Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Full Tube Amp Overdrive Questions (and others)

Discussion in 'Amps and Cabs [BG]' started by freshmeat1989, Jun 26, 2005.


  1. Everyone raves about tube amp overdrive (which I'm sure is not unfounded :bassist: ) but I've always been confused on how to do this. Is there more than one way? How?

    Also, what is the difference between the Gain and Master Volume knobs and how do you use them to acheive tube overdrive?

    I am thinking of in the future (after I get my cab) of getting an Ampeg V-4BH to get a taste of tube tone, feel, and the characteristics of a tube amp, but have concerns of headroom problems. Has anyone experienced any success in changing the tubes to get more headroom? Does anyone have any suggestions for doing that?

    Thanks,
    Jeremy

    :)
     
  2. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Well, you can overdrive either the power section or the preamp section. Overdriving the power section requires that you turn the master up high enough while having the gain low enough to overdrive. This usually sounds better than the preamp overdrive, but it also is very loud. For practicing, just use preamp overdrive which occurs when you turn gain up high and use the master to control volume. Also check out the Traynor YBA-200. Its only $600, but its got power and will overdrive a ton with the stock tubes. For more clean headroom with it you can get the tubes changed. Its 200 watts all tube.
     
  3. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    There are a lot of different ways to get a "tubey" tone without having to lug around heavy all-tube heads, deal with the potential unreliability of a tube power section, etc. Personally, I LOOOOOOVE fuzzy tube distortion and use it all the time. I use my SWR IOD preamp to dial in that "just about to break up" grind that you get from a pushed tube amp that's on the verge of either blowing up or taking you into the fifth dimension. :D The fact that the IOD is only the fraction of the weight of an all-tub head is nice, not to mention the fact that I can use it with the power amp of my choice (Stewart 2.1), AND I never have to buy replacement power tubes! ;)

    You can also approximate the tone of a grindy, fuzzy, pushed tube amp with a variety of solid state and tube distortion pedals...to varrying degrees of success. Many purists will argue that there's only ONE way to get true, pure tube distortion, and tha's with an all tube head (tube preamp, tube power section). But...there are so many other options that are more portable, more reliable, less expensive, and more versatile that it might be worth a look into your options. ;)
     
  4. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Some ears can tell the difference between all tube and hybrid. You need to try each for yourself before deciding.
     
  5. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    You need power tubes to get the good overdrive sounds (imo, like the clips in my sig), as most preamp overdrive sounds are often buzzy and harsh sounding.
     
  6. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL

    And differences between tube amps, for that matter.
     
  7. its due to the way power tubes clip, instead of sending harsh DC-like signals as a SS amp does, they keep a more natural algorythmn/wave pattern, in that it still curves to an extent at the peaks

    ( i think this is right-ish, but it was a long shift and is getting late-ish ; )
     
  8. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Doesn't your IOD have a pair of power tubes inside? Or don't they see any appreciable wear and tear in that configuration?

    Tom.
     
  9. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    The IOD has an EL-34 I think...
     
  10. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    The IOD is an oddball of sorts...it is a preamp, but it also has a power section specifically designed for distortion and tube-colored tone. The two EL84 tubes can be used as a 5 watt practice amp, can be used to generate a rediculiously wide array of tube tones, or can be totally by-passed so that the user can use the IOD as a typical "hi-fi" SWR pre. It is true that eventually one would have to replace the two EL84s, but I've had my preamp for years and they're still going strong. Plus....the cost of two EL84s isn't quite as much as replacing 6 power tubes. On top of that, I can still use my preamp if, for some strange reason, the tubes break or instantly go bad.
     
  11. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    I believe there is someone on this forum with an old Sunn tuber that has had the same tubes for 20 (?) years and they are still glowing strong. I think they are 2 (maybe 4?) 6550s.
     
  12. WalterBush

    WalterBush

    Feb 27, 2005
    Yuma, Az
    The "gain" knob on your amp generally controls the amount of signal reaching your preamp tubes. Turning it up increases the voltage transferred to the tube, which will result in the rich tube clipping that was referred to below. As a side effect to the way tubes work, this also limits the bandwidth the tube can amplify, which is why so many distortions lose bass frequencies while distorting.

    Your "master volume" knob generally controls the signal going from your preamp to your power amp (there are ALWAYS exceptions). The amount of power required for a power tube to function is impressive, using lethal DC voltages. No amount of voltage coming off of your preamp is going to cause it to distort, but it will draw more current than usual out of the wall in order keep up. Power tubes will get hot, inefficient, draw power faster than the rectifier tube can keep up, saturate the output transformer, etc in an effort to live up to their specs. This results in "power tube distortion."

    Don't take anyone's word about power tube distortion. In some amps it's sublime, in some amps it affects feel more than sound, in some amps it sounds horrible, and some amps are designed so that you can't push the power section hard enough to distort. The only way to become acquainted with it is to find a few tube amps, plug in, and crank the crap out of them until the tubes in back are cherry red with a bluish halo inside. Power tube distortion achieved mythical status before amps came equipped with a master volume knob, and I firmly believe that most people you might talk to don't know beans about it, and most likely would prefer a preamp or transistor distortion in a blindfold test, not power tube.

    This is (mostly) just my opinion, of course, and I don't question anyone's experience here. That last paragraph refers to the legion of hack g%^&%rists and occasional bass players that have been in a rehearsal or recording studio with me, and were the purveyors of bad information they got from some magazine in an interview once :confused:

    Bottom line, find someone who'll let you crank their rig to face-peeling levels, and expiriment for yourself before plunking down your hard-earned dough :)
     
  13. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Yeah, that would be me. And it's about 35 years now. :smug: Clips are in my sig.
     
  14. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    I love the overdrive/distortion I get outta cranking my Mesa 400+ at gigs. It sounds much better than the distortion I use from the preamp when just practicing.
     
  15. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Can you use the EL84s though for grind into a power amp, kinda like running a tube amp into an attenuator then into a U5 into a power amp?
     
  16. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    Ox,
    I'm not sure if I totally understand your question, but I'll take a stab. You can use the IOD in several different ways. You can use it as a pure SWR preamp, you can use it for pure distortion (and can adjust the level of drive), you can blend the two together, you can use the unit as an effect, as a DI, etc. The tubes don't produce enough power to use it on gigs as a stand-alone unit (it only puts out approx. 5 watts of power, which only good as a practice headphone amp), but you can pretty much use it in any other application.
    I use the unit as a preamp and get my power from my Steward power amp. I keep the clean to tube mix at 50/50 and usually have the drive set around 10:00 or so. Setting the drive at around 8:00 or 9:00 doesn't give you much distortion at all. The sweet spot for me tends to be around 10:00, and 11:00 and up starts to get really fuzzy.
    If you're thinking about the possibilities of using the unit as an effect (running it through the effects loop of a U5 and then adding the power amp of your choice), you can do this, but it isn't what the IOD was really designed for. It was designed as a preamp, but it can be used as an "effect" if you prefer the tone of a different brand or style of preamp. Some people don't care for SWR products, so if you fee the same way, using the IOD as an effect would be an alternative. I hope that answers your question. :)
     
  17. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    No, it really doesn't. Does the preamp use the EL84s for the overdrive?
     

  18. There is NO more 'potential unreliability' in a tube head than in a s/s head. Please stop spreading that myth. Tubes have equal service lives to transistors, period, end of story.
     
  19. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    Ah...sorry. I was afraid I hadn't understood what you were getting at. :smug: The preamp uses the EL84s for overdrive...yes. ;)
     
  20. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    First....show me the numbers and research that support your claim. I understand your point, but I think you're taking my post a bit too seriously. I'm not slamming tube amps here...just trying to help the original poster with a question and expressing some thoughts along the way. I'm not engaged in any kind of "anti-tube" campaign. :rolleyes:

    Second (and most importantly)....I don't see the logic in your point where you claim that tubes are not subject to more wear and tear (and potential failure) than solid state components. We're talking about TUBE DISTORTION HERE... we are not talking about pitting an Ampeg against an SWR Redhead, setting the volume levels at bedroom practice levels and then seeing which one breaks first. The poster specifically asked about DISTORTION. The last time I checked, distortion was an unintended consequence of stressing a tube amp...pushing it well beyond it's limits. The harmonics and dampened high-end that the human ear perceives as pleasing (the result of tube power) generally only happens when a tube amp is pushed beyond it's intended capabilities.

    If you operate your solid state equipment at "normal" levels and create distortion through the use of a pedal, onboard effect, or preamp with a power section specifically designed for distortion, you're not creating any stress or strain on the components of your amp/preamp setup than you otherwise would just by using them and having them powered up. If, on the other hand, you must stress the components of your tube amp to create the desired distortion that the original poster asked about, I find it hard to belive that this can be good for an amp, and that you won't prematurely stress and/or age the components of your preamp and/or power tubes. Granted, I probalby don't have the labratory numbers and stats that you do to back up my opinion on this, but it makes sense that the issue really isn't as simple as comparing apples to apples as you've claimed in your post above. If you've ever listened to any live rock recordings from the late '60s or have seen any live footage from this era, you can see and hear what happens to a tube amp that is pushed hard. If you tried to do the same thing with a solid state amp, who knows what you'd get (I don't know...I don't try to blow up my equipment), but the end result would NOT be the type of pleasing, musical distortion that the poster was asking about, so it's a moot point.

    Play your tube amp often and enjoy it...it's OK. Just don't ask me to haul it around for you! :smug: