I decided to listen to how a class D amplifier sounds on the IRS2092. After some time
An order was placed for a search on Ali. Out of curiosity “how it sounds,” a tone block was also ordered for it.
Since the amplifier is still on the road and the tone control has already arrived, I decided
review it for now. When the amplifier arrives I’ll do a review on
him with measurements.
The payment came in a bubble-stuffed envelope. The kit includes the circuit itself and
four handles for resistors. Vese flux washed off the soldering more or less
neat. The board layout is average. The controls in the photo are from left to right - HF, MF, LF, Volume.
NE5532P op-amps are installed on the board 
Also on the board are power stabilization circuits (L7812 and L7912) and a rectifier.
Can supply AC voltage from transformer for power supply
fees.
The regulator circuit diagram is similar to this one 
The values of some resistors differ and the absence of some pass-throughs
capacitors.
Now the most important thing is the tests.
Tested on this card 
Creative Sound Blaster X-Fi Titanium PRO with a slight modification - the reverse side of the printed circuit board is completely shielded, the output op-amp is replaced with OPA2134, all power supply capacitors are shunted with ceramics.
Frequency response (pink - from input to output bypassing the tone block, blue
- through the tone block - all tone controls in the middle position) 
A slight rise is visible at low frequencies (below 200Hz) and a dip at
high (above 6 kHz)
Bass controls in extreme positions 
Midrange controls in extreme positions 
HF controls in extreme positions 
THD "THD", the right channel goes bypassing the tone block for comparison (from the card output to
input), THD of the tone block 0.016%, I would like it to be less, of course. I tried installing OPA2134 instead of the native op-amps, the distortion decreased slightly, but not significantly, most likely due to the board’s not entirely correct layout. 
Dependence of SOI on frequency (the right channel bypasses the tone block,
pink color on the graph) 
The tone block does not invert the signal phase (the right channel goes bypassing the tone block,
pink color on the graph) 
A fairly average quality block, suitable for home crafts if you are comfortable with CNI.
I’m unlikely to bet on the planned strengthening due to the high
harmonic distortion. I will wire the board myself and assemble the tone block.
I hope the information was useful.
This stereo preamplifier is built around the popular NE5532 op amp and several discrete components. The preamplifier is suitable for working with any signal source, such as an MP3 player or computer, and in addition to the final power amplifier it will allow you to get good sound at home.
The preamplifier has a tone block that allows you to adjust the low and high frequencies, as well as adjust the volume using three paired rotary potentiometers. Placing the potentiometers on the edge of the board eliminates the need for wires connecting the potentiometers to the board, which in turn improves the amplifier's noise performance.
The preamplifier is powered by a bipolar power supply with voltage ranging from +/-18 to +/-30 volts.
The circuit diagram of the preamplifier is shown in the figure below: 
The amplifier consists of two identical channels. Let's study the operation of a preamplifier using one of them. The input signal is fed to GP1 and goes directly to a high pass filter consisting of capacitor C1 (1uF) and resistor R1 (100k) with a cutoff frequency of about 1.5Hz, this effectively cuts off the DC component and the lowest frequencies.
Next, the signal goes to the non-inverting amplifier U1 (NE5532) and resistors R3 (10k) and R7 (4.7 k), which provides a signal amplification of 1.5 times. A small capacitor C3 (10 pF) prevents excitation, while C5 (1 µF) separates the circuits on amplifiers U1 and U2 (NE5532).
The frequency regulator is built on the U2 amplifier, and the frequency control itself is built in a classical way. Elements that change the characteristics are located in the negative feedback loop of amplifier U2. When both controls are in the center position, resistance X1 (derived from elements: R9 (10k), C9 (33 nF), C7 (4.7 nF), and also: P1 (100k), P2 (100k), R11 (10k ) and R12 (3.3 k) - “in the middle position”) between the input signal and the inverting input of the amplifier U2 is equal to the resistance X2 (obtained from the elements: R15 (10 k), C11 (33 nF), C13 (4.7 nF) and in the middle also: P1, P2, R11 and R12 - “in the middle position”) between the output of amplifier U2 and the inverting input. The gain A is expressed by the following dependence:
It is equal to 1 for the entire operating frequency range of the amplifier.
P1 is responsible for adjusting the low frequencies. For high frequencies, capacitors C9 and C11 are short-circuited, so adjustment with the potentiometer has no effect at these frequencies. The potentiometer is responsible for adjusting the high frequencies, and due to the exclusion of capacitors C7 and C13, the adjustment has no effect on the low frequencies.
The signal from the output of the frequency regulator goes through resistor R17 (4.7 k) to the volume control potentiometer P3 (100k) and then to the next amplification circuit, namely U5 (NE5532). Elements R19 (15k) and R21 (33k) configure U5 to work as an inverting amplifier with a gain of about 2. From the output of U5, the signal through the filter R23 (100P), C21 (1 uF) and R25 (100k) goes to the output of the preamplifier GP3 .
The supply voltage for the operational amplifiers is obtained using regulators U3 (78L15) and U4 (79L15), and is filtered using capacitors C15–C16 and C17–C18. In addition, the power supply to each of the four op-amps is smoothed using capacitors C19-C20 and C23-C26 (100 nF).
(unknown, downloads: 4,047)
The article shows a circuit diagram and printed circuit board of a pre-amplifier, the main element of which is the NE5532 dual operational amplifier. You can also use in the circuit such as TL072, OPA2134, CA1458, OP275, LM6172, OPA627, AD826. This pre is suitable for use with almost any power amplifier. The author used it with amplifiers assembled on TDA7293 (TDA7294) and LM3886. There is a volume control on board. Pre-amplifier circuit diagram:
With the indicated values of resistors R5 and R6 (22k), the gain is 3, in most cases this is quite sufficient, but this is not the limit, increasing the values of the above resistors to 47 kOhm will give a gain of 5 times, increasing the value to 100 kOhm the gain will be approximately 10 times.
A stabilized power supply is pre-mounted on the same board with the circuit; it is implemented on IC2 and IC3 (7812/7912).
At the time of writing, we found a designer on Aliexpress that replicates this pre-amplifier circuit one to one. The only difference is that the PCB from Ali is designed to accommodate a DB107 diode assembly with a current of 1 Amp. We made a copy of the board using assembly 2W06 (current 2A).
Even taking into account the use of different diode assemblies, the difference is not significant. LAY6 format printed circuit board:
Photo view of the pre-amplifier board on NE5532 in LAY6 format:
The pre-amplifier board is single-sided, size 52 x 70 mm.
Source:
Appearance of the designer's printed circuit boards:
Assembly board:
And one more small difference: instead of a 50 kOhm logarithm, the designer uses a potentiometer with a linear characteristic with a nominal value of 100 kOhm. The components are quite good, the non-polar WIMA capacitors and the presence of a socket for an op-amp are pleasing.
List of elements to replicate the preamplifier circuit on the NE5532:
Resistors 0.25W 5%:
R1, R2 – 47k – 2 pcs.
R3, R4 – 10k – 2 pcs.
R5, R6 – 22k – 2 pcs.
R7, R8 – 1k – 2 pcs.
Variable resistors:
P1 – 2 x 50k – dual potentiometer with logarithmic dependence (can be supplied with linear dependence) – 1 pc.
Capacitors:
C1, C2 – 1mF - film or electrolyte – 2 pcs.
C3, C4 – 47mF/25V – electrolyte – 2 pcs.
C5, C6 – 2200mF/25V – electrolyte – 2 pcs.
C7, C8 – 100mF/25V – electrolyte – 2 pcs.
C9, C10 – 100n - film or ceramics – 2 pcs.
Chips:
IC1 – NE5532 (Tl072, OPA2134, CA1458, OP275, LM6172, OPA627, AD826) – 1 pc.
IC2 – 7812 – (Positiv) integrated stabilizer 12 Volt – 1 pc.
IC3 – 7912 – (Negativ) integrated stabilizer 12 Volt – 1 pc.
Diodes:
B1 – 2W6 (2W01, 2W02, 2W04, 2W08, 2W10) – diode assembly 2A – 1 pc.
Rest:
3 Pin connectors (input, output, power supply) – 3 pcs.
The archive for downloading contains a diagram, sources, a board in LAY6 format, as well as datasheets for diode assemblies of the DB101...107 and 2W005...2W10 lines. File size – 1 Mb.
