Audio Preamplifiers | Electronic Project Circuits

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FET Preamp with Tone control by 2N3819

The Preamp sensitivity and overload margin were designed to cope with most modern music programme sources like CD players, Tape recorders, iPods, Computer audio outputs, Tuners etc. The source selecting switches and input connectors are not shown and their number and arrangement are left to the constructor’s choice.
To obtain a very high input overload margin, the volume control was placed at the preamp input. After a unity gain, impedance converter stage (Q1) a negative-feedback Baxandall-type Bass and Treble tone control stage was added. As this stage must provide some gain (about 5.6 times) a very low noise, “bootstrapped” two-transistors circuitry with FET-input was implemented. This stage features also excellent THD figures up to 4V RMS output and a low output impedance, necessary to drive properly the Mini-MosFet Power Amplifier, but can also be used for other purposes.

Preamp Parts:

P1______________50K Log. Potentiometer (or 47K)
(twin concentric-spindle dual gang for stereo)
P2,P3__________100K Linear Potentiometers
(twin concentric-spindle dual gang for stereo)

R1_____________220K 1/4W Resistor
R2_____________100K 1/4W Resistor
R3_______________2K7 1/4W Resistor
R4,R5____________8K2 1/4W Resistors
R6_______________4K7 1/4W Resistor
R7,R8,R13________2K2 1/4W Resistors
R9_______________2M2 1/4W Resistor
R10,R11_________47K 1/4W Resistor
R12_____________33K 1/4W Resistor
R14____________470R 1/4W Resistor
R15_____________10K 1/4W Resistor
R16______________3K3 1/4W Resistor (See Notes)

C1,C2,C9_______470nF 63V Polyester Capacitors
C3,C4___________47nF 63V Polyester Capacitors
C5,C6____________6n8 63V Polyester Capacitors
C7______________10µF 63V Electrolytic Capacitor
C8,C10__________22µF 25V Electrolytic Capacitors
C11____________470µF 25V Electrolytic Capacitor (See Notes)

Q1,Q3_________BC550C 45V 100mA Low noise High gain NPN Transistors
Q2___________2N3819 General-purpose N-Channel FET

Read More Source:http://www.redcircuits.com/Page123.htm
thank you.

1 comment - What do you think? Posted by admin - November 6, 2007 at 10:48 am

Categories: Pre Amplifier, Tone control Tags: 2N3819, audio preamplifiers, tone control circuit

10W Audio Amplifier with Bass-boost by NE5532 + TIP41

This design is based on the 18 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It uses the widespread NE5532 Dual IC but, obviously, its power output will be comprised in the 9.5 – 11.5W range, as the supply rails cannot exceed ±18V.
As amplifiers of this kind are frequently used to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. Therefore a bass-boost control was inserted in the feedback loop of the amplifier, in order to overcome this problem without quality losses. The bass lift curve can reach a maximum of +16.4dB @ 50Hz. In any case, even when the bass control is rotated fully counterclockwise, the amplifier frequency response shows a gentle raising curve: +0.8dB @ 400Hz, +4.7dB @ 100Hz and +6dB @ 50Hz (referred to 1KHz).

10W Audio Amplifier with Bass-boost by NE5532 + TIP41

Parts:
P1_________________22K Log.Potentiometer (Dual-gang for stereo)
P2________________100K Log.Potentiometer (Dual-gang for stereo)
[...]
R10__________________R22 4W Resistor (wirewound)
C1,C8_____________470nF 63V Polyester Capacitor
C2,C5_____________100µF 25V Electrolytic Capacitors
C3,C4_____________470µF 25V Electrolytic Capacitors
C6_________________47pF 63V Ceramic or Polystyrene Capacitor
C7_________________10nF 63V Polyester Capacitor
C9________________100nF 63V Polyester Capacitor
D1______________1N4148 75V 150mA Diode
IC1_____________NE5532 Low noise Dual Op-amp
Q1_______________BC547B 45V 100mA NPN Transistor
Q2_______________BC557B 45V 100mA PNP Transistor
Q3_______________TIP42A 60V 6A PNP Transistor
Q4_______________TIP41A 60V 6A NPN Transistor
J1__________________RCA audio input socket
Power supply parts:
R11_________________1K5 1/4W Resistor
C10,C11__________4700µF 25V Electrolytic Capacitors
D2________________100V 4A Diode bridge
D3________________5mm. Red LED
T1________________220V Primary, 12 + 12V Secondary 24-30VA Mains transformer
PL1_______________Male Mains plug
SW1_______________SPST Mains switch

Please read more at the original source: http://www.redcircuits.com/Page61.htm

Be the first to comment - What do you think? Posted by admin - October 27, 2007 at 7:25 pm

Categories: Power Amplifier Tags: audio preamplifiers, bass boost circuit, NE5532, TIP41

Circuit Pre Amp With Transistor

When you want to enlarge sound signal from all source before costume amplify. Usual use Pre Amplifier or Pre Amp. Today I begs for to suggest again the one circuit. That interesting because of use Transistor just one ( the number replaces many the number such as C1815 or C945 or C828 , etc. ) The circuit easily and still be usable well. convenient for a novice as an example PCB be the character Stereo. Wasp Input from the CD player and Output with the amplifier immediately. Request enjoy please yes.