tube amp load and speaker cable question

Discussion in 'Cabinets & Speakers' started by rhoads_30, Apr 10, 2014.

  1. rhoads_30

    rhoads_30 New Member

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    Alright. Kind of new to tube amps and not quite sure of all the dangers of running tube amps with no load. Hopefully someone can help explain and answer my questions. I was playing through my jet city jca20h plugged into my marshall 1960b 4x12 cab. I have my amp against my music room wall with just a little bit of room behind it to be able to access the cables and plug in the power cable. I was playing at about 11 or 11:30 last night at a more quiet level and our cat somehow got behind my amps and got tangled up in the speaker cable running from the head to the cab and pulled it partially out of the cab. As I was playing the sound suddenly went dim but never all the way out. As soon as I noticed the change in sound I hit my kill switch on my guitar and ran to the amp to see what was going on! As I looked behind the amp our cat was trying to free herself from being tangled in the cable and by this time the cable came all the way out and she scurried away. I quickly plugged it back in and put my amp in standby. Ive tested it out last night and this evening and nothing seems to be wrong and still plays. Nothing ever blew out or smoked or was overly hot but im just really paranoid about that I may have done something to my setup. Like I said I got to test it a little bit this evening but cant come to a conclusion if it sounds the same or not. Hopefully someone can help out! Thanks!
     
  2. rhoads_30

    rhoads_30 New Member

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    *Hopefully someone can help out to determine if I have done any damage! Thanks!*
     
  3. anitoli

    anitoli Well-Known Member

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    If everything is working as normal you're prolly ok. If you had the amp cranked when this happened that could be different. The low volume saved the day. :yesway:

    Now about that cat.......:D
     
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  4. Micky

    Micky Well-Known Member VIP Member

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    You got lucky...

    Reminds me of this though...

    [ame=http://www.youtube.com/watch?v=PJW3Jpqjx5s]National Lampoon Christmas Vacation FRIED CAT scene - YouTube[/ame]
     
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  5. Ken

    Ken Well-Known Member

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    A couple suggestions:

    When playing your guitar and the sound abruptly changes or stops, put the amp on standby IMMEDIATELY. A kill switch on the guitar is only going to kill the amp.

    NEVER run a tube amp with no load. That's how they die, often in spectacular fashion.

    Hopefully you're using a quality speaker cable and not a guitar cable? If you were using a guitar cable it likely got quite hot and that may have attracted the cat! BTW it's always a good idea to keep the cabinet several inches from the wall. If it's on casters, it's possible the wall will disconnect/damage the cable end if it rubs against it, cat issues not withstanding.

    Your amp is likely fine, but like anitoli said, the low volume might have saved it.

    Ken
     
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  6. soundboy57

    soundboy57 Well-Known Member

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    If it still works, it still works. You are OK.

    How many more times are you going to let your cat in the same room with your gear?
    Once would be enough for me, just sayin':D
     
  7. Jucciz

    Jucciz New Member

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    Tube amps can actually tolerate surprisingly large amounts of misuse. Marshalls are a bit more notorious for their blown up transformers than, say, Fender... but more than once I have accidentally run my amps of different brands with mismatched or no speaker load at all - and nothing has blown up so far.

    Usually when powering up a tube amp I do, however, start with a very low volume level - and when I hear something coming out of the speaker cabinet, I know I'm on the safe side, the connections are good and the amp is ready to rock.

    Should the speaker cable get disconnected while the amp is running flat out, I probably would notice it in a fraction of a second, stop playing immediately and re-check the connections (if there's no smoke or bad smell already in the air). With a little luck, nothing would blow up even in this scenario. I still don't recommend trying it though...

    Your amp is most probably fine - and so is your cat. ;)
     
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  8. rhoads_30

    rhoads_30 New Member

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    Thank you all for your responses! I was using monster brand speaker cable. And no smoke no hot smell. Nothing happened except a change in the loudness from the cable coming partially out. And yes the cat will no longer be in the room haha. Everthing still seems to be ok. If something was wrong when that happened would I notice subtle changes in sound like when im playing now. Is there signs I should look for or would it have just instantly blown up?
     
  9. keennay

    keennay Well-Known Member

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    The cat must be disciplined.
     
  10. Ken

    Ken Well-Known Member

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    While an OT can die in stages, this isn't common and chances are if it sounds okay it's okay. While we rail on about avoideing mismatches for good reason, it's not like shorting the output of a SS amp which will fry it in milliseconds. A few seconds of no load at limited volume should be okay.

    Ken
     
  11. tubes

    tubes Well-Known Member

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    Welcome rhoads. Quite a story there. We should never under-estimate the influence of cats!

    No smoke is good.
    As Ken suggested - you escaped without harm this time...

    I'm going with SMOKE again,
     
  12. damienbeale

    damienbeale Well-Known Member

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    If something was wrong and partial damage had occurred to the OT, you might not notice anything different. I really wouldn't worry about it though. It's neither something you can do anything about, nor is it something likely to rear its ugly head short of a similar recurring event.

    Forget about it, move on, and enjoy.
     
  13. Webslinger

    Webslinger Member

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    I was at a garage rehearsal about 7 years ago, where an amp ran no load for at least five minutes, and nothing seemed to blow? Dont remember the manufacturer, but it was an old 70's era no-name head into some generic cabinet. It was powered-up about 5 minutes, we started to play, ...no sound?
    Powered it off, spun it around.... speaker cord unplugged, and I could see tubes inside the head. I figured, thats the end of THAT! The guy who owned it (a drummer who didnt play guitar) just pluged it back-in, swithced it on and it was fine? Go figure....
     
  14. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    If no AC signal is present in the power stage then there is not a problem.
    But it is best not to chance it.
     
  15. Ken

    Ken Well-Known Member

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    That's like a disease with no symptoms! LOL But true: if a few coils shorted to each other close together, it could still be working okay because most of the coil remains functioning. Or if a little insulation burned off it might not even be shorting if you're lucky.

    Ken
     

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