Hifi fully balanced tube preamplifier PCB blank board 6922x4, no electronic parts
LS69 true fully balanced design with 4 6922 tubes
Why use XLR balanced transmission?
The audio signal interface has a balanced and unbalanced connection. The so-called balance and imbalance are relative to the "ground" potential. If both ends of a signal are greater than the "ground" potential at one end, the other end. It is less than a certain value of the "ground" potential. In this case, we call it equilibrium; if both ends of a signal always have one end equal to the "ground" potential at a certain moment, this situation is called imbalance.
The advantage of balanced transmission is that the amplitude-frequency characteristics are good and the anti-interference ability is strong, so it is often selected by professional equipment. When unbalanced transmission is used, since the ground line is used to transmit both the audio signal and the shielding function, the anti-electromagnetic interference capability of the unbalanced connection method is poor, and it is easy to introduce noise such as periodic power supply interference.
The two transmission methods of forming balance and imbalance are determined by the circuit of the device. We know that amplifier circuits, whether they are tube circuits, transistor circuits or integrated operational amplifiers, are unbalanced. In other words, these circuits are all "ground", that is, the input and output are single-ended, and "ground" "There is their common end, the input end and the "ground" form an input loop, and the output end also forms an output loop with "ground". Therefore, it is the easiest and most economical solution to take the input and output of the circuit directly out of the chassis. This is the key to the unbalanced transmission of most home appliances and consumer electronics.
There used to be a saying that the transmission distance of civilian audio equipment is short. The use of XLR balanced transmission is not only costly, but also does not make much sense, but in fact high-end civilian audio equipment is often equipped with XLR balanced interface, the actual sense of hearing, XLR Balanced connection is quieter and more energetic than RCA's unbalanced connection background. This is because, in addition to the balanced transmission mechanism, the common impedance can be effectively suppressed. Good impedance matching between the front and rear stages can maximize the amplification equipment. The energy, such as the use of unbalanced connection, the signal amplitude at the output will be reduced by half, the signal level will be reduced by 6dB, and the transient response and distortion of the audio signal will also be reduced.
Motherboard size: 230mm × 150mm
The parts on the picture are only for display, The actual shipment is an empty board. You need to purchase additional parts yourself to install. All you buy is an empty printed circuit board, you must pay attention!
As different computer display the colors differently,and the color maybe is little difference from the actual items,but we can guarantee the style is same,but maybe some not same performance on different bodies as on the models.Hope you can understand it.thank you！
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