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8 Ohm Cab + Amp Switch to 8 Ohms = Full power?

Discussion in 'Amps and Cabs [BG]' started by DBMcCully, Jan 24, 2020.


  1. DBMcCully

    DBMcCully

    Mar 26, 2019
    South Carolina
    Hey all!

    Say an amp (Orange Terror) is rates at 500 watts @ 4 ohms, but it has an ohm selector switch between 4 and 8.

    If the amp is switched to 8 Ohms, will it drive a single 8 Ohm 4x10 with the full 500 watts?

    thanks!
     
  2. Redbrangus

    Redbrangus Supporting Member

    Nov 19, 2018
    Under The X In Texas
    Ja
     
  3. mmbongo

    mmbongo Five Time World Champion Supporting Member

    Aug 5, 2009
    Carolinas
    No. Plus the Orange Terror Bass has no such switch.

    orange.PNG
     
    DBMcCully likes this.
  4. a-37

    a-37

    Apr 23, 2015
    Helsinki
    The older model does. (EDIT: And is indeed 500W at 8ohm when switched to 8ohm.)
     
  5. DBMcCully

    DBMcCully

    Mar 26, 2019
    South Carolina
    It has the switch in this photo. But that answers my question. I love the idea of the terror bass, but it’s a little under powered for my needs if that is the case. Thanks!

    FA13F17C-0E23-4398-A1B5-B14557130C2A.jpeg
     
  6. a-37

    a-37

    Apr 23, 2015
    Helsinki
    The new version with the "clean" switch is what mmbongo quoted above. Your pic is of the older version.
     
    DBMcCully likes this.
  7. DBMcCully

    DBMcCully

    Mar 26, 2019
    South Carolina
    Right. It was discontinued for a while and then brought back. I’m not sure witch model is in the Amazon listing where I found that picture. That’s beside the point though, I just mentioned it as an example. Lol

    The gist of what I needed to know was whether the switch allowed access to the full power of the amp. I’ve read a lot of forums discussing impedance, but I hadn’t seen this particular question addressed.

    Thanks for the responses!
     
  8. DBMcCully

    DBMcCully

    Mar 26, 2019
    South Carolina
    So is this concept generally true for amps that have impedance switches?
     
  9. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Yes.
     
    Redbrangus and DBMcCully like this.
  10. Redbrangus

    Redbrangus Supporting Member

    Nov 19, 2018
    Under The X In Texas
    Yes, otherwise there's no real purpose for it...at least not in a solid state amp.
     
  11. a-37

    a-37

    Apr 23, 2015
    Helsinki
    You already got the "yes" in duplicate so I'll just nod in agreement to them :)
     
    Redbrangus and DBMcCully like this.
  12. mmbongo

    mmbongo Five Time World Champion Supporting Member

    Aug 5, 2009
    Carolinas
    The older version looks to have tubes in the output section, which is why there is an impedance switch. You have to match that switch to your load and should be 500 watts either way.

    The new version is class D so there is no need for the impedance switch. But it has to have a 4 ohm load to give you 500 watts.

    So it depends on which version you get.
     
    edencab and dkelley like this.
  13. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    Don't worry about it - you really can't hear the difference between 250 and 500W - it is barely noticeable. It takes a 10 dB difference (10x the power) to sound twice as loud to your ear. The advantage of high powered amps is that they can drive multiple cabs. When you double cone area, it does double the volume.

    I have a 2 x 15 cab with a 4/16 Ohm switch (series / parallel) and you can barely hear any difference when flipping it.
     
    Mike NCal, TN WOODMAN and Luigir like this.
  14. edencab

    edencab

    Aug 14, 2013
    Toronto, On
    <-------- that's the older version...TB500..with the switch, puts out 500 watts for either 4 or 8 ohm load..glad I have the option
     
  15. DBMcCully

    DBMcCully

    Mar 26, 2019
    South Carolina
    I wonder why more amps don’t have the 8 Ohm option? It seems like a single 8 ohm cab is a common set up. I guess it has to do with the very subtle audible difference, as was mentioned above?

    So, does a 500 watt 8 ohm amp produce a similar volume as a 1,000 watt 4 ohm amp? In an 8 ohm cab. (I know that probably isn’t exact math, or maybe it varies)
     
  16. Luigir

    Luigir

    Mar 15, 2018
    I completely agree! It's a super common misconception. Doubling power does something but surely doesn't double the perceived loudness.

    I suggest reading this article about the topic which is pretty clear:
    Doubling Power vs. Doubling Output – JL Audio Help Center - Search Articles
     
    TN WOODMAN likes this.
  17. JKos

    JKos

    Oct 26, 2010
    Torrance, CA
    There is quite a difference between tube and solid state amps in this regard. Tube amps can deliver full power into various impedance cabs because the output transformer is matching the amp to the load.

    Solid state amps, on the other hand, are limited by the rail voltages (internal power supply voltages) and other factors.

    - John
     
    Viperdink likes this.
  18. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Chillin' n Grillin' on the Best Coast
    Song Surgeon slow downer.
    More speakers more more air for more volume.

    And, of course, add a HPF if you haven't already. Cuts the mud so you can cut through the mix (and a bunch of other good stuff).

    For more info, see my TB Wiki on the topic: High Pass and Low Pass Filters
     
    dan1952 and DBMcCully like this.
  19. Coolhandjjl

    Coolhandjjl

    Oct 13, 2010
    Appleton
    Both new and older versions have solid state power amp sections.

    The older version has two 12xxx tubes, one is the preamp tube, the other is some sort of driver between the pre and power section. It had a Class D power section.

    The newer version does not have a Class D power section. Don’t know how the preamp is or if it has preamp tubes.

    Hope that helps.
     
    Last edited: Jan 24, 2020
  20. dwade

    dwade

    Feb 15, 2013
    Cincinnati, OH
    It's a matter of impedance, ie load on the amplifier.

    If a solid state amp is designed to run at 4 ohms, it will produce about half as much power at 8 ohms. But we're talking in guestimations here.
    When were talking about solid state amps, the issue becomes the minimum load it can handle before it reaches what the amp sees as a short and fails.
    Most solid state amps can handle anything above their minimum load without causing problems, at an overall power reduction. An amp rated to safely handle a 2 ohm load will produce maximum power at 2 ohms while under it's maximum load but still operate just fine at 16 ohms.......or 32 ohms.....with reduced power.

    With tube amps, you're matching the impedance of the speaker with the impedance of the output transformer. It's a matter of safe operating parameters for the amplifier.
     
    Last edited: Jan 24, 2020

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