Discussion in 'Amps and Cabs [BG]' started by Hybridsteve, Jul 11, 2003.

  1. I'm only a youngin so let that be an excuse if this is a dumb question.
    Can I use an 8ohm head with a 4ohm cab?

    I have a Hartke 3500 which is supposed to be a 4ohm head but at the back beside the speaker outputs its says 8ohms beside each of them.

    I'm confused.

    Thanx Steven
  2. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003
  3. The 3500 delivers 350 watts at 4 ohms, 240 watts at 8 ohms. You should be fine, as long as your cab is rated in the same order of magnitude. 4 ohms is the recommended minimum. I would make sure that your cab is rated at 200 Watts at least, and not more than 750 Watts if you are planning on cranking the volume and gain....

    The labelling is a little confusing, I suppose they are warning you to use only 8 ohm cabs if you are running two in parallel (which totals 4 ohms).

    Here is a link to the manual, which says what I just said...

    Hartke 3500 manual

    Trust me - I'm of Irish descent (O'Shaughnessy) and I'm an electrical engineer...:smug:
  4. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003
    rather than posting another topic ill ask here perhaps Big O can help me, If i get a single 4ohhm cab, i guess i just plug it into one of the outputs and i get my 350 watts?
  5. squire_pwr


    Apr 15, 2003
    San Diego, CA.
    I'm not Big-O, but perhaps I can help...

    I've read a bit about 3500's and yes, if you get a 4ohm cab and plug it in, you will get your 350watts. But only do ONE 4 ohm cab, if you do two 4 ohm cabs, you could damage your head. If you want two cabs, get two 8 ohm cabs.
  6. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003
    lovely job, im getting a 100w 4ohm 4x10 in the near future to give me room for upgrading my head if i ever need more than 350w from the hartke
  7. I've always wondered that myself if you 'HAVE' to run two cabs at 8 ohms each to pull the 4 ohms out, or if it would be okay to plug a single 4 ohm into one of the 8 ohm outputs from the amp... You should be fine though. Its not like your giving the amp a 2 ohm load.

    BUT... the 3500 is a 4 ohm head... just because there are 2 outputs labeled 8 ohms doesnt mean you cant pull a 4 ohm load out of it... Plugging two cabs that are 8 ohms each will result in a 4 ohm load, you are perfectly fine doing that... You will be FINE running a single cab rated at 4 ohms, but DO NOT use TWO four ohm cabs. THat'll be a 2 ohm load, that's not good, atleast for the hartke anyways...

    to Miccheck1516: I own this and am running it into an 8 ohm Avatar CB115 cab. Good lowend, and to those people who say you can't get massive lowend from the head, they're wrong. If you have a few speakers you can get a lot of low end. Not as much as other heads, but its an excellent head. They are reliable unlike other people care to comment on. I bought mine used and it's delivered nothing but good tone... You just have to make sure you're not sending too hot a signal into the amp or else it will distort, clipped signal. I use an active bass, leave the EQ on the bass itself centered and crank the volume and it's fine... The head is loud at 4 ohms, especially with a 4x10 + 1x15 setup:D
  8. zeh


    Jul 11, 2003
    Lisbon , Portugal
    Hey there =)

    Im kinda confused with all this ohm stuff , Could u please tell me what happens when I plug in a Mesa boogie M-pulse 360 to a Mesa Boogie
    2x10 PowerHouse Cabinet 300 Watt (8 Ohm) and a Mesa Boogie
    1x15 Deep PowerHouse Cabinet 400 Watt (8 Ohm) ? How much do I get per side?

    Tkx :bassist:
  9. Ívar Þórólfsson

    Ívar Þórólfsson Mmmmmm... Supporting Member

    Apr 9, 2001
    Kopavogur, Iceland

    When you plug two 8ohm cabinets into your amp, you get the optimum performance from it at 4ohms. That means that you are pumping out a total of 360W. Each cabinet receives roughly 180W. According to the Mesa Boogie website, your amp runs best with 4ohm load. If you only have one 8ohm cabinet hooked up, then the amp runs at 8ohms but with less power. It would be about 220-240W I guess.

    Here´s a link to a thread I made a while ago regarding calculating ohms.

  10. Scott D

    Scott D

    Apr 21, 2003
    Minneapolis, MN

    a 100 watt 4x10???
    4 25 watt speakers???
    thats very very low rated....
    are you sure its not 4 100 watt tens?
    what manufacuter?

    so do you guys get how the ohms thing works? (2 8 ohms =4 ohms )
    (2 4 ohms =2 ohms) etc...
    or a rewired 4x10 can be 2 ohms, it just has to do if its wired in parelell or series. i would do this in a second, except my SVT won't run a 2 ohm load... sucks.
  11. I have two cabs both 4ohms surely this means I should use a 4ohm head!

    But what I'm being told is that I should sell these two cabs and buy two 8 ohm cabs because this will give me the 4ohms from the head!Because at the minute I am overpowering the head!Is this correct!

    Go on the Irish
  12. listen... by plugging 2 separate 4 ohm cabinets into your amp, you will be getting a 2 ohm load!!! You will kill the hartke and/or your speakers! Use ONE AND ONLY ONE 4 ohm cabinet. If you want to use two separate cabinets you are going to need two bass cabs rated at 8 ohms each to use 4 ohms... DO NOT, DO NOT, DO NOT plug in two cabinets rated at 4 ohms each, that is NOT a four ohm load.
  13. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003

    I ment 1000w DOH!!!:bassist:
  14. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003

    my god your nearly 18 and you dont know Ohm's law! what has happened to teh irish education system :p
  15. Ívar Þórólfsson

    Ívar Þórólfsson Mmmmmm... Supporting Member

    Apr 9, 2001
    Kopavogur, Iceland
    bassist31588 is absolutely correct!

    You will fry your amp if you connect two 4ohm cabinets in your 4ohm head.

    Take a look at this formula:

    R = ohm
    R1 = ohm of cabinet 1
    R2 = ohm of cabinet 2 etc.

    R1 * R2
    ------------ = R
    R1 + R2

    In your case this would be:

    4 * 4
    ------------ = 2 -> fried amp head.
    4 + 4
  16. Ahh I see very good.Yeah the Irish educational system is a bit bolloxed!As you probably know considering I am 18 and nearly 19.Maths must be a problem here.

    Well Thanx everyone.

    Much Appreciated.