Table of Contents

Specifications

1 – Power Supply Wiring

Muting

2 – Output Connector Wiring

Stereo Single Ended Connection

Stereo Balanced Connection

3 – Input Wiring and Module Configuration

3.01 / 3.02 – Settings and Input wiring for current output DAC, stereo, single ended, 0V reference voltage, 1mA / 2mA full scale current

3.03 / 3.04 – Settings and Input wiring for current output DAC, dual mono, single ended, 0V reference voltage, 1mA / 2mA full scale current

3.05 / 3.06 – Settings and Input wiring for current output DAC, balanced mono DAC’s, balanced output, 0V reference voltage, 1mA / 2mA full scale current

3.07 – Settings and Input wiring for current output DAC, stereo, single ended, 1mA full scale current, ~2.5V reference voltage

3.08 – Settings and Input wiring for current output DAC, balanced Stereo DAC’s, balanced output, 1mA full scale current, 2.5V reference voltage

3.09 / 3.10 – Settings and Input wiring for current output DAC, balanced Stereo DAC’s, balanced output, 4mA full scale current, 2.5V / 0V reference voltage

3.11 / 3.12 – Settings and Input wiring for voltage output DAC, stereo, single ended, 1…1.5 VRMS full scale output voltage, 0V / 2.5 Vreference voltage

3.13 – Settings and Input wiring for voltage output DAC, stereo, balanced output, 2…3 VRMS full scale output voltage, 2.5V reference voltage

3.14 – Settings and Input wiring for single ended stereo output from voltage output DAC, stereo, balanced output, 2..3 VRMS full scale output voltage, 2.5V reference voltage

4 – Other applications of the Universal Tube Output Stage

Settings and Input wiring for use as SE Linestage 6db Gain

Settings and Input wiring for use as SE Linestage 12db Gain

Settings and Input wiring for use as Balanced Linestage 6db Gain

Settings and Input wiring for use as Balanced Linestage 12db Gain

Settings and Input wiring for use as simple single ended stereo RIAA equalisation preamplifier

Alternate 12db Gain Stage in Shunt mode

Pro-Audio Project

Introduction and Overview

The Universal Tube Output Stage has been designed to offer a State of the Art tube amplification stage, mainly intended to be applied to CD-Players, DVD-Players and DA-Convertors to completely replace the original solid state analouge circuit

Additional applications include the use as Line Preamplifier with 6dB or 12dB gain.

The module can also be used as low noise, high gain (gain appx. 30db) amplification block for low level applications such as RIAA pre-amplification stages and as microphone or instrument amplifier.

Using one module we have either a stereo single-ended input and output (two independent channels) or a mono balanced input and output (single balanced channel). If a stereo balanced input and output are required two modules must be used.

Each configuration can be used either as single ended in/out stereo for one PCB or as balanced in/out per PCB.

If using a balanced output DAC with a single ended input Tube output an additional resistor or resistor/capacitor needs to be added externally to the tube PCB.

All DAC types listed below names the most commonly encountered types, but is by no means exhaustive.
Some examples:

1) Analog stage for current output DAC – 2V out for 0dbfs with 1mA or 2mA full scale current, can be configured for DAC’s having their output referenced to either ground (TDA1541, PCM56/63/1702/1704, AD1856/1862/1865) or an arbitrary reference voltage of 2 – 3V (TDA1543/1545, PCM1738,AD1853 and many others) , < 100R output impedance.

2)Analog stage for voltage output DAC – 2V out for 0dbfs with 1V or 0.5V full scale voltage, can be configured for DAC’s having their output referenced to either ground (CS4328) or an arbitrary reference voltage of 2 – 3V (CS4329/9X; PCM1716/1728/1732/1741; AKM4393/4394/4395; AD1852/1854/1855; NPC SM5872/5865/5866 et al) , < 100R output impedance.

3)General high level gainstage – 6db gain, inverting output, >400KOhm input Impedance, < 100R output impedance

4)General high level gainstage – 12db gain, inverting output, >200KOhm input Impedance, < 100R output impedance

5)General low level gainstage (Microphone, Phono, Tapehead etc.) with around 30db gain and > 40KOhm input impedance, < 100R output impedance

Some possible applications past the use as line stage (obvious) or DAC output stage
(equally obvious):

Single Ended MM Phono Stage – 2 Modules, add a RIAA EQ of 10K or higher impedance at low frequencies (calculator @ http://kabusa.com/riaa.htm) or 10K RLC EQ… (add pre-pre or MC stepup TX for MC)
Balanced MM Phono Stage – 4 Modules, add a balanced RIAA EQ of 10K or higher impedance at low frequencies (calculator @ http://kabusa.com/riaa.htm) or 10K RLC EQ… (add pre-pre or MC stepup TX for MC)

Single Ended Tape Head Stage – 2 Modules, add a NAB etc. EQ of 10K or higher impedance at low frequencies (calculator @ http://kabusa.com/riaa.htm) or 10K RLC EQ…

Balanced Tape Head Stage – 4 Modules, add a balanced NABetc. EQ of 10K or higher impedance at low frequencies (calculator @ http://kabusa.com/riaa.htm) or 10K RLC EQ…

Classic high gain 1-Channel transformer coupled Microphone Preamplifier using 1:4/5 input transformer and 5/4:1 transformer balanced output with level control between stages – 1 Modules – maximum gain ~60db.

Classic high gain 2-Channel transformer coupled Microphone Preamplifier using 1:4/5 input transformer and 5/4:1 transformer balanced output with level control between stages – 2 Modules – maximum gain ~60db.

Classic low gain 2-Channel transformer coupled Microphone Preamplifier using 1:4/5 input transformer and transformerless balanced output (10K load) – 2 Modules – maximum gain ~40db.

Classic high gain 2-Channel transformer coupled Microphone Preamplifier using 1:4/5 input transformer and transformerless balanced output (10K load) with level control between stages – 4 Modules – maximum gain ~72…75db.

Input and Summing Amplifier in a classic tube mixer, for example, a 6 – 2 mixer could be build using 6 Microphone transformers(plus instrument input jacks), 3 tube stage modules for inputs, suitable volume and pan control faders/potentiometers per chnnel and one tube output module with 4/5:1 stepdown output transformers fo balanced output… Maximum gain in to out using 1:4/4:1 transformers is around 60db.

For ease of application all connections on the Universal Tube Output Stage are provided as screw terminals and all configurations are handled by gold-plated jumpers, so no soldering is required on the actual Universal Tube Output Stage Module.

For those desiring soldered connections instead we recommend to either unsolder the screw terminals and solder the wires in the holes thus available or to simply solder the wires to the solder pads below the PCB.

Equally, for those wishing a soldered configuration instead of jumpers simple solder bridges can be soldered across the jumper pins below the PCB.

In the following Manual the application of the Universal Tube Output Stage is broken down into three distinct sections.

Section one covers the connections of the included power supply transformer while section two covers the connections of the output sockets to the module.

Section three covers the different arrangements of the Input connections and the jumper configuration to suit the various available DAC Chips and the other applications.