"All tube" amps (signal path) in production today?

Discussion in 'Amps and Cabs [BG]' started by AlexanderB, Jan 21, 2014.

  1. AlexanderB


    Feb 25, 2007
    I searched but did not find any recent discussion on the subject.
    I did check the Ampeg V-4B manual briefly and it seems the signal path is all tube? The SVT amp has some sort of (silicon) diod between the pre and power amp, if my memory serves me? (The user manual's schematics does not show if things are SS or tube.) What about other tube amps in production, are they really "all tube"?
    The Traynor YBA 300, for instance, is called "all tube" but uses OP amps in the tone control stages, according to the Service manual.
  2. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion

    Aug 25, 2010
    The Great Midwest
    I'm pretty sure the SVT is all tube are you talking about point to point wired?
  3. spiritbass

    spiritbass Supporting Member

    Jun 9, 2004
    Ashland, MO
  4. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    The anti-parallel diodes in the SVT between the pre and power amp are there to catch spikes. This can occur when you plug in to the pre out or power amp in. Otherwise, they don't affect the signal.

    There is sand in the pathway in the form of operational amplifiers if you are going through the balanced out. But that signal is usually fed into a solid state mixing board so that isn't an issue.
  5. AlexanderB


    Feb 25, 2007
    Great replies!

    What about the new Fenders? Pre-amps could also be included, such as TBP1, Demeter etc...
  6. StuartV

    StuartV Finally figuring out what I really like Supporting Member

    Jul 27, 2006
    Manassas, VA
    Don't most tube amps these days have SS rectifiers? I think the very first SVTs had tube rectifiers, but didn't they also change to SS rectifiers after just 1 year or so of production?
  7. AlexanderB


    Feb 25, 2007
    (signal path) = not rectifier...
  8. If you see a graphic equalizer on a tube amp you can be pretty sure you are running through silicon. Channel switching is often through switching opamps and many effects loops use opamp buffers.
  9. mancefine


    Jul 7, 2013
    Endorsing Artist: Orange Amplifiers and Spector Basses
    Orange AD 200B
  10. nostatic

    nostatic Supporting Member

    Jun 18, 2004
    los angeles, CA
    Endorsing Artist: FEA Labs
    The top half of this combo:

  11. Yeah, that's usually a giveaway that the signal path isn't all tube. Graphic EQs are active device intensive and are easier to implement using devices with much lower output impedances than triodes can typically provide.
  12. AlexanderB


    Feb 25, 2007
    I belive the Fender Studio Bass has an all tube five band (rotary, but might as well had been graphic!) equalizer, though.
  13. AlexanderB


    Feb 25, 2007
    That Jule amp looks very nice, but perhaps a bit more fragile than, let's say an SVT... :smug:

    We will probably never see them here in Sweden. Well, at least you can get an Aguilar here... :meh:
  14. chicago_mike


    Oct 9, 2007
    Chicago - LA - Rome
    Endorsing Artist : Genz Benz
    Don't worry about a piece of silicon in the signal chain man.
  15. ThePoloHobo


    Aug 18, 2013
    Tulsa, OK
    The new Mesa Boogie Prodigy and Strategy are all tubes
  16. Without seeing a schematic (not a block diagram), don't assume all tube.

    This looks like an all tube signal path amp?

    It's not. :)
  17. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    The best a single rectifier tube can do is power a 50-60W amp. A 300W SVT would require six rectifier tubes unless exotic rectifier tubes are used.
  18. ThePoloHobo


    Aug 18, 2013
    Tulsa, OK
    What makes this not "all-tubes signal path"?
    Makes me want to open up my 2012 SVT...
  19. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    The SVT has always had solid state rectification. The earliest one had a turn-on time delay relay tube. Perhaps what you are thinking of.

    Early amp designs all incorporated tube rectifiers. But there is a limit as to how much current a tube rectifier can deliver. As amps started getting more powerful, greater than around 50W, they needed a better solution. Some amps had more than one tube rectifier running in parallel but the better solution was to use solid state diodes in the power supply.
  20. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Oh yes, put the B-15 at the top of your all tube with the best tone list. Underneath that put the new V4B that you mentioned. A very well designed and built modern amp.