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Gigging with a tube amp

Discussion in 'Amps and Cabs [BG]' started by BLU Dragon, May 27, 2002.

  1. Well, actually, it's a hybrid -- but anyway... I'm a guy who's just getting back into playing in bands after a long hiatus (about 10 years). The first thing I discovered this time around is that either the bands have gotten louder or the type of music we're playing (blues and classic rock) simply needs more amplification than the country and 50's and 60's tunes I was playing the last time around. The Yamaha B100 head that got me through about a million gigs is now vastly underpowered. I picked up an amp on ebay that may do the job. It's a SVT III, which appears to be the earlier model to today's SVT 3Pro. It has three 12 AX7's powering the preamp section. The only other bass amp I own with tubes in it is my Bassic Black w/ one 12ax7. That's just for practice and home use. Now, here is my dilemma:

    I love the tone I'm getting from this amp and the 350 watts seems to be satisfactory for most of the clubs we're playing. However, it kind of freaks me out when I start thinking about trying to gig with this thing. The Yamaha once survived an 8 ft. fall onto pavement and still played the gig, after I replacing the fuse which shattered upon impact. Another time, we were late getting to a job, and the amp had been in the trailer all weekend during a record cold snap. I hooked it up and found that all the knobs were frozen in their previous settings. Oh well -- we were late and the show must go on. Played it that way. After a few minutes, the heat from the amp thawed out the knobs. No problems. Obviously, since the Ampeg has those little light bulb thingies in it, I can't treat it that way. I already assume that any amp with vacume tubes must be handled with kid gloves. My question for those of you who are gigging with tube amps is, just how much TLC does it require to pull this off?

    AMS has a four space shock rack for $330. That seems a bit hard to justify, considering that's about what I paid for the amp, itself. Is that really necessary? Looks to me like, if it gets knocked off the stack, those tubes will shatter with or without the shock absorber springs in the rack. What about replacement tubes? (I think I need to retube it anyway.) How many extras do I need to carry? Do you carry a full compliment of tubes to gigs or just one or two in case one blows out? Do vacume tubes even blow out individually, by the way, or do they just gradually get noisy and lose power? What would that sound like? Do you carry another full amp for back up?

    Sorry for the long post. I tend to be a little wordy. I appreciate any advice you have for me.

  2. Gman


    Jan 4, 2000
    Indianapolis, IN
    Hi Brad,

    Good to have another Hoosier aboard. What part of the State are you in ?

    I had an SVTIII-Pro, but soon found that I didn't like the tone and got rid of it, and I don't use tubes anymore. But, almost every guitar player that I've ever played with uses a tube amp, and they carry 1 power tube and 1 pre-amp tube at the most. You may get some different opinions here. I suppose if your going to re-tube anyway, it wouldn't hurt to keep the old ones and carry them with you in case you lose 1. 12AX7's aren't all that expensive. Wouldn't hurt to keep a full set since you're so worried about it. Might be a good cheap way to have piece of mind.

  3. I'm in Crawfordsville. Playing with some guys from Frankfort. Have jammed with some guys from Indy, but it didn't turn into anything.
  4. Thanks for the info Psycho. I should clarify that I would never intentionally mishandle any gear. But in the course of playing hundreds of gigs over about a 13 yr. span of time, stuff happens. As I mentioned, my old amp did get knocked off of the speaker cabinet, which happened to be setting on the back of a flatbed semi once. I didn't do it, but it happened. It also got stored in the band trailer one weekend when it dropped to something like -20, I believe. I realize that it has to be very, very cold before oil will freeze, but, what can I say? It happened to me.

    So, more details, please. Sounds like, if I put it in a regular (non-shockmounted) rack and haul it around in the back of my truck or the band's equipment van, I'll be O.K., then, huh? No special handling requirements of any kind?

    What about tubes going out? Are you saying that they don't blow out -- ever???? I thought they had to be replaced every so often. Not true? The amp is about four years old, according to the guy who sold it to me on ebay. (In other words, I actually have no idea how old it is and how it was treated.) At my gig Saturday, the power seemed to be dropping from time to time. Just a minute ago, in my basement, it was dropping completely out. It's also a bit noisy. Is this indication that the tubes are dying, or something else?

    Appreciate the info.
  5. Gman


    Jan 4, 2000
    Indianapolis, IN
    Well, I don't know if you've done a search for info on that amp, but it sounds like you're experiencing the same thing alot of us have, and the reason that alot of us no longer have that particular amp.

    But it could just be that a tube is going out. I don't know, but if you do some research, you'll find that that is a very common complaint.

  6. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Also, take care of your equipment.
  7. PsychoBassGuy,

    Is this the reference to which you're referring?:

    'It's an unstable design and once problems start, they don't stop. I rebuilt mine THREE times (with parts and diagrams from SLM) before I got rid of it. It's overrated and constant high current (4 ohm loads) demands eventually make the thing just go plain haywire.
    The driver circuitry which is solid state, NOT tube as SLM leads people to believe, cannot swing enough voltage for transients. The power supply is too slow and undervoltaged for loud playing at low impedance loads. In addition, there are protection relays for all the voltage feeds which get easily knocked out of whack. When they screw up, the output tarnsistors see full rail voltage with no bias at all; bye-bye outputs.'

    So, there are no proposed solutions to this problem, huh, other than just get another amp?

    Thanks again for the input.
  8. Chasarms

    Chasarms Casual Observer Supporting Member

    May 24, 2001
    Saint Louis, MO USA
    I am not familiar with the concerns about that specific Ampeg amp, but I will say that in 16 years and several thousand performances and rehearsals, I have never once seen a 12ax7 fail, whether in a hybrid bass amp or an all-tube bass or guitar amp.

    The 12ax7s (and the 12au7) in the '73 SVT that had were the originals and I used that amp until 1994.

  9. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    Ask your guitar playing buddies. I'll bet they toss their Fenders and Marshalls around quite a bit and probably don't even bring spare tubes to the gig. This is how life was before solid state :cool:

    Yes, if you plan on dropping the amp a lot, carry spare tubes :rolleyes:

    If the amp is frozen, thaw it out before ou fire it up and wait for it to cool down after you use it before you toss it back into the freezer ;)

    Not much to it at all.
  10. However, I assume it's too late even for that, now, right? Keep in mind, yesterday I was playing it (with 2 8 ohm cabs) and the power dropped COMPLETELY DOWN TO ZERO, then faded back in. That freaked me out. In a quarter century of playing bass, I've never had that happen before. I turned it off at that point and haven't fired it up again. However, I assume that something is fried beyond hope at this point. Are you telling me that all I have to do is go unplug one of the two cabs and it'll start working just fine again (although only at 200 watts, of course)? Or is it probably just a boat anchor at this point?

    Thanks again,
  11. Gman


    Jan 4, 2000
    Indianapolis, IN
    I don't know as much about these things as PBG, but I think it will work when you try it again. And if you only run at 8 ohms, you may never have a problem again.

  12. Wow! That would be some really good news. I hope that's the case.

  13. Ty McNeely

    Ty McNeely

    Mar 27, 2000

    Well, if the damage has already been done by the 4 ohm load, it may or may not work well.
  14. :(
  15. Lackey


    May 10, 2002
    Los Angeles
    From what I know tubes are quite durable,, just look at how rarely your guitar player buddies put in new tubes in their old Marshalls. I was just talking to a guy at Guitar Center the other day about tube bass amps,, he's had a mesa boogie all tube bass head since 1980,, has gigged HEAVILY with it,, its been dropped before,, and he's only put two sets of tubes in it!
  16. dadams


    Jan 26, 2002
    Piqua, Ohio
    on the tubes. I would check to make sure your tubes are in the sockets fully. Sometimes when they are a little out they can do some weird things. 12ax7's seem to last a long time. The power tubes only need replaced when they are weak on the grid current or leaky. Sometimes a tube tester wont put a perfect load but can give an indication of a tubes performance and how much life is left. I would carry a few spares on the power tubes better yet a spare head, if something like a resistor burns out well you wont have power at all.
  17. Wow, thanks for all the guidance, folks. Perhaps this would be a good time to summarize what I've learned so far.

    1) Tubes are much more rugged than I've given them credit for being.
    2) There are no special handling requirements for tube amps and hybrids, compared to solid state amps. You can rack 'em like any transistor amp and haul them around in a trailer with the rest of your gear. (The Ampeg went to it's first gig in the front, passenger seat of my truck, not in the bed of the truck. I was afraid the road vibrations would damage the tubes. Well, what can I say? I didn't know.)
    3) It would be considered perfectly reasonable to gig with an amp with tubes in the pre without any backups whatsoever. (Although I would probably carry them anyway.)
    4) The problems I'm having with my new (used) Ampeg is probably not simply a matter of the tubes burning out, but rather something wrong with the amplifier, either a general design flaw in the model or a problem with this particular amp. (I've had at least a half dozen different ideas on what the specific problem could be across two different threads.)
    5) You can care for a tube amplifier by simply following all the same reasonable precautions that you would take with any other amplifier. (Once again, I would like to emphasize that I have never, ever intentually abused any amplifier. However, after reading all the comments here and taking the suggestions under careful advisement, I promise to make a extra special effort not to store my amplifier in a deep freeze until immediately before an outdoor gig in July, nor will I ever throw it down a flight of stairs -- you know -- just for fun. Of course, I assume that if I DID pop for one of those really nice shock racks, it WOULD be O.K. to chuck it down a flight of stairs once in awhile, right? JUST KIDDING! :D )

    Anyway, thanks.
  18. Yesterday, after work, I unplugged one of the eight ohm cabinets. Messed around with the amp for a half hour or so with no problems. This seems to confirm Psycho and Gman's theory that the amp is only unstable into a four ohm load.

    Unfortunately, that still means the amp is of no real use to me. I already have four other bass amps, everything from a Workingman's 10 to a component system with separate pre/power amps. What I'm needing is a "medium sized" rig (350-500 watts) that will drive both JBLs at decent volume for general gigging duties. Oh well...

  19. Gman


    Jan 4, 2000
    Indianapolis, IN
    Glad to hear it's working. Sorry that it's not going to work for you.

    I know it sounds like a strange move, but I went fro m the SVT-IIIPro to a Gallien Kreuger 1001RB, and don't have any regrets. It's not nearly as warm sounding by itself, but in a band situation it sounds great and cuts like a mutha'. 540 watts at 4 ohms, plus 50 watts in a seperate amp for highs.

  20. Yeah, the funny thing is, for that brief period of time when the amp was driving the two JBL 15's at 350 watts through that Ampeg preamp, the sound was just AWESOME. I was likin' it big time. I immediately thought, "Yeah, that's it!" And now, I can't get that again.

    Another funny thing is that, of the five bass amps that I now own, the other one that has a tube preamp (an SWR Bassic Black with a single 12ax7) is also malfunctioning. It's making a horrendous noise, which seems to be some type of an electrical short. So, five amps, two of which have tubes. The three solid state amps have never given me a bit of trouble, but both of the ones with tubes are currently not working right (or not at all in the case of the SWR.) Now, I realize that these are two completely different problems, neither one of which seems to have anything at all to do with the vacume tubes. However, it sure does look to me like the patron saint that watches over bass players really, really wants me to stick with solid state.


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