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- Adcom gfa 555 vs pcr 800 driver#
- Adcom gfa 555 vs pcr 800 manual#
- Adcom gfa 555 vs pcr 800 download#
Adcom gfa 555 vs pcr 800 download#
You can download them here (you have to register first): Service Manuals.
Adcom gfa 555 vs pcr 800 manual#
Note: All this information are drawn from Adcom GFA-555 MKII Manual and from Adcom GFA-555 MKII Service Manual. The output transistors have 0,22 ohm ballast resistors to ensure current sharing and bias stability. This configuration minimizes distortion caused by varying load impedances. The output stage consists of two sets of 4 parallel transistors operated as emitter followers, driven by another pair of emitter followers. R901 and C901 provide a load for the amplifier at high frequencies, stabilizing the amplifier under varying load conditions. Mid and high frequency bypassing is provided by C104. The bias network of R117 through R119 and Q307 form a temperature-compensated DC bias voltage to the input of the triple Darlington follower output stage.
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Any DC error at the amplifier output is servoed back through IC101 to adjust the DC current through the input transistor. Any DC imbalance in the amplifier is corrected by R125, R126, R127, C107, C110 and IC101. The amplifier has a DC coupled global negative feedback and this requires a DC error correction provided by IC101. C106 provides a high frequency roll-off above 200kHz, improving stability by taking high frequency feedback before the triple Darlington. Open-loop gain is defined by R112 and R113, with R201, R301, C105, C201, and C301 providing high frequency compensation.įeedback is provided from the output to the base of Q102 by the network R123, R124 and C106. The next voltage gain stage consists of Q107 with Q108 as a current-source load. The small -signal gain is approximately 825/(2x25)=16. Open-loop gain is defined by R105 ancd the bias current through Q101 and Q102. The small signal transistors Q101 and Q102 form the differential input stage. The input signal are AC coupled by C101 and filtered through network C102 and R103. This high voltage signal drives the high current triple Darlighton follower output stage which amplifies the current by a factor of about 50000. This amplifier employs a discrete differential Class-A front-end followed by a Class-A voltage gain stage (VAS) which amplify the input signal to the voltage required at the output of the amplifier. Though the Adcom GFA-555MKII is globally well projected amplifier, it has some flaws. power supply with 1500VA toroidal transformer and 60000uF of filter capacitance.