YuSynth Output Stage & Monitor

Introduction

A bare double sided PCB (no need for the wire jumper links shown on the PCB layout) for the Yusynth Output Stage & Monitor synth module. These PCBs are manufactured by Soundtronics with a percentage of the sale going to the creator of the YuSynth - Yves Usson. These are early days for the YuSynth Modular Synth at Soundtronics, our plan is to stock PCBs for all of the projects as well as components, kits and front panels. This is going to take time but will eventually be as comprehensive as our MFOS range.

No components are included with the PCB but check out our Synth Components section where you should find what you need. We do suggest visiting the YuSynth Mixout VC Panner project page for detailed information on both this PCB and the accompanying VC-Panner including Yves panel layouts but a summary is shown below.

Erratum

The YuSynth parts list has incorrectly identified resistors R10, R24, R31, R32, R36, R37 as R15, R16, R20, R21, R26, R31. The PCB is correct

Thanks to dummyplugconspiracy on the Modwiggler forum for identifying a problem with the ground trace on U1.

The trace highlighted in red is missing from the YuSynth PCBs so simply replace the missind trace with a wire link as shown in green.

Description

The Mixout VC Panner module is the combination of two utility modules :

• the first utility is a quadruple VC-PANNER (and mixer, though not VC ) using our PCB 7220-041 which is available separately.
• the second utility is an output module providing master volume control, tonality control and old-school vu-meters as well as a monitoring output for headphones using this PCB 7220-044 described below.

The PCB can accept a choice of three types of power connector, it can be either a Synthesizers.com 6 pins MTA connector, a MOTM 4 pins MTA96 connector or a 10-pin Eurorack connector.

Circuit

The Mixout-VC Panner This sub module is based on very classical circuits that can be found in many electronics textbooks.
For one channel and from left to right :

• a classical baxandall tonality filter, with both cut & boost for treble and bass, it is build around two OPA (U1a,d)
• a line output buffer based on a classical buffer inverter (U3b)
• a level display, based on a single OPA amplifier and a rectifier bridge (D5,D6,R28,R29) and an oldschool analogue panel vu-meter connected betwen the diodes,
• and a headphone amplifier stage (based on the Yamaha CS15 circuit) using a single OPA combined with a complementary pair of transistors providing enough current to drive a HiFi stereo headset.

Click on the schematic thumbnail above for the circuit diagram.

Wiring

The wiring schematic image in the above thumbnails show the panel wiring to the pots and sockets etc.

Setting and Trimming

Output monitor
Set all channels to zero except channel 1, set the TREBLE and BASS pots to 12 o'clock.
Then send a SINEWAVE wave (1kHz) with an amplitude of 10Vpp (-5V/+5V) on the input of  channel1.

• Set the PAN LEVEL pot to 0, and the PAN pot to 12 o'clock.
• Set the level pot of channel 1 to 10
• Set the Master Level pot to 7 (you may use another tick mark if you wish)
• Adjust the trimmers T1 and T2 such that the Vu-meters reaches the -12dB mark (this way when sending the maximum signal level on all the four channels at the same time you get 0dB on the Vu-meters

Parts List

The parts list below is direct from the YuSynth website. The value in the parts list is the default value and may differ to that quoted in the schematic / PCB silk image.

The parts list excludes knobs although we have standardised on the Cliff KM20B but it does include 1/4" jack sockets. All parts are available individually (use the part number in the search box above) or as a components kit that excludes sockets and knobs.