R-55 thyratron VCO user`s manual
Contents
1. IMETASONIX R 55 thyratron VCO user s manual Copyright 2012 Metasonix All rights reserved READ THIS DAMMIT LLL 1L1 RETAIN INSTRUCTIONS The safety and operating instructions should be retained for future reference HEED WARNINGS All warnings on the R 55 and in the operating instructions should be adhered to FOLLOW INSTRUCTIONS All operating instructions should be followed WATER AND MOISTURE The R 55 should not be used near water e g near a bathtub washbowIl kitchen sink laundry tub in a wet basement near a swimming pool etc Care should be taken so that liquids are not spilled onto or near the enclosure VENTILATION AND COOLING The R 55 normally operates warm to the touch It MUST be situated so that its location or position does not interfere with convective cooling The R 55 MUST NOT be used ona bed sofa rug or similar surface which may prevent proper cooling It is NOT a toy If the R 55 is mounted in a synthesizer rack or other built in installation space must be left around it to allow convection cooling HEAT The R 55 MUST be situated away from heat sources such as radiators heat registers stoves or other devices including power amps that produce heat POWER SOURCE The R 55 should be connected to a power supply ONLY of the type described in the operating manual or as marked on the R 55 WARNING Each R 55 requires 5 volts at 2 amps maximum as well as 12v at 50 mA and 12v at 20 mA The cabinet power2. supply must be able to deliver this current 5v adapters made as add ons for Euro cabinets such as the ones made by Doepfertm and Kilpatrick cannot deliver enough current to run an R 55 WARNING there is 95 volts DC present in an R 55 when powered up It is a low current supply and unlikely to cause injury but might startle the unprepared or clumsy WARNING The thyratron tube on the left gets very hot in normal operation and should not be touched after 10 minutes with power applied CLEANING The R 55 should only be cleaned with a soft cloth moistened with water Unplug the power supply before attempting to clean NON USE PERIODS The R 55 should be shut off when left unused for a long period of time DAMAGE OR TUBE REPLACEMENT REQUIRING SERVICE The R 55 should be serviced by qualified service personnel when The power supply has been damaged The R 55 has been dropped physically damaged or subjected to force Liquid has been spilled onto the R 55 or it has been exposed to rain The R 55 does not appear to operate normally or exhibits a marked change in performance SERVICING The user should not attempt to service the R 55 All servicing should be referred to qualified service personnel METASONIX LIMITED WARRANTY and standard legal disclaimer Thank you for purchasing this Metasonix product The following terms and conditions apply 1 Warranty period is for ONE YEAR from date of purchase with proof of purchase submi
3. V inputs You MUST plug in a CV control of zero volts DC or more to make the R 55 produce sound DO NOT assume it is broken because it produces no sound when first powered up By applying an audio signal from a conventional VCO to either PITCH CV INPUT the R 55 may be forced to track the pitch of that VCO A square or pulse waveform is preferred The PITCH CV INPUTS control the module s frequency with a control range of approximately 0 4 volts with the TUNING OFFSET control offsetting in parallel As usual with thyratron VCOs of this type the total pitch range is dependent on individual tubes and typically spans something over 2 octaves AS set at the factory and with MASTER TUNING centered the R 55 gives its first octave 66 to 132 Hz with CV varying from 0 0 volts to 0 25 volts and the next octave from 0 25 volts to 0 75 volts As usual with thyratron VCOs it is not perfectly Hz V linear and the top of the range will typically be slightly flat in pitch This is a natural consequence of the thyratron VCO All CV inputs have 100k ohm impedance The audio output is able to drive a 600 ohm load The CV inputs are limited to 10v range except the VCA CV input which can accept up to 80 volts USAGE For typical use as a sawtooth VCO adjust the R 55 controls approximately as shown MASTER OCTAVE OVERDRIVE OUTPUT TUNING LEVEL LEVEL MAX dB Max dB B o SK 10 Note that the R 55 controls have considerable extra rang
4. e beyond what they absolutely need This is made necessary by variations in tube samples and to allow for tube aging Do not assume these settings are written in stone and if a different setting gives optimum results for your R 55 this is normal Because the R 55 is likely to be totally different from any other synthesizer module you have ever used you may be surprised by some of its quirks as needed Increasing OVERDRIVE LEVEL will start to clip the sawtooth wave Maximum level will give a passable square wave The VCA CV INPUT may be used to control the output level of the R 55 as with a standard VCA Note that the R 55 will produce maximum gain with nothing plugged into this input The CV used on this input will completely cut off the R 55 signal when 4 volts is applied and a moderate signal output with 0 0 volts So if full control over the gain is needed as with an envelope generator a negative offset will have to be added to the EG s output This may be done with a module such as the Malekkorm 8NU8R or Doepfer A183 2 ADJUSTMENT As said above the R 55 is adjusted at the factory so the first octave occurs with CV from 0 0v to 0 25v and the second octave from 0 25v to 0 75v This is similar to what the Kentonm MIDI CV interfaces produce when set to Hz V output The R 55 may be readjusted for other interfaces via the OFFSET and SPAN trimpots in the open hole on the front panel Note that the R 55 WILL NOT track with conventiona
5. explanatory note IMPORTANT To save yourself unnecessary cost and inconvenience please check carefully that you have fully read and followed the instructions in this instruction manual This warranty is in lieu of all other expressed warranties obligations or liabilities ANY IMPLIED WARRANTIES OBLIGATIONS OR LIABILITIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FORA PARTICULAR PURPOSE SHALL BE LIMITED IN DURATION TO THE DURATION OF THIS WRITTEN LIMITED WARRANTY Some states do not allow limitations on how long an implied warranty lasts so the above limitations may not apply to you INNO EVENT SHALL WE BE LIABLE FOR ANY SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES FOR BREACH OF THIS OR ANY OTHER WARRANTY EXPRESS OR IMPLIED WHATSOEVER Some states do not allow the exclusion or limitation of special incidental or consequential damages so the above limitation may not apply to you This warranty gives you specific legal rights and you may also have other rights which vary from state to state METASONIX shall not be held liable for any incidental consequential or direct damages or expenses associated with the use or misuse of its products The audio output of this product is capable of damaging some types of solid state audio equipment such use is entirely at the risk of the user METASONIX does not guarantee that any of its products are designed for any particular use or purpose The entire risk of s
6. l solid state VCOs using V octave CV The adjustment procedure is similar to that used on the S 1000 Wretch Machine and requires a suitable tuning tool a chromatic tuner or frequency counter and some patience Note The Metasonix R 60 MIDI CV may be used although its auto tuning cycle might not work properly with the R 55 s bizarre signal Connect the AUDIO OUTPUT of the VCO to be aligned to a chromatic tuner or other method of determining equal tempered pitch Adjust OUTPUT LEVEL so the tuner is showing a stable reading Set MASTER TUNING to centerpoint 1 Press and hold a low C usually MIDI note 36 use the controller s octave selector to obtain the correct range Adjust the OFFSET trimpot on the R 55 until the low C is obtained 2 Press the C one octave ABOVE Adjust SPAN until the C one octave up is obtained 3 Press the lower C and readjust OFFSET It may help to adjust MASTER TUNING slightly 4 Repeat the steps until the two Cs are within 10 cents of the correct pitch Please note that due to the variations of the thyratron tubes there may be small variations from equal tempering between the two Cs and in the range above them MAINTENANCE Powering the R 55 requires a power supply producing 5 volts DC at 2 amps cold and 650 mA after warmup when first powered on the R 55 briefly draws greater current so be aware of this when using a power supply to run it plus other modules You MUST assure the power supply is able to ha
7. ndle the R 55 load plus the load of other modules The tubes in the R 55 are being run VERY conservatively They should last for tens of thousands of hours of normal use Still the R 55 produces a lot of waste heat so we recommend shutting it off when not in use UNLESS YOU KNOW EXACTLY WHAT YOU ARE DOING DO NOT REPLACE OR SUBSTITUTE THE TUBES YOURSELF Please note not all tubes have easily visible heaters If you can t see a heater glowing DO NOT assume that tube is bad We get many foolish complaints of this type TUBE REPLACEMENT despite their expected long lifetime the tubes might be damaged or develop faulty internal wiring connections requiring replacement This particular R 55 was shipped and wired for one 2D21 5727 or PL21 tetrode thyratron and one 6AK5 pentode Those types are MANDATORY for use in the R 55 as no other types will have the proper pin connections and heater power requirements Do NOT attempt to substitute other tubes These types are quite easy to find and are available from distributors such as Radio Electric Supply vacuumtubes net or Antique Electronic Supply tubesandmore com Note this is an ADVANCED MODIFICATION and is NOT RECOMMENDED for inexperienced personnel The R 55 can be modified to accept 15v power supply rails and DOTCOM standard power connectors The user is responsible for fabricating a suitable front panel and adding controls and jacks as needed for a given modular synth form fac
8. tor Addition of a 6 pin Dotcom power connector is involved The R 55 PC board will fit onto a 2 wide Dotcom MU panel if it is drilled appropriately Contact us for more information on this modification If you are confused or have ANY technical questions feel free to contact us Please DO NOT ASSUME and if you are not an experienced technician DO NOT TRY RANDOM TUBES OR MODIFY THE CIRCUIT IN ANY WAY 495 N Main 109 METASONIX LAKEPORT CA 95453 USA 707 263 5343 synth metasonix com www metasonix com
9. tted Warranty covers electrical failure of vacuum tubes and gas filled tubes except in cases explained in 3 below 2 Operating instructions must be followed This device was intended ONLY for use by AUDIO AND MUSIC PROFESSIONALS IT IS NOT INTENDED FOR USE BY ORDINARY CONSUMERS Product must not have been damaged as a result of defacement misuse abuse neglect accident destruction or alteration of the serial number improper electrical voltages or currents repair alteration or maintenance by any person or party other than our own service facility or an authorized service center use or installation of non Metasonix replacement parts in the product or the use of this product outside of the U S A or Canada except as a product distributed by an authorized Metasonix dealer or modification of the product in any way or incorporation of the product into any other products or damage to the product caused by accident fire floods lightning or acts of God or any use violative of instructions furnished by Metasonix 3 Obligations of Metasonix shall be limited to repair or replacement with same or similar unit at our option To obtain repairs under this warranty present the product and proof of purchase e g bill or invoice to the authorized Metasonix service center transportation charges prepaid When returning the product for repair please pack it very carefully preferably using the original packaging materials Please also include an
10. uitability and performance of this product lies with the user Products manufactured and or sold by METASONIX are not authorized for use as critical components in devices used in life support and other systems whose failure or performance could result in compromised safety or danger to life or property NOTE All sales are FINAL especially custom designs Only a Metasonix authorized dealer is permitted to return products to Metasonix for a refund or exchange What it does The R 55 represents the endpoint of our 20 years of technological development in tube electronic music devices It is quite similar to the VCOs in our S 1000 Wretch Machine synthesizer but with an added pentode clipping stage with optional CV input to provide voltage control over gain and clipping level The R55 like any thyratron VCO is far from a perfect device and will demonstrate a number of inherent peculiarities It is what it is raw and perverse MASTER TUNING tunes the circuit through its full sweep range from about 32 Hz to 250 Hz manually It is normally set to center of rotation OCTAVE raises the pitch range of the R 55 by two octaves when pushed up Note that these controls have very large control ranges and their effective range is much smaller than their full rotation This is normal it was done to allow for variance of the vacuum tubes and other components Note that as shipped the R 55 WILL NOT produce a signal with nothing plugged into the C
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