One thing about that pentode/triode switch, it cuts the power in half, only reducing volume by 3dB, which isn't much. It is sometimes more useful as a tone changer then a volume reducer. It might get the amp to break up a little sooner but a lot of people say it changes the tone too much and don't use it much unless they like the different tone.
Here is one additional place where I've seen it, exactly the same 100K/39K here in the Mesa Dual Rectifier also on V2B:
http://circuitdiagram.net/wp-content/uploads/2011/04/mesa-boogie-dual-rectifier.jpg
1.8K cathode, 220K plate resistors, and 1 uF cathode bypass are also common between the two designs.
Wondering, which one came first?
I don't know much about the reissue Orange amps, but the originals were pretty high gain, and with only 2 preamp tubes! Didn't like the sound as much as Marshalls but the old Orange amps are great for sounding like early Black Sabbath.
I remember the original Orange 120. It had it's own thing going, somewhat British but different. The FAC control does let you tame the farty bottom end. Personally I never thought it had enough gain.
Gary
Gary
I agree that the initial Orange design isn't really that "gainy" at all, unless you really crank it up to ear shattering volume levels.
Most Orange tube preamps follow the same overall architecture: First gain stage drives a passive "James" tone control, which is followed by an attenuating volume control pot. These passive circuits have high insertion losses and pretty much use all the voltage gain provided by the first stage. As a result, input signals to both first and second gain stage are at levels not likely to overdrive the gain stages.
The clever trick of the "Overdrive" series was naturally the post phase inverter master volume arrangement (one of the first in guitar amps, BTW): What there is, is enough gain to overdrive the driver / phase inverter stage as well as subsequent gain stages, (the power tubes). With post phase inverter master volume this could be done at sane volume levels.
Phase inverter distortion somewhat resembles genuine power tube distortion because likewise it is constructed by summation of two asymmetrically distorted out-of-phase signals. Hard asymmetric distortion in such signals converts to soft symmetric distortion when the signals are combined in push-pull arrangement. In comparison to real power amp overdrive the small signal triode distortion is different from power pentode tube distortion. Also the arrangement will lack dynamic effects caused by current draw and associated effects of power supply sag, and dynamic effects caused by power tube grid clipping and associated bias shifts / crossover distortion. Like modeling amps "it's close but no cigar".
This, coupled to "flat-ish" response of the Orange amps (there's very little mid-range notch unlike in Marshall, Mesa, Vox, Fender, etc. amps) in general creates that "fuzzy" overdrive tone.
BTW, F.A.C.S. control was replaced by a somewhat similar "contour" control in later amps. This provided more complex voicing filters than just a user-variable coupling capacitance (a.k.a. low pass filter).
See here:
http://www.orangefieldguide.com/OFG_SCHEM/overdrive_series21.jpg
Most Orange tube preamps follow the same overall architecture: First gain stage drives a passive "James" tone control, which is followed by an attenuating volume control pot. These passive circuits have high insertion losses and pretty much use all the voltage gain provided by the first stage. As a result, input signals to both first and second gain stage are at levels not likely to overdrive the gain stages.
The clever trick of the "Overdrive" series was naturally the post phase inverter master volume arrangement (one of the first in guitar amps, BTW): What there is, is enough gain to overdrive the driver / phase inverter stage as well as subsequent gain stages, (the power tubes). With post phase inverter master volume this could be done at sane volume levels.
Phase inverter distortion somewhat resembles genuine power tube distortion because likewise it is constructed by summation of two asymmetrically distorted out-of-phase signals. Hard asymmetric distortion in such signals converts to soft symmetric distortion when the signals are combined in push-pull arrangement. In comparison to real power amp overdrive the small signal triode distortion is different from power pentode tube distortion. Also the arrangement will lack dynamic effects caused by current draw and associated effects of power supply sag, and dynamic effects caused by power tube grid clipping and associated bias shifts / crossover distortion. Like modeling amps "it's close but no cigar".
This, coupled to "flat-ish" response of the Orange amps (there's very little mid-range notch unlike in Marshall, Mesa, Vox, Fender, etc. amps) in general creates that "fuzzy" overdrive tone.
BTW, F.A.C.S. control was replaced by a somewhat similar "contour" control in later amps. This provided more complex voicing filters than just a user-variable coupling capacitance (a.k.a. low pass filter).
See here:
http://www.orangefieldguide.com/OFG_SCHEM/overdrive_series21.jpg
It's all about that DCed Cathode Follower-Tone Stack to me, that I really find interesting/like
there is some interesting/intriguing compression/clipping/impedance/buffer like characteristic's to it, depending how its setup.
there is some interesting/intriguing compression/clipping/impedance/buffer like characteristic's to it, depending how its setup.
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well in the stealth's case, previous stages/opamps etc messed with that, stumbled upon something interesting using NE5532
actually tlo82 is on second stage and yeah that last-NE5532/CF etc so I don't know what you want to call it haha
Just know..telling you sounds wicked with the GE 12ax7s GE/Sylvania 6l6s, but now wish had some different output Iron, regardless pretty cool with 50w Marshall type haha
kick myself so much because I had V30s waay back..and now telling you this thing would go insane with V30 types like no **** haha
I don't know 6l6s trip me out haha
https://www.youtube.com/watch?v=k1vhyDcdVfQ
at like/starting at 0:47 that cool Rhythm part man I could never get that before I swear haha
actually tlo82 is on second stage and yeah that last-NE5532/CF etc so I don't know what you want to call it haha
Just know..telling you sounds wicked with the GE 12ax7s GE/Sylvania 6l6s, but now wish had some different output Iron, regardless pretty cool with 50w Marshall type haha
kick myself so much because I had V30s waay back..and now telling you this thing would go insane with V30 types like no **** haha
I don't know 6l6s trip me out haha
https://www.youtube.com/watch?v=k1vhyDcdVfQ
at like/starting at 0:47 that cool Rhythm part man I could never get that before I swear haha
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Go listen/play through any non CF Amp....some quite noticeable differences.
what exactly that is, Not sure hard to describe...different compression/not as aggressive sounding maybe?
what exactly that is, Not sure hard to describe...different compression/not as aggressive sounding maybe?
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