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A bunch of tube questions re:yba200

Discussion in 'Amps and Cabs [BG]' started by failuresXbass, Nov 28, 2006.


  1. failuresXbass

    failuresXbass

    Jul 19, 2006
    SoCal
    Got a yba 200 about a month ago from the classifieds here. Upon first play, I loved it, but when playing with a full band - I found what many here had already known, it distorts way too early.

    I replaced both preamp tubes with EH 12ay7 - picking the ay because of the low gain when compared to the stock ax7.

    While this did allow me to turn it up more, and the distortion is much more smooth, i am still not getting the clean volume i require.

    So after a long introduction, my question is - are these the right preamp tubes to use? Did the reduced gain cut output?

    I am considering KT88s for the power tubes - any brand in particular i should look at? EHs OK? or should i look for something else? YBA experts - what is the final word on rebaising with KT88s? I know this amp is self biasing, but does that apply to the 88s?

    Sorry for so many question - I really want to make this amp work. I cant afford to spend much more than i did on this amp, and I am not interested in carrying much more weight.

    Thanks in Advance.
     
  2. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Preamp tubes shouldn't be related to breakup vs volume...you're probably finding the weakness of the power section.

    Check your EQ to see if you're running scooped and pushing volume to make up for it. Use a frown EQ (upper bass and mids boosted) and you'll get more sound with the same power.
     
  3. Brent Norton

    Brent Norton

    Sep 26, 2003
    Detroit, MI
    While the preamp, power amp, trannies and overall circuit design dictate an amp's performance, preamp tubes DO have a direct impact on the amount of clean headroom available. Do a search, there have been many threads about the YBA and various tubes.
     
  4. steamthief

    steamthief

    Jan 25, 2006
    Mentone Beach
    I just put a Telefunken 12at7 and Amperex 12at7 (paid $5 shipped for both on eBay!) in V1 and V2 in place of the Sovtek preamp tubes. With 60% of the gain of 12ax7s, the swap has taken the trebly edge off of the sound that the stock tubes emitted. I'm not sure if it's any louder, but the gain can definitely be driven higher before distorting, and the overall tones are smoother.

    What cabs are you running with your Traynor? Might cabs with higher efficiency help the cause?
     
  5. failuresXbass

    failuresXbass

    Jul 19, 2006
    SoCal
    I am running a trace elliot 4x10. I have no idea how effecient they are - but i may try another combo. I already put EH AY7s which have 40% of the gain that AX7s have in an effort to increase clean headroom.

    Just wondering if I should procede with replacing the 6550 with kt88 (or possibly kt90s) or is this gonna be about as good as it gets.
     
  6. In my experiences, JJ tubes have had the highest clean headroom, but I dunno if that still applies to the KT-88/6550 tubes. You may want to try a volume pedal or something if you aren't getting enough volume out of the preamp.
     
  7. Willem

    Willem

    Dec 26, 2005
    Belgium
    Maybe your band is just too loud?
    Maybe you plugged your passive bass in the active input?
    Crank the mids on the head.
    Disable the scoop function.
    Try different range settings.
    Try it with resonance at 0-2.
     
  8. Voltaren

    Voltaren

    Sep 11, 2005
    far far away
    Well failureXbass, I know where you are coming from.

    When I first got my YBA200 I was a little more than dissapointed, I could get no decent volume from it without sounding like an old bloke who just ate a jar of prunes. no one but no one is going to get away with that crap sound in any gigging band.

    Why on earth Traynor make and sell a bass amp this way has got me buggered, they sell them cheap but why oh why Traynor do we have to retube these amps from brand new to make them a reasonable amp. what's with you lot.

    Now I got that gripe out of the way failureXbass I will explain how I went about getting the most headroom out of it.

    Firstly, I changed the first two ax7's to at7's, the last is an
    ay7, this works and will certainly give you more volume before farting.

    Due to the Sovtek output tubes crapping themselves I also changed these over to old Svetlana 6550's, once again an increase in clean volume and better tone also.

    I leave the scoop off and keep the resonance control to about 3.

    I believe any change over to JJ tubes will be a good one and help even more. That will be my next move when needed.

    My band plays loud old school rock and that is the way you play it. If thats what you do then go for it.

    Phil
     
  9. failuresXbass

    failuresXbass

    Jul 19, 2006
    SoCal
    Voltaren

    Thanks for your reply, while my band doesnt play old school rock, I am going for that sound. Deep, clean, loud.

    Getting in to this I new 200 watts may not be enough, but i was playing through a hartke 3500, and at 8 ohms - i was only getting about 240w.

    Your post did help, and i think i will leave the ay7s in the pre for now, I am going to search for some better mains.

    I am interested in the KT90s. Anyone have any input on these?
     
  10. Voltaren

    Voltaren

    Sep 11, 2005
    far far away
    failureXbass, I recommend you put in a new post about the KT90's.

    I was also interested but did not have the time or dollars to experiment.

    If you decide to go with KT88's, go for jj's, if you look into it a bit you will find certain brand KT88's and 6550's are exactly the same tube with only minor cosmetic changes, this is not so with the JJ's, my guitarist friends are using them and have had measurable improvement in tone, maybe not in volume in the guitar amp but I believe it will in clean headroom for our amps.

    If you have the dollars I also recommend changing the preamps over too, this will allow you to run the preamp at a higher setting and back off the output valves.

    Let me tell you from experience, do not run the output valves flat out or close too it. When they go they take out some resistors with them. you will need a tech to get it going again.

    best of luck
    Phil
     
  11. failuresXbass

    failuresXbass

    Jul 19, 2006
    SoCal
    Voltaren

    Thanks again for the advice. I already changes the pre tubes to ay7s, which have 40% of the gain of a ax7.

    I have ran the ouput stage at pretty close to wide open, but it was insanely loud, and I am trying to get the whole band to tone it down a little. Hard to do with a loud drummer and a guitar player playing through a 150w randall head.

    I will post about the kt90s, as well as possibly contacting yorkville to see if they feel they are an acceptable replacement.

    thanks again.
     

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