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GB shuttle 6 tube swap for different type???

Discussion in 'Amps and Cabs [BG]' started by Slapstyle, Jan 6, 2012.

  1. Slapstyle


    Dec 3, 2009
    Ok, so I've been reading about people swapping for a new 12ax7 in their heads, and not noticing much difference in tone, which makes pretty good sense to me. I'm wondering though, if anyone has swapped for a different type of tube, like a 12AT7, 12AU7 or 12AY7? Here's my dillema. I sold my Ampeg SVT pro 6 because it was too heavy. Bought and love the GB, but it's not the same. The sound is very clean, and even when driven to the max, even the distortion sounds clean, if that makes any sense. Grindy, but not warm and fuzzy and rich and glassy in the harmonics. Not at all like the ampeg. I also have a markbass compressore, which, when I crank the tube gain to about 3 o clock, breaks up nicely and gets a great sound for everything from the B note on the A string up, but the notes lower than that sound like a wet fart. Too bad. Tried swapping the 12AT7 for a 12AX7 and it sounded almost exactly the same. More upper harmonic richness, but the same wet fart sound. But I digress...

    So, anyone tried a different tube type in their shuttle? Get a fatter warmer wooly tone? Is it just wishfull thinking on my part?
  2. impactwrench


    Feb 22, 2009
    Ive not swapped the tube, but I thought that a 12AT7 gets you less gain, and a 12AU7 even less than that? Should one of those tubes allow more grit?
  3. Slapstyle


    Dec 3, 2009
    That's my understanding, but it's not more edge that I'm after... I don't think. I'm thinking it's less. I'm trying to find the place where the signal juuuuussstttt starts to break up, and the harmonics are jumping out and everything is really articulate, and just on the edge of distortion. But with my shuttle, it's either distorted or not. Can't get the in between that I'm looking for.
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    There's plenty of in between, the amount of saturation is set by the tube gain control and the volume of the saturated signal is set by volume control. The master is also available, to scale the overall level to the applications and lso to help level matching when using the effects loop.

    The difference in gain is not only dependant on the tube, but the circuit that is used normalizes the wide range of variations across the tube families. The reason for this is that many of the curves (operating parameters) can vary as much as 200%, so for the sake of uniformity between the different tubes on the market (and I am talking tube to tube variations if the same part number) the circuit has a lower absolute dependancy on the variation of these parameters. In other words, player will have consistency from amp to amp and won't encounter a "stinker" due to an otherwise "normal" tube parameter difference.

    One thing that may help it to put a compressor on the front end coming into the amp. This will halp tame the peaks of the envelope and maybe give you the result you are looking for. I don't think changing tubes is what you are looking for.
  5. Slapstyle


    Dec 3, 2009
    Thanks man. You're input is greatly appreciated and obviously valuable due to your direct knowlege of the GB amps. However, that's what I've been doing all along. The Markbass compressor is the front line of my bas rig. I did try the amp without it, to see about different tone coloring and see if the compressor was effecting my tone in a negative way. Not the case. But if I used the compressor to get the tube gain where I wanted it, it only sounded good in the high register. That's a separate point though. Let me say also that I love my shuttle. It's got this flavor that's similar to the old GK stuff, but with a modern edge. Great for clean slap tones and funk stuff in like a 3 piece band. Perhaps I'm trying to make it do something It's not meant to do. I'm playing in a big ass 6 piece rock band with 2 les pauls into marshal stacks. I'm looking for more of that classic fat tone in the hopes of cutting through better. I set the volume and master to appropriate listening levels and start cranking the gain, but by the time I notice any difference in the sound, it's already got that grindy bass fuzz sound (which is nice by the way, but I can get the same sound and many more from my Fender SubLime pedal), and even that tone sounds really clean and bright, not rich and warm. I've considered putting a preamp in front and I'm fine with it if that's what it takes, but with all this tube gear around, I wanted to try to get the sound I want without buying more stuff. I tried some Presonus blue tube pres with different levels of tube gain, and even daisy chained the stereo one to use both tube channels and couldnt find anything I liked. I also tried an ART DPSII and that wasn't the magic ingredient either. (these are mic pres I have as I'm a recording engineer and this is just stuff I had lying around to test. These are not true bass preamps). So I dunno... maybe I'm fooling myself and need to accept that the shuttle is what it is, and doesn't quite hit the mark for the band that im playing with now. I still LOVE the amp. I love the portability and hi fi tone. I just might be trying to make it do something it doesn't want to do.

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