How does a tube amp work?

Discussion in 'Tube Audio' started by BmWr75, May 15, 2012.

  1. Salguod

    Salguod Member

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    Sorry about my post! Don't want to trash the thread.
     
  2. doctor fuse

    doctor fuse Active Member

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    Edited
     
    Last edited: Nov 7, 2016
  3. Dandy

    Dandy Super Member

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    Doc fuse, this sticky is for posts explaining how tube amps work, not repair queries. You'll probably get a better response if you post the query as a new thread.
     
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  4. -Bobo-

    -Bobo- Member

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    I didn`t want to open another thread so i just decided to ask here.
    What is the difference in power between a Tube amp and a SS one, i`ve seen alot of people using tube apms 2x25 watts to power speakers that require 100watts to run properly?
     
  5. Gary Mattis

    Gary Mattis Active Member

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    It's just an electron theory , no one has actually seen them !
     
  6. Gary Mattis

    Gary Mattis Active Member

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    The inputs connected to the pre amp , the pre amps connected to the volume , the volumes connected to the tone, the tones connected to the splitter , the splitters connected to the output tubes, the output tubes are connected to the output transformers and then they go to the speakers and then your ears and it's all powered by a AC transformer, Capacitors, rectifier, resisters and by a on off switch !. A signal chain with multiplication action or what we call amplification !
     
    Last edited: Jan 16, 2017
  7. GordonW

    GordonW Speakerfixer Subscriber

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    This is, mind you, a pretty gross generalization- but, generally, tube amps do have the ability to be run closer to clipping, without the histrionics that can plague solid state amps, approaching clipping.

    This is, primarily, due to the fact that most tube amps use far less global feedback than solid state amps- and therefore, have much less problems with the feedback causing unwanted effects near clipping (increased higher-order harmonics, non-harmonic overtones, latch-up and the like).

    So, while you might not want to ever run many solid state amps at over 50% of max output- a tube amp can frequently be run up to 90%+ of output before clipping, and still sound pretty much just as good as they do at lower volume levels. So, a smaller tube amp will do.

    Also, due to the peak transient levels in music (20+dB over steady state level, in many cases)- if you're running into a situation where you're momentarily clipping the amp on a peak (which happens all the time)- a typical tube amp will generally do those momentary-clipping transients more gracefully than a typical solid state amp.

    Also, consider this- a 25 watt amp is only 6dB less loud than a 100w amp. It takes 10dB to subjectively appear twice as loud, to the human ear. So, it's not like more power gets you more volume level, very quickly, either. So, if you have a 25 watt amp which you can "use" to 24 watts, vs. a 100w amp that you can only "use" up to 50- that's only 3dB difference. Not that much perceived volume difference at all...

    Regards,
    Gordon.
     
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  8. -Bobo-

    -Bobo- Member

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    GordonW Thank you for giving me an answer.
     
  9. Gary Mattis

    Gary Mattis Active Member

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    Interesting explanation there tube vs. transistor , lately I have worked on a few Geranium transistor Amplifier's and to me they seem to sound pretty good overall compared to most transistor Amplifier's. I'm a tube amplifier man myself but I must admit that the Geranium transistor Amplifier's don't sound that bad . I run at home a stereo 6V6 / 5U4B / 12AU7 power amp with no tone or volume at full output nfb with a mixer that controls it , My speakers can take full volume so I can turn off the EQ mixer if I want to, it sounds great both ways ! . A friend of mine James Henderson - James Audio FT.Worth TX. (RIP) built this Amplifier for me , he said I could disconnect the nfb if I wanted to if I didn't like it with it , I left it alone because it sounds great , is there any advantages to removing the nfb ? . Most Amplifier's use nfb even in guitar Amplifier's . I was wondering why I can get away with it playing up at full volume sence 90 percent is the normal ? . I had a MIG Lead 100 guitar amplifier EL 34 that put out 130 watts through a Marshall 300 watt Celeston cab , 580 plate volts and -80 bias volts , it was a hell of a lot louder than any 25 watt amplifier ! At 3 volume it could eat up any 30 watt speakers in less then 20 minutes ! But what a great sounding 20 minutes !
     
    Last edited: Jan 29, 2017
  10. jokerman

    jokerman New Member

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    I have a question I have been wanting to ask someone about my tube preamp and this thread is a good place. I have a Dared MC-7P tube preamp that has the following tubes:

    (2) 12ax7 phono stage
    (1) 12aT7 and (1) 12AX7 line output
    several other tubes that I assume are for power stage

    I recently bought an upgraded external phono stage that I plugged into one of line inputs. I notice that the phono quality is still changed by rolling tubes in the Dared preamp phono stage sockets. If you remove any tube from the Dared it powers off so I assume that the power goes through all the tube sockets. Does the sound also go through the phono stage sockets if it comes in through the line inputs? It would be great to take the 2 expensive Mullard 12AX7s that I currentlyhave in the Dared preamp and put them in the new phono stage but have felt like I dont understand how things are working. Any advice is appreciated!
     
  11. danielhaden

    danielhaden New Member

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    The devices aren't nearly as different as the approach. In my view, the differences are apparent at the power supply style and the clipping pattern output. Please continue to avoid using watts as a quality/relevance measure.
     
  12. sunrayjack12

    sunrayjack12 AK Subscriber Subscriber

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    I am just thankful they do work, my solid state days are over.
    It is always good to have a decent working knowledge about any equipment you own.
    One thing for certain, the guy's on this forum have enough knowledge to help with any problem that may arise.:jump:
     
  13. RobRob

    RobRob New Member

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  14. Dswankey

    Dswankey Super Member

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    ^ Welcome to the forum!, I'm assuming your Rob Robinette?
     
  15. RobRob

    RobRob New Member

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    Yes, I'm Rob Robinette (robrob on many tube amp forums). I've been buying vintage audio gear lately and audiokarma seems to be THE source for good info. I'm in the process of picking up a Techniques SL-1610 turntable from craigslist to go with my Marantz 4400 receiver. I also have a 1979 Sansui BA-2000 I purchased new from the Camp Casey Korea BX. I recently replaced the CA-2000 preamp and matching tuner I lost many years ago.
     
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  16. opnly bafld

    opnly bafld AK Subscriber Subscriber

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    What does that even mean?
    Who decides what power is needed to allow speakers to "run properly"?
     
  17. SPL db

    SPL db It's all about the music! Subscriber

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  18. finom1

    finom1 New Member

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    I found this video was helpful to me:Tube Amp Grounded Heater test
    This helped me, I hope it helps someone else.
     
  19. RobRob

    RobRob New Member

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    This is an old video I edited down to three minutes and annotated to make it more understandable:

     
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