POWER AMPLIFIERS BUILT BETWEEN 1996 AND 2008.
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SE 845 55W Pure Class A MONO BLOC.
9 Pictures of these amps made in 2008, 11 schematics, detail sheets and distortion graph,
plus other 845 amp information.

300W MONO BLOC. Class AB1, 12 x 6550 per channel, very basic general details.
300W amp input/driver and output stages. 
300W amp power supply.
300W amp active protection.
300W amp dynamic bias stabilization.
300W amp power vs load graphs.
300W amp images, tubes with blue glow, more blue glow, 2 amps on bench, umbilical cables, amp end view.

100W mono bloc. 6 x 6CA7/EL34,
Picture of  two 100W UL-AB1 mono amps, general description.
Schematics for 1 power amp, power supply , bias & protection circuits.
Graphs for power vs load graphs, THD. Full explanations of all included.

8585W integrated.  4 x 6550/KT88/KT90 per channel, CFB output stage, class AB1.
Schematics and notes for one 85W channel, power  supply for two channels, active protection.
Graph of  THD vs output voltage and power levels for various RL,
Load line graphical analysis for 2 x KT90 with 12.5% CFB, AB1.
Revised details for lower THD in october 2006 and use with 3 pairs of stacked Quad ESL.

5050W integrated. 2 x KT88/KT90 per channel, Ultralinear class AB1.
Schematics and notes for one 50W amp channel, 5050W amp power supply, and 5050W amp bias balance indication and active protection.

SEUL22W mono bloc. Single Ended Ultralinear class A with one 13E1 tube.
Schematics and notes for the latest version of the amp, power supply.
Graph of THD vs power output into various loads.

SE35W mono bloc. Parallel single ended class A with 4 x  6CA7/EL34/5881.
Schematics and notes for the SE amp, power supply, active protection.
Graphs for THD vs power output, frequency response, and comparisons of  THD for SE35 and SEUL 13E1 amps.

SE32W mono bloc.  Single Ended 13EI beam tetrode with 33% local cathode FB from OPT.
These were SEUL 22W but benefitted from the upgrade in 2007.  Full explanation for addopting the new design topology
with output stage similar to the SE35.
Schematics and notes for the latest version of the amp, power supply.

4+4W SET with 2 x 2A3. Two channel amps. Pictures only.

2323 integrated JBS triode amplifer.
Informal chat about the 2323 amp development, use of the 6CM5 or EL36 with Ra, gm, µ and best triode operating points. 6FW5 can be used as direct replacement for 6CM5 but without top cap.
Schematic for 23 watt channel and for power supply with notes.
Picture of the amp in 2006.

SOLID STATE POWER AMPLIFIERS 1. MOSFETS.
Brief note about my experience with solid state amps,
Picture of 2x300W amp.
Schematic of 300W AB amp channel with mosfets.
Schematic operation, topology, heatsinks, performance specification, NFB, thd, output current limiting, input voltage limiting,
class A operation.
Schematic of 600VA power supply for stereo 2 x 300W amp.
Picture of amp underside.

SOLID STATE POWER  AMPLIFIERS 2. 300W BJT.
Fig1. Schematic for one channel of 300 watt SS power amp with high current bjt output stage.
MJL21194 and MJL21193 power device choice, thd in driver stage, buffer stage cure, cross conduction
phenomena at 27kHz.
Fig 2. Schematic for 600VA psu for 2 x 300w amp channels with choke input filters.
notes on psu, chokes.
Fig 3.  Schematic of input switching, gain pots, input signal limiting, bridging phase.
Fig 4. Schematic for detector of DC offset in output, speaker protection.
Fig 5. schematic for metering.
Comments on metering. Why I won't repair any more Phase Linear 700 amps.

SOLID STATE AMPLIFIERS 3, 40W BJT.
1959 JBL amplifier re-build.
Fig 6. Schematic for one 40W amp channel with all bjts and psu as replacement of germanium  transistors.
Explanations of schematic.
Fig 7,8,9,10, pictures of JBL amplifier after reformations and singing lessons.

SOLID STATE  POWER AMPLIFIER 4, 50W MOSFET.
Picture of  2 x 50 watt class A amps.
Schematic, full descriptions, OPT, core GOSS, air gap in C-cores, bias.
2SK134 design parameters of µ, Rd and gm. Mosfet gain calcs, 3 loops of NFB explained.
Schematic of Basic model of SE mosfet amp with 1 x bjt and 1 x 2SK134 output mosfet
with all voltage / current path calculations, more on NFB.
Shunt NFB explained, alternative B+, loads, power, psu notes, heatsinks.
Notes on SE mosfet designs with choke feed and cap coupling,
class A PP alternatives. Picture of inside the amp