1. Manuals
  2. Brands
  3. Paradise Datacom Manuals
  4. Recording Equipment
  5. Calvin Buffer
  6. Quick start manual

Paradise Datacom Calvin Buffer Quick Start Manual

Hide thumbs
1
2
3
4

Advertisement

Table of Contents

Calvin Buffer for Paradise phono stage
Many thanks to „Calvin" a.k.a. Christoph for letting us use his clever buffer design.
This is the assembly instructions for the Calvin Buffer, a add-on for the Paradise phono
stage. But it can also be used as a standalone buffer. The schematic is shown below:
The JFET Q1 is cascaded with Q2, and its current flows through the base of Q3. R5 and
R6 are used to adjust the idle current. R1 and R2 serve as the load resistance for Q1, and
will provide a scaled-down version of the input voltage. The lower half of the buffer is
identical to the upper half, except the trimpot that is used to adjust the idle current in the
lower half, to allow setting the voltage offset to zero. And, the capacitor C3 will connect the
scaled-down input voltage to the lower buffer circuit, to help with distortion cancellation.
Not shown in the schematic is an inductor of approx. 10μH that is connected in parallel
with R14.
The supply voltage is +/-18V, and the supply current is 30mA. The bandwidth is about
10MHz -3dB, and C1 and C2 can be used to adjust the square wave response for no
overshoot.
The following picture shows the stuffing of the PCB. It is 120mm wide and fits exactly on
top of the Paradise phono stage PCB. To the left and the right, the heatsinks with Q3 and
Q6 are located. In the middle of the PCB, the output resistor R14 and inductor are located.
The left half contains the upper buffer circuit, the right half contains the lower buffer circuit.
Below are the „IN" and „GND" terminals, that can be connected with small wires to the
„RIAA EXT" connector on the Paradise PCB. Above are the „+18" and „-18" connectors as

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the Calvin Buffer and is the answer not in the manual?

Questions and answers

Summary of Contents for Paradise Datacom Calvin Buffer

  • Page 1 Many thanks to „Calvin“ a.k.a. Christoph for letting us use his clever buffer design. This is the assembly instructions for the Calvin Buffer, a add-on for the Paradise phono stage. But it can also be used as a standalone buffer. The schematic is shown below: The JFET Q1 is cascaded with Q2, and its current flows through the base of Q3.
  • Page 2 well as „OUT“ that can be connected easily to the Paradise PCB as well. Bill of material 2SA1381 PNP power transistor PF5102 n-JFET, IDSS=6mA, VTH = -1V J107 n-JFET, IDSS=100mA, VTH=-3V 2.2Ohm Resistor 0.5W 22Ohm Resistor 0.5W 51Ohm Resistor 0.5W 100Ohm Resistor 0.5W 100kOhm...
  • Page 3 connections only afterwards. The inductor is a 10cm piece of wire, make 10 turns around a small screwdriver or similar, and take care that the windings are not touching each other. Simply solder this on top of the output resistor. Mounting onto the Paradise PCB First, remove Q99 and Q91 from the original buffer.
  • Page 4 What can go wrong: Constant offset of 60mV, no adjustment possible – the power bipolars are inserted the wrong way Shunt regulator LEDs do not light up – check for short circuits on the buffer or the connection Wandering offset, thermally very sensible – check the input ground connection (both „RIAA EXT“...

Table of Contents