Running amp without speaker cables connected

Discussion in 'Marshall Amps' started by hopkinwfg, Nov 24, 2019.

  1. MickeyJ

    MickeyJ Active Member

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    smoke, bad smells, loud crackling through the speaker, low volume, a bit of heat is ok. You'd know if there is a problem.
    Go ahead and enjoy your amp friend.
     
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  2. hopkinwfg

    hopkinwfg Active Member

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    Thanks Mickey !!! Thanks all the good people here !! :)
     
  3. Madfinger

    Madfinger Well-Known Member

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    I’d have to take the Darwin award on this one I think. The fuse in my Egnater blew so I replaced it with another but it was a lower amperage, then that blew...der, so then I wrapped some foil around the fuse thinking no worries she’ll be right mate this will sort it…but silence. I strummed a few chords, tweeked with a few knobs, strummed a few more chords….BANG-Crackle. I thought oh well maybe that wasn’t such a good idea so switched amp heads but still silence…WTF. Not wanting to fuck around and blow up the Orange as well I thought maybe I should check its not the cab ( 1x12 ) sure enough when I checked one of the wires to the speaker had broken and fallen off. I’m not 100% sure but I assume the series of events that led up to a catastrophic outcome was all started by a speaker not connected.
     
  4. Alter

    Alter Active Member

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    You can blow up the output transformer on both solid state and tube amps if turning them on and operating them without a speaker load, even without playing. So it's always a bad idea.

    That's the only thing I disliked about the Marshall Dsl-1 head, having to unplug the speaker to use the emulated headphone out. Problem waiting to happen..
     
  5. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    To understand and appreciate either tube or solid state amps then you have to understand the difference in how the speakers are connected to the amp.

    Tube amps use a what you guys call an OP transformer, what is it used for and how is it made?

    Solid state amps are connected to the speaker via a blocking capacitor, just think about that.

    It all very well listening to idol chat but to understand it properly is a different thing, that takes many many years of training and hands on experience.

    A lot of good Techs will just tell you what sounds good to impress the owner of an amp, that has just been repaird to soften the blow of his bill, some will tell it as it is, thats being going on for a very long time not only in amp repairs, but almost every thing else.

    All of this needs to be understood like Drive, as opposed to Driver, Primary as opposed to Secondary, its all very well quoting abbreviations but knowing what they stand for and mean is another thing entirely.
     
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  6. ampeq

    ampeq Well-Known Member

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    I think it depends on the amp as well. When I was first getting into tube amps I didn't know about speakers being plugged in was that important. My X100b combo took some serious shit for awhile, I would change speakers with it on, forget to plug in the cab, run a 4-12" cab along with the 1-12" speaker in it, all kinds of stupid stuff. Never had a problem, in fact that amp still works perfect and is still completely stock and original. Now fast forward to about 3 years ago, I go into a GC and see a Carvin V3 head, always wanted to see if they were any good. I looked over the amp, saw the speaker cord running out of the back, down to the floor and back up to the cab it was sitting on. So I grabbed a guitar and switched it on..... hmmmm that shouldn't smell like that? Within 15-20 seconds I had the smell of burnt wires and a little smoke trail, cooked it in a heartbeat! Come to find out the speaker wire went down to the floor and ANOTHER wire came back up... ut-oh. Funny note, a buddy of mine walked in and bought that amp for peanuts. He replaced my handy work and was happy. So, some will take it some won't.
     
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  7. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Driving it into an empty load will certainly make it unhappy, and it did, rule of thumb is never to assume, always check first
     
  8. Sustainium

    Sustainium Well-Known Member

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    DSL1H does NOT need to be connected to a speaker while using emulated output jack.
     
  9. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    Generally speaking, SS amps do not have an output transformer. I have done it many many times over the years witb SS anps, both PA and guitar. It's not a problem. There is no circuit completed with no speakers so no problem. DSL1 does not need a load either.
     
  10. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    I can only speak about the Randall RG-80 solid state combo I have. It's been left powered on, with no speaker attached for days at a time by one of my speaker builders (by accident). It suffered no damage.

    A tube power amp, on the other hand, is another matter. I've never done this by accident, but others have and most have fried their output transformer for having no load on it after a minute or two (Marshall designs from 60-80's).

    Maybe there is protection now for newer amp designs, but I've heard plenty of clients, and fellow players tell me about how they cooked their amp by having it on and left unplugged from a speaker/speaker cab.
     
  11. Alter

    Alter Active Member

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    About the Dsl 1 I knew it's safe to use the headphones without the speaker. However, knowing me, I'll often forget to connect the speaker back in when I'm done.. :(

    Solid state amps have no output transformers, but you can still potentially harm output capacitors or filter circuits, or just overheat the amp (especially D class amps which often are high power). Many current brands can handle it, but why not be safe. Plus once you get the habit, it's very easy to forget and by mistake use a tube amp that way too..

    May just be me having met Murphy's law too many times :)
     
    Last edited: Nov 26, 2019
  12. pedecamp

    pedecamp Well-Known Member

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    I have a solid state Gallien Krueger head and it's been about 30 years since I really sat down and used it but I'm pretty sure I used to plug headphones into it without a cab for quiet play.
     
  13. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Some very cocky answers here today.

    Plugging Can`s in is a load but you dont drive it as hard as having a speaker connected, so no problem there.

    Some of you guys fall into the category of a little knowledge is very dangerous, dont get above your selves guys.
     
  14. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    So do not run SS without a load? I have had that happen here and there over the years with stereo amps, PA, guitar etc and never had a problem. I have also researched it, in as much as I can, amd save for a few instances, it seems like this is not a problem at all. I do not have the knowledge nor experience that you have, thus the question.
    Can you enlighten us all Ken? Cheers
     
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  15. Dmann

    Dmann Well-Known Member

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    If you want the actual answer refer to the manual provided by the manufacturer for YOUR specific product, because there is no one answer that applies to every amplifier made.

    Otherwise always have a speaker load connected for peace of mind, which is what I'd recommend.
     
  16. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Well thats the most sensible answer to date, well done that man.

    Basically what you are saying is use your common sense, very wise.
     
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  17. SkyMonkey

    SkyMonkey Well-Known Member

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    A lot of folk on the MF have said SS with no load is fine. But no one can seem to explain why my VS65R started to smoke immediately when I accidentally switched it on with no load and the chassis out. I shut it off in time to save it.
     
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  18. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Proving a point that no matter what amp or what you have been told that do not take a chance of running your map without a load, always check first before you throw the mains switch.

    Think of your amp like a good women, treat her kind and get a nice return.

    You were lucky Mr SkyMonkey.
     
  19. d95err

    d95err Member

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    Regarding fuses, their main function is to protect agains short circuits. A big voltage spike would damage stuff in the amp long before any fuse will blow.

    Due to the indutive nature of transformers, voltage spikes can occur if there is no load present. However, they are even more likely to happen due to intermittent load, (disconnecting or connecting the speaker while playing). This can happen for example if the speaker cable is damaged, causing the connection to glitch as the cable moves.

    As I recall it, Kevin O'Connor once wrote that he had never seen an amp damaged by a mismatched load (e.g. 4 ohm output to 16 ohm cab), but dozens damaged by intermittent loads (e.g. by a glitchy speaker cable or jack).

    You can easily protect the amp against intermittent loads by putting a resistor across the speaker output jack terminals. Something like 270 ohms 5W should work for most amps. It won't affect tone and costs virtually nothing.
     
  20. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    As mentioned always follow the manual's instrunctions, notes and warnings.
    For good measures since most do not know the true design of any particular solid state output amplifier design, always connect a speaker/cabinet.

    As for ValveState amplifiers, Marshall does mention to always have a cabinet connected in one manual, the Pro 120/120 manual which is the only one that is not a combo with internal speaker.

    The valvestates have a fault at the output as far as I am concerned whether a safety feature or not. There is a parallel circuit for the speaker output with low voltage and wattage ratings. They are doomed to fail with no speaker load connected. If it shorts during melt down then poof, there goes the output amplifier.
     
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