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Sunday, November 25, 2012

Making of a 10Y line preamplifier


This post will show the assembly process of a 10Y line preamplifer in the classic 'landscape style' chassis. This preamp is meant to be used with the E55L LCR phono stage presented earlier this year. So the same wood, color and chassis design was chosen.

I call this design 'landscape style' to distinguish from my earlier preamp design which is placed with the short side at the front, for example the 801/26 preamp.

As always, the assembly process starts with the metal plates wich carry the whole circuit. The linestage plate:

The switches,  RCA and power supply connectors are aleady attached to the plate as well as the vibration damped sub assemblies with the tube sockets for the 10Y (801A can be used as well).

From below:

The plate of the external power supply:

The plates get mounted into assembly rigs for further construction. The capacitors are mounted. They are clamped onto the plate with aluminum profiles. Inputs are already wired to the selector switch:

In the PSU the sockets of the rectifier bridge of 4 6AX4 TV dampers is wired up and teh caps are mounted with the same technique as in the preamp. Also the power amp is attached to the top side, placed on some rubber damping elements:

Chokes (2 for high voltage and 2 for the filaments), line output transformer and Slage transformer volume controls are mounted on a second level below the metal plate:
In the PSU, filament transformers, filament rectifiers and another 4 chokes mounted on the second tier:
The finished preamp with power supply.

Another view:

4 Inputs and 2 paralleled outputs:
The PSU uses 4 6AX4 TV Dampers in bridge rectifier confoguration (Gratz bridge).
The 6DQ4 can be used as well.

The preamp can operate with all these tube variants: 10, UX210, 10Y, VT25, VT25A, 801, 801A, VT62 and 1602.
Best regards



  1. Hallo Thomas,
    It looks like each 10Y has it's own filament supply. Could you be so kind as to elaborate on the reason for this?


  2. Hi Daniel,

    the tubes are cathode biased. Sharing the filament supplies would mean the tubes cannot settle for their own ideal op points any more. I always keep filaments of directly heated triodes separate. Even with fixed or filament bias

    Best regards


  3. Thomas, What type of power supply connector are you using? I am referring to the multi-pin socket that will be connected to the umbilical from the power supply. I have been looking for something similar for my phono preamp.

    Best regards.


  4. Hi David,

    these are Amphenol military grade connectors.

    Best regards