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Push-pull driver with ECC82 and E88CC

The push-pull driver in RV100Spezial

This blog describes the installation of the Start Blog Gegentakttriebers described in the tube amplifier ELV RV-100. Please have the circuit diagrams invites you to RV 100, ELV server download as pdf.
http://www.elv-downloads.de/service/manuals/RV100/RV100_KM_G_011107.pdf

reason for the modification: RV100
When the bias on the 220KΩ resistors R117 and R120 is supplied. The reduction of bias by the output tube grid current and the related rocking up to the congestion avoided by the new driver circuit.

Other benefits:
is also ensured by the Gleichtaktverkopplung that despite the power tubes are not electrically coupled Katodenfolger driven to grid electricity. This avoids, in contrast to conventional Katodenfolgertreibern the congestion of the output valves and present, as one defined by the grid current use and age-independent modulation limit without grid rectification for the power tubes firmly.

free power source:
get the same phase rotation stage that the RV100 is designed as LTP, a high quality power source to replace the Long Tail resistor R115. The Long Tailed Pair required under asymmetric activation unequal load resistors for an exactly symmetrical output signal. The necessary by the Long Tail resistor R115, the tube state-dependent adjustment of the phase rotation stage of R109 can be eliminated by the current source. The phase rotation stage is enhanced so from Long Tailed Pair to full-differential amplifier .

modifications in the power supply:
For the negative supply voltage C121 replaced by a series connection of two 100uF capacitors. Your connection point is set to an AC power connection which causes a voltage doubler. Greinacher doubler After additional filter element from 1KΩ 100uF on the amplifier circuit board is obtained about-135VDC to Katodenfolgern differential amplifier formed from the E88CC. R133 is now designed in accordance with 82KΩ impedance. Is important to me that is negative and not positive when exposed to an adjustable resistor bias. This will be a 100ppm resistance between the wiper of R134 and the junction of C122 and R133 down and changed the wiring of amplifiers symmetry adjuster R122 on the amplifier PCB.
The two resistors R132 and R136 15KΩ be replaced by a 10W resistor 33KΩ, which is off the circuit board attached. The circuits and
Si102 is replaced by a correspondingly revised soldered fuse wire or soldered motor vehicle safety. picture of the power supply

changes to the Main Board:
few holes to hold the additional components and tube sockets for the E88CC be drilled and the two holes in the steel sheet also be cracked. The layout itself remains intact it can be used for the new circuit. So you can remove, for example, R114 and R110, R109 work for a 470KΩ resistor and put a link to the node R113R116R115, etc.. The vibration protection resistors R121 and R123 contact directly to the text the EL34 solder 1KΩ enough. Is important to me, the resistors R124 and R125 to get rid of. They cause an undesirable current feedback. To illustrate this, 10Ω in the cathode correspond approximately 730Ω in the screen grid supply.
Rough estimate for rg2 μg2Rk = x B = 11 x 10Ω x 100mA / 15mA = 730Ω
For the load resistors of the differential amplifier pair from you spar. At the two 470KΩ resistors to GND, point X, a protection circuit be similar to the previous blog described clamped. Since the output tubes are in the old circuit several times managed in addition to the supply line U1 + to the transformer inserted F315mA trigger control, I have not made the protection circuit.

balance quiescent current:
ST 104 and ST 105 on the transformer short-circuit with alligator clip. R134 for the highest negative bias adjust and get R122 during the first synchronization to center. Load resistance and Prüflautsprecher celling. Pegelvoreinsteller turn. With R134 set the voltage drop between U1 and + clip on 2VDC.
balance symmetry power amplifier:
short with a short clip of the anodes of the ECC82. For example, at the capacitors C107 and C108, see image. Brumm (100Hz!) turn away, while the Prüflautsprecher to the Ear.
When adjusting the safety course on handling high voltages. ;-) Carry out several times and after several days of operation.