Today’s one is dedicated to pre-amplifier boards for homemade audio power amplifiers. A pre-amplifier is needed if the main amplifier has a low gain, and it adds to the ease of use of the main amplifier. There is an integrated tone block, input selector, remote control, etc.
Let’s take a look at several popular options for preamplifier boards (analog and digital) on the AliExpress platform from sellers with a large number of orders.
Opens a selection of a simple schematic and inexpensive option from AIYIMA. Preamplifier A1 is based on a pair of NE5532 op amps. Operational amplifiers are installed in «cribs», and, if necessary, can be easily replaced with their better ones.
Dimensions of the assembled board: 92x50x28 mm. Textolite 1.6 mm. Device power supply: 12-25 VAC mid-point. There is an indicator LED. Signal input and output and power supply are organized on screw terminals.
Next, a similar version of the pre-amplifier with an integrated variable resistor for volume control. Here, by the way, is the Alps “variable”, model 27. Or you can choose the option without a variable resistor.
The preamplifier is based on a single NE5532 op amp (replaceable) with a metal shield. Power circuit 12-18 VAC with midpoint.
The size of the board is small: 70×64 mm.
Another very budgetary version of the “pred” on one NE5532 op-amp, but only there is no volume control, but convenient 12-35 V DC power supply.
The NE5532 op amp can be replaced with any (higher quality) op amp in a DIP8 package. Wiring connections are organized on terminal blocks.
The board is compact (50×40 mm), easy to integrate into any audio project. There is an option for a pair of OS.
Digital version of the preamplifier with remote volume control by encoder from Sure Electronics. High-quality components, convenient connections on connectors of different types.
The gain and volume are controlled by the PGA2311 chip (THD+N: 0.0006%), adjustable from -95.5 to 10 dB in 1.5 dB steps.
Device power supply 8-15 V DC. 122 x 91.6 mm main board and 51 x 38.2 mm encoder board.
Another digital version on the PGA2311 chip. Here, the implementation from YJ includes an input selector (3 pcs.), A volume control on a push encoder, and a fairly large screen (128×64). It also comes with a mini remote control.
The preamplifier consists of three parts connected by loops: the main board with a relay input selector (102×55 mm), a board with a screen (75×46 mm) and an encoder for control.
The power supply of the device is variable with a midpoint of 6-10 V.
A similar block version of the pre-amplifier with a remote control. But this version from AIYIMA is built on the LC75342 chip from SANYO. Volume control -79 to +20 dB in 2 dB steps. And it also has a built-in tone block. Gain 30 dB.
This implementation has a small screen (1602) and a 4-input selector on RCA connectors. There is a settings memory.
Power supply of the device with alternating voltage 12-15 V with a midpoint.
A set from GZLOZONE with volume control on a high-quality NJW1194 chip (THD 0.0015%). Adjustment range: -80 +20 dB. As well as a timbre block of high and low frequencies of 10 dB. There is a choice in the lot: an assembly kit or ready-made boards. Comes with a small but stylish remote control.
The dimensions of the main board are only 68×68 mm. Four inputs are also connected there, there is a selector. Power supply 9-0-9 VAC. Control of two encoders, two-section display.
Rounding out the selection is a classic analog preamp with tone controls. The A8 model is based on three JRC5532 op amps (replaceable). The volume is regulated by a variable resistor ALPS27, there is even a toggle switch. In general, high-quality components are selected.
Tone control in three bands: LF-MF-HF.
Board dimensions 270×60 mm, power supply 12-18 VAC with midpoint.
I hope that the selection of preamplifier boards was useful and you will choose an option for your taste and budget.
Happy shopping! Don’t forget to apply AliExpress coupons and discounts.