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Difference between 700 watts into 4ohms and 480 watts into 8ohms?

Discussion in 'Amps [BG]' started by jfh2424, Feb 10, 2014.


  1. jfh2424

    jfh2424

    Joined:
    Jan 10, 2009
    Location:
    Montreal, Quebec Canada
    Hello! I have a GK 1001RB. The time has come to buy new cabs. I have found a cabinet that I like. Here is the issue: I can buy it used in 8ohm for cheaper. However, I would only be able to use 480 watts of the GK, that's how much wattage it puts into an 8ohm cab. Or I can buy it new at 4ohm and use all 700 watts of the GK. Both the cabs are rated at 800 watts.

    I won't be able to hear the difference between these two before buying.

    My question is this: am I likely to hear a big difference in terms of overall volume between these two cabs? I don't mean volume in terms of numbers, I understand the 4 ohms will be louder. I mean volume in terms of real life volume, on a gig?

    Thanks!
     
  2. Hawkbone

    Hawkbone Supporting Member

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    Mar 23, 2009
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    Newfoundland
    I'd buy the 8 and add another like it if volume is an issue.
     
  3. bongomania

    bongomania Gold Supporting Member

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    Location:
    PDX, OR
    Disclosures:
    owner, OVNIFX and OVNILabs
    IF the cabs are otherwise the same, with the only difference being one is 8 ohms and the other 4 ohms, then the volume difference will not be huge. But as Hawkbone said, the 8 ohm one gives you the chance to add another 8 ohm cab, doubling your speaker area, which --in combination with the extra wattage-- will give you a huge volume bump.
     
  4. Zooberwerx

    Zooberwerx Gold Supporting Member

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    Location:
    Virginia Beach, VA
    ^^^ What these guys said.

    Riis
     
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  6. dincz

    dincz

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    Czech Republic
    If the 2 cabs are the same except for impedance, then I doubt you would hear the difference even if you were able to compare them. That's about 1.6dB difference, which is almost nothing.
     
  7. Tractorr

    Tractorr Supporting Member

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    I would get the 8ohm simply because if you need all that power you are likely going to hit the mechanical limit of a 800 watt cab before the thermal limit. Also, I have the 700rb going into a 4 ohm cab and 480 GK watts is insanely loud. Louder than I need and I play in a very loud rock band.
     
  8. jfh2424

    jfh2424

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    Location:
    Montreal, Quebec Canada
    Really, I'm surprised by the responses I have gotten here. I would have thought that a 700 watt amp into 4ohm would have been a lot louder than a 480 watt amp into 8ohm.

    700 watts is almost a third more watts than 480...I guess there is a point of saturation or something where more wattage doesn't really make a difference?

    I don't know, I'm not aware of the tech things behind the issue, that's why I'm asking here. I really appreciate the responses, because otherwise I have to make a blind guess. As you know, buying a cab is a huge investment (at least it is for me), so your comments and experiences are really appreciated.

    John
     
  9. BrentD

    BrentD Supporting Member

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    Jun 7, 2008
    Location:
    Lansing, MI
    John,

    The relationship between watts and volume is not a linear one. To double your volume, you need ten times the wattage. That 30% difference is marginal in this case and, depending on EQ and voicing, (as dincz pointed out) should be unnoticeable.
     
  10. andrklet

    andrklet Guest

    ^Yes. And doubling your wattage, increase volume by only 3 db. Effective volume increase is done by expanding speaker area.
     
  11. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    Some of the above advice assumes that the OP may choose to add another cabinet which would dictate an 8 Ohm box. if this were a 1 cab only situation there would be reasonably small increase in SPL with a 4 ohm cabinet all things being equal.

    What are the cabs in question?
     
  12. JHAz

    JHAz

    Joined:
    Jun 29, 2011
    It really depends a ton on the cabs. A one dB increase in sensitivity will make up for about a 20 percent decrease in available power, and a 3 dB difference in sensitivity makes the more sensitive cab just as loud as the less sensitive cab while using one half the power.

    But how loud it sounds to you may depend a lot on your EQ and the cab's frequency response in addition to the bare sensitivity measurement.

    All of which is why essentially everybody says "if everything else is equal" in their answers. Whether it's really equal is the big question . . .
     
  13. AstroSonic

    AstroSonic Supporting Member

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    rural New Mexico
    +1

    The spl advantage from a power standpoint (1.6 db, 700w vs 480w) is trivial. The cab similarity or difference is most important. Typically, 4 and 8 ohm versions of the 'same' cab are pretty similar, especially if a full HP/LP crossover is used. I think you will be quite pleased with the 8 ohm cab.
     
  14. jfh2424

    jfh2424

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    Hello! The cabs in question are Markbass 104 HF. Here is a link: http://www.markbass.it/product_detail.php?id=33

    The 8ohm and 4ohm versions are both rated to 800 watts.

    Thanks again for all the opinions!

    John
     
  15. Downunderwonder

    Downunderwonder

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    I'd be surprised if you can't fart out an 8ohm one anyway. Amps make lots more than the rated power on the heavy hits.
     
  16. jfh2424

    jfh2424

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    Hello! I really don't understand what you mean...could you please explain it? Thanks!
     
  17. jfh2424

    jfh2424

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    I'm not sure what an HP/LP crossover is...is that a Speakon cable? My GK can send a Speakon cable and the cab can take one, but I don't really know the advantage of this.

    If anyone can school me about this, it would be great!
     
  18. BassmanPaul

    BassmanPaul Gold Supporting Member

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    Location:
    Toronto Ontario Canada
    A high pass filter has nothing what so ever to do with a Speakon per se. All bass players should be using Speakons anyway, they are significantly better and electrically safer than Phone plugs.

    As to the 4Ω/8Ω question - get the 8Ω version. If you go with the 4Ω cabinet there is nowhere else you can go if you need expandability. As mentioned, an 8Ω cabinet allows you to add a second 8Ω cabinet to get more out of your GK amplifier.
     
  19. bongomania

    bongomania Gold Supporting Member

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    owner, OVNIFX and OVNILabs
    What he meant is in two parts:
    1) Speaker power ratings are badly exaggerated, so it is possible to make them distort (fart out) using less power than the maker would lead you to believe.
    2) Amplifiers can actually make MORE than their rated wattage if you drive them into hard clipping (crank the master volume to max and play hard, resulting in much distortion).
    Speakons can handle higher power, and they lock into place.

    The reason somebody mentioned hp/lp xover is because SOME Speakon plugs have four connectors, and SOME speaker cables have four wires, so if your amp has an output for the highs and an output for the lows, one speaker cable can connect the "combination" output of the amp to a special receiving-end jack on certain special speaker cabs, sending that high output to one speaker in the cab and the low output to a different speaker in the cab.

    This only applies, and only works, if using an amp and a cab that are specially designed for this purpose together. It does not apply at all to most general amp or cab setups.
     
  20. Downunderwonder

    Downunderwonder

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    Aug 26, 2009
    Location:
    New Zealand
    Amp RMS rating is the clean power it can give, note after note. Distorted sounds can go well beyond the RMS voltage.

    800w 4x10 is a thermal rating, it melts and burns. These are done at much higher frequency. At low frequency the distance the speakers have to move increases, if you put that much power in at low frequency you break things mechanically. Before you get that far it farts. Rule of thumb is half the thermal limit.
     
  21. AstroSonic

    AstroSonic Supporting Member

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    Location:
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    Four and 8 ohm versions of drivers can be quite similar (TS parameters, amplitude response, etc.), but often differ at the high end of their frequency range due to the difference in voice coil mass and inductance. A well designed crossover will cross the bass driver below that difference, so that the range used (in the pass band) is the same (for the two versions). In such a case the 4 and 8 ohm versions could potentially sound quite similar. More commonly, the bass driver is used without a low pass crossover (run 'wide open'), and only the tweeter has a (high pass) crossover. Since the frequency range over which the 4 and 8 ohm versions differ is used (not 'blocked' by a low pass crossover), any difference in response is more likely to be heard (at least close to on axis - in from of the driver). Some manufacturers specify the type of crossover used. Many don't.
     

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