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LM-3875 Amplifier with ECC88 Tube Buffer

2016-05-05 07:16  
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Circuit diagram LM-3875 Amplifier with ECC88 Tube Buffer

Power Supply- toroidal transformer 230V/8*12V/180VA
- output amplifier rails 2*32V DC(2*24V), two bridges with two BYW95C diodes in parallel
- caps Samsung 470uF/100V, four per channel
- tube buffer rails 2*45V (half-wave voltage doubler of 1*36Vac), two BYW95C's, CLC network, 470uF Samsung +100mH+6800uF Panasonic
- tube heating 6V DC, 4xBYW26c, 2* 1000uF Nichicon, stabilized with 7806, 1*1000uF Nichicon .

Input- standard gold plated cinches, Alps selector 2*1in3, Preh pot 2*10klog .

Tube Buffer- tube E88CC (NOS Tesla CH), or ECC88 (OS Siemens)
- standard metal-film resistors .

Output Amplifier- LM 3875 - inverted setup - gain ca 30dB
- input capacitor 2u2/250V ROE MKT, LPF 2*680pF ROE MKC, 2*47nF/160V ROE MKP
- standard metal-film resistors
- output DC offset about -5mV .

Power on Delay- relay 10A/30VDC on output .

Input Impedance10k .

Frequency Range10Hz-20kHz (-1dB, -2dB)/1W/8ohm/THD=0,1%/IMD2=0.075% .

Output Power36Vpp - 20W RMS (8ohm/both amps on/THD lower than 0.15% 100Hz-20kHz)
24Vpp - 18W RMS (4ohm/both amps on/THD lower than 0.25% 100Hz-20kHz) .

MORE...... http://www.moxtone.com/Tube-buffered Gainclone.htm

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