DAC with TDA1541. only TDA1541

D/A converters were made as a modular device. Individual tiles perform one system function, each of them has a separate power supply. The block diagram of the proposed solution is shown to Figure 1.

SPDIF receiver.

The SPDIF signal from the J1 connector through the TR1 separating transformer is given to the U2 system input. Role of the SPDIF/I2S decoder The WM8804 system is full - the Wolfson receiver, popular and enjoying good reputation. WM8804 is very easy to apply, it is also characterized by good parameters of the I2S output signal, e.g. a small jitter. The ideological diagram of the receiver is presented in Figure 2. The system is configured. Generator work frequency The WM8804 clock receiver is stabilized with an external XT1 quartz with a frequency of 12 MHz. It is worth taking care of the quality of the clock signal generator and try to buy a quartz with the best stability.

The correct recovery restart is provided by a specialized MCP100T (U1) system in a version powered by a voltage of 3 V, because, according to my experience - the often used RC circuit sometimes fails causing incorrect operation of the receiver. The decated I2S signal is connected to the J4 connector. The receiver is powered by two LDO stabilizers, the digital and analog (U2) part are powered separately. An additional circuit consisting of a L2 choke and a capacitor C4 filters the power supply of the PLL loop. Variable voltage is straightened using the rapid bridge and filtered by CE1 capacitor with low ESR. The 6 V/0.5A alternating voltage is taken from a separate power transformer winding. The LD1 LED signals the correct collection of SPDIF data.

D/A converter.

The I2S signal from the receiver, through the U1 and U3 lines transceivers ensuring a signal converting 3.3 V to the TTL level accepted by the transducer system, is supplied to the I2S U4 system inputs. The 3.3 V power supply required for the correct operation of transceivers is supplied from the receiver module. Capacitors C3...C16 separates TDA1541 conversion levels. It is worth taking care of their quality because they have a direct impact on the transducer operation. Very good quality plastic capacitors should be used, preferably from proven manufacturers. Philips recommended the use of 100 NF capacitors, but in many factory applications larger capacities are used, from a fast diode rectifier and a separate transformer winding. In addition, each of the voltages is filtered with a choke and capacitor (e.g. a choke L1, C18 and CE1 capacitors) to ensure unused power supply and low influence of cooperating analog and digital transducer. The processed analog current signal is connected to the J5 connector.

Conversion system I/U.

The diagram of the system is shown in Figure 4. The output converter current is processed into a voltage signal and filtered in a system based on high -quality operational amplifiers. The converter has separate amplifiers for each channel. AD797 amplifiers have been used characterized by the precision of work and a wide transfer band as well as the good opinion of users. The filter is built on a modern double LM4562 amplifier. In the system, to fully use the properties of amplifiers, it is necessary to use high quality passive elements. This is necessary due to the shaping of frequency characteristics, and what is associated with it - a direct impact on the sound. Precise or at least selected for the sake of value tolerance and to minimize the differences between stereo channels.

The system is powered from a separate power supply with a systemic solution identical as in the D/A converter. Due to on a large required coupling capacity at the output is possible to use a single C5L, C5R axial capacitor or a set of several smaller block C6L...C8L, C6R...C8R.