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retube Ampeg SVT-VR

Discussion in 'Amps and Cabs [BG]' started by jamaica, Jun 16, 2009.


  1. jamaica

    jamaica

    Feb 11, 2003
    Hi all,
    I need to retube my SVT-VR.

    I like dirty sound, which tubes are the best for this sound?

    I'd like to try the tung sol kt88,but I read somewhere that the KT88 vs 6550 give more clean headroom..is it true?

    Let me know


    Best Regards,
     
  2. Even though I only have experience with 6550's I have heard that the KT88 sound awesome!!
     
  3. Jazzman

    Jazzman

    Nov 26, 2002
    Raleigh, NC
    Hold on, the SVT-VR hasn't been made long enough to require new tubes under normal use. What are you doing to that thing? Why did the original tubes die so quickly?
     
  4. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    +1 for Jazzman. How could it need a retube?

    BTW, don't expect miracles with tube changes. The majority of tube changes result in subtle changes at best.
     
  5. seamonkey

    seamonkey

    Aug 6, 2004
    This could be bad advice
    Ampeg says:
    http://www.ampeg.com/pdf/SVTVR.pdf
    "Tubes wear out in direct proportion to how often and how hard you use the amplifier. Power tubes should be
    checked at least once a year - more frequently if you use the amplifier nearly every day."

    "... Depending on the failure mode, they may even cause severe damage to
    the audio output transformer and/or other components in the amplifier. Replacing the tubes before they fail completely has the potential to
    save you time, money and unwanted trouble."
     
  6. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Here we go again.

    I don't know how many times Seamonkey quotes manufacturers saying this nonsense. Seamonkey doesn't even like tube amps. Yeah, we're the ones with bad advice...not a guy who hates tube amps and hops into tube amp threads just to tell people not to get them.

    BTW, I would agree with getting your tubes checked once a year if you use them heavily at top volume. Otherwise it's not necessary. I have many tubes that have seen regular use for over 10 years, and I have a handful of tubes are that over 40 years old and test like new.
     
  7. limit6

    limit6 Supporting Member

    Dec 5, 2007
    Philly, PA
    Hahahaha, I really do appreciate dry humor.
     
  8. Jazzman

    Jazzman

    Nov 26, 2002
    Raleigh, NC
    Nonsense. Checking them is good, but unless there is a manufacturing defect or junk tubes where put in there originally, they should be lasting a good ten years or more.

    Do you replace the transistors in your solid state amps every few years?
     
  9. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    People attribute the KT88 with more headroom and a cleaner sound. This depends on the design of the amp. For dirt, some like the small bottled NOS Sylvania tubes because they put out a little more power. Others like the GE 6550's in the SVT. Both are very expensive.

    How long the tubes are in service and how hard they are pushed are two big factors that affect tube life. Also important though, are how often the amp is turned on and off (thermal cycling - it is even worse if the amp has been in the cold and you turn it on without first waiting for the tubes to come up to room temperature), tube ventilation (don't block the vents), mechanical vibrations transfered from the speaker cabinet to the amp or being bounced around during transport, whether or not you use the standby switch to ensure that the filaments are heated enough before using the amp, the design of the amp and the condition of its components, the tube itself (some manufacturers design the tube for an extended life with larger glass envelopes, stronger internal structures, etc.), and how the bias is set (exceeding the maximum cathode current is bad for the tubes).
     
  10. Surly

    Surly

    Feb 2, 2007
    South Florida
    No because they're not made of breakable glass ;)
     
  11. 3toes

    3toes

    Aug 30, 2006
    Denver, Colorado
    What tubes are best for slap?







    :bag:
     
  12. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I'll bite.

    For slap look for anything that maximizes pre and power amp headroom. If you like it bright and punchy, maybe the KT-88 in the power amp would work for you. I don't play a lot of slap, but when I do, I like it rich and on the dark side which I don't find in a KT-88.
     
  13. 3toes

    3toes

    Aug 30, 2006
    Denver, Colorado
    Totally wasn't expecting an answer to that... :)
     
  14. seamonkey

    seamonkey

    Aug 6, 2004
    You can't win on this board.
    If you don't read the manual you'll get "RTFM", if you do read it you'll get comments that it's nonsense. Write to Ampeg and ask them to change their manual.

    No, I don't replace transistors, unless some design flaw or environmental conditional destroys them. There are 1 billion transistors for every person on earth. And growning. For many good reasons - one reason is they don't need regular replacement.

    To the OP - I'd suggest you find a local tech that has a good tube supply - you may have to drive for hours. When you get there have him change out tubes and try them out until you get a set you like. It may cost you more for the techs time, but then you'll leave with a set you'll like.
     
  15. +1 to visiting a reputable tech before swapping. Unless the tech finds a problem, you'd probably just be paying for a new set of tubes for your tech (when he keeps your perfectly good, old tubes).

    -1000 to this unless you've got money to burn or are really particular about your tone.
     
  16. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Ya, really. Tubes don't perform miracles, and changes are subtle at best.
     
  17. jamaica

    jamaica

    Feb 11, 2003
    Hi there,
    no one trouble on my head..It goes perfectly and the tube are at the 1/3 of their life because I used the amp very much and I have not too much care of it..

    I have another question: where are the preamp tubes? on the rear of the head there are the six 6550 and two 12AX7 and one 12AU7..Where are the other five preamp tubes? where could I find them? Have I to pull out the preamp of the head? I tried to make it but I wasn't able to make it

    Best Regards,
     
  18. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    That's exactly what you have to do...pull the preamp out.

    Anyway, rather than replace them, take them to get tested. You might be surprised how little wear is on them. You might also have a couple bad ones, sure. But it's highly doubtful that you need to replace them all. A simple rebiasing by a tech can go a long way into making tubes that you think are dead work perfectly again. And as always, the "if it ain't broke, don't fix it" rule applies.
     

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