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Peavey VB3 rms watts

Discussion in 'Amps and Cabs [BG]' started by tabooze24, Oct 7, 2013.

  1. I have a Peavey VB3 and I love it. At 37lbs and an output of 300w, it’s the king in lightweight tube bass amplification.


    How the heck is Peavey getting 300w rms out of eight EL34's? Also, what is the transient rating of the VB3?

    Experts pleas chime in!
  2. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    300 watts with 8 el34 tubes? What's the THD for that rating at 30Hz.
    Probably not an available figure from Peavey, as is the answer to your other question.:bassist:
  3. Well to be fair, there are a LOT of tube amps that will have limited capabilities at 30hz. Would depend on a lot of specifics, but the OT is pretty important on that list.
    Sartori likes this.
  4. What plate voltage will these el34's be running at to get 300w rms?
  5. EL-34s are capable of 100 watts RMS per pair if ran at 800V. Says so in the data sheet! I wouldn't test fate running them that high and I'm not sure if modern EL-34s can handle that high a voltage but 300 watts with 4 pairs is not unreasonable if the voltage is high enough and the circuit was designed for it.
    Sartori likes this.
  6. Tractorr


    Aug 23, 2011
    Plus it is probably a little easier than traditional tube (though I could imagine it could be done with those as well) because of the efficiency of the switching power supply in the VB3
    Sartori likes this.
  7. BbbyBld


    Oct 13, 2005
    Meridian, MS
    Plate voltage is 500V. The power supply sags at full power with a traditional power supply. You get more power at a lower plate voltage with the switcher because it's regulated. The lower plate voltage improves reliability. The power supply has a lower output impedance than a traditional supply, so low notes don't mush out--the power supply sort of pushes back against the power amp. The VB-3 plate power supply can supply 1000W. some of that is wasted on class AB inefficiency, and some is extra just because.

    Getting 75 watts per pair out of EL34's is not difficult. The output transformer is a special design. The core and windings are designed to work down to 30Hz while keeping the size and weight down.
  8. LowB-ing


    Aug 3, 2005
    The Sadowsky SA200 got 225 watts out of 6 EL34s. That's the same 75 watts a pair as the Peavey VB-3. Actually, the Peavey VB-2 also gets 225 watts from 6 EL34s, just like the Sadowsky.
    Sartori likes this.
  9. Thanks for the great info.

    On another note, when is Trace Elliot coming out with a new amp????
  10. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    I want to be Tesla (tinkerer at Dayton Amp Co)
    Do you know the output specs though? Say RMS power at 1% THD @ 1kHz into a 4 ohm load to at least give us a ballpark value? I haven't read anything that suggests to me that those 300 watts are RMS, including the Peavey website.

    Don't get me wrong, RMS isn't everything. Does the power amp design at all resemble what Mesa does with their rather lightweight tube amps?
  11. I have the manual and it does state that the amplifier produces 300w RMS into 2, 4, or 8 Ohms. However, the manual doesn't say anything about THD.

    The Peavey VB3 is way different than the new Mesa amps. The VB3 uses a switching power supply and a normal iron output transformer where the Mesa amps use iron for both the power and output transformers. If Peavey eliminated the wooden enclosure, as Mesa has done with the new Prodigy and Strategy, the VB3 would weigh about 21lbs!!!!
    spankdaplank likes this.
  12. BbbyBld


    Oct 13, 2005
    Meridian, MS
    At the factory bias point it varies because, frankly, even with matched sets, some sets of tubes are better than others, but AT LEAST 300W "rms", 1KHz, 5% THD. Most of them will do it at 1%. It can be biased "hotter", but Peavey chooses to compromise between low THD and reliability rather than tune for max power. Some of them with an especially good set of tubes will do 350W.

    I don't know what Mesa does, but I doubt it's revolutionary as far as technology goes. It seems like pretty much everything tube related was figured out by the 50's. I have a vintage 300W tube radio transmitter that had an optional solid state switching supply available for mobile use, so the VB-3 isn't exactly revolutionary either.
    spankdaplank likes this.
  13. Awesome.
  14. Agreed but for stability they need a dedicated and stable, possibly regulated screen supply and their Suppressor grids, G3, returned to the raw negative bias supply.
    michael tomlin likes this.
  15. BbbyBld


    Oct 13, 2005
    Meridian, MS
    You can get 100W / pair with a 620V plate.
    Sartori and michael tomlin like this.
  16. But why bother? There exist no need to get every last watt out of a pair of tubes. The only place it makes sense is in a laboratory environment. Run this way the tubes life span is greatly reduced.
  17. seamonkey


    Aug 6, 2004
    I know it's an old thread, but this is a great post. SMPS (switching power supply) really can deliver.

    The power supply is really key in all amps. In the VB3 case the switching power supply contributes to it's great sound. The power supply isn't really separated from the "signal path". Things like power supply impedance is important. An amp simplifies to a voltage source with a series resistor. Part of that resistor is from the power supply. There's also a lot different aspect to sag, normal power supply sag adds in 60hz or 50hz ripply which increases ripple inter-modulation distortion. It messes with harmonics, like ring modulation. It's not natural, and in blind studies, some individuals can readily hear this.

    "All tube amplifier" is a misnomer as the power supply is king. A good solid-state, or SMPS contributes quite a bit to the sound.

    I don't know why other tube amp makers are Not jumping on the SMPS bandwagon? Other than they don't have the technical abilities to build one themselves. They could get one built by one the SMPS makers. Higher cost yes, but more control of the overall sound of the amp over time more reliability. If there was any problems it would be an easy field replaceable unit.

    There's now some manufacturer who's marketing are bringing back "Class-AB". I think mainly due to consumer folklore are consumers thinking it's what they want. Maybe a bad experience with a poorly designed early class-d or maybe they believe tube amps are class-ab and so the "class" must be important.
    These new "Class-AB" amps using SMPS to keep the amps small and light and reliable. The SMPS can deliver.
    michael tomlin likes this.
  18. The_Janitor


    Jun 30, 2012
    Madison, Wi
    I don't want to speak for Bobby, but when I was at Peavey HQ two years ago I got the impression from speaking to a couple of engineers that the implementation of the SMPS power supply into an all-tube amplifier was not without its challenges and required quite a bit of work to get it functioning properly.

    Peavey has a team of very talented engineers working on products like this, I don't know what other brands' R&D department looks like, but I was very impressed at both the size and the collective genius of their engineering team.
    TheRealKong, mech and Korladis like this.

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