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400w all valve amp is too much to play small gigs??

Discussion in 'Amps and Cabs [BG]' started by panazza, Jan 15, 2004.


  1. panazza

    panazza

    Nov 23, 2003
    italy
    hi
    I tried this marshall amp at the shop and it's very nice but it's an all valve 400w amp.... I'd like to buy it but I am worried about playing small gigs... surely it will be ok playing outdoor venues but what about playing in small clubs?? for small clubs I mean smaller than 1000 sq feet........!! what if I couldn't raise the volume enough to make it play good?? will the soundguys always tell me "less volume,please!" ??I need something reliable... but this amp really sounds cool... it's a vba400 head with 4 x 12'
    so... should I buy it or it's better buying a hybrid head with a mosfet power amp??
     
  2. Get the amp YOU like and the soundguys can get over it. The amp isn't going to sound any worse turned down. The idea that tube amps have to be cranked to sound good isn't true with most modern amps, especially bass amps. Most guitar players only say that their amps only sound good played loud because they're deaf and that's the only way they can hear themselves.
     
  3. I agree. That´s the thing I most hate in guitarists - that constant whining about sound not "opening up" when you ask them to turn it down.
     
  4. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    I disagree. If a tube amp is turned down too low before the power tube saturation kicks in, it's not gonna sound the greatest. But you can pull power tubes so that the tubes will saturate sooner.
     
  5. 20db pad

    20db pad

    Feb 11, 2003
    I been everywhere, man...
    None. At all.

    FWIW, I'd take the word of a PBG, who has been repairing tube amps for over 15 years - longer than some TB posters have been alive.;)
     
  6. tkarter

    tkarter

    Jan 1, 2003
    kansas
    IMHO

    Tubes work consistent after warm.

    Transistors do the same thing until too hot.

    Should be able to turn enough knobs to make it sound good at lower settings but it will change with time with power applied.

    tk
     
  7. Lockout

    Lockout

    Dec 24, 2002
    Illinois
    I use my 400w Aguilar tube poweramp at home as well as for practices/gigs, and it sounds fine in both situations, even when playing very quiet.

    The volume knob is there for a reason. ;)
     
  8. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Take whosever word you want. I'm speaking from my limited experience. My sound requires the sound of overdriven powertubes (Think Live at Leeds). Thats why I have a low wattage tube head (Fender Bassman 135). I wouldn't want an SVT because they're harder to break than virgins, and once they do break up, they're way to loud for my purposes. YMMV however.
     
  9. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    my question is, would you wanna drag a huge mofo of a tube amp to a small gig like that?

    i guess some guys do, but i'd rather just sling a Mesa Walkabout or my Acoustic Image Clarus on my shoulder and go.
     
  10. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Yep, that's what the fender bassman 100 or 135 are for!:cool:
     
  11. Niskamies

    Niskamies

    Jan 13, 2004
    I've played a Ampeg SVT 300 watt tube head with the 8*10 cab, and it worked well even with smaller volumes. Of course it sounds better when you get the slight tube overdrive, but it sounded perfect to my ears when gain and master were at nine o'clock, and the volume was alright on a small gig.
     
  12. "Power tube saturation" is a frequently misused term to describe output stage compression. Power tubes themselves do NOT "saturate." They are voltage amplifiers that are either "on" or "off" (or shorted if you exceed their ratings.) That is a function of the output transformer, which turns voltage peaks above its rating into heat and literally compresses the sound mechanically. This is the most common form in large bass amps.

    Compression can also occur in other ways by using an amp that has un under-designed power supply and the B+ rail literally runs out of voltage to supply the output tubes and compression occurs on signal peaks that require more voltage than the rail can supply. This condition is more common in guitar amps.

    Pulling tubes does two things: it drives up plate voltage due to the loss of other power tubes drawing it down and simultaneously raises the primary impednace of the output transformer and it requires an increase in the secondary (speaker) connection to prevent an inductive voltage spike from "flying back" from the output transformer and toasting the tubes and most of the rest of the amp.
     

  13. Tubes don't work AT ALL until their heaters have warmed their cathodes enough to emit electrons. They DO get hotter with prolonged high voltage use, but it doesn't make them sound different
     
  14. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Sorry, but ignore that last post by Psycho Bass Guy. None of it is true. (Sorry).

    Here's the skinny:

    Power tubes DO in fact saturate. Ask any guitar player. That's what tube amps are all about. That's why people like them. Ask anyone who's ever used the "fake" saturation created by overdriving preamp tubes. It just doesn't sound the same as a nice saturated set of 6L6's or 6550's.

    Power tubes are not "either on or off". There's no truth in that whatsoever. They're linear amplifiers just like any other audio tube (assuming they're biased correctly).

    Compression is not a function of the output transformer. At least not when the amp is well designed and it's behaving correctly. There may be a small amount of OT saturation at full volume, but in general that's a bad thing and not at all pleasing to the ear.

    The second paragraph there is talking about "sag", which is a function of the rectifier tube (if any). It doesn't generally tend to happen (much) with solid state rectifiers.

    And finally, the impedance changes brought about by pulling a pair of output tubes isn't related to "flyback" in any way. Transformers transform a "ratio" is all, so to maintain the proper ratio when you pull half the output tubes, you have to plug your 8 ohm cab into the 4 ohm output of the amp.

    Psycho Bass Guy, I love you like a brother, but you really should be careful about spouting off on stuff you obviously know very little about. Study up on your basic electronics my friend. And get a good book on tube amps, like one of Gerald Weber's books or something. They'll tell you everything you need to know.
     
  15. panazza

    panazza

    Nov 23, 2003
    italy
    so I think I should get this amp... someone asked me if I'd like to carry that beast at a small gig... well to me a head and cabinet are easier to carry than a 70lb big combo like mine with two handlers on the top of it.... it's terrible to carry it.... at least cabinets have handlers on the sides and wheels...
    Anyway I still have my old 120w laney rbw200 combo but I think I'd prefere using a tube amp even at small gigs that my little old mofo.... laneys sound so punk..!
     
  16. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    panazza, go for it dude. There's nothing like the sound of a good tube amp!

    And yeah, the weight would be the one drawback (that and the 10 amp fuse). :)

    I'm getting too old to lug around an SVT anymore. A couple of months ago I herniated a disk and it gets aggravated every time I gig (which is frequently).

    So now I use a Walter Woods amp head. 7 pounds, can't beat that. It's not a tube amp, but it's got a nice preamp that'll give you a wonderful fat sound, and you can even get a little distortion out of it (sounds pretty good, again not like a tube amp, but still among the better sounding solid state preamps I've heard).

    But hey, if I were still young I would definitely want my SVT at every gig, or even a Marshall Major or some such thing.

    One of these days they're going to figure out how to make a tube guitar or bass amp without any humongous transformers. I'll definitely be interested in that!
     
  17. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I doubt it.

    Alex
     
  18. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    I hear you Alex. Then again, that's the same thing they said about Orville and Wilbur.

    Are you familiar with the "OTL" (output transformer-less) tube amps?

    Apparently some crazy dude in Long Island (Julius Futzenberg or some such thing, I don't remember exactly) invented a transformerless tube amp, but never could get it to work quite right (reliably).

    Then many years later, someone rediscovered his invention and improved on it, and today they're making hi-fi OTL amps. Supposedly they're pretty good (and expensive), although I haven't actually heard one.

    But they require a special tube with unique characteristics (in other words you can't just use an ordinary 6L6 or something). And, they don't deliver much power "per tube", so to get 400 watts you'd have to have like 40 tubes, which kinda defeats the purpose.

    But now that they're making tubes again, I'll just bet someone will come up with a design that works for guitars and basses.

    And you could use a switching power supply to get rid of the huge power transformer too.

    Don't laugh, stranger things have happened. :)
     
  19. You could do well to take your advice.

    Take a basic electronics course and quit assuming that just because someone has a book out, they know what they're talking about. Gerald Weber's book is FAR from an accurate resource and so is your post.

    What exactly saturates? What component in a tube saturates?

    You're talking about mechanical compression.

    You have absolutely NO idea what you're talking about.

    Amp topology 101(regardless of device type): Class A - output device is emitting full cycle, 360 degrees, or is "on" all the time

    Class A/B -output device time of emission is governed by its bias setting. The device is "on" until driven into cutoff. This is the operating class of most amplifiers.

    The "sound", the amplified AC in a tube amp, is a function of DC voltage variations in the plate and screen of the tube caused by voltage variations in the tube's cathode. These occur so long as the tube is emitting or "on."

    Tubes are NOT "linear amplifiers" unto themselves. They are simple voltage amplifiers, turning low voltage cathode variation into high voltage plate variation. The CIRCUIT is the audio amplifier. Without coupling, supply voltage, and a resistive load to produce a voltage drop, a tube by itself, does NOTHING.

    This is patently false as well. Any time an output transformer is presented with a voltage that exceeds its rating, that voltage is absorbed by the core of the transformer as heat and not passed on to the speaker. Hence, it is a mechanical compressor. It is not a "desired" effect and rather a by-product,but considering that transients can carry over ten times the amount of "normal" output voltage, it occurs even when the amp is NOT being "pushed."

    There are two kinds of sag: voltage and current. Voltage sag occurs from rectification loss and is the result of the relative innefficiency of a tube rectifier. Current sag is the result of an under-designed power supply with too low a damping rate.

    You've obviously NEVER worked on a television. The extremely high voltages of the picture tube are the result of flyback effect from, of all things, the flyback transformer, which operates by inducing a voltage spike into a high impedance load (the picture tube).It's basically an output transformer hooked up before the tube instead of after and works exactly the same way. The voltage spike is determined BY the ratio of turns in the transformer.

    Transformers are coils, period. They turn a high voltage, low current flow from the tubes into a low voltage, high current flow for the speakers.

    Really? That's news to me. I don't pretend to to know everything, but you have absolutely NO idea what you're talking about. Take a look here:

    http://www.triodeel.com/tubedata.htm

    for several good links to get you started in the right direction. Anyone is free to believe whomever they like. Do the resaerch. I just gave you a serious heads-ups.

    Dude, I'm an ENGINEER, posting this from work. Babysitting a TV transmitter makes audio amps look like childs play.

    I'm sorry, I though you said a good book. Kendrick amps are OK for Bassman copies, but Gerald talks about FAR more than he actually knows. Kevin O'Connor's books are good, but I just use the old tube manuals.
     
  20. OiBass

    OiBass

    Apr 9, 2003
    Columbus,OH
    I'd like to know when Marshall put out an all-tube
    400-watt amp-