Balanced to Unbalanced XLR to RCA Single Ended OP-AMP Preamplifier Board CD Play
Description:
 
Balanced XLR to single-ended RCA output dual op amp line finished board small size: the line by the famous British amplifier designer Douglas Self design, line design unique, making the circuit with ultra-low distortion of the excellent performance, noise is very low.
 
Circuit principle:
 
The distortion and noise of this line is much lower than the average circuit, so the circuit looks less simple and slightly complicated, the purpose is low distortion and low noise. In general, the balance signal should be converted to unbalanced (single-ended) output signal, you can use 1/2 of the NE5532 plus 4x10K resistance, according to the schematic diagram IC2A can be achieved. At this point in the figure R5 ~ R8 are taken 10K, a pair of balanced signals from the left side of the R5 R6 input, from the right end of R9 can be single-ended output signal. This differential amplifier circuit is fairly simple. Output noise is also low, roughly up to -104dBu (0dBu = 775mV), but still feel the noise is large, for this purpose using the so-called double balance level, that is, by the IC2A, IC2B composed of two differential amplification stage, they were simultaneously received The balanced input signal is then added so that the irrelevant noise is partially offset, resulting in a 3 dB reduction in noise while also improving the circuit common mode rejection ratio (CMRR).
 
Further improvements are also in the IC2A, IC2B before the increase of a voltage follower IC1A, IC1B. This is not only improve the input impedance, but also to IC2A, IC2B 8 resistance R5, R6, R7, R8, R13, R14, R15, R16 resistance from the original 10K down to 820ohm, greatly reducing the thermal noise resistance, Ultimately, the level of noise reduced by -112dBu, than the traditional single differential circuit to improve the 8dB as much.
 
Note: A board is a mono, and if you need to make a stereo, please buy two pcs.
 
Fine FR4 double-sided glass fiber board, gold-plated high-quality PCB board (65 × 27mm), arc alignment a little ground. Import high quality RC components assembly. Japan KOA 1 / 4W high-precision five-color ring metal film resistors, Nissan brand electrolysis, gold-plated IC socket (easy to upgrade), the United States NE5532 dual op amp 2pcs, connected to ± 5V ~ ± 15V stable voltage to work.
 
Working mode: This circuit board is used for CD player balance XLR signal output through the line to single-ended RCA output to the next level (pre-amp or amplifier).
 
Default with 2 ne5532 opamp, the circuit board can be replaced by a better op amp, such as AD826, AD827, OPA2134, OPA2604, OPA2111 and other high-end op amp, the effect of legislation stand.
 
Friendly reminder: the use of special attention to the power supply voltage should not exceed ± 18V, balanced XLR signal of the three lines can not be wrong.
 
Package Included:
1x Balanced XLR to Single Ended Unbalanced Board (assembled)
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