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Bad tubes?

Discussion in 'Amps and Cabs [BG]' started by Dgl44, Feb 24, 2016.


  1. Dgl44

    Dgl44

    Oct 30, 2014
    Slovenia
    Hey,

    My Ampeg diamond blue series b200r all of a sudden started making weird loud rattling noises and producing a load of hum from time to time while playing. Also I noticed a much higher level of hum coming from the amp when a cable is plugged in recently. The amp is somewhere from 8 - 10 years old and the preamp tube has never been changed. Could it be that the tube is done?
    The amp hasn't been treated too gently before I'd acquired it.

    In any case I'd like to start out by replacing the tube and work from there. It's a 12AU7 type. Any recommendations to which brand would work well?
    The easiest for me to get are TAD RT005, JJ NN05 and Electro Harmonix EH.
     
  2. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    It's very possible by now, absolutely. JJ's are usually a safe bet. EH makes a decent tube. Not all that familiar with TAD but I hear they rebrand other tubes as their own, then charge a small fortune for them.
     
    Dgl44 likes this.
  3. Dgl44

    Dgl44

    Oct 30, 2014
    Slovenia
    Great! JJ's are actually the most acquirable for me, since I can get them in my local music store. :)
    What's up with replacing AU's for AX's or AT's? Is that possible and how would that effect my amp and tone that it produces?

    I'll probably stick to the default type anyways, but just exploring options and widening my horizons.
     
  4. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    The different designations signify how much gain they have. A 12au7 isn't as high gain as a 12ax7, for example. I know some people have swapped them out in some amps and enjoyed the results, but I'm not into it. I like using the tubes specified. Replacing a low gain tube with a high gain one can cause early overdriving the preamp, and vice versa results in weaker tone IMHO, although some like having more clean range on the gain knob.
     
    Dgl44 likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The AU can also deliver significantly higher current which can affect tone where used in lower impedance loading circuits. Same but to a lesser degree with the AT7.
     
  6. Grissinerl

    Grissinerl

    Feb 7, 2016
    Germany
    The TAD preamp tubes that I know of are mostly Shuguang (chinese) - but they claim to design their own versions.
     

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