Project: "Monoblocus" hi-end power amplifier

Monoblocus is an high-end mono amplifier, capable of delivering up to 45W to 4Ohm loads and up to 29W to 8Ohm loads. This amplifier has a muting on power-off function, that mutes it once the same is turned off. For that, it uses an optocoupler, a TLP521-1. This makes this project very unique and quite interesting. Note that this project is not recommended to beginners, since it uses the mains. The project eventually can be adapted to work with 115V~: all you need to do is to use a 120VA transformer suitable for 115V~, and a proper primary fuse (the secondary fuses won't change).

List of components:
C1/4 – 10mF electrolytic capacitor (50V);
C2/5/7 – 100µF electrolytic capacitor (50V);
C3/6/11 – 100nF polyester capacitor (63V);
C8 – 1µF polyester capacitor (63V);
C9 – 220pF ceramic capacitor (63V);
C10 – 22µF non-polarized electrolytic capacitor (6,3V);
D1-4 – 1N5400 rectifier diode;
D5/6 - 1N4001 rectifier diode;
F1 – 1A slow-blow fuse;
F2/3 - 3.15A slow-blow fuse;
HS – 1.2°C/W passive heatsink;
IC1 - TLP521-1 optocoupler;
IC2 – LM3876 audio power amplifier (LM3876TF);
J1 – IEC C14 connector;
J2 – RCA female connector;
JW – 26AWG stranded wire;
L - Air core coil, 16 turns with 6mm dia. of 22 AWG wire;
LP – 230V~ resistored neon bulb;
R1 – 1.2KR carbon resistor (5% tol., 1W);
R2/6 – 33KR carbon resistor (5% tol., 1/8W);
R3 – 12KR carbon resistor (5% tol., 1/8W);
R4 – 47KR carbon resistor (5% tol., 1/8W);
R5/7 – 1KR carbon resistor (5% tol., 1/8W);
R8 – 2,7R carbon resistor (5% tol., 2W);
R9 – 10R carbon resistor (5% tol., 1/2W);
S – DPST switch;
T – Toroidal transformer 230V~ pri. 2x18V~ sec. 120VA.

Electrical parameters:
- Va min = 207V RMS
- Va max = 253V RMS
- Ia (Va = 230V RMS, Z = 4Ohm) = 496.4mA RMS
- Ia (Va = 230V RMS, Z = 8Ohm) = 343.9mA RMS
- P (Va = 230V RMS, Z = 4Ohm) = 114.2W
- P (Va = 230V RMS, Z = 8Ohm) = 79.10W

Amplification characteristics:
- Input impedance: 9.559KOhm
- Input sensitivity: 500mV RMS
- Gain: 30,63dB (34V/V)
- Frequency response (-3dB): 27.19-120000Hz
- Output power (Z = 4Ohm): 45W
- Output power (Z = 8Ohm): 29W

Hello,

An other nice project by you.
Simple but effective.
Can you translate the PDF again in english?

Bertus

Well, thanks to you we can say that AAC has a nice collection of amplifier projects. Nice one!

bertus said:

Hello,

An other nice project by you.
Simple but effective.
Can you translate the PDF again in english?

Bertus

Click to expand...

Thanks Bertus! Yes, I'll post a translation in English ASAP.

Georacer said:

Well, thanks to you we can say that AAC has a nice collection of amplifier projects. Nice one!

Click to expand...

Indeed! In fact, the muting circuit works so well that I'm planning to use it on the next revision of Taurus, amongst other goodies!

Just uploaded the translation in English, as requested. Hope you enjoy!

Hello,

Thanks for translating the PDF.
I have attached the datasheet of the used power amplifier for those who are interested.

Bertus

Just a note that I forgot to mention. The PCB is not compatible with the LM3886. Use a LM3876TF, as suggested.