BUILT BETWEEN 1996 AND 2012.
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 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, umbilical cables, other views.
100W mono bloc, 2004. With 3 x 6SN7 and 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.
mono bloc, 2014. Much
more info on 100W UL amps. Includes
recommended balanced biasing for multiple output tubes, revised protection,
delay circuits, plus schematic for 100W amp with 4 x KT120 / KT90 / 6550 / KT88,
with 12AU7 input and 2 x ECC99 in LTP driver stage.
100W UL OPT details for 2k5 primary load with many secondary load choices from
1 ohm to 45 ohms.
integrated. 4 x 6550/KT88/KT90 per channel, CFB
Schematics and notes for one 85W channel, power supply for two channels,
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.
Mr Zel's 100-100W
Two channels each with 4 x EL34, CFB output stage.
Pictures, schematics and graphs and many options and explanations provided.
80Watt power amp.
A page about using 4x EL34 in output stage similar to amps in 8585.
uses 6CG7 input diff amp, 2 x EL84 LTP driver. Delayed B+, Active Protection,
LED bias monitoring, Full OPT details.
integrated. 2 x KT88/KT90 per channel, Ultralinear class
Schematics and notes for one 50W amp channel, 5050W amp power supply,
and 5050W amp bias balance indication and active protection.
mono bloc. Parallel single ended class A with 4 x
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.
mono bloc, 2005. with 13E1, 2005 Single Ended Ultralinear
with one 13E1 tube. Schematics and notes for 2005 version of the amp and
Graph of THD vs power output into various loads.
mono bloc, 2008. with 13E1, 2008
Single Ended class A amp with 33% local
cathode FB from OPT.
These were SEUL 22W but benefited from the upgrade in 2007.
Full explanation for adopting the new design topology with output stage
similar to the SE35.
Schematics and notes for 2008 version of the amp, power supply.
bloc, 2012. with 13E1, 2012 Single Ended
class A amp with 33% local
cathode FB from OPT, but with choke feed to driver and other changes to 2008 version.
A rare picture of Mr Turner, 2012.
Schematics and notes for 2012 amp and power supply.
More amp pictures and close up pictures showing gettering wear changes to 13E1.
SE31W SE amp and PP amp mono amps. with 13E1, 2012 SE and PP amps
both with CFB. Schematics and notes.
4+4W SET with 2 x 2A3. Two channel amps. Pictures only.
2323 integrated JBS
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
the anode top cap. Schematic for 23 watt channel and for power
supply with notes. Picture of the amp in 2006.
OTL amplifiers. Much about pros and cons for OTL amps.
SOLID STATE AMPS.
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.
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,
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
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
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 calculations,
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.
STATE 5, MOSFET POWER AMPS WITH TUBE DRIVER STAGES.
Class A operation of power mosfets and audio applications.
Vacuum tube input and driver stages for mosfet output stages.
Fig 1A, Graph - 2SK1058, SE class A loadline 15r0, Ed +16Vdc, Id 1Adc.
Fig 1B, Schema for testing SE class A power mosfet properties.
Fig 1C, Schema SE 2SK1058, 1:1 OPT 15r0 : 15r0, Ed +16.3Vdc, Id 1Adc.
Fig 3, Schema Complementary Source Follower pair buffer 2SK176+2SJ56,
for VLF to 5MHz.
Fig 4, Hybrid - 1, Schema 12.5W A-AB amp, EL34 drives 2SK176+2SJ56
source followers with NFB to EL34 screen.
Fig 5, Schema for CCS for EL34 anode dc, 2 x 2SK1924.
Fig 6, Basic models Voltage and Current generators.
Fig 7, EL34 basic model current gene of pentode and g1 and g2 gm function.
Fig 8A, EL34 pentode, small signal amp stage, use and properties.
Fig 8B, EL34 triode, small signal amp stage, use and properties.
Fig 9, EL34 Schema of basic model driving comp pair source follower output.
Fig 10, Hybrid - 1, Schema, Remote PSU for 12.5Watt amp in Fig 4.
Fig 11, Graph Po Vs RL for 12.5W amp Fig 4.
Fig 12A, Hybrid - 2A, Schema 12.5W, A-AB amp, EL34 + IST
+ Series Pair 2 x 2SK176.
Fig 12B, Hybrid - 2B, Schema 12.5W, A-AB amp, EL84 input,
Technics EL84 phase splitter, Series Pair 2 x 2SK176.
Fig 13, Hybrid - 3, SHEET 1 Schema, 50W push-pull amp,
12AU7 input phase splitter, 2 x EL34 drivers + balanced screen GNFB,
6 x 2SK1058 as balanced source followers + auto OPT with CT to 0V.
Fig 14, Hybrid - 3, SHEET 2 OPT Bobbin Winding layers.
Fig 15, Hybrid - 3, SHEET 3 OPT terminations, load ratios, strapping.
Fig 16, Hybrid - 2, SHEET 4 Schema PSU for 50W amp Fig 3.
Fig 17, Hybrid - 4, Schema Circlotron 40W A-AB amp, 2 x EL84 + CT choke
in LTP input.
Fig 18, Hybrid - 1, Picture of prototype of amp Fig 4.
Fig 19, Hybrid - 5, 40W A-AB amp, Schema Compound Complementary Pairs,
EL34 input/driver with GNFB, 2SK176+2SJ56 source followers + 2SJ56+2SK176
in common source.
Fig 20, Picture 2x300W SS amp to show heatsinks 300mm x 150mm x 40mm.
Pictures of future mono block amp chassis, details of stocks available.
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