AVT1023 Gramo Phone Preamplifier Instruction Manual
- June 9, 2024
- AVT
Table of Contents
AVT1023 Gramo Phone Preamplifier
Gramophone preamplifier with RIAA characteristics
Despite the explosive growth of digital audio technology, “black” vinyl
records remain an enduring favorite among fans. To listen to them, you need a
turntable with an MM cartridge (with a moving magnet) equipped with an
amplifier with RIAA characteristics.
Recommendations: kit recommended for all music fans using an analog turntable
as a signal source.
Characteristics
- two-channel stereo system
- gain: k = 38 dB (f = 1 kHz)
- input voltage: (maximum) 55 mV
- signal-to-noise ratio: > 78 dB
- non-linear distortion: < 0,08% (across the band)
- power supply: 12 V DC
- board dimensions: 41 × 53 mm
Circuit description
The kit uses a good-quality dual operational amplifier of the TDA2320A type. The features of this circuit include a low-noise input stage that introduces minimal linear and nonlinear distortion, full frequency compensation (optimized for audio applications), nearly 100 dB of channel separation, and high open-loop gain. Due to the relatively low value of the SR parameter (the rate of rise of the output voltage), the circuit is designed for operation with signals with small amplitudes. RC elements in the negative feedback loop (the same for both channels) cause the amplifier’s frequency response to be established in accordance with the RIAA standard.
Assembly and start-up
The assembly should be carried out in accordance with standard considerations. In case of problems with circuit excitation or “collecting” interference from the environment (e.g., mains hum), the device should be enclosed in a shielding box or the circuit board be encased with appropriately cut pieces of sheet metal.
The layout of the components is shown in Fig. 2. The supply voltage should be
well filtered and stabilized.
The input and output wires should be shielded, paying attention to the very
accurate addition of the shield to the circuit ground.
List of elements
Resistors:
- R1, R8:……………..1 kΩ (brown-black-red-gold)
- R2, R9: …………….220 kΩ (red-red-yellow-gold)
- R3, R10: …………..22 kΩ (red-red-orange-gold)
- R4, R11: …………..820 Ω (gray-red-brown-gold)
- R5, R12: …………..18 kΩ (brown-gray-orange-gold)
- R6, R13: …………..100 kΩ (brown-black-yellow-gold)
- R7, R14: …………..120 kΩ (brown-red-yellow-gold)
Capacitors:
- C2, C9: …………….82 pF (may be labeled 82)
- C3, C10: …………..15 nF (may be labeled 153)
- C4, C11: ………….3,3 nF (may be labeled 332)
- C17: …………………100 nF (may be labeled 104)
- C1, C8:……………..4,7 µF ! (may be labeled 475)
- C5, C12: …………..10 µF !
- C6, C13: …………..1 µF !
- C7, C14: …………..47 µF !
- C15, C16:…………100 µF !
Semiconductors:
- D1:……………………1N5819 or similar !
- US1: …………………TDA2320A !
Other:
- IN1, IN2:………….goldpin 1×2 pins
- OUT1, OUT2:…..goldpin 1×2 pins
- POW: ……………….goldpin 1×2 pins
The assembly should be started with soldering the components onto the board in
order of size, from smallest to the largest.
When installing components marked with an exclamation mark, pay attention to
their polarity.
You may find it helpful to have a wireframe with drawings of the leads and
symbols of these components on the board printed and photographs of the
assembled set.
To access high-resolution images as links, download the PDF. Download PDF.
AVT SPV Sp. z o.o.
Leszczynowa 11 Street, 03-197 Warsaw, Poland kity@avt.pl
This symbol means do not dispose of your product with your other household waste. Instead, you should protect human health and the environment by handing over your waste equipment to a designated collection point for the recycling of waste electrical and electronic equipment.
AVT SPV reserves the right to make changes without prior notice.
Assembly and connection of the device not in accordance with the indications
within the instructions, arbitrary change of components and any structural
modifications may cause damage to the device and expose users to harm. In such
a case, the manufacturer and its authorized representatives shall not be
liable for any damages arising directly or indirectly from the use or
malfunction of the product.
DIY kits are intended for educational and demonstration purposes only.
They are not intended for use in commercial applications. If they are used in
such applications, the buyer assumes all responsibility for ensuring
compliance with all regulations.
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