8Watt RMS Class A amplifier 20W peak. This amplifier, which was
originally designed by J. Hiraga, is an exellent amplifier for driving
your tweeters, or as a horn amplifier. If used with speakers of
conventional sensitivity, an active crossover should be used It is
equipped with DC-servo, double cascode input stage, and CFP output stage.A
suitable transformer is 2x9V 300VA and approx. 2x30000uF of decoupling
capacitors *HIGHLY RECOMMENDED!*
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10Watt RMS Class A Single-ended amplifier 20W peak.
This amplifier is capable of
high slewrate and bandwidth. A low output impedance is ensured by high
feedback ratio, and also by the White-follower outputstage. This raises
the current in the constant current source when a load is drawing current
from the output. This also makes the emitter-follower more linear. The amp
is supposed to run on a quiecent current of 1A, but due to the
white-follower it draws about 2A peak when driven to max in an 8Ohm load.
Building the amp requires some extensive soldering skills, due to the
component density of the printboard. Because of it's excellent control in
the bass region it may be used as a fullrange amplifier, but requires a
loudspeaker of high sensitivity (DON'T run this on your LS3A speakers!).
Best use of the amp would however be in horn tweeters and low mid horns
especially, where it will produce outstanding dynamics aswell as
musicality. Voltage gain is about 18 times.
Postscript file for the printboard layout
Schematics for the 8W Class A amp
Partslist for the 8W Class A amp
PCB file for redisigning the 8W Class A
amp
Another version of the amplifier, with slightly altered feedback loop,
that gives about 4 times gain. Especially well-suited for high sensitivity
speakers:
Postscript file for the 4x gain printboard
layout
PCB file on the 4x gain version
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Single-ended no-feedback current-mode preamplifier.
A single-ended preamp with no global feedback, with low distorsion, good
bandwidth and slewrate, and capable of producing an output swing close to
each rail. The preamp is originally designed for the ALPS "blue velvet"
motorized potentiometer. What puts this preamp apart from others, is the
fact that the pot isn't used as a standard voltage divider, but it is used
as a variable resistance, and is playing an active part in the
voltage-amplifying stage. This means that with the volume all the way
down, you also short out the noise generated by the voltage amplifying
stage. Another advantage is that the preamp can handle very large voltage
swings at the input before clipping (20 V p-p). Maximum gain is ten times
(20dB) which should be sufficient for the most demanding applications, and
max. output swing is 24V p-p (on a +/- 15V powersupply). For this preamp
it is cruicial to use a regulated pw. supply, and you MUST also use a
4,7uF high-quality polypropylene decoupling capacitor at the input (no
fitted at the printboard, because of their large size and different
footprint). The preamp is fitted with a DC-servo to ensure zero offset at
the output.
The postscript printboard layout file.
The PCB file for making alterations to the preamp
(Protel Design)
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100W/8ohm amplifier, simple and compact A
really good amp with an outstanding bandwidth of 1.55MHz and slewrate of
80V/us. The amplifier will produce about 200W into a 4 ohm load. Standard
circuit design makes for high stability. For this amp I've laid out the
following files: postscript printboard layout, schmatics, partlist, and
even the original PCB file for anyone of you that might want to make
alterations without having to re-route the whole amp. Simple is often
better!
Postscript file of the printboard layout
Schematics for the 100 W amp
Partslist for the 100 W amp
PCB file for redesigning the 100 W amp
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150Watt / 8ohm amplifier, simple and
compactThis amp is in basic
the same as the 100W amp above. Output transistors have been changed to
a type that can handle more power without degrading the design of the 100W
amp. Also there has been added a separate powersupply for the input
stages. This will increase power output for a given supply voltage
significantly. A good tip is to use this version even if you're building
the 100W amp, as it has a separate powersupply for the input stages. You
can just run the two powersupply inputs in parallel, and build a separate
powersupply for the input stage in the future to acheive a higher power
output. In any case the supply voltage for the input should be min. 5
Volts higher than for the output to acheive any real power increase. Run
into a 4 ohm load the 150W amp will produce about 300Watts of continous
output power. A really excellent amplifier! Files included: Postscript
file for printboard layout, schematics, partslist and PCB file, same as
for the 100W amp.
Printboard layout file
Schematics for the 150 W amp
Partslist for the 150 W amp
PCB file for redesigning the 150 W amp
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90W/8ohm, 170W/4ohm amplifier. REV 1.6Sounds
nice. Cascode gain stage, improved complimentary feedback IGBT output and
vxb-multiplier. DC-servo. Only the output transistors
are to be mounted on a heatsink. Suitable transformator is 2X35VAC 500VA.
The rectified DC-voltage should not exceed +-48V DC. Suitable quiecent
current is from approx. 150mA and upwards (depending on the size of the
heatsink). For further details E-mail me:
kentj@omegav.ntnu.no
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100Watt bass amplifier Especially suited for powering subwoofers
as it has superb control in the bass region. Simply the best
bass-amplifier I have ever heard! Simple to build, with extensive
descriptions. Suitable transformer is 2X35V 500VA *EXCELLENT!*
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50W/8 ohms amplifier, CHEAP.
Per request from some of the people who have visited this page, I have
designed an amplifier that should be quite cheap to build, while it still
is high quallity, and quite high power. I tested the amp in a 4 ohm load
and it produced some 90W continous RMS output on a +/- 30V supply, which I
guess many would find satisfactory. The design is quite compact, which
should make the amp perfect for say small active speakers. Supply voltage
may range from +/-12V to +/- 45V, but I would recommend +/-30-35V
(2x24Vac transformer).
90W/8 ohm amplifier, same as above (also CHEAP), but added output
transistors for increased powerhandling. This amp should run on a +/-45V
supply to obtain 90W in 8 ohms (33V AC trafo). The amp should be able to
deliver about 160W into a 4 ohm load.
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15Watt Very simple little surround and center channel amp. Based
on a 5532 op amp, and a complimentary feedback output stage, it provides high
fidelity at a bargain price. The amplifier can also be used in
small integrated amp projects, and will probably provide more musicality
than many commersial small integrated amps. Intended powersupply is +-20V
DC, but +-25V also works well.
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Headphones amplifier Push-pull class A headphones amplifier with
approx. 3x gain. The amp is designed to run from a line level preamp
output. high bandwidth, and capable of delivering 1A output current and
12.5V amplitude voltage swing on a +/- 15V supply, would make this
suitable to run even the most demanding headsets.
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+6dB to +20dB/25 Hz variable bass boostDesigned for boosting low
frequencies on an open-baffle loudspeaker with a roll-off of some
6dB/okt. from 150Hz. The circuit provides a variable boost of 6dB to 20dB
with a center frequency of 25 Hz. The magnitude of bass boost will
determine the upper corner frequency (the frequency where the circuit no
longer will provide any boost). The slope is 6db/okt.
Supply voltage ranges from +-8V to +-18V. Active component is an NE 5532
op-amp.
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+/- 15V regulated powersupply made especially for the single ended
preamplifier listed above.
Simple, +-15V regulated supply with LM 7815/LM 7915 regulators, nice for
preamplifiers and other applications. Transformer should be 2X18V AC 50VA
or greater. For an improvement you can add a discrete regulator to the
output of this one for better HF-regulation, but this is strictly not
neccesary.
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Discrete regulated supply.
Designed for producing +/-10V, but this can be altered simply by altering
the zener diodes voltages. The transistors need cooling according to how
much power they will deliver. Use this powersupply for circuits that
having low powersupply rejection, as it has a good
HF-supression. I've used it in my preamp, which uses discrete buffers with
low psr ratio. Conbine this regulator card with a pair of LM 78XX /LM 79XX
regulators (the powersupply described above), and you will have one of the
quietest powersupplies available.
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