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I got the Sunn 2000S..

Discussion in 'Amps and Cabs [BG]' started by Rockbobmel, Sep 1, 2003.


  1. Rockbobmel

    Rockbobmel Supporting Member

    I approached a guy last week for a 2000S and he wanted to sleep on it. I called him today and bought the amp. It looks like a 30year old amp. Tolex is old looking, it has some corrosion on the chassis, the pin holders in the tube sockets are loose and the fuse holder is busted. There is a Mullard 12AX7, an Amperex 6AN8A, 2 Amperex GZ34/5AR4, and 4 RCA 6550s. The wood is solid,and the braces, back and front piece are excellent. I think some cleanup and a trip to the doctor will bring this relic back into service. I am hoping that the tubes are good. I have a feeling they are........Any input will be appreciated.
     
  2. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    Cool Rockbobby! Just get the thing serviced; maybe change all the electrolytic caps and you should be in good shape! If the 2 GZ34's are good then try the amp with those and see what you think. If they're not good then get a tech to rewire one of the sockets with SS diodes or buy 2 WeberVST copper caps with no wire mod needed. I like SS rectifiers for bass amps.

    Please let us know what you think when you get it going.

    Tapp
     
  3. James Hart

    James Hart

    Feb 1, 2002
    toms_river.nj.us
    Endorsing Artist: see profile
    Cool Deal! Congrats!
     
  4. Be careful about subbing diodes for those 5AR4's. Diodes will cause a rise in plate voltage that could toast the filter caps and possibly the tubes. That's the cool thing about the Weber copper caps, they still have voltage "sag" that is equivalent to a tube rectifier and you won't have to worry about a rise in voltage. SS diodes will give you a much tighter bottom and better transient response, and they cost literally pennies, but you'll have to make sure the tech subbing them knows exactly what they're doing.
     
  5. Rockbobmel

    Rockbobmel Supporting Member

    Thanks Guys,
    I have been hearing about this amp a lot lately. Some have said the tone was superior. Do you think that those amps have SS rect. in them? Would I be disappointed if I left the tubes? I really don't like mushy bass. Does this thing really put out 200 watts? It does not look as good as an Ampeg of that era. It almost seems like a hand made amp. It is point to point wired and bundled neatly with mono fliment line.
     
  6. rumblethump

    rumblethump Supporting Member

    Mar 25, 2000
    Pioneer CA. 95666
    The Sunn 2000S was originally rated 120 watts. You have the first version. The 2nd version has the SS rectifier. I haven't had the opportunity to hear the difference between the two, but at this website http://www.dangpow.com/~sunn/phpBB2/ you can find much info about your amp and the board members are very helpful.
     
  7. James Hart

    James Hart

    Feb 1, 2002
    toms_river.nj.us
    Endorsing Artist: see profile
    Sunn calls a pair of 6550/KT88 @ 60watts RMS. Lots of websites I've read call the pair @ 100watts RMS... either way you should have plenty of power.

    point to point wiring is a 'Good' thing I've been told. And Yes, they were hand assembled.

    If you do keep the tube rectifier, JJ makes GZ34's now. I plan on getting mine fitted with all JJ tubes (I've got a SS rectifier model)
     
  8. Rockbobmel

    Rockbobmel Supporting Member

    My tech said it needs tubes.The ones in thre were blowing fuses.He is goung to get a new contour pot, cap job, SS rectifier. It wll prolly be another $250.
     
  9. Make sure you get the old "bad" tubes back from him. If you don't, those "bad" tubes could end up on eBay going for $150 or so. I'm just saying, I wouldn't have expected those tubes, especially all (4) of them to be bad.

    And congrats on your score. Now learn to fix it yourself and you'll be even happier with it.

    Chris
     
  10. Rockbobmel

    Rockbobmel Supporting Member

    He said two are OK, and two pretty shot. They are GE 6550s and about 20 years being used old.
    This guy put in a variable bias onmy 400+ for $25. and did a complete cap job on my V-4 for $100.
    I'm not too worried about the pulls.
    Thanks for the heads up.
    Bob
     
  11. Rockbobmel

    Rockbobmel Supporting Member

    I got the amp back. It needed 4 6550s (Svet), 2 GZ34 (Mullards) a Sylvania 12AX7. A total cap job and re touch all solder joints. The cost was $290.+ the $200 = $490. total. I cleaned up the Tolex and gave it some Armour All.
    This amp sounds soooo good.!!! I have to keep the bass on 2 and the boost off. It is very bass heavy with the Sonic 1-18. I'll bet it is incredible with an 8-10 or 2-15. I'm gonna try out the Berg NV cabs soon at Rock City Guitars in Somerville, MA. I have plans for some Karlson cabs. A pair of them would be stellar.
     
  12. Rockbobmel

    Rockbobmel Supporting Member

    BTW, The 6550 pulls were RCA, not GEs, that I thought. He gave them all back to me with a bag of caps.
     
  13. rumblethump

    rumblethump Supporting Member

    Mar 25, 2000
    Pioneer CA. 95666
    You have a great point to point wired tube amp now! The Sunn be shining on Greenfield MA :D
     
  14. Phat Ham

    Phat Ham

    Feb 13, 2000
    DC
    I'm not quite sure I follow you on that one. With SS diodes, when they are positively biased there is a relatively small drop in voltage across the diode. So if you have a 300 V source positively biasing a diode the "output" of the diode will be around 299V, depending on the type of diode used. A diode can only drop voltage across it; it can't add to the voltage.

    The voltage sag in tube rectifiers only occurs when there is a signal present. What I mean is that if there is no current being drawn the voltage will be just as high as the voltag e when using an SS diode. Once there is a signal the voltage sags as current is drawn. As the signal decays, the sag rises back up to its nominal voltage, effectively cancelling out the decay of the signal. This is audibly discerned as compression, and guitar players love it.

    So, if the plate voltage is biased at say 300V, it will be 300V whether you use a tube rectifier or diodes. In the case of the tube rectifier that plate voltage can momentarily drop, but with an SS diode the plate voltage will remain constant. In either case the plate voltage will not rise above the bias voltage.

    Of course I could be wrong about all of this;)
     
  15. Phat,

    What you say is pretty much correct, except for the fact that even when you are not putting audio signal through the amp, there is still DC idle current flowing through the signal tubes and rectifier tube(s), so there is a little voltage sag in a tube rectifier in guitar amps even when you're not playing, and more sag when you are playing loud. Also, rectifier tubes do have a fixed votage drop of a few 10's of volts even with no current flowing through them, unlike SS diodes which have approximately 0.6V drop across them whether current flow is zero or max rated current (actually goes up to 0.7 or so at high current).

    Chris
     
  16. Phat Ham

    Phat Ham

    Feb 13, 2000
    DC
    ah i stand corrected. I totally forgot to take into account the fact that there could be a large voltage drop across the rectifier tubes. What they don't teach you in school these days.

    BTW, Bukowski is awesome.
     
  17. Yep, here's exactly what we're talking about. And according to the graph, as current approaches 0, voltage drop approaches 0 too. Neat.

    [​IMG]

    Chris
     
  18. Rockbobmel

    Rockbobmel Supporting Member

    Thanks.. I do have fun with it. Kinda brings me back to when I was a young teen. I had a B-25 with TWO bottoms w/JBLs in them. I could only get so so vol, but the tone was great. Other guys were all hard about the SS stuff. Ihe Sunn Colliseum SS head sounded awful! I did settle down with an Acoustic 370/301 wi a 2-15 extention cab that I loved. That rig got stolen in 1994. More recently I have gone full circle with the big SS thing too. I always return to tubes. I hardly use anything except chorus. No compresor, No SansAmp, No BBE. I even use cables mostly, and I have an X-wire. (No, it's not for sale).......I love reading Rich Brier's posts and his web site. He sais it better.