The only technology that directly competes with London Power's Power Scaling is Maven Peal's Sag Control circuit, designed by David Zimmerman. If, on the surface, the technologies look very similar, it is because they are very similar, despite what David tries to portray.

In his promotional material he compares his Sag control with our Power Scale control - in fact, comparing an apple to an orange.

In real use by musicians, the functional perception is that Maven Peal's Sag is like London Power's Sustain control, and MP's Wattage is like our Power Scale. These comparisons are apple to apple and orange to orange. We each have an apple and an orange, but London Power's are tastier - with much more dynamic range available in every bite!

Competition can lead to unseemly behaviour. Below is text from David's site*, where, unfortunately, he makes false assertions about Power Scaling. They are not the truth:

MP: "Under 2-3 watts, the tubes begin to produce a fuzzy tone instead of an overdriven tone. Below 0.5 watts (the lowest Sag Circuit Wattage setting), the speaker cannot physically move enough to get good tone; and de-tuning the cabinet does not help the speaker to move at this low voltage."

Truth: Perhaps Maven Peal amps become "fuzzy" at low levels, but amps with Power Scaling do not - unless the player sets other controls to achieve this effect.

Our detuned cabinets play quieter than Maven Peal's (or anyone's) open-back cabinets while retaining full tone. "Speaker movement" has no direct correlation to "getting a good tone". The fact is rather that at very low loudness levels, the speaker's frequency response may differ from its response at higher levels. The ability to retain the same response at various loudnesses is called "dynamic linearity". Our own hearing has a much more varied dynamic response than most speakers, and it is thus human physiology that is more restrictive to the sense of "quiet but still good tone".

MP: "Our philosophy is that if you need to amplify your sound at a level quieter than 0.5 watts, you don't need an amplifier at all--what you need is a good set of headphones."

Truth: The minimum loudness produced by Maven Peal amps through typical guitar speakers is therefore 87-90dB, depending on whether you are restricted to the Zeeta low power limit of 0.5W or the higher Ganesha lowest output of 1W. Many guitar speakers have efficiencies of 100dB@1m/1W and this is then how "quiet" a Ganesha can go.

Here, David is making a judgment that if you want to actually play quietly, you should not buy one of his amps nor anyone else's. Headphones don't sound like guitar speakers, so you are into a whole different equipment scenario: two rigs, one for quiet and one for loud. This is one person's opinion, that to most players is unacceptable.

At London Power, equipment is designed for players to really use, and to use everywhere they play. The only control that requires manipulation going from one venue to another would be the Power Scale.

MP: "All Sag Circuit wattage control settings are usable. With power scaling, some settings are not. "

Truth: Not true. The controls on a Power Scaled amp can be used in any combination the player wishes.

MP: "Mr. O'Connor goes on to explain that "Power scaling supplies have a soft-rectifer sound and do not tighten up as you dial down. Diode noise is inherently filtered, and you can play as quietly as you want." "

"No power supply can avoid the sticky problem of ever more tightening as you turn down the wattage. Rectifiers cannot eliminate this problem. However, the Sag Circuit's patented design gets around this problem by giving you a knob to control power supply sag, the technical cause of "loose" or "dirty" tone. "

Truth: Again, perhaps Maven Peal power supplies tighten up as you dial down, but ours don't.

MP: "The Sag Circuit gives you direct control power supply sag. Power scaling technology does not. "

Truth: London Power's Sustain control has the same sonic effect as the Sag control. London Power always implements the Power Scale control in conjunction with the Sustain control, so the above MP statement is false. It is a well-accepted fact that in electronics and electronic circuit design, multiple approaches will achieve the same end result.

MP: "Power supply hum, not diode noise, is the major cause of unwanted noise in a well-built guitar amplifier."

Truth: This is untrue. Well-designed amps have proper grounding, which eliminates hum and makes buzz inaudible. Less well-built amps do not suffer from hum either, exhibiting a bit of buzz due to poor grounding. Buzz is a rectifier noise artifact.

MP: "Because the Sag Circuit is a new power supply design created for today's components, it does not hum, nor is there any diode noise. With the Sag Circuit, amps are so dead quiet, you can easily record without noise gates.

The Sag Circuit completely eliminates unwanted power supply hum. Power scaling technology does not."

Truth: The diode noise in a Maven Peal supply is actually much more extreme due to the large electrolytic capacitors used throughout the power supply. Brute force regulation then filters this noise out so the amp ends up quiet.

London Power amps use proper grounding to eliminate hum and buzz. The soft rectifier effect combined with Solen polypropylene power supply caps completely eliminates diode noise effects.

In the final analysis of Power Scaling vs. Sag Control functionality, here's the truth::

Power Scale and Wattage are equivalent controls.

Sustain and Sag are equivalent controls.

London Power amps will go down to milliwatts of output power. Maven Peal amps will only go down to 1W or 1/2W depending on the model.

Maven Peal amps are well made. However, they do not play as quietly as the power supply technology allows, due to assumptions made by the designer on the player's behalf.

London Power amps are also well made. Versatility is key to every London Power product, giving the player access to the full range of all parameters, so the player can decide what limits to impose.

* Maven Peal has since removed the above misinformation posted on their site.

Update November 2005:

Maven Peal has updated their site to remove the comparison to Power Scaling and Sustain, which would (if accurately listed) show that their amps are not unique. Instead, they make these statements:

Maven Peal: "Linear in nature, preamp distortion is widely understood..."

Truth: Preamp distortion is only linear if you are discussing precise feedback-controlled solid-state circuitry. Tube preamps tend to be free-running gain stages that are not linear. They are "reasonably" linear when handling small signals but they add increasing distortion with increasing signal swing, and not in a linear fashion.

Tube gain stage distortion is asymmetrical over the signal cycle, due to the curved transfer function of the stage. For as straight as it looks for small signals, the curve is very obviously curved for large signals, and this has been understood since tubes were invented.

Maven Peal: "Being nonlinear in nature, power supply sag is not widely understood, and the industry has not been able to offer any flavors other than blasting."

Truth: This is in fact three statements, all of which are incorrect.

First, power supply sag is extremely linear, based on fixed internal resistances of the supply components and wiring. Resistors behave in a constant predictable fashion, and you might characterize them as the most linear devices known. They are in fact passive components, but their non-frequency-dependent nature means any resistance, whether intended or not, behaves linearly. Ohm's Law clearly states that fact.

Second, the result of power supply resistance is power supply sag, a known phenomenon since the beginning of electrical study - predating electronics! The Radiotron Designer's Handbook contains extensive discussions regarding supply sag and filtering, and ways to minimize sag.

Third, sag in switchable, variable and user-selectable forms has been available on guitar amps very obviously since the early 1990s, and in all tube amps with a tube rectifier, i.e., since the 1940s. It is well known that changing the tube rectifier from one type to another will change the amount of sag the amp has.

The trick of adding a fixed resistor to an amp to increase sag has been around since the 1970s and became very popular upon release of our book TUT in 1994. There are many amps in production in which such a resistance is placed on a switch and given various names: "vintage", "tube rectifier", "sag", "attack", and others.

Maven Peal inevitably refers to Power Scaling, because not to would suggest ignorance of the marketplace. However, the statements made reflect a different kind of ignorance:

Maven Peal: "The marketing term 'power scaling' refers to an automatic internal variable transformer. While power scaling is impervious to varying wall voltages, it comes with all of the other problems associated with variable transformers."

Truth: Obviously, David has never seen a Power Scaling amp or its circuitry. Even though we have had numerous private e-mails, in the course of which I virtually told him what the circuit is, he is either not knowledgeable enough or is simply too fearful to recognize similarities where they exist.

Consumers are becoming more knowledgeable and are able to see through the obfuscations of the truth. Educated consumers make the best customers.

See also www.MavenPeal.com.