|
La Petite Audiophile - …(schematic added 08/08/08) |
|
Leach Amp 120 Watt Power Amplifier - 270-Watt Double Barreled Amplifier published
in Audio magazine (added 4/02) |
|
Leach Superamp - Latest update of the "Low Tim Amplifier" One
amplifier builder found that the 2N5416 PNP transistors that he purchased were NPN. I
have tested them and verified this. Two of the transistors are shown in the linked
photo. They are identified by the letters ON surrounded by a circle, signifying they
are products of ON Semiconductor. You can check... (added 4/02) |
|
Line Level Signal to Microphone Input Adapter - 270-Watt Double Barreled Amplifier
published in Audio magazine (added 4/02) |
|
LM1875 - 20-W Audio Power Amplifier - Sometimes there is need to convert line
level signals to such signal that it can be connected to microphone input. Because the
line level signals are typically in range of 0.5..2V and the microphone signals are in
millivolt range, quite much attenuation is needed to match the signal levels. This
means that typically you will need 40-50 dB of attenuation. (added 11/05) |
|
LM1876 - Overture Audio Power Amplifier Series Dual 20-Watt Audio Power Amplifier with
Mute and Standby Modes - The LM1875 is a monolithic power amplifier offering very
low distortion and high quality performance for consumer audio applications...(added
04/2002) |
|
LM380 Power Audio Amplifier - National Semiconductor Application Note 04-Nov-1995
(app note added 4/02) |
|
LM386 0,325W Audio Amplifier - The LM386 is a power amplifier designed for use in
low voltage consumer applications. The gain is internally set to 20 to keep external
part count low, but the addition of an external resistor and capacitor between pins 1
and 8 will increase the gain to any value from 20 to 200. ….(electronic schematic
added 11/08) |
|
LM386 Audio Amplifier - This simple amplifier shows the LM386 in a high-gain
configuration (A = 200). For a maximum gain of only 20, leave out the 10 uF connected
from pin 1 to pin 8. Maximum gains between 20 and 200 may be realized by adding a
selected resistor in series with the same 10 uF capacitor. The 10k potentiometer will
give the amplifier a variable gain from zero up to the maximum. ….(electronic
schematic added 11/08) |
|
LM3875 GAINCLONE - Gainclone is a single integrated circuit based on an
operational amplifier (op amp) on a single substrate of silicon. The LM3875 is the
"weapon of choice". This great chip, is a little larger than the size of a thumbnail
and can deliver up to 56W RMS continuous with 100W peaks and it can do this at 0.05%
distortion! Because they are DC amplifiers (DC coupling right through the amp) they
can go all the way to 400kHz! The first chipamp I built was a pair of monoblocks.
Though these are a little industrial looking, they deliver big time. ….(circuit design
added 11/08) |
|
LM3875 Gainclone Amp - You read where the subjective reviewer tells of the
equipment vanishing and revealing the music unfettered. Well for the first time with
any of mine or anyone else's gear that this is what I hear. There are no speakers
there is just the music. A soundstage projecting from the wall behind and from the
sides fills the room (7 x 8 x 2.5 m) with clear detail and multilayer texture and
complex timbres. The setup consists of a NAD C542 CD Player, DIY Cotton ConneX
interconnects (similar to the DIY Silver Interconnect Cables but with cotton
insulation), the Synergy LM3875 amp and small two-way bookshelf speakers. Speaker
cables are twin runs of oxygen free copper cable. I expect the amp to improve over the
next weeks but for now I am stunned! |
|
LM3875 Gainclone Amplifier - GainClones have VERY few components and this one is
based on the National Semiconductor LM3875 IC. The PCBs and components are very simple
and quick to make, only took about 20 mins to assemble both amps and rectifier board.
DC offset was about 80mV on one channel and about 40mV on the other. I used the
optional Ci capacitor in the national datasheet for the IC which reduced it to between
0-4mV: This is the capacitor I chose, its an Elna Starget (expensive). The case was
MUCH more time consuming and difficult to make though. I bought all the aluminium from
a scrap metal yard including the heatsink. I got my aluminium panels cut at a sheet
metal shop as I cant make straight cuts with a hack saw. ….(design added 11/08) |
|
LM3875 Gainclone Power Amplifier - This is a basic design with a single LM3875TF
chip per side, and one shared toroidal transformer. I will be making two of these
amplifiers simultaneously but with a few critical component differences. One is based
on standard components, and one on premium components. There was a lot of deliberation
on the type of transformer to get, particularly the secondary voltages. The concern
here is the target load as, generally speaking, the higher the voltage, the less
suited it is to drive low impedance loads (4ohms). I settled on 20 volt secondaries
which I think is a good compromise, feeling that 18v is perhaps a little too low and
22v a little too high to get the max with a 4 ohm load whilst minimising output loss
if using 8 ohms. The ability to run stable at 4 ohms is paramount to me to keep it
open to different applications, and output wattage is relatively unimportant for this
design. ….(electronic schematic added 11/08) |
