hot rodded tube amps!

Discussion in 'Amps and Cabs [BG]' started by K Dubbs, Dec 3, 2005.

  1. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    From what I read around here on talkbass, I get the impression that lots of people swap out the tubes in their tube heads and rebias them accordingly to get "that" sound.

    Has anybody done anything similar to what Dave at Thunderfunk did with the AMP 420, but with their tube amp? AKA, has anybody bought, say, a lower priced tube head like a traynor YBA 200 and upgraded the capacitors, resistors, and/or inductors to tighter tolerance, higher quality parts?

    If so, has it made a positive impact on tone, clarity, noise, hum, headroom, etc?

    Post pictures of before and after if you've got em'!
  2. Though bias could potentially impact tone, that's not the real reason power tubes are biased--they are biased to ensure that the tubes are functioning in their proper operating range (for a simplistic description...) Kinda like having the right amount of oil in your car....if you're off a litle bit, by say half a cup of oil too much, your car's not gonna go any faster or slower, but if you're further off-say two or three quarts low----kaput....

    Sure, people change preamp tubes or power tubes, it's a relatively cheap easy way to experiment with the tone. Though I personally believe most of the time the difference will be subtle.

    As far as other components, I think the bass community isn't as radical as the guitar crowd. A few of us tinker with old amps, so we change filter capacitors for example, or upgrade coupling capacitors, but I don't get the impression there's a whole lot of us bass guys that are trying massive mods. We don't seem to be quite as "amp tone-obsessed" as the guitar guys IMHO...
  3. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    Nono. I know why tubes are biased. I was simply citing the two most common modifications of a tube amp, which are switching tubes (to modify tone) and the necessary rebias accordingly (so they work properly). My question is whether anybody has performed additional modifications to their amp other than the two most common, noted above.

    I want to see if switching out the capacitors, resistors, rheostats, inductors, etc. has any noticable improvement on the tonal characteristics I originally described.

  4. Passinwind

    Passinwind I Know Nothing Supporting Member


    I used to get requests for guitar amp mods frequently, but I can barely remember any for bass amps. When I did get any, they were usually to clone a given Fender or Ampeg circuit. I had lots of ideas for radical circuit mods, but that seems to be the domain of guitar players, for whatver reason.

    As far as meaningful upgrades, upgrading the transformers would be my first thought. This is prohibitively expensive for most people though. Changing tube type can definitely help in some cases, of course. Substituting metal film resistors for old carbon comp ones can improve noise, but lots of people prefer the sound of the carbon ones. There are a few cap type substitutions that some guys like (so-called audiophile pieces, etc.), but messing with the values often tends to have more payoff than changing the type, in my experience.

    Passive component tolerances aren't generally that important in the tube musical instrument amps I've worked on, except perhaps in the power supply side, and many old guitar amps "benefit" from out of spec components. I've seen many guitar amps disappoint their owners when rebuilt to original factory spec. There really is a voodoo element at work, it seems.

    Sorry I can't help more. I'm actually not a fan of tube amps for bass for the most part. But if you have the technical chops, I hope you'll keep us posted on your adventures. ;)