Op Amps in Valve amps

Discussion in 'Amps and Cabs' started by dtb, Oct 24, 2008.

  1. dtb

    dtb Member

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    Your thoughts ?


    I'm currently looking at changing from Marshall to Laney.

    But the Laney VH and TT amps have TL0725m op-amps in the pre-amp path and for the FX S/R.

    Am I being to fussy or should I insist on a true valve signal path ( with the exceptions of Resistors and Caps in the chain ).
     
  2. felim

    felim Member

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    Don't know a whole lot about the technical side of those amps but if the op amps are only in the signal path when the loop is used it should make no difference to you, the gear you'll put in the loop probably won't be all valve anyway.

    I used to have a Laney LC50, they're nice amps.
     
  3. wildschwein

    wildschwein Member

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    Most modern Marshalls - like from the JCM800 onwards (except for the earliest ones) actually have diodes in the signal path for high gain sounds - kind of like a built in distortion pedal. As you probably know, solid state rectifiers have been used in valve amps for a long time and most "tube purists" don't care much about that. I personally wouldn't worry about it - most people don't have all-valve signal paths, especially if they use pedals - op amps abound in guitar pedals. In the end if it sounds good it is good. Valve purity is a bit of an advertising slogan (that some people believe in) and I don't think it's really 100% achievable; unless you fork out for it - vintage, build your own clones, or boutique remakes of golden oldies. IMO, if you have a valve power section you're still playing a tube amp - tube mojo is mainly in the power section and how it interacts with the speaker.
     
  4. dtb

    dtb Member

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    They are in the Pre-amp path and they are feeding the Master Volumes. So they are an intergrated part of the sound.

    In fact in the TT50 that is the "new pre-amp " that they advertise.

    As for clipping diodes, I only use Marshalls with a true valve path ( same with my Hi-Watts and believe it or not, the Peavey Valvekings which are all valve signal )
     
  5. drewl

    drewl Member

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    There's a big difference between a SS rectifier or clipping diodes than opamps being used for signal shaping like in some of the JCM900's.
     
  6. ruppert240

    ruppert240 Member

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    not if you are using the built-in boost :)
     
  7. FortinAmps

    FortinAmps Member

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    The way I think of it is if you are buying a tube amplifier, it should be 100% tube signal path.

    Cheers,
    Mike
     
  8. skipm45

    skipm45 Member

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    Whatever turns your crank....
    The use of SS devices in tube amps isn't new, check out the schematic for a Dumble ODS. The signal goes directly to a JFET. Or a Boogie with the graphic EQ for tone shaping.
    The designers of those two example amps had no reservations, they just wanted to "get the job done". Personally, I like an all tube signal path, but If I wanted to add an effects loop, an op amp circuit would be my preferred method.

    my .02

    Skip
    www.skipzcircuits.com
     
  9. Rosewood

    Rosewood Member

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    The Vox AC30CC is packing about 4 ic's and and maybe a transistor or two, it's been leaning this direction for a long time. Like a Peavey classic 30, tube path all the way through till you turn the reverb on or use the effects loop.
     
  10. jdh

    jdh Supporting Member

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    Inside of the amp, I would use solid state components in the signal path only when they start serving snow cones in Hell.
     
  11. dtb

    dtb Member

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    This has always been my view ( except when using the boost on the VK100 head ;) )


    But that dont leave a lot of amps left. In fact all the low end budget amps ( Epi So Cal, VK etc ) tend to have a more traditional signal path.

    But the Laneys sound so right.

    :hide
     
  12. fullerplast

    fullerplast Senior Member

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    Most of the time, where op amps are used in a tube amp for effects loops and reverb send/returns the function is as a buffer or cathode follower equivalent. It's generally not a stage that is set up to be driven into distortion. As such, the benefit of a tube there is minimal IMHO, relative to gain stages. So while I might prefer an all tube amp as a rule, I don't avoid amps that use an op amp for those functions. Fuchs, Fender, and Vox all do that and in a way that does not compromise tone in a significant way IMHO.

    Dumble's use of an FET is a different case, and is simply an alternate signal path. It does affect tone.
     
  13. Rosewood

    Rosewood Member

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    Well lets face it, if your using an effects loop to drive a solid state, digital device it's not gonna matter much if there's one more in ic in front of it. But I'm like a lot of tube guys, I try to keep all tube path if I can.
     
  14. ChickenLover

    ChickenLover Member

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    It depends on what you really want. If you want an all-tube signal path then you aren't being fussy. If you want the best tone then you are.

    I would suggest not going into it too closed-minded (and insisting on an all-tube signal path when you're just trying to achieve the best tone is just that) and just go with whatever sounds best.

    In many cases...op-amps in the FX loop are closer to 'true bypass' tone than a tube-loop. Not that that matters though...lots of folks like the Dumbleator because it's not transparent. All that matters to me is the tone...not whether or not it's 'all tube'.
     
  15. cradlefish

    cradlefish Member

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    for me if it sounds good and it's reliable. Doesn't matter to me if they can put a squirrel inside there for all I care. Just as long as it sounds good:banana
     
  16. fullerplast

    fullerplast Senior Member

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    Black squirrel or grey squirrel? :hide
     
  17. fetishfrog

    fetishfrog Member

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    +1...especially the squirrel part...someone should try that ;).
     
  18. fetishfrog

    fetishfrog Member

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    Grey, with an EF86 shoved up it's rear...to cut down on microphonics.
     
  19. dtb

    dtb Member

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    I'm still browsing the circuit diagram, but the op-amps look to be shaping the pre-amp signal.

    http://tremolo.elektroda.net/Firmowe/LANEY/TT50.pdf
     
  20. Tone_Terrific

    Tone_Terrific Member

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    A tube signal path is not a guarantee of getting the tone you want.
    Buy the tone not the components.
     

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