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London Power: Power Scaling circuit licensing, Studio and Session Amps

The London Power "Studio" amp by Kevin O'Connor enables power-tube saturation, directly driving a guitar speaker, anywhere between full power and the milliwatt range, using power-scaling technology. This unit was designed to drive a guitar speaker with full power-tube saturation at the milliwatt level, for 3 A.M. apartment recording studios and for jamming without anyone else being able to hear, while obtaining uncompromised, actual cranked-tube-amp Tone. If you don't want to hear the guitar speaker at all, because you want to monitor a post-processed signal later in the chain, or because you need to monitor exactly what your mixer is hearing, then you can use a speaker isolation cabinet, with post-mic parametric EQ. Speaker distortion is reduced at low levels.

2006 book about Power Scaling: Advanced Techniques for Modern Guitar Amp Design

by Kevin O'Connor

Official webpage about the book
Power Press Publishing

In November 2000, Kevin notified me about Power Scaling.

>The SESSION and SESSION-3D amps ... have Power Scaling and a lot of features to make them versatile tonally. Both have a full effects loop, 3-way EQ, Body control for dialling between single-ended and push-pull, and accept any type and combination of power tube. The -3D has reverb. Both are available as 0-10W or 0-50W just like the STUDIO.

>We also have a 0-100W version of our SPECTRUM bass amp, with or without reverb. This amp can go way quieter than any 1W amp, just as any Power Scaling amp can, and also accepts any type or combination of power tubes.

>Also, we have two amp switchers: The STAGE LINK allows one of two amps to be connected to a single speaker. There is a tube buffer that is splittable at the input, allowing one or two sources to feed the respective amps. The footswitch input is expanded through the Sync outputs.

>The SORCERER is a dual effects loop with fully featured independent loops. Each accommodates -20dB or 0dB signals, can switch pre or post-effect, can be set for series or parallel operation, and has Send and Return controls. The loops can be used in parallel, series or completely independent from one another. All audio path circuits are tube. Each footswitch is expanded through its own Sync output.

>There will be the 0-50W STANDARD coming out shortly, with two switchable channels, each with its own 3-way EQ, Drive, Level, effects loop, reverb level, 2-way active EQ, and Power Scale control. As usual, any type or combination of power tubes can be used.

>Have fun
>Kevin O'Connor

Kevin O'Connor wrote:


>We just updated our London Power Instrument Products page, including info about our full line of Power Scaling amps, and a Q/A about Power Scaling.

>You can also download up to date info about the STUDIO, as some of what is on your page is a couple of years out of date. Specifically, the reference to a "Power Mode switch" which is something I experimented with during the development of the STUDIO amp but never incorporated. It would have allowed voltage variance to the output stage, driver stage, or both. This was deemed redundant once the rest of the product evolved. The "Triode-Pentode" switch remains, but is altogether different.

London Studio and other power-scaling amps
London Power home page

Power Scaling technology scales down an amp's output without changing tone. This is a different approach than "power starving" methods, which can have some interesting sounds, but do not sound like classic tube amps.

To: Michael
Subject: Amp review
Date: 1/13/2000

Hi Michael

Rich Hessian sent me a copy of his STUDIO amp review that he said he was forwarding to you and to Harmony Central. I have not seen it in either place and wonder if you have heard from him? Or if it is "in process" at your end?

Some of the info on your site regarding the STUDIO is way out of date. There are 13 aga listings of discussions from quite a while ago, but nothing about the whole 284 vs. Studio thread.

-- Kevin

Here is a copy of his review:


Revolutionary Product Alert! - London Power "Studio" Amp (review)

The Canadian-made London Power "Studio" is a rack-mountable guitar amp with some very unique abilities available nowhere else. I have the 10 Watt version, optimized for studio use. There is also a 50 Watt version oriented for those with stage volume needs. The Studio's most unique feature is the "Power Scale" control. Sort of like having a Variac built into your power section, it can reduce the amount of power the amp puts out down to near the hearing thershold. Unlike attenuators which reduce the output signal between the power amp and the speaker (losing frequencies and tonal integrity in the process), the Power Scale reduces the strength of the output signal from the power amp itself. This allows full power saturation at any volume with no lost signal, reduced frequency range, or other tonal compromises.

Does this "Power Scale" work? I tell you this is the only amp I have heard in 30 years of playing and gear-mongering that lets me dial down the true dynamic, rich, punchy blast of a wide-open tube power section to literally a whisper with no audible sacrifice of tone or touch sensitivity! In this regard the Studio smokes every attenuator or master volume circuit I've ever heard by a country mile. I've been waiting for someone to do this right for a long, long time.

The amp can also accept any type of octal-based power tube in its two power tube sockets, and even allows dissimilar tube types to be used together (i.e. a 6V6 with an EL34, 6L6 with a 6550, etc.) thanks to having separate bias pots for each tube. The amp is easily user bias-able with only a $25 Radio Shack Digital Volt Meter. The amp can be used with any speaker cab, 4-16 ohms. It also features a dramatically effective triode/pentode switch, cathode/fixed bias switch, and a rotary dial allowing any blend of push-pull or single-ended operation between the two power tubes. It has a built-in 2 stage preamp block which can be patched into the signal path if desired (like a typical guitar amp). It also has a mono send/return FX loop, and an "Input" dial for adjusting the strength of the signal into the power section.

The Studio provides an amazing degree of control over power tube characteristics, preamp drive, and final output volume. This yields a rainbow of clean, semi-clean, semi-distorted, and full crunch tones, from any tubes of your choice, at any volume of your choice. I use it like this - dial in my fat power tube saturation with the "Limit" dial. My razory, trebley preamp grind with the "Pre" dial (or I may plug direct into the Power amp if I'm using an OD pedal or booster). Set Push-Pull vs Single-Ended balance to taste (full Push-Pull gives a bold, punchy sound, full Single-Ended, meaning one tube operation, like a Champ, gives a thinner, gnarlier sound). Set cathode/fixed bias and triode/pentode to taste. Set the max volume with the Power Scale. From that point I use it like any single channel amp, dialing down my guitar volume knob for cleaner tones.

This amp's features allow for a huge variety of tonal options while keeping the signal path as clean as possible. There are no EQ controls. None. Guitarists may frown at this, but it's a common practice in high-end audio designs. The builder, Kevin O'Connor, engineered this to have the shortest signal path possible. Use an EQ pedal if you want. I don't miss it. Pure tone, baby! Want it brighter? Change strings, speakers, or tubes. Why clutter this pristine signal path?

The 10 Watt version I have gets plenty loud for my purposes (home/studio/jamming). Remember that 10 Watts is exactly half as loud as a 100 Watt amp. The 50 Watt version is made specifically to allow for gig-oriented power levels (but otherwise is identical to the 10 Watt version). This amp's forte, however, is not volume but its ability to give you the total clean to full saturation range of any power tube at fractions of the volumes usually associated with tube amps. You can use any 6L6, EL34, 6V6, or 6550 tube type in the amp. The only tubes it can't use are EL84's, KT66's (about 1/4" too tall), and I question if KT88's will fit (the bases are very wide).

It's bit spendy. $1280 base price. Plus you will be spending more to take advantage of all the options it allows. Power tubes, preamp tubes, speakers, cabs. The fun is only limited by your wallet. But every time you change components you get a new amp! Te Studio has little sonic character of its own, you determine that by the tube, speaker, and cab choices.

Kevin told me he designed this to sound good with any components/gear. Well, it does, but......I think he made it too good for its own good. This thing has such high quality parts and such a pure, short signal path that it is virtually a "tonal microscope". I find it to be ruthlessly revealing, especially using the power amp alone. Any sonic tendancies of your gear, good or bad, will be shoved right in your face. I think that's a plus. The different characters of various tube types shine right thru.

Take preamp tubes for example. The stock Sovtek 12AX7WA's lent a traditional buzzy, fuzzy preamp grind to the sound. A set of Philips 12AX7WA's were warm and creamy. Sounded very "right" for Fendery tones. Then I tried some Tungsram ECC83's. Wow! Almost as transparent as the power amp alone. The preamp sounded like a clean booster with these. What a contrast! Never heard such pronounced differences just changing preamp tubes. The Studio has similar sensitivity to power tubes, speakers, cabs, guitars, and pedals. It really rewards using good gear/components.

The 10 Watt version I have would hold little interest to pro guitarists who live and die by their gig amps. It isn't designed to provide lots of "on the fly" options. But for home players, studio tweakers, jammers craving "dimed" amp blast at garage volume, and tone-hounds in volume-restricted situations, it's an answer to a prayer. In a live setting its no more flexible than any single channel amp, but with the advantage of being able to set the exact volume that max distortion will occur. However, in a home or studio setting it has unrivalled flexibility. The tone recipes are limitless. Try a set of Philips 6L6WGB "stubbies" on triode power/cathode bias setting thru some Weber P12R's for a "Tweed of the God's" tone. Or a set of hot-biased Svetlana EL34's thru Celestion Greeen backs for that "Marshall in my pants" crunch at living room volume. Maybe a set of cold-biased Sylvania 6L6GC-STR's thru a Weber "California", with some tube reverb, for a clean ultra-linear Silverface Twin tone. Perhaps an RCA 6V6 in one socket, a Tung-Sol 5881 in the other, thru a reissue Jensen for the "vintage Fender that-never-was" tone. I could go on all day.

I hope these examples offer a glimpse of the utility and FUN that's available with the unique London Power "Studio". This amp ends any discussion about how to get the best tone and tube saturation at low volumes. It brings no-compromise boutique amp tone into small studios, practice rooms, and jam sessions with an unrivalled flexibility. The 50 Watt version gives the additional ability to set the maximum power tube breakup at the exact stage volume you want (don't you wish Marshall's did this?). There is nothing on the market to compare it to. This is the Holy Grail of "quiet crunch".

Go to londonpower.com for more detailed information on the 10 Watt "Studio", the 50 Watt "Studio", and other top-quality London Power products.


We just updated our site with a stereo Power Scaling amp called the STEREO 50, 0-50W + 0-50W. There is also a 10-band tube EQ, a stereo tube reverb, the 3-D; and a bass and guitar preamp. Pictures will be up soon.

Hope the new year is good to you Kevin O'Connor

To Michael
Subject Re Amp review

Hi Michael

>>Rich Hessian emailed me today to say that a slightly expanded review has been posted to you and to Harmony Central, and he gave the URL of the HC listing. It comes up "Document not found". Maybe they are in process, too.

I checked out the deja-link you provided.

There is still a lot of inaccurate data on your site and in the postings. These days, we ship the STUDIO with 6L6s, but the user can plug in 6V6s, 6L6s, EL34s, 6550s or any of their variants, or, mix two different tube types, just with a bias adjustment. All of our 0-10W and 0-50W models have this feature.

The current manual that comes with the STUDIO is 16 pages, and that includes the bias procedure, system connections, and set-ups to hear sounds in isolation-- like what does cathode-bias sound like? triode operation? output tube distortion? preamp distortion? etc-- you cannot hear these all on their own with any other amp we know of! The STUDIO lets you hear the tonal contribution of a single aspect of ciruitry, or tube operating mode, etc, so that you will know what each really sounds like, and can then determine if it is a desirable feature for your own guitar system.

Regarding power levels, the 10W STUDIO amp can go down to about a 150-micro-watt level (0.00015W). This is miniscule numerically, but is as loud as a typical conversation. This is why we refer to the amps as 0-10W, 0-50W, 0-100W (coming) and 0-700W.

We have been shipping STUDIO and SESSION amps all over North America and Europe. The STUDIO-2 is now just a 10W SESSION amp, so the name has been dropped.

Kevin O'Connor

User Scott Hunt purchased and reviewed this unit:
You can dial down the output power to a very quiet final-output level with no apparent degradation to the sound. There is no sacrifice of Tone when monitoring very quietly, unlike with power attenuators, such as the THD Hot Plate or Marshall Power Brake. Driving a Fane 12" speaker, it sounds just as good at these low levels as when the speaker is being driven hard. Kevin O'Connor says that 12" speakers tend to sound much better than 10" or 8" speakers. You can make the amp saturate to any degree, from minimal breakup to complete overdrive, at any final volume level. You can choose to overdrive the amp at the initial input stage and one intermediate stage. It's easy to determine what this unit's power amp distortion sounds like, because there is an instrument-level input into an independent gain block that feeds the amp; this lets you overdrive the tube power amp and listen to it alone, uncolored by any external preamp or any internal preamp distortion.

Gain structure must be carefully set up so that you don't get into noise problems when you play too close to the noise floor. If the final output level is too low, the mic and mic preamp's self-noise becomes audible.

Using the Studio in a live setup could be challenging unless you take the "set it and forget it" approach. The Power Scale sensitivity is such that turning it down too fast collapses the circuit and kills output. All other settings can be changed on-the-fly without problems, but they usually affect the volume, so that a power scale adjustment would be needed.

[I would surround the studio, speaker, and mic by two MIDI processors, to compensate automatically, and not touch the Studio's controls. But then the guitar speaker would vary in loudness, which would be a problem. That's why I use a speaker isolation cabinet, and powerful post-mic EQ. I call this whole approach the "Tone Engine". - Michael]

Now that I have an amp that will drive into power-stage saturation at very low monitoring levels, I have to wrap my speaker and mic in a blanket, so that the mic does not directly pick up the acoustic sounds of me playing my electric guitar. The gain on the mic preamp, in the mixing board, is up high enough that I can easily hear my pick and strings through the mic, so I wrapped a moving blanket around the mic and speaker cabinet to block it.

The Studio does fit the bill for getting real overdriven power tube distortion at low levels without compromising the tone. Between using the Studio, $2K large-diaphragm tube mic, Tac Bullet console, and Tascam 234 4-track cassette, I'm getting really great sounds.

The documentation for the amp is still pretty sparse and assumes a good bit of knowledge about tube amplifiers. After speaking with Kevin O'Conner a few times I started to get a better feel for what to expect and not expect from the amp.

My needs were exactly like Michael's: cranked tone at extremely low levels. The Studio delivers this perfectly in my opinion. I own a large recording studio but I also do a lot of recording at home when preparing to use the large studio. I use the time at home to work out arrangements and sounds. I bring home a nice mic and turn the Studio amp way down and the tone is as good at the milliwatt level as at 10 watts. In fact, the only real "problem" I've had is isolating the mic enough so that it doesn't pick up the accoustic sound coming off my Charvel's strings as well as the speakers output -- what a great "problem" to have, compared to the outward sound leakage of conventional amps! I solved that problem by wrapping a heavy moving-blanket around the speaker and mic to isolate them from ambient noises.

I have not used the Lexicon Signature 284 amp. But my experience with cabinet simulators has been disappointing at best; they just don't sound right! I use the cabinet simulator in my Rocktron Replifex at my live gigs because I'm too lazy to drag around a speaker and the Studio (it's a cover band and the gigs are professional, but we live to keep it as simple and light-weight as possible).

The Studio is not inexpensive, but I have no buyer's remorse. The Studio is a piece in the tone puzzle that all the big manufacturers have ignored. To get the sound really right, and flexible, you have to build a signal chain much like the one Michael writes about. To date, there is no single amp that can produce every tone, but the combination of processing stages described by Michael, together with the Studio, should get you as close to that Nirvana as possible.



I wrote:

I wonder if the Studio sounds better at 10 watts than at less than 1 watt. It does not have a load built in. It sounds like a well-conceived unit.

From: Kevin O'Connor, London Power/Power Press, 11/6/98


>There is no load built in, because a load is not the way to get *true* over-driven amp tone. Although you favour a speaker isolation cabinet (along with compensatory post-mic EQ), most good-sounding methods do involve hearing sound -- that is, playing an actual guitar speaker, audibly and openly in a room. The intended application of the London Power Studio amp is to be able to get the amp just to the cusp of distortion-- or well past it-- at a tolerable or desired sound pressure level, directly driving a *real* speaker. That speaker can be anything from a tiny 3" radio job, to a 4x15", or an isolation cabinet.

>Every real speaker interacts with the tube power amp in a unique way that emulators can never duplicate exactly. That's why the Studio does not have a built-in dummy load or cabinet response simulation filter. This interaction of amp and speaker can be perplexing, especially if you are used to using a favourite reference speaker that you use for stage or jams, but then you change speakers and the amp responds differently.

>Another reason to avoid using a load and filter is that load boxes shorten the life of power tubes. Tube life in the Studio amp at less than full power settings is increased, even if the output stage is fully saturated. The reason is that as the supply voltage to the output section is dialed down, the current and power go down, too. This means that the maximum waste heat and maximum saturation currents both are reduced, substantially reducing the stresses on the output tubes. In accelerated tests, the output tubes in the Studio circuit can last as long as any preamp tube.

>The London Power Studio amp is unlike any other product on the market. A lot of the testing we do is at the milliwatt level -- ranging from conversation-level down to a whisper -- since this is where home studio use lies, most often. Pro studios can easily accomodate a fully cranked Studio amp [10 watts] through efficient speakers, achieving suitably high room volume, such as 100-110dB sound pressure level.

>With all controls set for maximum output, the Body control can dial out half the output stage and reduce the clean power level to 1 watt. The other controls can:

>The audio path is simple, but the Studio has many atypical user-defined parameters that take a while to get used to, but reveal extreme diversity in tone.

>It is not a "patch on the fly" product but a serious tool for the studio.

>We'll probably send one to GP in a few months. Meanwhile, all of our customers are happy.

>As far as suggested settings, I plan to write a comprehensive user guide for the Studio amp. There are lots of system possibilities, using various settings. As far as particular tone settings, everyone perceives sound in different ways, so if we were listening to the exact same sound at the same time in the same room, we would still have different impressions. This is in part due to tastes, health and physiology. So I don't think I could ever say, "For an SRV sound, do this". People have asked about this before, with regard to mods. They suggest we make a CD with the stock sound, change something and record that, and so on. This gives a progressive relationship between the circuit amendments and the change in sound. For the "progressive tone variation", such directions are useful, but to define a colloquial convention, like SRV, EVH, etc, depends too on speakers, guitars, and soul. The amp sounds better through bigger speakers and definitely bigger cabinets, even at low volumes-- just like most amps.

>Have fun in your own Tone Zone!
>Kevin O'Connor


By "it has many atypical user-defined parameters", Kevin might mean what I'm saying power amp designers should focus on. Rack-mount tube power amps should not have a whole bunch of preamp controls, but they should have controls that are unique to power tubes, such as Class, triode/pentode, plate voltage, and tube type. I'd like these to be MIDI-controlled, too. Let preamps specialize, and power-amps specialize, with MIDI control possible everywhere. -- Michael]

My only concern if this amp is great, is, we now need the same essential circuit, in a pedal, for $100! And in the middle of MIDI-programmable multifx processors, too.

Designed by Kevin O'Connor, London Power, in Ontario, Canada

Excerpts from the above pages:

A variable-output rack power amp. The Studio amp by London Power (Kevin O'Connor) is a "ten watts and less" power amplifier that has many classic voices. It has the quick attack of a large fixed-bias amp or the round warmth of a cathode-biased amp at the flick of a switch. You can have shimmering highs, exquisite mids and tight bass. You can plug your guitar through the independent gain block to overdrive the power stage right up to "full shred" or develop your own "tweed metal" sound. You can get the sound of any vintage amp you desire, or any modern amp that appeals. How can so many sounds come from "just" a power amp? And one without the usual tone controls? The London Power Studio amp is like having an amp with a built in variac. The Studio's unique linear AC regulator is controlled by the Power Scale, which dials the voltage of the output stage down to impossible levels for other circuits. And it does it without nuisance noises normally associated with DC regulators. The most amazing feature on the Studio is the Power Scale control, which provides continuously variable power from 100% down to zero by altering the power supply voltage. Uses a pair of 6v6 tubes with a solid-state rectifier for about 10 watts max. This allows you to record a cranked amp sound miked through a speaker even in the most sound-sensitive situation - like 3 am in an apartment. Many amps have a low-power mode that is typically half of full power. Others have further reductions to one-tenth power, but even this could be too loud. One watt can produce over 100db of sound through efficient speakers, so the "fractional-watt" output of the studio is very useful and desirable. In a cranked amp, with no equalization after the distorting amp other than that provided by the speaker itself, the low frequency response can be floppy. But not with the studio: flip the shape switch and crispness is restored. Although the Studio amp was designed for use in quiet studios and personal recording spaces "at home", many musicians use their Studio amp on s tage. It can be the distortion track and be the answer to every sound man's prayer. Line outputs and all of their tone alterations may all but disappear now that the Studio lets you wail at a whisper. Its highly researched combination of features offers an extremely wide range of tones and distortions, not usually associated with just a power amp. The loud, clear pentode push-pull tone is there. The rolled-off high end of the push-pull triode operation is there, too, selected with the triode-pentode switch. [this might be the "mode select" referred to below] Unique to the London Power Studio is the continuously variable symmetry control, which dials the tone between push-pull and single-ended. The tone can have sparkle, or be warm at the whim of the user (via a switch). A continuously variable input level control accommodates a wide range of input signal amplitudes from the 1/4" and RCA input jacks, and allows fine setting of overdrive levels. Several bias modes allow a variety of tones and maximum power levels. Has a speaker selector switch, for one of the two 1/4" connected units. In keeping with our philosophy of versatility, all of the studio's controls can be used in any combination. Conservative operation of all components allows predictable and reliable performance from any quality, origin, or brand of tubes used. Vertical orientation of the tubes extends their life, and the larger chassis space makes service work much simpler. A low-speed fan keeps all components within safe thermal limits. 20-year warranty on the complete unit. $1,280 list.

Kevin, the designer, said:

>It was envisioned at one point that there would be a Mode Select switch but this has not been incorporated, as testing illustrated better results without it.

O'Connor wrote (a year earlier):

>5 watts! Ouch! This could be WAY too loud-- especially through efficient
>speakers. Which is exactly why all of my amps have a "1-watt" switch.
>Even this is too loud most of the time!

>One of the amps that will be available in February '97 is the 'Studio'
>which will have a special output section unlike any other in production;
>featuring "dial-able" power from one watt up to 10W+ , in a rack mount.

>More details will be available late November on my website.

>Keep the prognostications coming, Monk!

I am spreading the prophecy, preparing the world for the coming mind-blowing combinations of power tubes, speakers, transformers, speaker cabinets, and effects. As much as I've written, the Old Guard just doesn't seem to understand. But many others do know where I'm coming from. Sure, nothing can really match a blasting vintage 100 watt Marshall stack, but that's no reason to limit ourselves to unnecessarily mediocre tone when we're not on stage or in the studio. "Practice amp" means mediocre tone... I want to phase out the concept of practice amp and replace it with "great sounding personal amp".

I love great tone but I generally just don't like loud noise. I think we only need to make a very slight compromise in tone, in order to get a vastly more enjoyable volume level.

One area of research that needs more attention is low-watt speakers. Look at the Greenback -- the lowest powered 12" speaker, with the best tone. People should get the hint and try even quieter, smaller speakers. The Micro Room literature claims that you can use a 6" speaker with a properly scaled cabinet to get a balanced tone that includes speaker stress.

Kevin, I was *wondering* if 5 watts would be too loud. 1/2 a watt is actually more like the personal, intimate level of a classical guitar -- the level that most people want to use when playing around at home. I don't like other people to hear me when I'm working on musical ideas. I just like to stay in my own musical bubble, even using headphones.

I'm glad you're working on a low-wattage rack-mount tube amp. It's crazy that our only choice is these huge 60 watt amps mixed in with delicate line-level effects units in the racks.

Time will see me in the pro studio with a wall of monster amps. But that's too easy, the brute force approach to tone. And it's too inaccessible. I want to be able to get passable, genuine cranked-amp tone any hour of the day, wherever I am. I refuse to bow to the 100 watt 4x12 cabinet. We should not be forced to go on stage or in a studio to get satisfactory tone. Somewhere between loud amps and raw preamps, there are awesome compromises. Most importantly, when you learn to mix cranked amp tone properly with effects, at private-listening levels, this provides a magic combination of fairly high convenience and fairly great tone that supports more awesome guitar playing than a convenient but mediocre raw preamp tone, or a awesome but inconvenient Marshall stack tone.

We can have *most* of the convenience of a multieffects unit, and *most* of the tone of a cranked amp. The technology is there. It's not really hard to do. What I found in my research a year ago with speaker isolation cabs, small tube amps, and the 2101 effects processor, is that a compromise between raw preamp and cranked amp tone is possible by the right combination of gear. This combination, this compromise, gives superior artistic control compared to the raw preamp or screaming amp approaches. The combination of effects processors, low-watt power tubes, and possibly speaker isolation cabinets gives the overall greatest artistic power.

Kevin, I might include your low-watt tube amp in my rack. Let us know if there's an URL to look at now. There are a thousand 50 and 100 watt amps to choose from, but zero low-powered rack tube amps to choose from. There's a huge, lucrative gap in the available guitar gear, in between preamps and conventional guitar amps.

When will Fender get a clue and reissue their 5-watt Champ? Actually I'd rather have a larger cab and spk -- like the Cornford Harlequin 6-watt amp.

DIY discussion for Power Scaling

London Power to offer power scaling mod kits, book about power scaling

This is the biggest possible news item for quiet cranked-amp tone. Everyone will be able to run their existing conventional tube amp with something like a variac inside the power supply and power amp stage, to obtain power-tube saturation at the coveted 10 mW "TV" listening level. Or you can design an amp to use any power tube at any power level from a few milliwatts to the full rated power of the tube, by studying the forthcoming book about power scaling.

A new era of ergnomic actual cranked-tube-amp Tone is upon us.

about power scaling
book: Power Scaling Revealed - click "Upcoming Publications"
power scaling mod kits for old Marshall and Fender amps - search for "power scaling"

What I especially look forward to is a full-featured amp head directly driving a 2x12 cab, able to produce pure power-tube saturation at any level from 0-50 watts, as London Power now offers. You could possibly even do a closed-back combo with just a little ventilation.

Harmony Central review: London Power -- Studio

DejaNews query: ["london power" and "studio"]

Messages 1-13 of exactly 13 matches for search "london power" studio:

Date   Scr        

   1. 98/10/27 052 
Re: Amp emulators, speak#1/3 alt.music.4-track     Michael      
   2. 98/10/27 052 
Re: Amp emulators, speak#3/3 alt.music.4-track     Michael      
   3. 98/10/27 052 
Re: Amp emulators, speak#1/3 alt.guitar            Michael      
   4. 98/10/27 052 
Re: Amp emulators, speak#3/3 alt.guitar            Michael      
   5. 98/10/27 051 
Re: Amp emulators, speak#2/3 alt.music.4-track     Chris Gieseke  
   6. 98/10/27 050 
Re: Amp emulators, speak#1/3 alt.music.4-track     Chris Gieseke  
   7. 98/10/25 049 
Re: Low-watt power-tube devi alt.music.4-track     Michael      
   8. 98/10/23 049 
Low-watt power-tube devices? alt.music.4-track     Michael      
   9. 98/09/02 042 
Re: Traynor vibrato mod help alt.guitar.amps       John Templeton 
  10. 97/05/15 042 
London Power Studio Amp Info alt.guitar.amps       Ken Brakebill  
  11. 96/11/01 039 
Re: 5 watt tube power amps?  alt.guitar.amps       O'Connor       
  12. 97/03/14 038 
Re: STEREO 6V6 AMP INFO      alt.guitar.amps       Ken Brakebill  
  13. 97/06/25 034 
Re: Speedster Amps           alt.guitar.amps       Ken Brakebill  

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