All-Tube STUDIO & KC25 Power Amps

London Power offers two feature-packed all-tube power amplifiers for use in the studio. Just $2,820 each (approx. $2,170us)

 All-Tube STUDIO Power Amplifier (0-25W, 2U) [click to enlarge]

London Power STUDIO Power Amp

KC25 All-Tube EL-84 Power Amp (0-25W, 2U) [click to enlarge]

London Power KC25 Power Amp

Power Scaled 0-25W output
STUDIO uses any octal-based tube: 6V6, 6L6, 5881, 6550, EL-34, KT-66/77/88
KC25 uses EL-84 output tubes or E84L, EL-844, N709, 6BQ5, 6p15
uses any 12A_7 tubes: 12AT7, 12AU7, 12AY7, 12AX7, ECC-81-/82/-83
operate single-ended (SE) or push-pull (PP)
either tube in cathode or fixed bias
either tube in triode, ultralinear or pentode mode
direct-impedance jacks for 4,8,16 ohms
switched 'Match' speaker output
2U, 6.1kg, 17"W x 3.3"H x 6.5" D (plus tubes)
100V, 120V, 240V range switch
rack-mountable with optional kit
rubber foot storage on rear panel when rack mounted

STUDIO is the world's first production guitar amp with Power Scaling, allowing players to use output stage compression and distortion effects within the Human Scale of loudness. Since its introduction in 1995, STUDIO has always been in a class of its own - truly unique - with a range of tonal expression far beyond traditional tube amps, and capable of using all the common octal-based power tubes in singles, in pairs and in mixed pairs. KC25 is a variation of STUDIO that uses EL-84 output tubes. Both are identical in their capabilities apart from their output tube options, making KC25 the most versatile EL-84 amp ever produced. KC25 is in a class of its own as EL-84 amps go - with a range of tonal expression far beyond traditional "18W" and "AC" amps, and capable of using power tubes in singles, in pairs and in mixed pairs.

London Power Studio Amp rear

STUDIO & KC25 combine a sophisticated power section with an equally sophisticated front-end. The input stage has true variable gain, so any signal amplitude is easily accommodated with as pristine or as warm a result as the player desires. Equalisation is distributed throughout the circuit,  offering a much wider range of tone than is found in traditional guitar power amps. The touch responsiveness of the amp is affected by these and other controls, such as Vibe, and by the choice of tubes used.

STUDIO & KC25 can be used as a stand-alone guitar amp with effects pedals in front. You will hear exactly what the pedals do and exactly what the instrument does with them. STUDIO & KC25's input stage has far more headroom than that of a standard guitar amp, so over-driving the first stage grid is not possible, and thus grid-blocking distortion is avoided. The very low noise, high-quality components and careful circuit design make STUDIO a "tone microscope".

Each power tube has its own bias switch for cathode-biasing or fixed-biasing and can be operated in triode, pentode or ultralinear mode. Both tubes can be set the same way or quite differently - one cathode biased and the other fixed-biased, for example. Cathode bias is set here to maximise tonal difference at the expense of output power. Each power tube also has its own Level control, allowing either to be dialled out leaving the single-ended tone of the other tube. Bias pots and meter jacks are on the rear panel, accessible from the outside of the amp.

STUDIO accepts any of the pin-compatible octal-based power tubes singly, in pairs or in mixed pairs. Use any of: 6V6, 6L6, 5881, 6550, EL-34, E34L, KT-66, KT-77, KT-88, or any equivalents.

KC25 uses any EL-84 or equivalent tube in singles, pairs, or mixed pairs. Use 6BQ5, EL-84, E84L, EL-844, N709, 6p15

Yes - you can use a single power tube in STUDIO or KC25!

Power Scaling allows tube compression and distortion effects at any loudness down to a whisper. The standard loudness range is "unusably loud down to unusably quiet" so the player or sound engineer can decide how quiet "quiet" is. The 25W maximum output is loud enough to damage hearing when used with typical high-efficiency guitar speakers, but Power Scaling lets you have "cranked" tone at safe sound pressure levels.

Specs & details:

STUDIO & KC25 incorporate all of London Power's standard design and construction features:

toroidal power and output transformers
fusing for all power transformer windings
worldwide mains compatability - with 100V for Japan
Galactic Grounding
active hum filtering
long-life capacitors low noise metal-film resistors
metal-oxide and wire-wound power resistors
zero wiring except for the transformer fly-leads
zero standby power when switched 'off'

STUDIO & KC25 can be rack mounted using the optional 2U6-BRKT, sold as pairs.

"Fantastic tones"

"STUDIO can out-tweed a tweed amp"

"It's amazing to be able to play really quietly but have this ripping overdrive for my recording."

"KC25 does everything you said it would. I'm so pleased!"

For our price list, see Studio Gear Ordering.


Photo Gallery - click to enlarge

London Power STUDIO Power Amp

London Power KC25 Power Amp from above

Below: inside shots of the STUDIO Power Amplifier. The KC25 Power Amplifier is very similar.
London Power STUDIO Power Amplifier - inside

London Power STUDIO Power Amplifier - inside


About London Power

London Power was founded in 1990 by Kevin O'Connor, after two decades of research into innovative audio amplification techniques. Kevin is an audio designer, author and speaker, known for his proprietary methodology called Power Scaling, and for his eleven books on audio subjects. Whether you seek amps, kits or information, you'll find useful answers here on not just the "how" but the "why" of audio amplifier design. Please enjoy the information on this site, and don't hesitate to contact us with questions.

Contact Us

(807) 473-0952
11 am - 6 pm, M-F
PO Box 10012, Thunder Bay, ON P7B 6T6 CANADA