Sunn 200s

Discussion in 'Amps and Cabs [BG]' started by TrooperFarva, Mar 4, 2006.

  1. TrooperFarva


    Nov 25, 2004
    New City, NY
    I had a lesson today, and my instructor said that he had an old Sunn 200s that he doesn't use at all, and would let me borrow, but he thinks that it needs to be retubed. He said he'll pay for the tubes. So a few questions. 1) Does anyone have any info on replacing the tubes in a 200s, specifically rebiasing, or does it need to be taken to a tech? 2) Any recommendations for tubes? 3) Can I connect the 200s to be Bergantino? The only pictures I found for the 200s showed a 16 Ohm and an 8 Ohm output, and my cabinet is 4 Ohms. Thanks.
  2. edbass


    Nov 8, 2004
    The 200S circuits was initially designed for the Gold Lion KT88 power tubes, the later models (1969 or so) switched to 6550's. Gold Lions would be optimum but, if you could find any, they are roughly a million dollars a pair. The preamp runs a 12AX7 in all models. Any 6550's/KT88/KT90 will work, I won't specify a brand because everybody has their own "favorite flavor". Unless you are experienced and have the proper test equipment, I'd take it to a tech an get it biased right. It makes a ton of difference in the tone/tube life balance.

    I've found that using KT90's in the power tube positions and a lower gain 12AT7 in the preamp gets a cleaner, more defined, modern hifi sound out of the old Sunns. In stock configuration a 200S gets pretty Entwistle Live at Leeds sounding at about 6-7 on the volume knob. Of course, that's not to say that the Entwistle's Leeds sound is a bad thing! with the 12AT7 & KT90's it will still break up, but you'll be able to get louder before it happens.

    The 200S has output transformer taps for 4, 8, and 16 ohms. They also have only two speaker out jacks. Sometimes they are 8 & 16 ohm, usually they are 8 & 4 ohm. If your instuctor's 200S has 8 & 16 ohm jacks, the tech (while they are rebiasing the new output tubes), can easily switch them around for you. It's very important in all tube power amps to match the output impedance to the speaker load.