Wattage Differance Between Tube and SS

Discussion in 'Amps and Cabs [BG]' started by skypn, Jul 24, 2018.

  1. skypn


    Feb 8, 2011
    It seems to me, and I may be wrong, but tube power amps seem louder at lower wattage than solid state.
    What wattage tube amp would be equal to a solid state rated 400w @ 8ohm?
    Note: I was once told that the only stupid question is one you ask of someone of whom you already know doesn't know the answer :)
    bobyoung53 likes this.
  2. primusfan1989


    Jan 17, 2005
    new jersey
    There is no difference from what Ive found. What I have found is a lot of companies fudge the power ratings.
    pcake, JRA, RobertUI and 3 others like this.
  3. mmbongo

    mmbongo I have too many basses. Supporting Member

    What you are probably hearing is that the master volume pot maxes out earlier on the tube amp. So if you set both of them at 'halfway' to compare, the tube amp may be louder, but it's done. It can't do any more. But the other amp is only truly halfway up and you've got a whole other range of volume left to worth with.
    HeavyBass likes this.
  4. Roland GR 88

    Roland GR 88 Commercial User

    Sep 16, 2013
    Ontario Canada
    Retail store manager
    Tube amps can be driven well above their power rating, compressing and/or distorting the signal in pleasing harmonic ways. SS amps distort quickly when driven past their maximum and the signal doesn't compress, it just gets it's peaks chopped off and the resulting distortion is not so pleasant.
    Speaker sensitivity plays a huge role too and can't be discounted.
    squarewave, C_Becker, dfoehr and 16 others like this.
  5. skypn


    Feb 8, 2011
    Thx for the help.
  6. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    That is true, with the caveat that power ratings are extremely subjective and very hard to nail down as to how that that wattage rating transitions to "loudness." That is a whole can of worms. Then there is the whole ohms thing.
    The general consensus is that an SVT-CL, which is rated @ 300w, is supposedly one of the loudest amps around, even though there are many class D amps that have higher ratings. Part of this discrepancy is that you can push tubes a lot harder and sound better when pushed. IMO, and that of many others, is that SS amps start sounding terrible when they start to clip.
    There is a lot of black magic involved, including marketing BS, but painting with the broadest possible brush, one might be able to say that there is a 2:1 ratio of SS watts to tube watts. That is based on nothing.
    HeavyBass, eff-clef and bobyoung53 like this.
  7. lfmn16

    lfmn16 Inactive

    Sep 21, 2011
    charles town, wv
    Maybe the way to think of it is 'usable' watts. Just a thought.
    dbsfgyd1 and dfoehr like this.
  8. bobyoung53

    bobyoung53 Supporting Member

    Tube amps get thicker sounding above their distortion point, SS amps don't and usually sound ratty above their distortion point, feel free to use my technical analysis anytime without attribution.
  9. Because you can push tube amps into the 'red' (i.e. distortion) and they still sound good, you can get more perceived, consistent volume from a tube amp than SS. You never want your SS amp to clip (distort), because most of the time it will sound awful, whereas a tube amp will distort 'gracefully' and you can use (many players even desire) the extremes of the amp's operating parameters.

    It's my understanding that when you push a tube amp close to it's volume limit, lots of complicated things start happening with distortion, compression & harmonics, which mean that you perceive a higher volume from the amp, even if the Actual Power Coming Out Of The Speakers is only whatever the amp is rated to.

    As has been stated above, when you push a SS amp hard enough to clip, the signal just hits a brick wall and starts distorting nastily, so most people avoid it.

    I used to hear a lot that 'tube watts = SS watts x3', so a 100w tube amp would put out the same power as a 300w SS amp. Scientifically that makes little sense, but it's a good rule of thumb for how loud things sound/feel in the real world.

    I hadn't heard that you can actually squeeze more than 300W of power out of a 300W tube amp though - is that true?
    basscapes and Gearhead17 like this.
  10. This might be a long thread. With tube amps, it's really hard to lie about your wattage because the tube number and type and output transformer/s and your bias settings have to be of certain measurement to support your wattage claims.

    Also you can routinely crank a tube amp to maximum. I think Fryette support in another forum, told that tubes run cooler when there is more load. I need to get a quote on that directly.

    With solid state , pre Class D, I actually like how the power section sounded, when working hard but when pushed hard, you can get into thermal shutdown situation also. Maybe Peaveys and old Acoustics are the exception but I am wary of pushing the GKs and SWRs that I have/had

    That is why I think even though watts is watts, I always think SS for the safety margin , should be double the wattage of a tube amp, to get your work done.

    Class D. They have too much power. I do not have experience how hard you can push a class D amp. My Carvin B1000 can power my loudest cabs insanely loud and I am not past 6 on the dial.

    I like/love tube amps. Even if they are heavy and less watt per lb.
    Kro likes this.
  11. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    This debate will rage on. Short version is that there is no formula. There is no ratio that works every (or even most of the) time.

    Probably a better discussion would be to describe your needs and ask for suggestions for a tube amp that might meet those needs.

    Good luck with this. Short of nuclear war, nothing will bed down the monster you have unwittingly released. :D
  12. seamonkey


    Aug 6, 2004
    A watt is a watt
    Work done is the same for the same rating.
    Every SS amp designer now alive knows that limits will get pushed on an amp, and they should account for it.
    For example, FOH SS amps always get pushed into the red and nobody goes screaming and running to the hills.
    JimChjones and adk teleman like this.
  13. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    But only for the fourth time this week.
  14. Wasnex


    Dec 25, 2011
    I have a basement full of tube and solid state amps. The perceived loudness they produce relates directly to the amount of watts the amps put out. Watts are Watts. The controls on the amps are not calibrated to produce full power when the volume control is at its maximum setting. Many amps reach full clean power with the volume control around 30-40%.

    IMHO the biggest difference between tube and solid state is the way they overload. Tube amps tend to compress and then ease into overdrive. Many tube amps can be pushed significantly above their power ratings and they will still produce nice distorted but musical output.

    Many solid state amps remain clean and punchy until they hit their limit. Pushing many solid state amps louder produces a nasty unmusical distortion.

    These are generalities and there are exceptions among tube and solid state amps that do not meet these descriptions. Some tube amps don't sound that great when pushed into distortion and some solid state amps do.
    Last edited: Jul 25, 2018
    HeavyBass, baxter_x and rickdog like this.
  15. higain617


    Sep 12, 2013
    I can't really explain the physics behind it, but my 150w tube amp seemed louder than my 575w solid state amp.
    bobyoung53, eff-clef and SactoBass like this.
  16. micguy


    May 17, 2011
    The notes you play have short peaks and longer sustained sections to them - it's not completely that simple, but for the purposes here, it's close enough. Tube amps tend to clip more gracefully than solid state ones - you can drive the peaks harder into clipping (overload) with a tube amp than with a solid state one and get away with it. Thus, if the continuous power you're demanding of an amp is, say 50 watts on the continuous parts of the notes, and the peaks are 10 times that (500 watts) if passed cleanly, you'd probably want a 500 watt solid state amp, but could get away with less (maybe 200 watts) with a tube one.
    el murdoque, RaggaDruida and ThisBass like this.
  17. gricko


    Mar 29, 2004
    watt [W] is a unit of power. volts multiplied by amperes. 1V x 1A = 1W. it is not a unit of loudness.
    not every watts is 'watts'. for example - ampeg svt vr is declared to have power output of continuous 300 watts with THD <5%. and the power output of most tube amps is declared that way. some amplifiers' declared power output is not of continuous power but of peak power. with higher THD... could be.

    a question for an engineer: is there a perceptible loudness difference between two amplifiers that have the same power rating but one have harmonically richer output?
  18. The_Janitor


    Jun 30, 2012
    Madison, Wi
    Yes, it's true. The 300W rating of an SVT is specifically the amount of power it can put out, over a sustained period of time at or below 5% total harmonic distortion. Ampeg was designed to be clean and loud, the founder of the company hated distortion. If you push the input gain high enough or get the power section loud enough, you'll go above 300W, with added distortion/clipping. So, the SVT can do 300W "Clean" but if you push it into distorted territory it can put out a fair amount more than 300W.
  19. Lance Bunyon

    Lance Bunyon

    Jul 17, 2018
    The concept of the watt was derived in 1882, long before the first bass amp was engineered.
    It's an outmoded and fairly useless measurement for deciding which bass amp into which cab will be louder.
  20. ThisBass


    Aug 29, 2012
    As @micguy very nicely explained with his post #16, yes it is.

    And as an impressing natural property of musiacal signals its (almost always) not possible to get all of the (rated) watts. It depneds on the designers goals about the way an amplifier deals with "short peaks and longer sustained sections to them" but, in my experince Jeff Average don't wants to turn the volume knob above 1/4 of rated power cause the signal might sound way to dirty versus his default sound goals.