Pre vs. Output Tubes / Solid State

Discussion in 'Amps [BG]' started by jd_watt, Apr 2, 2014.


  1. jd_watt

    jd_watt

    Joined:
    Mar 22, 2013
    Hi all,

    I'm currently using as SVT-4 Pro. While I really like it, I can't say I hear much "tube tone" difference from running direct or using a solid state amp. This particular amp has three pre-amp tubes, and uses mosfet power in the output section.

    Are output tubes key to the tube tone? I'm referring to things like "touch" "sag" and "saturation".

    What's your experience?
  2. JimmyM

    JimmyM Supporting Member

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    Apopka, FL
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    Endorsing: Ampeg Amps, EMG Pickups
    Output tubes plus the output transformer are the key to those things.
  3. CL400Peavey

    CL400Peavey Supporting Member

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    Where are you running the gain and compressor?
  4. jd_watt

    jd_watt

    Joined:
    Mar 22, 2013
    Compression noon to one o'clock. Pre-amp light hitting pretty hard into the red on my heaviest attack. Just not what I'd call "tube" magic. I don't hear it come alive like I read in the forums. That's why I was thinking it must be all about those output tubes.
  5. Bassmec

    Bassmec

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    Yup the output tubes, a certain amount of sag in the power supply and a
    slightly saturated output transformer is where it's getting good for me.
    Not that you can't get something similar and very good going on with the amp you have.
    If you are prepared to spend a load of money on a varimu type tube compressor like a Gates Sta Level or Manley varimu or indeed the old Altec 436 type compressor stuck in the send an return loop.
  6. teleharmonium

    teleharmonium

    Joined:
    Dec 2, 2003

    There are multiple kinds of tube tone, but for the classic old school bass amp tone, the power amp and speaker(s) are what matters because the preamps in those designs are all very clean sounding.

    A really good SS preamp can do low level clean signal amplification as well as a tube circuit; it can be very difficult to tell them apart, when you're comparing something like, for example, a high quality, high gain 1960s professional tube mic preamp that uses a lot of negative feedback and has an outboard power supply, to a solid state mic preamp with a simple vintage circuit using discrete parts and an output transformer.

    You can generate crunch in tube preamps but that's a different approach resulting in a different sound.
  7. jd_watt

    jd_watt

    Joined:
    Mar 22, 2013
    Hey everyone, thanks for the replies. I definitely see the points you're all making. It's different from pre-amp break up. I just wondered what everyone else's experiences were. I'm thinking about the difference between any of the svt pro series amps and something like an early 70's, all tube svt (which my father owns). What a gem!
  8. JimmyM

    JimmyM Supporting Member

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    Endorsing: Ampeg Amps, EMG Pickups
    Nothing at all wrong with the 4 Pro. I use them on rental gigs fairly often. True, not quite like your dad's SVT, but still darn good. You ain't hurtin' ;)
  9. Sartori

    Sartori

    Joined:
    Apr 9, 2009
    Location:
    San Francisco Bay Area, CA
    It'll sound closer if you crank the gain (ignore the light), but yeah, a solid state power section is just not going to react in the same way as a tube one would.
  10. jd_watt

    jd_watt

    Joined:
    Mar 22, 2013
    Thanks again, guys.

    I'm definitely loving the 4 Pro, Jimmy!

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