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Running amp without speakers? Good idea?

Discussion in 'Amps and Cabs [BG]' started by bozha, Jun 20, 2009.

  1. bozha


    Jun 5, 2008
    There is no way I can often use couple hundred watts amp+cabinet for practicing in my apartment. But still, I plan to use amp head DI for home recording and practicing with my headphones.

    Is it absolutely necessary to connect speaker load prior turning the amp on? It’s a hybrid type of amp (Hartke LH500), and I found few opposite opinions, but I need to be sure, not to risk or damage anything.

    Also, if I have to carry that heavy box up and down regularly, is it at least possible to keep it turned down silent all the time when practicing? Still don't want to try my chances with overheating and such…

    many thanks!
  2. RWP


    Jul 1, 2006
    Running an amp with tube finals is a huge NO NO. Without a load, voltages on the secondary of the output transformer can get so high they can arc and damage the transformer.

    However, your amp has a solid state final and as long as you have head phones plugged in you are OK. Even without head phones plugged in it would probably be OK as most modern amps have open circuit protection built into the design. I would just make sure you run it with the head phones plugged in and not any louder than necessary.
  3. bozha


    Jun 5, 2008
    It’s a bit of enigma with solid state final stage. Wish there is one definite answer…

    Consider that this amp don’t have dedicated headphone output. Only DI for the mixer, which I plan to use. DI signal is not affected by EQ and master volume.
  4. bmc


    Nov 15, 2003
    Drop $60-80 on a small Behringer 4 channel mixer, or similar cheap unit. They work great. Bought one for my daughter three years ago. I use it now.
  5. B-string

    B-string Supporting Member

    Solid State outputs do not require a load, with no load no current is drawn so it will run happy with no load (speaker) connected. Tube amps a very different story you will need a load resistor twice it's reated output (just to be safe) and it will get hot so beaware of the fire danger. I have not seen a output transformer on a SS amp since the early 1960's so no worries there.
  6. No enigma.........

    You DO NOT need to be running a load on the amp.
  7. BassmanPaul

    BassmanPaul Inactive

    There IS!

    Running a SS amp that has no output transformer without a load, the vast majority, is perfectly acceptable. The amp will be quite happy working that way.

    If you have a tube output stage then you mUST supply the amplifier with a suitable load.

    There y' go.

  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    There is. Direct coupled SS power amps do not need a load.
  9. bozha


    Jun 5, 2008
    I just got the same confirmation from Hartke customer service. This one is definitely solved.

    Thank You all for answering!
  10. JTE

    JTE Supporting Member

    Mar 12, 2008
    Central Illinois, USA
    To reiterate...

    If it's a SS power amp that's direct coupled, then you don't need a load on the amp. If it's a tube amp, you MUST have a load on it.

    At one Gallien/Krueger (or GMT) advertised amps that were apparently solid state amps with output transformers (way back in the dim dark days of information- I saw some ads in Guitar Player for them, and this was years and years before there were any bass rags). That's the only one I don't know about, but I'd assume that the output transformer needed a load on it.

  11. bovril


    Nov 16, 2008
    Hey, I just recently got a SVT and being my first tube amp, I was sure to learn all about proper use and was super anal about evertying, etc, only to come down the next day, fire it up, and try to play, and- nothing. I freak out, only to realize for some reason its not plugged into the cab. Did I do that? Why would I do that? No matter now, so I freak out more and turn it off. Give it a few minutes to recover, plug in and turn on again, and it seemed ok. Is it more likely that I got away with one or is there surely horrible damage that I dont know about yet? It was on for maybe 3 minutes with no cab...:rollno:
  12. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    You probably got away with one. I wouldn't do it again.
  13. Running it for a minute without a load won't destroy it instantly. It's happened before, and it will happen again. Just try not to let it happen too much.
  14. akaTRENT


    Jan 10, 2009
    New Jersey
    I actually just did this by accident about 2 hours ago. I had my svt in standby for a minute and then realized there was no speaker load. But you dont have to worry when the amps on standby?
  15. B-string

    B-string Supporting Member

    If the amp is in standby you have no worries, no high voltage to the output tubes or output transformer.
  16. akaTRENT


    Jan 10, 2009
    New Jersey
    Phew! Thanks
  17. Hmm...My hartke won't turn on without a speaker plugged into it.
  18. BassmanPaul

    BassmanPaul Inactive


  19. HA 2500

  20. wallybill


    Apr 4, 2007
    Tuscola, Il.
    My B15 has to have the speaker plugged in or it stays in stand-by.
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    Apr 19, 2021

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