The Bayer A1 amp is a very classic amp. The circuit features benefit from the 2-stage inverting input voltage gain stage.The voltage at the two input terminals of the inverting amplifier circuit is always 0 and does not change with the input signal. The transistor at the input of the amplifier（Field effect tube）The input voltage is constant, and the bias state always maintains the operating point. . It''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''s worth making. Very low noise, very good separation
The kits need to be welded by themselves, you can choose to buy a finished board
Design features of this kit:
1Two-stage inverting input voltage gain stage, the two input voltages of the inverting amplifier circuit are always 0, and do not change with the input signal, the transistor at the input of the amplifier（Field effect tube）Constant input voltage, low distortion
2The core part adopts imported VIS non-inductive resistance, the line transmission distance is low, the tone is transparent, and the all-aluminum alloy shielded shell is equipped, not only the noise is low, but the background is greatly improved.
3The main filter capacitor is compatible with 18-30MM diameter main capacitors, and is no longer limited to ordinary small-sized ELNA RA3 blue robe series capacitors. It has better production flexibility and is equipped with British NOVER main filter with very good sound quality by default
4The output uses the Fairchild BD-139/140-16 driver tube purchased directly by RS, which is low in built-in, and has better sound quality than ordinary ST BD139 tubes.
5The potentiometer is compatible with ALPS27 and ALPS16 potentiometers, which can be upgraded flexibly. The headphone socket adopts the original genuine Swiss Neutrik 6.35 gold-plated headphone socket
6Perfect UPC1237 plus Omron relay protection circuit, safe and reliable work
7Coupling, decoupling, and high-frequency compensation all adopt high-quality accessories such as precision color ring capacitors imported from WIMA ERO from Germany to ensure the excellent performance of the line.
If you need a complete set of materials, you can take a picture of 1 kit 1 transformer 1 chassis kit（Contains 2 US CMC terminals）, Because the transformer is a variety of options, the chassis bottom plate has no pre-opened mounting holes.
PCB size:98mm X125mm
* This circuit does not need to be debugged, as long as the components are not installed wrongly, it can work normally, and there are clear icons on the board.
*There is 1237 on the front of upc1237, and the left one is 1 pin, and the actual installation is on the outside of the PCB.
3. MC33078 op amp（The original Beyer machine is equipped with this op amp. We replaced it with another advanced op amp and found that the sound is not as good as MC33078, so there is generally no need to upgrade）
4. The volume potentiometer can be selected from 50K and 100K
5. The transformer voltage can be double 14-double 22
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This kit has been carefully crafted by you, combined with high-quality power transformers and more standard front and rear equipment, and the sound performance is good. This is the reason why many fans continue to pursue the production. After all, the original machine is more than 6,000 licensed.
Better indicators than the original machine, good separation
Fully gold-plated IC socket, compatible with all dual op amps, flexible upgrade
To achieve excellent results, the general ST BD139 140 is not enough for the output tube. It will be refreshing to use the BD139 series tube with -16 post sequence as the input.
RS Europe time electronic brand new original genuine goods, 1.5A/80V
（Or use the professional output tube of Little Hedgehog, which is also full of music）
Protected useOriginal OmronSignal relay, The contact resistance is small! The loss of audio signal is small.
