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SVT6 vs SVT4

Discussion in 'Amps and Cabs [BG]' started by Son of Bovril, May 16, 2005.


  1. has anyone tried the SVT6-PRO that can give me a comparison with the SVT4-PRO?

    I know the 4 has a bit more power, and the 6 has more tubes, whats the tone diff?
     
  2. TheChariot

    TheChariot

    Jul 6, 2004
    Boston, MA
    I havent had the priveledge of playing with a 6Pro yet... but the general idea of the 6Pro seems like its supposed to be a more powerful version of the SVT 3Pro. The 3Pro and 6Pro are both hybrid heads with driver tubes. To get a feel for something like that, simply try out the SVT 3Pro.

    The 4Pro and 6Pro are probably about the same volume, because the 200Watt difference isnt much at all.
     
  3. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    I've heard this as well, but I will still be curious to hear how it sounds with the addition of the extra preamp tubes.
     
  4. r379

    r379

    Jul 28, 2004
    Dallas, Texas
    It doesn't have more preamp tubes; it has one less. It has the 3 Pro power section doubled and, therefore, has two more driver tubes. If I understood him correctly, that was what I was told by an Ampeg tech guy. It has some kind of parametric eq section instead of the tone adjustments that the 3 Pro has.
     
  5. What is the difference btw preamp tubes and driver tubes? driver tubes obviously aren't the same as power amp tubes, so what is their purpose?

    they seem to fall in somewhere btw the tone shaping & tubes of the preamp, but before the power amp?
     
  6. 6 > 4 - Therefor SVT6 Better than SVT4 :)

    But seriously, I tried the SVT6, wasn't too impressed, kinda sounds like a cheapo version...odd isn't it.
     
  7. r379

    r379

    Jul 28, 2004
    Dallas, Texas
    From what I was told (or from what I gathered), the idea behind making the 6 Pro was to provide a 3 Pro with more power and, perhaps, better tone shaping. Lots of folks think the 3 Pro has good tone but not enough power and the 6 Pro is supposed to address that issue. It is my understanding (it would be nice if Jerrold Tiers would comment on this) that driver tubes in the power section provide a cross between the tone of an all-tube and a SS amp.

    Edit: I haven't heard or even seen a 6 Pro yet but the concept interests me. I like the tone of the 3 Pro but I wish it had more power. Right now I'm considering getting the SVP CL preamp to go with my power amp and maybe the 6 Pro head will be an option.
     
  8. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    That would have been difficult for you to try, since the 6PRO is about to be shipped for the first time...

    If you tried them out at Musikmesse in Frankfurt, those were representative in appearance, but were not like the production units power-wise. Just a matter of shipping deadlines.

    As far as the tube deal, "driver tubes" etc.....

    3PRO and 6PRO are "tube driven mosfet". That means the "driver" tubes provide ALL THE GAIN for the poweramp, and the Mosfets are just "followers" with no voltage gain, and hardly any influence on sound.

    It is different from an SS amp, obviously. It is also somewhat different from a standard tube amp, since there is no output transformer. Sort of like getting your preamp output at speaker level.
     
  9. Cool, it sounds like it will definately be worth a try! I prefered the tone of the SVT3-PRO to the SVT4-PRO, but I couldn't understand why? I thought the 4 was just a bigger version of the 3, but now I know!

    great, can't wait to take one for a spin!
     
  10. Tash

    Tash

    Feb 13, 2005
    Bel Air Maryland
    OK...how exactly is this different from the SVT4? In the 4 the preamp tubes are just there to color the signal before it hits the power section right? All volume increase comes from the MOSFETs?

    In the 3/6Pro the preamp tubes are responsible for the volume gain...then what the hell are the MOSFETs there for?
     
  11. preamp section colours the sound, the signal is then sent to the power section in the 4

    in the 3 and 6 the preamp tubes colour the sound, just as most preamps are designed to do, then the driver tubes control the gain and the mosfets just act like a power amp, the volume gain is not the output volume, its essentially so it can get a sound similar to that af a tube power amp section (i think)

    correct me if im wrong Jerrold
     
  12. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    In the SVT4PRO, the power amp is purely SS, using lots of transistors, and pre is tube (aside from graphic eq etc).

    In the 3PRO and 6PRO, the power amp is a mix....12AX7 and 12AU7 tubes with mosfets.

    The function of the mosfets is to "match" the high impedance tube output signal to the low impedance speaker. They simply act as a "buffer" or "unity gain follower" after the tube.

    The tube output directly controls the mosfets to convert high voltage low current tube signals to high current speaker signals.

    Its hard to explain without getting into engineering terms.

    But it's as if you were lifting something for your little brother...if he grabs your wrists and pulls up (weakly) when he wants you to lift, and pushes down (weakly) when he wants you to lower, that is the sort of thing we are talking about.

    Both of you move the same distance, but you do almost all the actual work....with him in direct control of exactly how far you lift and when.

    In a completely SS amplifier, its more like he stands off to the side and says "lift" or "lower". That way, he doesn't have as much direct control over exactly when and how much you lift and lower, but he does even less work than in the first example.
     
  13. Tash

    Tash

    Feb 13, 2005
    Bel Air Maryland
    That makes total sense actually. Thanks.
     
  14. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    Very well said on your explanation Jerrold :bassist: