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Switching between tube amps into one cab

Discussion in 'Amps and Cabs [BG]' started by Razman, Jul 16, 2014.

  1. Razman


    Feb 10, 2005
    Orange Park, FL
    So before roasting me over a fire please hear me out. And my disclaimer is that I already know what I would do, but here goes.

    My church has a theater where we put on concerts, etc. and we have two live bands, one metal group and the other is country. The metal band is the headlining act so our rigs (bass stack and two full guitar stacks) are set for their sound. When the country group goes on, they sound like a rock band (not undesirable IMO but YMMV). My friend, the country band's guitar player and main sound man wants to use his tube amps for both full stacks and switch between the metal band's amps and his when we both play on the same nights.

    He claims that many pros do this. I understand the risks of blowing up tube heads and don't want to do this (the metal band's amps belong to the church and aren't cheap). My preference would be to run our Marshall cabs in stereo and power one side of each top and bottom with one head, run two more mikes up to the FOH system, and we'll only have to turn them up a bit to compensate for any loss in volume. The 12's will act like a line array so that will help, and we won't have the complexity and inherent risks of switches failing, blowing up amps, etc.

    Thoughts or suggestions?
  2. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Hey, I'm with you on this one!

    Use one rig and let the bands deal with it. No sense in futzing around swapping components between acts. Heck, even the pros have to deal with rented backlines.

  3. I guarantee they aren't switching tube amps to "share" a cab or stack while powered up--if I understand his proposal. Perhaps he's seen bands that swapped heads around in between acts, when they weren't powered, or saw some other switching arrangement.

    Maybe a sketch of his proposal versus your proposal would help my understanding, my coffee has not kicked in yet.

    But IMHO multiple heads into one cab= very bad, bad idea. I'm with you.
  4. Meh. Unplug amp1, plug in amp2, everybody is happy, nothing blows up.
    will33, RickenBoogie, Remyd and 3 others like this.
  5. groovaholic

    groovaholic The louder the better. Supporting Member

    Sep 19, 2004
    Grand Rapids, MI
    Go with your gut -- it's leading you right in this instance.

    Tube amps running without a proper load connected have a tendency to fry output transformers.
  6. So much of this.

    Why do something stupid, to avoid 10 seconds of work?
    RickenBoogie likes this.
  7. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Not if you put them on standby. Still, I wouldn't do it, just because logistically it makes no sense.
  8. Shabz


    Jun 20, 2014
    Surely he just means to unplug his amps and plug the metal band's amps in?
    Obviously you'd turn them off first..
  9. johnpbass


    Feb 18, 2008
    Glen Mills, PA
    Yes Pros do that with amp switchers but they don't do it to accomodate band setups. It's actually done by many guitar players who use multiple amps switched on the fly to get different tones for different songs or parts of songs, like for example, Plexi for heavy crunch, Mesa Lone Star for "sweeter" lead parts, etc. And you need to make sure that you have everything connected properly and have a robust well made professional amp-switcher to avoid blowing up your amp collection.
  10. Not plugged into one cab though.
    johnpbass likes this.
  11. johnpbass


    Feb 18, 2008
    Glen Mills, PA
    True. Usually multiple cabs are usually part of the equation for different tones but you could, in theory, run one cab. For what the OP is talking about though, I wouldn't use a switcher that way.
  12. Woolber

    Woolber Supporting Member

    Sep 27, 2013
    Here's a link for a switch that will do the job safely and effectively. Not sure it would be worth spending the money unless this comes up a lot.

    chaosMK likes this.
  13. Running a tube amp without a load poses a risk to the amp. Even with a very well made switch and appropriate dummy loads, at the split second that the switch changes, the amp will become unloaded for a split second--the switch MUST be "break before make". That may cause an inductive transient which may be enough to spike through the OT and fry the amp, even with a well-made switch and dummy loads.

    Note that even experts have debated the risk to the OT. I've followed spirited discussions on this subject on other forums. Some guys go into great theory on whether the inductive spike can or cannot kill the OT, others claim "well I've run without a load for years and never damaged an OT" At the end of the day, though, there are folks who produce damaged OT's-- with the most likely culprit being a loss of load while under power. Even if it's only a remote possibility, the risk of frying an amp IMHO makes any discussion of switching a tube amp's load while powered on...well, not worth the risk.
  14. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Ampeg used to make a unit to do this in the SLM days called an Ampeg System Selector. It placed a dummy load on the tube amps when they were not selected. One model allowed you to select between eight heads and eight cabs.

    Other companies make amp switchers that route your signal to different amps or combination of amps.

    Bob Bradshaw, who makes pro switching systems has this product. It switches up to four amps, one at a time, into a single cabinet.
    johnpbass likes this.
  15. johnpbass


    Feb 18, 2008
    Glen Mills, PA
    As I said, I would not use a switcher for what the OP is talking about, and I'm not by any stretch an expert on bulding a switching system, but I would expect that the guys who build professional level switchers have taken dummy loads, etc. into consideration. Otherwise, Joe Bonamassa would have blown up his stage rigs by now. Unless I'm missing something in how these guys are setting up and using their rigs.
  16. johnpbass


    Feb 18, 2008
    Glen Mills, PA
    I remember that unit. Our local mom and pop store had one so you could try different amp/cab combinations.
  17. Razman


    Feb 10, 2005
    Orange Park, FL
    Thanks for all the great input so far, and to you TB SME’s for chiming in.

    Some more info that was implied but not spelled out in my additional post (I hate trying to type long posts on a phone/tablet): our stage is static, meaning that we don’t move gear around, neither do we have room to do so – most we’ll have during a show is two bands, so really no need for all that fuss. But I get it that the band needs a different sound and less volume. It’s easier to put yourself into your playing when you are using what you’re used to. However, my friend is set on this idea b/c as Johnpbass has indicated, he’s seen some artists with one cab and 2/3 heads stacked on top for that reason – getting different sounds/tones out of the rig w/o bringing multiple cabs. I also know he doesn’t want to compromise the tone of the entire stack.

    My issue is that I don’t want to introduce unnecessary risk to the equipment (church’s or his) and keep it as simple as possible. Any time you introduce complexity to a system that requires human intervention you will have problems eventually. Our other guitarists are not as tech savvy – the thought of them having to coordinate the engagement of standby and cab switches on a dark stage horrifies me. I just want them to focus on hitting notes, hot licks and keeping time with the drummer! And I definitely don’t want someone screaming my name when our $2K Mesa Stiletto starts smoking because one of them didn’t hit the switch in the right order.

    Thanks for the link to the Headbone, that’s good to know – I’ll present that info to my friend. I’ll also inform him that we’ll need junction boxes to combine each half of the cabs together, in addition to more speaker cables. The cost alone is prohibitive at this time, never mind the additional complexity which is enough to kill that idea for me. More than likely we’ll try the less-complex option of just running our cabs in stereo. I’m making some speaker cables from components we already have, all we need are a couple more mikes (don’t think we have any SM57’s lying around though), mike cables and stands. I don’t understand his aversion to this approach.

    Thanks again to all, I’ll post updates as they come.
  18. Switching tones mid song is one thing. Switching amps between sets is another.

    I would avoid the asshattery and potential damage to equipment, and just plug in a different amp between sets. Tight stage or no, it takes 10 seconds, and is worth a lot, when frying your amp (or amps for that matter) is on the line.
    johnpbass likes this.
  19. johnpbass


    Feb 18, 2008
    Glen Mills, PA
    Agree with CL400. Again, if it were me, I would not use a switcher for what your guitar player is talking about doing. Easier and safer to have the two sets of rigs up there, turn one off, turn the other on when switching bands.
  20. Far out.

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