Balanced XLR to Single-ended RCA Output Circuit Board with Excellent Performance of Ultra-low Distortion LG139C
Type 1: LG139C empty board
Type 2: LG139C finished board without 4 NE5532
Type 3: LG139C finished board with 4 NE5532
LG139C BalanceXLR Turn to single endRCAOutput two-way Board：The line is made by the famous British amplifier designer.Douglas SelfDesign，Unique circuit design，Make the line machineExcellent performance with ultra-low distortion，The noise is also very low。
\\
\\
Circuit principleOnlyPaintingOutOneASoundTao：
\\
\\
The distortion and noise of this circuit are much lower than that of ordinary circuits.，Therefore, the circuit looks less simple and more complicated.，The purpose is low distortion and low noise.。Generally speaking，To convert the balance signal into imbalance（Single End）Output signal，Can be used1/2OfNE5532Plus4Only10KResistance，According to the figureIC2AThe connection method can be realized。At this time, the pictureR5~R8Take All10K，A pair of balance signals are fromR5、R6Left end input，FromR9The right end of the can get a single-ended output signal。This differential amplifier circuit is quite simple。The output noise is also low.，Can be roughly achieved-104dBu（0dBu=775mV），However, I still feel loud noise.，For this reason, the so-called double balance stage is adopted.，That is,IC2A、IC2BForm two differential amplification stages，Receive balanced input signals at the same time and add them together，Irrelevant noise can be partially offset，Thereby obtaining3dBNoise reduction，At the same time, the common mode rejection ratio of the circuit is also improved.（CMRR）。
\\
\\
Further improvements are alsoIC2A、IC2BBefore adding a voltage followerIC1A、IC1B。This not only improves the input impedance，Also makeIC2A、IC2BOf8Resistance onlyR5、R6、R7、R8、R13、R14、R15、R16The resistance of from the original10KReduce820Europe，The thermal noise of the resistor is greatly reduced，Finally，The noise of this level is reduced-112dBu，Better than the above traditional single differential amplifier circuit8dBSo much。
\\
A board isTwoChannel stereo。
\\
ExquisiteFR4Double-sided glass fiber board，High qualityPCBBoard（80×78mm），Plate thickness2mm Arc routing point grounding。Imported high quality resistance and capacitance component assembly。JapanKOA 1/4WHigh precision five-color ring metal film resistor，Nissan famous brand electrolysis、Gold platingICSocket(Easy to upgrade)，US productionNE5532 Double operational amplifier4Only，Connect±5V～±15VStable voltage can work。
\\
Input balance signal，Output unbalanced signal，Suitable for sound source with balanced output，The rear equipment only has an unbalanced input sound system.。
\\
\\
\\
This circuit board can be replaced with a better operational amplifier.，Such AD826、AD827、OPA2134、OPA2604、OPA2111Such as high-end operational amplifier，Effect stand Rod shadow。You can also assemble different types of op amp according to customer needs.，The price is calculated separately.。
Friendly reminder：When using, pay special attention to the power supply voltage should not exceed±18V，BalanceXLRThe three lines of the signal cannot be connected incorrectly.。On the circuit boardNE5532The integrated block is a second-hand disassembly product.。Components on the board vary depending on the assembly batch.，Brands used in some capacitors、Model、Specifications and parameters will be slightly different，Components assembled on the received board、Parameters shall prevail！
\\
\\
\\
\\
The finished machine assembled with this board is as follows，Using a gold sealOPA2111Dingshi operational amplifier，Excellent effect，Good voice！
\\
