Este tipo de amplificador se presta de muy buena manera a instalar un circuito “Power Scale\u00b4\u00b4 SV1<\/strong> para poder tener la distorsi\u00f3n natural de la etapa de potencia a cualquier volumen, con la ventaja de alargar la vida de las v\u00e1lvulas de manera exponencial. Poder sacar el jugo a un Plexi a cualquier volumen es una realidad<\/p> Cualquier duda preguntad, por favor.<\/p> <\/p> What is Power Scaling? <\/em><\/strong><\/p> Power Scaling’s<\/strong> goal is to achieve the same tone as one’s\npreferred “loud sound,” but at a much lower volume. The\nmethod can involve one of over sixty distinct approaches, each with many\nvariations.<\/p> Power Scaling\u2122 is a\nmethodology developed by Kevin O’Connor of London Power.<\/strong> \u2022 Not at all. Speaker load boxes<\/strong>,\nspeaker emulators, and speaker attenuators are all forms of attenuation\ninterposed between the power amp’s output and the speaker. They work for some\npeople, but are notorious for sounding “buzzy” at high attenuations. \u2022 Only in specific situations. If you only play clean or\nyou only use preamp overdrive or distortion tones, then a master volume will\nsatisfy you. \u2022 All London Power Power Scaling<\/strong> amps are designed to provide smooth, sweet,\nclean sounds up to their limit of power. Set to full power, Power Scaling<\/strong> will not alter the clean sound of your amp. If\nyou set Power\nScale <\/strong>to a lower setting, the amp now behaves as\na lower-power amplifier with a lower maximum loudness for clean sounds.<\/p> \u2022 With the POWER SCALE<\/strong> dial set to\nany setting less than maximum, tube life will actually be extended<\/em><\/strong>. In accelerated tests, power tube life is as long as\nthat of a preamp tube … up to 100,000 hours if the tube is not mechanically\nupset. Ths is a great attribute for players using NOS tubes (new-old-stock). \u2022 Yes. It is perfectly safe to do this, although you\nlose the benefit of frequency shaping provided by the speaker and the\ninteraction of the output stage with the speaker. \u2022 No. A low-watt amp only has one compression point,\none cusp of distortion and one maximum loudness level through a speaker. \u2022 In technical terms, all that must be accomplished is\nto keep the “transfer curve” of the amplifier the same. The transfer curve is simply the\nrelationship between the input and output signals<\/strong>, but as we know, tube amps respond differently to\ndifferent-size signals. This is because the transfer is not straight and not\nuniformly curved. \u2022 No. Because the shape of the transfer curve is\nmaintained, the plate resistance of the output tubes is also maintained. So,\nthe output impedance of the amp does not change even though much less power is\navailable once you dial down.<\/p> \u2022 The circuits are simple and small<\/strong>, and are easily retrofitted into existing tube amps.\nBut… the tech performing the installation must be very good at mods and not\njust a good repair tech – as these are two different skills. \u2022 No. If you only need 3W of power,<\/strong> only\n3W is produced; if you need 29W, then you get 29W. The simplest Power Scale<\/strong> circuits are soft regulators, and as such, they\ndivide the voltage available from the raw power supply between the amplifier\nand itself. In that voltage sharing, there will be some waste heat. \u2022 Power Scaling<\/strong> allows\nthe player to dial the sound down to whisper levels – actually unusably quiet.\nIf you have a detuned speaker cabinet or any other design that extends dynamic linearity,\nyou can play below a normal speaking level. With London Power’s Power Scaling<\/strong> design approach, the player can choose how quiet\nto play, with typically 44dB of dynamic range – that is 100W down to less than\n0.01W. \u2022 No. There are many amp brands licensed to use our\ntechnology and trademarks. Each builder begins with traditional or original\naudio circuit ideas enhanced by Power Scaling<\/strong>.\nYou can also have your own an amp fitted with Power Scaling<\/strong> by a recommended installer<\/strong><\/a>.<\/p>![\"\"](\"https:\/\/www.mpf-sound.es\/wp-content\/uploads\/pwrscl.jpg\")
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\nIs Power Scaling simply power\nreduction?<\/strong>
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\n<\/strong>\u2022\nNo.<\/strong>
\nEarlier designers made attempts to achieve effective scaling of power, but\nnever quite got there. London\nPower<\/strong> refined and fully developed the\ntechnology to allow the maximum power of an amplifier to be dialed down to\nwhatever level a player needs. It was first used in the amazing London Power<\/strong> STUDIO<\/strong>amp.<\/p>
\nIsn’t this just like a speaker load\nbox?<\/strong><\/p>
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\nA speaker\nattenuator<\/strong> forces your amp to be run flat out,\nproducing its full power all the time. The power that is not needed is thrown\naway as heat, with only the required power going to the speaker. It is quieter\nthan full-tilt, but now the speaker is isolated from the amp and cannot interact\nwith it, so some tone is lost.
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\nPower Scaling is none of\nthese.<\/strong>
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\nThe key to Power\nScaling<\/strong> is that it is applied to the power\noutput tube stage itself, and so comes before<\/em><\/strong>the output transformer. Power Scaling<\/strong> allows a dynamic power range over 40dB. Most speaker\nattenuators alter the tone before they reach 8dB reduction. Minus 8dB is just a\nlittle bit quieter than full blast; minus 40dB is literally a whisper.<\/p>
\nWouldn’t a master volume do the same\nthing?<\/strong><\/p>
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\nPower Scaling is the\nbest solution for players who incorporate some output stage “effect”\nin their sound.<\/strong>
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\nThis effect can be light or heavy clipping, or just that cusp of compression\nyou get in a tube power amp approaching clipping. Power Scaling<\/strong> allows you to live at that cusp or beyond, but\nat ANY loudness you need.<\/p>
\nSo, Power Scaling will help my\noverdrive sounds. How clean will a Power Scaled amp play?<\/strong><\/p>
\nHow does Power Scaling affect tube\nlife?<\/strong><\/p>
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\nOutput transformer life\nis also extended<\/strong>, since it is subject to much lower\nvoltage stress even with fully squared output signals and unexpected load\ndisconnection.<\/p>
\nCan I run a Power Scaled amp without a\nload, right into a mixer?<\/strong><\/p>
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\nThe POWER SCALE control\nreduces voltage and current stress on the output tube<\/strong>, so even at a fully saturated distortion output, the\ntube is under less stress than it would be in, say, a 3W amp.<\/p>
\nCouldn’t a low-power tube amp do the\nsame thing?<\/strong><\/p>
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\nPower Scaling amps can\nplay both louder and<\/em> quieter than amps of less nominal power. <\/strong>
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\nAnd, the compression point stays in the same position relative to the cusp\npoint for all settings, allowing the touch responsiveness to remain consistent.<\/p>
\nHow is this possible? Is the circuitry\ncomplex or expensive?<\/strong><\/p>
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\nThink of the transfer\ncurve as a mirror. <\/strong>
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\nA flat mirror, parallel to you, will reflect your image perfectly and full\nsize. If you move the mirror away, the image is smaller but still perfect. A\ntube’s transfer curve is like a slightly curved or rippled mirror. In this case\nthe image is slightly distorted, but this is exactly what we want – it is why\nyou chose a tube amp in the first place. So, moving the mirror farther away\nreduces the size of the image, but it is still perfectly imperfect.
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\nElectronically, it is very simple and inexpensive to achieve this goal. The diversity of electronic circuits\nallows countless approaches by different designers,<\/strong> with greater expense added or bulkier components\nused. In the end, it is all Power Scaling<\/strong>.<\/p>
\nDoes it affect the output impedance of\nthe amplifier? People on the web say Power Scaling changes the tube plate\nresistance.<\/strong><\/p>
\nCan Power Scaling be added to any tube\namp? Is the circuitry large?<\/strong><\/p>
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\nDepending on the amp, some heatsinking or a fan might be required to cool\nthe Power\nScale<\/strong> circuit.<\/p>
\nIs the Power Scale circuit just\nconverting the unwanted audio power into heat?<\/strong><\/p>
\n
\nAt POWER SCALE<\/strong> control settings between fully clockwise and\nabout 12-o’clock, there will be waste heat from the Power Scale<\/strong> regulator. At settings between minimum\n(counter-clockwise) and 12-o’clock, the regulator runs cool. Meanwhile, as\naudio power is reduced, waste power in the power tubes goes down in direct\nproportion, which\nincreases their reliability.<\/strong><\/p>
\nHow does Power Scaling compare to\nMaven Peal’s Sag circuit?<\/strong><\/p>
\n
\nMaven Peal’s designer chose the half-watt lower power limit for their WATTAGE\ncontrol, so that the player would not encounter the point where the matching\nopen-back combo’s speaker loses its tone at lower volumes. To put this into\nperspective, most guitar speakers produce 90-100dB of sound, with just one watt\nof input. Half as much input power only reduces loudness by 3dB, so you are at\n87-97dB of sound, which is a loud party level.
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\nSo, even though Maven Peal has amps that go from 100W down to 1W (20dB range),\nand 20W down to 0.5W (16dB range), those lower power levels are still fairly\nloud. To some players, they are “quieter” or “quiet\nenough”. But it is obvious that a power range that is smaller than these –\nsay, 100W down to 5W – is even less useful at just 13dB dynamic range. The quietest\nlevel is still too loud for most players.
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\n“Sag” is an\ninherently signal-dependent effect<\/strong> exhibited\nby all amplifiers with conventional power supplies. A regulated supply with a\nvery beefy transformer will exhibit much less sag. Sag is merely a voltage drop under loading<\/strong>, which affects the attack of a note. Once the supply\nsags, its stays sagged and then power-limits the entire signal.
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\nMaven Peal products use stiffly regulated power supplies to reduce noise, and\nthus their amps have no inherent sag effect. Sag must then be added by letting\nthe signal modulate the supply reference. Despite the potential of the system,\nthe limits imposed by the designer restrict the range of sounds, both in the\nsag effect and the possible power reduction.
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\nPower Scaling supplies,\nin contrast, have a soft-rectifier sound and do not tighten up as you dial\ndown.<\/strong> Diode noise is inherently filtered,\nand you can play as quietly as you want. “Sustain” is the sonic\nquality of sag, and London\nPower<\/strong> uses various Sustain circuits to\nincrease this tonal characteristic.<\/p>
\nMust I buy a London Power amp to get\nPower Scaling?<\/strong><\/p>