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Single Tube Pre Amp Hybrids

Discussion in 'Amps and Cabs [BG]' started by socialleper, Jul 27, 2019.


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  1. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    I have very limited experience with tube pre amp hybrid heads. Some have 2 or 3 pre amp tubes, which isn't that far off from what a all tube amp would have. However, there are a couple hybrids that have exactly ONE tube. The highly suspicious, skeptical part of me thinks that this might be more of a gimmick than something that translates into real tone.
    So I put it to you, the amp hoarding TB players: do you think, or know, that having ONE pre amp tube really makes that big of a tonal difference?
    Do you have, or have had, an amp you really liked that was a hybrid like this, and did the single pre tube do something for you, or did you just like the amp in general?
    Do you think just straight up SS (either A\B or D power) is more or less the same?
     
    JC Nelson and Ellery like this.
  2. jbrew73

    jbrew73

    Dec 24, 2006
    I’m gonna say it is generally a gimmick but the classic fender tone stack/preamp that many amps use only requires one tube. One 12AX7 tube has two triodes(sections or stages) inside.
     
    Clark Dark and monsterthompson like this.
  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    It depends on the design...
     
    LowWatt, chadds, Clark Dark and 17 others like this.
  4. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    Let's narrow it down to something you probably have experience with.
    The M9 carbine has a single 12ax7 pre amp tube. What is that adding to the tone, if anything. Or is that for just compression or gain?
    Based on features and when it was released, a competing amp would be the Ampeg SVT4 Pro, which has 3 12ax7 tubes in the pre amp. Does that add more "tube" sound, or more clean head room, or is adding more pre amp tubes to a hybrid something of a gimmick?
    Similarly, the new WD800 has one pre tube, where as my standard D800 is SS. Beyond the snazzy EQ, which absolutely has an appeal for me, is there something I am going to hear in just the base level tone of the WD800 I won't hear in the D800? Grit, warmth, transient harmonics, any of that? Or is it just for a little tube dirt when pushed? (I almost never push my D800 into the "yellow". The break up I hear when I do isn't pleasing to my ears.)
     
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  5. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    Without going too far down the SS v Tube rabbit hole, what exactly is a player getting for that one tube?
     
  6. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Those are all very different amps with different circuits and flavors. The tubes do exactly what the designer intended then to do.
     
  7. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    I'm a little to ignorant about what exactly that would be.
    In the case of the M9 Carbine, what was the intention for the tube in the pre amp?
     
  8. Are most of these tube preamps class A designs? Multiple class A gain stages?
     
  9. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I owned an Alembic F2B preamp for a while. Each channel only uses one tube and I've never heard anyone who's played through one call it a gimmick piece. FWIW, I've built essentially the same circuit in various solid state topologies and they all sounded mostly different, or mostly the same, depending on what I intended and how well I realized that. Play feel is pretty hard thing to quantify, but to me it's more or less what it's all about.
     
  10. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    For gain and flavor, especially when driven hard. In the case of the Carbine, the flavor is quite different from t hat of say the WD-800 which also uses a single tube for gain.
     
    MAXSPINRUN likes this.
  11. stuntbass77

    stuntbass77

    Nov 6, 2007
    I believe that most of the “tube” sound comes from the power section of an amp ( this has been my experience). Tube pre Amos May warm up the sound a bit but the real magic is in the power amp, just my 2 cents
     
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  12. Wasnex

    Wasnex

    Dec 25, 2011
    I don't think most people consider the M9 very tubey. I think part of the reason is because of the way the Master Volume is scaled. It goes from off to super loud if you have the gain cranked up very much. Unfortunately this limits your ability to explore pushing the gain on the preamp tube. I have an M9 and I don't have the slighted idea what happens if you really crank the gain, because it would not be possible to set the output low enough to be usable. So if there is any tasty tube drive available in the circuit, it's not realistically accessible to most players. I don't have any worries, as I have other amps.

    I did see one M9 that the factory modded on request with a different output pot and also a discrete microswitch for the mute function :thumbsup:.
     
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  13. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Perhaps in the amps that you have tried. This is not at all consistent with many of the amps on the market.
     
  14. Jeff Scott

    Jeff Scott Rickenbacker guru..........

    Apr 11, 2006
    This brings to mind something I did in the late '90s. I have an Aragon 24k preamp. I borrowed an Audio Research SP9 to try in my system for a while, and found that the Aragon was "warmer"/more musical sounding than the Audio Research. That is all; it probably doesn't mean much in the context of world problems. ;)
     
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  15. Rip Van Dan

    Rip Van Dan DNA Endorsing Artist Supporting Member

    Feb 2, 2009
    Duvall, WA
    I have an Eden WT500/800 and an Eden Nemesis RS400. The WT500/800 is a hybrid amp with one tube. The Eden Nemesis RS400 has a 100% FET front end...no tube and yes there is a noticeable difference between them. The WT500/800 is definitely warmer than the RS400. The RS400 has a great sound - full, clear, and articulate, but it just doesn't have the warmth that the WT500/800 does.

    All of the old Eden WT hybrid amps use one 12ax7 tube in the impedance matching section of the preamp operating within set parameters to add that warmth. It's not adjustable and swapping different brands in and out makes little to no difference in the sound. But there is absolutely no way to get any overdrive out of one unless you hook up a pedal.

    The new Eden WTP series has two 12ax7 tubes in it. One tube is in the traditional place and another one in the gain section. The tube in the gain section is what allows that amp to overdrive like mad. It can get really dirty.

    Back to the one tube versions though, I had to send my amp in for service a couple of years ago and had to use my RS400 instead of it. I had no problem doing so because I do like the sound of that RS400. I gig with the WT500/800 though because the warmth it adds just sounds better. So it's not really a huge difference, but it is a noticeable difference. As @agedhorse said about 1-tube hybrid amps, "It depends upon the design".

    The older Eden hybrid amps used that tube specifically to add that warmth because that's what David Nordschow wanted it to do. The newer WTP amps that the Marshall designers came up with, kept that warmth because it just sounds good, but added the tube in the gain to add that overdrive sound that Marshall has so much experience with. Different designers like different things.
     
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  16. Wasnex

    Wasnex

    Dec 25, 2011
    Of course it all depends on how you define "tubey," and plenty of people apparently define it in a similar manner to @stuntbass77
     
  17. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    The old Mesa 400 Bass I had was a little like that too. You couldn't crank it high enough without blowing out everything else to hear the pre get any grit into it.
     
    Wasnex likes this.
  18. 40Hz

    40Hz Supporting Member

    You can also get a very tube-like tone out of some solid-state amps if they have been designed to have very good tube emulation. So it might make more sense to look into one of those rather than a hybrid if you’re not going for an all tube amp.

    I never thought most tube preamps I’ve experienced made things sound all that much like a full tube amp. I’d have to agree with @stuntbass77 when he said most of that tube vibe people are after occurs in the power amp rather than preamp stage.

    I’ve got all three amp types - all tube, hybrid, and solid-state. And my solid-state (B-100R) sounds far more like a classic all tube amp than my hybrid (SM-400) with the 12AX7 does - because it was designed to sound like a tube amp.

    Tube loaded preamps will give you a different sound. But to me it’s more their own sound than anything else.

    Something else to be aware of is just because there’s only a single glass envelope doesn’t mean it’s just a single “tube.” The 12AX7 is what’s called a dual triode, which means there’s two complete “tubes” inside that are sharing a single glass envelope.
     
  19. socialleper

    socialleper Bringer of doom and top shelf beer Supporting Member

    May 31, 2009
    Canyon Country, CA
    @agedhorse @Wasnex @Rip Van Dan:
    This is all good info, and you have all sort of hit on a bugaboo that has always confused me. That is "what exactly is tubey?"
    In these three videos of some hybrid class D amp, it seems to end up all over the place. The Ampeg PF has more high end grit than the SS Aguilar TH, which to me sound warmer and wooley. Then the Orange Terror Bass starts off pretty scooped, breaks up in a way that might be more of what people would consider tube warmth, but to me sounds a little messy. I tried a V4B in a store and when I pushed the heck out of it, the tone was more crusty like the Orange, but a SVT-CL never sounds warm to me at all, and it actually pretty scooped.
    Is there really no actual definition of "tube" tone when it comes to bass?


     
    Rip Van Dan likes this.
  20. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Well, different all tube amp designs can sound VERY different as well.

    It's not as much the device that's used as the intent and skill of the designer. Tubes CAN make it easier to achieve a specific effect or tone, but it's not the only way to do it. I have done it both ways, depending on specifically what I was trying to achieve.
     
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