Amplifier circuit tda7294 2.1 or tda7293 2.1, you can also use TDA7295 and TDA7296 or combine these cis. Uses single amplifier configuration for the satellites and bridged for the bass amplifier or subwoofer amplifier. Complete project including preamplifier with tone control, bass filter with frequency adjustment, power supply, 3 amplifier circuits, and protection circuit using UPC1237 IC and relay.

About 2.1 amplifier circuit using IC TDA7294 2.1 or TDA7293 2.1

Preamplifier circuit.
The signal input goes through p1 for overall volume adjustment, R11/C18 form a low-pass filter to avoid RF in our amplifier. The component values can be changed to suit your need.
IC1A and IC1B form the tone control circuit, with bass-mid and treble adjustment. P4 adjusts the volume of the satellite amplifiers.

Dual operational amplifiers can be used equivalently, but prefer the original and better quality ones.

Subwoofer (Bass) filter circuit.
The signal of this circuit comes before the pre-tone, IC5A forms a buffer if you prefer you can change the resistor to increase or decrease the gain of the signal. Ic5B forms a high-pass filter with a cutoff frequency of about 43Hz and Ic7A low-pass filter with a cutoff frequency of 157Hz, i.e., a band pass from 43Hz to 157Hz. In Ic7B in P5 makes the cut-off frequency adjustment between 54 and 157Hz. P6 makes the volume adjustment of the bass channel. The signal from this stage goes to the subwoofer amplifier formed by IC8 and Ic9.

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Power amplifier circuit.
Uses the classic configuration for TDA78xx family, and can use TDA7294, TDA7293, TDA7295 or TDA7296. The mute and stand-by circuitry is shared between the 4 cis. The capacitor on the cis input sets the input impedance at 22K and together with the 1uF capacitor forms a high-pass circuit. The subwoofer amplifier is bridged and should be used with loads of 8 ohms or greater.

Symmetric power supply circuit.
The linear symmetrical power supply circuit uses a rectifier bridge and 6 capacitors from 4,700uF to 10,000uF. The transformer should be able to supply up to 10A per winding when it is 24V voltage. But it can be 12 + 12 to 25 +25V. If you prefer you can use a supply only for the preamplifier circuit.

Protection Circuit
A protection circuit for the speakers and delay was adopted, using the UPC1237 IC and 2 relays. The power supply for the circuit comes from the transformer, being rectified by D2/D4. The resistor R35 was calculated to be used with a 24V relay.

Table of CIS that can be used in our Amplifier 2.1.

CI	TDA7293	TDA7294	TDA7295	TDA7296
maximum power	100W	80W	60W	50W
Maximum power of the subwoofer	180W	170W	100W	60W
Maximum voltage in 4 or 8 ohms satellites + 8 ohm subwoofer	22 + 22 VAC	22+ 22 VAC	18 + 18 VAC	12 + 12 VAC
Maximum voltage at 4 or 8 Ohms + 16 ohm subwoofer	25 + 25 VAC	25 + 25 VAC	22 + 22 VAC	18 +18 VAC

*Symmetrical source, mount 2.1.

Printed circuit board PCB suggestion for 2.1 amplifier assembly with tda7294 2.1 tda7293 2.1

BOM for mounting or amplifier 2.1

Last Update: 05/30/2022 11:43 AM

Part	Valor	Descrição	Quantidade
Resistors 1/4W
R1, R22, R23, R25, R28, R29, R31, R36, R38, R39, R41, R62, R63	10K	Brown, Black, Orange, Gold	13
R2, R6, R8, R10, R51, R52, R54, R56, R57	22K	Red, red, orange, gold	9
R3, R9, R53, R55	680	Blue, gray, brown, gold	4
R4	30K or 33K	Orange, black, orange, gold	1
R5	20K or 22K	Red, black, orange, gold	1
R7, R14	4,7 ohms 1W	Yellow, violet, gold, gold	2
R11, R13, R27, R43, R50	1K	Brown, black, red, gold	5
R18, R24, R26, R32, R34, R37, R40	100K	Brown, black, yellow, gold	7
R12, R15, R16, R17, R20, R33, R42, R59	47K	Yellow, violet, orange, gold	8
R19, R35	2K	Red, black, red, gold	2
R21	15K	Brown, green, orange, gold	1
R30	3.9K	Orange, white, red, gold	1
R44, R46, R47, R49	6.8K	Blue, gray, red, gold	4
R45	200K	Red, black, yellow, gold	1
R48	68K	Blue, gray, orange, gold	1
R58, R60	220 /2W	Red, red, brown, gold	2
R65	220/3W	Red, red, brown, gold	1
Capacitors
C1, C16	47µF/50v	Electrolytic capacitor	2
C2, C17, C43, C52	1µF (105)	Capacitor film	4
C3, C4, C5, C7, C9, C20	22µF/50v	Electrolytic capacitor	6
C6, C8, C67, C68, C69, C70	4.700uF a 10.000µF/50V	Electrolytic capacitor	6
C11, C12, C23, C24, C61, C62, C72, C84, C86	100nF (104)	Ceramic Capacitor	4
C14, C15	100µF/50v	Electrolytic capacitor	9
C18, C19	120p (121)	Ceramic Capacitor	2
C21, C22, C30, C75, C76	10µ/50v	Electrolytic capacitor	5
C10, C13, C32, C33, C41, C55, C56, C78	100n (104)	Capacitor film	8
C25, C31, C36	47p (47)	Ceramic Capacitor	3
C26, C37	2.2n (222)	Capacitor film	2
C27, C28, C38, C39	47n (473)	Capacitor film	4
C29, C40	10p (10)	Ceramic Capacitor	2
C34, C35	220n (224)	Capacitor film	2
C42	10n (103)	Capacitor film	1
C57, C58, C59, C60	10n (103)	Ceramic Capacitor	4
C44, C65, C66	100µ/50v	Electrolytic capacitor	3
C64	4.7µ/50v	Electrolytic capacitor	1
C83, C85	220µ/50V	Electrolytic capacitor	2
C87	33µ/50V	Electrolytic capacitor	1
Semiconductors
D1	1N4448	Signal diode	1
D2, D3, D4	1N4004 or equivalent	Silicon diode	3
IC1, IC4, IC5, IC7	NE5532 or equivalent	Dual Operational amplifier	4
IC2	UPC1237	IC protector and delay	1
IC3, IC6, IC8, IC9	TDA7293 or TDA7294, or TDA7295, or TDA7296	Audio Amplifier IC	4
IC10	LM7815	15V positive voltage regulator IC	1
IC11	LM7915	Positive voltage regulator IC -15V	1
Led1	Led 3 mm	Green Led	1
LED, LED2	Led 3 mm	Red LED	2
B1	GBJ3510TB or equivalent	1000V 35A rectifier bridge	1
Miscellaneous
CN1	Connector JST-XH-03 2.54 mm 3 pin or equivalent	Audio Input	1
OUT	Connector KF8500 (Kf7.62) 3 pin	Stereo audio output	1
POWER	Connector KF8500 (Kf7.62) 3 pin	Power transformer connection	1
SUBOUT	Connector KF8500 (Kf7.62) 2 pin	Subwoofer output	1
P1, P2, P3, P4	47K or 50K	Dual potentiometer	4
P5, P6	47K or 50K	Simple Potentiometer	2
K1, K2	G2R-2-DC24 or  SMI-24VDC-SL-2C	Double relay 24V 5A	2
Solder, Wires, PCB, box, transformer.

Download the material list for this assembly, including the plate in Gerber, PDF, PNG, PS format, and datasheet of the components used.

Download the PCB files
Mirror

• TDA7294 datasheet in PDF — Atualizado
• TDA7293 datasheet in PDF – STMicroelectronics
• TDA7295 datasheet in PDF – STMicroelectronics
• TDA7296 datasheet in PDF – STMicroelectronics
• UPC1237 datasheet in PDF – UTC (Unisonic)
• UPC1237 datasheet in PDF – NEC
• GBJ3510 Datasheet PDF – Diodes incorporated
• Datasheet PDF G2R-2-DC24 — Omron
• SMI-24VDC-SL-2C PDF Datasheet — Songle
• Ne5532 Datasheet in PDF
• LM7875 Datasheet in PDF
• LM7915 Datasheet in PDF
• Diode 1N4148 Datasheet PDF
• Diode 1N4004 Datasheet in PDF

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Toni

Xtronic.org blog author. Electronics technician for the technical school of Brasilia - Brazil. Interested in electronics, circuits and technology in general.