Real Basic Question about watts..

Discussion in 'Amps [BG]' started by ping23, Feb 2, 2013.


  1. ping23

    ping23

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    I have searched the forums and internet and still have no simple answer. I have a Backline 600 head at 300w 4ohm with a GLX 4x10 cab thats 400w 8ohm. So right now I am only getting about 150w correct? Was planning on adding a 1x15 8ohm. Now when I add that would the head then put 150w to each cab or 300w to each cab?
     
  2. MrDOS

    MrDOS Gold Supporting Member

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    If you have two cabs of the same impedance, power will be distributed equally between them.
    Your assumption of 150 depends on the amp.
    Is the new cab from the same manufacturer? Please find some threads about mixing cabs for more info. :)
     
  3. ping23

    ping23

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    Yea, I was a drummer and now play bass so I am moving up from a combo to keep up with the guitars and drums. Both the head and cab are GK and was planning on adding another GK 1x15. So if I added a 1x15 200w 8ohm, I should be good?
     
  4. smogg

    smogg

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    You are correct in assuming two 8 ohm cabs will split the power of you amps output at a 4 ohm load. So yes, in your case each cab will get 150 watts. However it is best to pair your cab with a second identical cab. Less headaches in the long run. If it were me I'd get another GLX 410 and call it a day.

    hope this helps,
    smogg
     
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  6. Cadfael

    Cadfael

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    Hi ping,

    I made a (PDF) compliation about your question - but it is in German ...

    Short:
    Your amp is a transistor amp - which follows different rules than tube (power) amps.

    With a transistor amp you have a "minimum impedance" (4 Ohms in your case).
    Doubleing the impedance means about 1/3 loss of power. So, with an 8 Ohms cab, your Backline (had the 210 version!) brings about 180-200 watts max.
    With 16 Ohms it brings 120-150 watts max ...

    As the additional cab has the same impedance, it gets the same power as the 410 cab.
    As the backline has a max. power of 300 watts @ 4 ohms, the two 8 ohms cabs get 150 watts max. ...

    So, your 410 cab won't get 200 watts anymore but 150 watts max. ...

    But power is not loudness!!!
    The loudness depends on speakers and how the cab is built.
    With a 410 on top, you won't be able to "locate" the 115 below (when same series and quality). You will hear that the sound gets wider and you have more punch - but you will not be able to hear the 115 itself.

    You should at least try two 410s with your Backline!
    You will be impressed about the difference! Two 410 are not only louder with the same sound! There will be much more bass and punch. And you can even play in two bands with the same cab - and when you have a bigger stage gig - take both cabs ...

    As I had a Backline 210 I can also recommed a 410+210 solution!
    You will hear the 210 becasue its speakers get twice as much watts as a speaker in the 410 (both cabs 150 watts > 75 per speaker in the 210, 37.5 per speaker in the 410). The 410 will add the base of the sound ...
     
  7. ping23

    ping23

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    thanks..i was under the impression that adding the 1x15 would give good low end? would a 2x10 be a good addition, im not sure i want two 4x10...any other configurations that would be appropriate?
     
  8. ping23

    ping23

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    Cadfael thank you so much, that was so simple and clear. I appreciate it. So I think I will look into the 4x10 or 2x10 option. I do really like my Backline hope you did too!
     
  9. kevteop

    kevteop

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    Personally I would sell the 410 and get a 4 ohm cab. Lugging a pair of 8 ohm cabs sounds too much like hard work, and there are plenty of modern lightweight 4 ohm cabs that will give you a lot of loud from 300w.
     
  10. ping23

    ping23

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    I don't mind having the two 4x10s actually bc my band practices in two places so it could give me more flexibility. Or even just the 2x10 added.
     
  11. dincz

    dincz

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    There's a potential problem with adding a 1x15 (8 ohm) or a 2x10 (8 ohm). Your 4x10 divides half of the amp's power between 4 speakers, the 2x10 between 2, and the 1x15 has to deal with it alone.

    At the moment your amp is not delivering enough power for this to be a problem but if you later upgrade to a higher power head, the smaller of the 2 cabs will run out of steam before the 4x10.
     
  12. ping23

    ping23

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    Even if the 2x10s watts are rated higher than what the head would be sending to it?
     
  13. Denny Coon

    Denny Coon

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    So.. If you were to run a 4x10 with a 2x10 cab on top and both were 8ohm cabs...if you daisy them together dosent that drop it to 4ohms? Full power from the head?
     
  14. dincz

    dincz

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    In that case, no, but be wary of speaker power ratings. They usually specify the power level required to overheat/fry the voice coil. A speaker can be mechanically damaged by much less than that.
     
  15. ChrisB2

    ChrisB2 Bass... in your fass Supporting Member

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    Pretty sure the BL600 is rated at 180W@8ohm.

    +1 to getting another 8ohm 410. Someday a gig will come where you will love having 8 10s behind you. However you may want more amp for that.

    As far as "can a 210 work"... yes but since it will be getting the same power as the 410 the 210's drivers will be pushing more air so even if the drivers can handle the power, the cabinets will not sound matched...
     
  16. ping23

    ping23

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    Ok so I'm getting about 180w through the cab I have now and if I add a second 410 ill be pushing the full 300w. So to get a better matched sound another 410 would be better than a 1x15 or 2x10?
     
  17. dincz

    dincz

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    Another identical 4x10 will be better in every way except maybe size and weight.
     
  18. fdeck

    fdeck Supporting Member

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    I wrote a geeky review of the BL600 head:

    http://personalpages.tds.net/~fdeck/bass/gkbl600.pdf

    You're basically correct, except that the BL600's rating at 8 Ohms is 180 Watts. However, the difference between 180 and 150 is academic.
     
  19. Cadfael

    Cadfael

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    As far as I know, GK stopped selling the 1001 210 combo because even the high class 210 speakers could not deal with the power of a 1001 (at 8 Ohms) ...

    BUT ... GK kept on producing the Backline 210 and other 210 combos ...

    What's the problem when the upper 210 speakers get double watts of the 410 below?
    I always felt secure because I watched the 210 speakers. If they manage the setting, I needn't go on my knees to see if the 410 does. When the 210 became critical, it was time to slow down ...

    The 210 doesn't have so much bottom and has a "clearer" sound. That's good for hearing my set. The 410 adds the volume / punch.

    The 210 cab should surely be as good or better as the 410 speakers because each of them has to handle double of the power as the 410 speakers.

    By the way ... that's critical about a "cheap" 410/115 stack. The lower speaker has to handle half of the power alone and you have to go onto your knees to see if it can handle the power ...

    The 2x 410 is surely a good alternative (especially with two rehersal rooms). With an 810 the highest speakers are also nearer to your ears. It also depends on the style you play or if you want to "impress" people. Heavy Metal with a Promethen 110 combo looks strange ...

    Not to be taken too honest ...
    An 810 hits you like a pan.
    A 610 hits you like a baseball bat.
    A 110 hits you like a knife.

    Same power on a smaller "all speaker surface" may not be so impressive (for the body feeling), but it is better to hear/listen to ...
     
  20. derrico1

    derrico1 Supporting Member

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    Well, watts aren't really a very useful way to think about this. In normal use with an amp well sized for the gig, the moment-to-moment wattage generated will typically be well below the rated wattage--jumping up only on the bass signal's transient peaks.

    As others have said, for overall rig loudness, the efficiency and mechanical limits of the speaker cabs matter a lot more than the amp's wattage specs. But the amp's wattage spec can give you at most a *general* sense of how loud it might get, in that (driving enough speakers and all else being equal) a 1000 watt amp will be noticeably louder than a 300 watt amp, which in turn will be noticeably louder than a 100 watt amp.
     
  21. BassmanPaul

    BassmanPaul Gold Supporting Member

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    this is a complete myth. The size of the cone is irrelevant to the lows it will produce.

    Adding a 2x10 could work BUT it MUST be twice the impedance of the 4x10. This will balance out the power to each driver. So 8Ω 4x10 needs a 16Ω 2x10. 4Ω 4x10 needs an 8Ω 2x10 and your amp will have to be 2Ω stable.
     

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