samick...beyond that I can't find much in the way of specs. It looks like it's probably a 10watt practice amp. Fer now, I'd use what you have, and save up for something a bit more substantial. None of the power listings above can tell you anything about your amp's output, but as it's a small combo, I wouldn't be thinking about a second cab.
     
  8. Daytona955i

    Daytona955i

    Feb 17, 2005
    Albany, NY
    Just remember that amps rated at a certain resistance cannot go lower than their rating, but can go above. A 4ohm amp can take an 8 or 16, etc ohm load, but can't take a 2 ohm load.

    Also, just one other issue I wanted to point out is that you should never ever use an instrumental cable between the amp and the speakers. While they do have the same 1/4 inch connections, speakers cables and instrument (guitar) cables are different. One is made for a small electrical signal, and the other is made for a large electrical signal. The best way to fry an instrument cable is to use it to connect your amp and speaker.

    Also, not all cabs and heads have speakon connections, but it is a better choice IMHO.
     
  9. AlembicPlayer

    AlembicPlayer Im not wearing shorts

    Aug 15, 2004
    Pacific Northwet, USA

    ditto what Daytona955i said.
    just don't do it :rollno:
     
  10. Dirty Dave

    Dirty Dave

    Oct 17, 2004
    Boston, MA
    Sorry, but I'm not quite agreeing with this as it's written. To me it reads as though you are limiting the lower powered 300 watt, 4 ohm head to only "one 4 ohm cabinet".

    However, I'm sure that's not really the message you were trying to convey. ;)
     
  11. Iruleonbass

    Iruleonbass

    May 29, 2005
    New York
    Oh, I didn't know that, Ampeg said that speakon was recomended when you where using the amp at near or full power. I was planning on buying speakon either way just becuase they're safer cables IMO. They lock in and let the current more more free, I was just throwing out options.