a couple of questions about 6550 tubes?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by spacetime, Apr 19, 2003.


  1. spacetime

    spacetime Guest

    I want to replace the tubes in my old and trusty sunn 50 watter head. the tubes are 6550's.

    Can anyone recommend anything?

    Also what is the difference between 6550 C, 6550 R, and i've even seen 6550 A ? Will any of these work?


    On top of that what does "hardeness" in reference to tubes mean?

    If anyone can help with any of this I'd greatly appreciate it.
    Thanks in advance...
    Eric
     
  2. spacetime

    spacetime Guest

    so..
    I edu-ma-cated myself at
    www.tubestore.com
    great "answers to basic tube questions" section.
    somebody mentioned it over on another thread.
    Thanks whomever that was.
    eric
     
  3. devin

    devin Guest

    I tried 6550's in my Alessandro Bloodhound, and after doing it, I understand what is meant by "hardness". There is not much "give" in the tubes when you lean into them. EL34's, for example, have a softer feel and distort more quickly whereas the 6550's did not. The 6550's also had a quicker transient attack and and a stiffer bass. They sounded OK, but I liked the EL34's better because of the midrange and the "give".

    Hope that helps.

    Devin
     
  4. spacetime

    spacetime Guest

    can i replace 6550's with EL34's ? Obviously it would have to be rebiased, but i mean to say...is that possible?
     
  5. devin

    devin Guest

    I'm not familiar with Sunn amps, but it is most likely possible, and probably a very simple mod. I'd check with a tech first, however. I had to replace a resistor value to get the right bias.

    Devin
     
  6. spacetime

    spacetime Guest

    hmph. okay cool thanks devin...something to consider at any rate. I love the sound and feel of good old EL34's but until now, didn't realize that was an option. I will check with my tech guru in the morning.
    Thanks again...
    Eric
     
  7. Braciola

    Braciola Silver Supporting Member

    Messages:
    4,816
    Joined:
    Jan 14, 2003
    Location:
    Oviedo Florida
    I would recomend the JJ KT-88's
    Bob at Euro Tubes retubes all of his sunn amps with these and swears by them.
    They are also considered the best current production model 6550/KT-88 replacment avalible.
     
  8. KLB

    KLB Member

    Messages:
    3,047
    Joined:
    Feb 9, 2002
    Location:
    West of the Sun, East of the Moon
    Considered the best by Bob, and he may be right -- but then he sells them. The set I bought from another vendor a couple of years ago quickly became too microphonic to use if the head was on top of the cab. They did sound fantastic in a Fuchs modded Sound City 50+.

    I want to try another variation, perhaps the Sovtek 6550-WE, only $40 a pair at Triode Electronics.

    Ken
     
  9. KLB

    KLB Member

    Messages:
    3,047
    Joined:
    Feb 9, 2002
    Location:
    West of the Sun, East of the Moon
    I agree, and this is why the 6550/KT-88 tube type excels in master volume amps that get most of the tone from the preamp, and tend to have a bit too much compression with EL-34 or 6L6.

    Ken
     
  10. Braciola

    Braciola Silver Supporting Member

    Messages:
    4,816
    Joined:
    Jan 14, 2003
    Location:
    Oviedo Florida
    I'm sorry you had a bad experience with them, maybe you got a bad tube;)
    These where rated best new production KT-88/6550's not only by Bob but by quite a few very reputable tube vendors.
    I mentioned Bob at Euro Tubes because he is a great guy to deal with, is very knowledgeable, and sells good tubes at very fair prices.
     
  11. spacetime

    spacetime Guest

    thanks everyone...
    are KT88's direct replacement? In other words will I need to re-bias the head?
    What about the elctro harmonix 6550's ? decent?
     

Share This Page