Schema and production of PA Ampli Ibiza

 

This article presents the schematic and detailed analysis of the amp Amp Sound Ibiza-300-S. It was disassembled and observed in detail. This is a PA amp entry level to very affordable price.

Characteristics of the amplifier manufacturer Ibiza Amp-300-S:

Max power: 240 Watts x 2
Power RMS: 106 Watts x 2
MOSFET technology with silent fan
Weight of amp: 5035 kg
Bandwidth of the amplifier: 20 - 20000 Hz
S / N ratio of the amp:> 98dB
Applications: the requirements of modern sound

Presentation of ad Ibiza amp Amp-300-S

Critical characteristics of the amplifier

About the power of the amp, it is not mentioned on what impedance is given the power (at 4 ohms or 8 ohms). Presumably it is the power of the amp to 4 Ohms. At 8 ohms, the amplifier should give about 2 x 70W RMS. The output transistors are MOSFETs but bipolar (see below). Apparently, there is no MOSFET amplifier in the audio itself.

Diagram of the amplifier PA Ibiza Amp-300-S

Diagram of the amplifier PA Ibiza Amp-300-S

View of the printed circuit of the amplifier

This pattern appears in the forums dedicated to the amp and it can be found by observing the single-sided circuit board of the amp.

Power amp Amp Ibiza PA-300-S

 

Transformer of the amp Amp Ibiza-300-S

The toroidal transformer is, good size, and provides 2 x 26V.

Diode bridge and capacitors in the amp 1000uF/50V Ibiza

The rectified voltage will be + /-38V or so. 1000uF/50V capacitors are ridiculously small in size! It would take at least 4700uF/50V on food, and again, it's a minimum sound. In Hi-Fi, it would rather 10000UF or more ...

Bridge Diode 800V 8A, however, is very correct.

Analysis of the pattern of Ibiza amp Amp-300-S

The diagram of this amplifier PA has a remarkable simplicity.

Diagram of the PA amp with features surrounded

The input signal is filtered by all 4.7uF/470Ohms/33k (high pass filter). 100pF capacitor removes high frequency noise as possible. The resistance of 470 Ohms is irrelevant and can be bypassed!

The differential pair (circled green), based on two 2SA1015 is very conventional. Its power supply is through the resistance of 33k taken directly from the unregulated supply + Vcc. Ripple current is therefore the differential pair, but it works pretty well anyway. 2kOhms load resistor used to balance the currents in the differential pair.

The voltage gain stage (circled purple) based on an NPN and a "pseudo" current source made by a resistance of 4.7k! There is no bootstrap capacitor normally. The solution is really very low cost and does not allow a voltage swing up or an optimal open-loop gain high. Reducing the open loop gain can however be a better system stability. The 1N4148 diode in series with the resistance of 33 Ohms polarizes the basis of the output stage. Transistor 2SC1815 only supports 50V Vce of when the maximum voltage at its terminals can be up to 80V (between + Vcc and-Vcc)!

The output stage (circled red) the amp is based on a quasi complementary assembly. The output transistors are curiously the PNP (NPN and not!) 2SA940 (150V, 1.5A, 25W) sized just too much running and power! They are still parallel and balanced currents through the resistance of 0.22 Ohm and to a lesser extent, through the 33 ohm resistors to the base.

The cons-reaction (circled blue) defines the voltage gain of the amp: 1 + 18k/470 = 39.3 (higher than the average trade Amps)

A signal of 500mV is sufficient for 20V output (100Wrms / Ohms). A CD (line level) can be connected directly to the amp, without going through a mixer.

The 100nF capacitor in parallel with the 100uF is unusual and seems unnecessary for this application.

Details of the design of the amplifier PA Ibiza

There, for reasons of cost, few component values ​​are used. The 33 ohm resistors are placed in many places. Only three references transistors are used: 2SA1015, 2SC1815 and 2SA940. There is always a saving for the industry to have a minimum number of reference components (inventory management, sourcing in case of obsolescence).

No protection against short circuits exist. Attention to the use of 6.35 Jack behind the speakers. Never plug a jack behind the speakers if the amp is turned on because there is risk of short circuit when you plug in the Jack Socket.

Conclusion on the amp sound Ibiza Amp-300-S

The construction of the amp is very simple and highly economical. The amp has no protection against short circuits and the output stage is sized just too much. The power transformer seems satisfactory and provides a power 2x90Wrms about 4 ohms. Design, with its trendy modern backlight, sound will appeal to beginners who do not have a big budget.