Twinolux into 8ohm Rockcrusher

Discussion in 'Amps and Cabs' started by jmfreeland, Feb 22, 2015.

  1. jmfreeland

    jmfreeland Member

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    I remember reading that one could run an amp into a higher load than spec but not lower, but I'm out of my element on these questions. I got a great deal on a Twinolux, and I run everything else through a Rockcrusher, which only has an 8 and 16ohm load setting. Will I be asking for trouble if I run this guy into an 8ohm load or should that be fine?
     
  2. IM4Tone

    IM4Tone Member

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    Most electronics experts tell you 1 step up and 1 step down mismatches will do no harm, but there's another issue here. One pair of speakers @ 4 ohms and one pair @ 8 ohms will give a 2 to 1 power distribution imbalance which will give unbalanced volumes (assuming the speakers' sensitivities are the same). Volumes won't be 2 to 1, but in all likelihood will be fairly noticeable.

    I personally never mismatch impedances of amp to load. Here's a device that eliminates that issue:
    https://taweber.powweb.com/store/zmatch.htm

    EDIT: If the Twinolux is 4 ohms internal speaker load with an external jack (in parallel) for another 4 ohm load, then it is safe to run a total load of 2 ohms. If you run the internal speakers (4 ohms) with the external cab of 8 ohms, that would yield a total impedance seen by the amp of 8/3 or 2.7. Surely this would be safe, being between the 2 an 4 ohms, so try it to see if you like it. If you were wanting to disconnect the internal 4 ohm speaker and run the extension only (8 ohms) then what I stated above applies.
     
    Last edited: Feb 22, 2015
  3. jmfreeland

    jmfreeland Member

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    Yeah, the impedance matcher be kind of where my head is right now, but always welcome expert advice!
     
    Last edited: Feb 22, 2015
  4. IM4Tone

    IM4Tone Member

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    OP, note my edit
     
  5. SteveO

    SteveO Member

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    This applies to solid state amps. Go below the rated impedance load and components in the amp overheat and eventually fail. Tube amps are generally safe in a one-step mismatch in either direction, as already noted above. Some tube amps, however, are extremely sensitive to impedance mismatches and this should be avoided with them.
     
  6. jmfreeland

    jmfreeland Member

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    Thanks, I will probably just buy the Zmatch and be done with it, but I did contact Fender to see what they have to say, as the inside of the amp says a 4Ohm minimum load, which is quite vague.
     
  7. IM4Tone

    IM4Tone Member

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    Yes, Fender is quite confusing on all of their tube amp impedance instructions. I've been through this and there are several other threads here on the topic (but regarding other Fender tube models). If the Twinolux has an internal speaker load of 4 ohms and an additional external speaker jack, ANY added external cab will bring the total load below 4 ohms....so that makes no sense. Good luck getting to the right person @ Fender to answer your question. Some (non-tech customer svc. personnel) will just parrot the 4 ohm min. statement which is obviously in need of further clarification.

    The techs at Weber could probably give you a better answer including the best way to configure the Z matcher with the Twinolux.
     
  8. jmfreeland

    jmfreeland Member

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    I'm going to try Mercury magnetics as well, as they make the custom trannies.
     
  9. IM4Tone

    IM4Tone Member

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    Good idea!
     
  10. jmfreeland

    jmfreeland Member

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    Mercury said going up in impedance to 8ohm would be fine. I think I will take their word for it. Amp already shipped, so can't wait.
     
  11. IM4Tone

    IM4Tone Member

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    Good luck. Let us know how it sounds.
     
  12. Dad love mom

    Dad love mom Supporting Member

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    I don't believe the Twinolux has an disconnectable speaker jack.
     
  13. IM4Tone

    IM4Tone Member

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  14. Dad love mom

    Dad love mom Supporting Member

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  15. IM4Tone

    IM4Tone Member

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    I guess jmfreeland will be able to tell us the facts soon.
    I don't think Fender lies in their specs. but they do seem to have some incorrect or misleading info. there all too often.
     
  16. Dad love mom

    Dad love mom Supporting Member

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    :jo I own the amp. It doesn't have a disconnect jack for the speaker. :wave

    Could you imagine if Fender did allow users to switch speakers? How many warranty-related calls would they receive for some ding-dong not following the rules for amp ohms and the like when using the attenuator knob? I'm quite sure Fender didn't include a speaker jack to protect users and their bottom-line.
     
  17. IM4Tone

    IM4Tone Member

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    :waiting Why didn't you say that to start with?
    Yes, the impedance issue in light of the attenuation feature(s) puzzled me.
     
  18. Dad love mom

    Dad love mom Supporting Member

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    I was trying to assert my knowledge on the matter by stating "they're either lying or it's a misprint."

    I wish it were not that way. I'd love to play my EC Vibro Champ through the 2x12 Alnicos.
     
  19. Dad love mom

    Dad love mom Supporting Member

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    The amp is running at 4 ohms at full power, 4 ohms at 20 watts and two speakers, and 8 ohms at 20 watts and one speaker. I'm guessing when the amp is clicked to the single speaker, half-power mode that the load of the 8 ohm speaker is sent to an 8 ohm tap from the output transformer. :tapedshut
     
  20. IM4Tone

    IM4Tone Member

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    You have both the EC Twinolux and the EC Vibro Champ? :aok
     

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