Human Voice Module Builder`s Guide
Contents
1. only one connection A special compact low voltage supply has been made for this and other Oakley rack projects in the form of the Oakley RPSU You don t have to use this as any decent split rail supply will do but it is an easy build and is flexible enough to suit most builders needs Please see the RPSU Builder s Guide and User Manual for more details 11 Inputs and Ouputs If you are building the suggested design then you have only one input and one output Both input and output are balanced and you should use TRS jack sockets TRS tip ring sleeve sockets are ones with three poles and are also used for headphone outputs Even though both input and outputs are balanced they are still compatible with unbalanced signals This means you can plug ordinary two pole mono jacks into the TRS sockets and the unit will work as expected Audio projects should really be built into metal cases to prevent interference and because of this we now face a bit of a conundrum Ideally balanced input and output sockets should be grounded to the case If you have internal mains transformer then the case will be grounded via the power supply so this will ground the socket and any connecting cables But this only works if your sockets have a metal frame and can be guaranteed to make a permanent electrical connection to the casing when they are tightened up It also means that your PSU must be grounding the case directly which unlike with the internal mains tr2. that you are able to read the schematic well The four main circuit sections are pre amplifier chorus filter network vox filter network and parametric equaliser 1 Pre amplifier Input via the balanced input of the header INPUT Pin 2 is hot tip and pin 1 is cold ring Output via pin 2 middle pad of the UPR LWR switch The output is also hardwired to the wet dry mixer pot s dry end Thus the pre amplifier s balanced output is also available via the FBO filter bank output header Pin 2 is hot tip and pin1 is cold ring 2 Chorus filter network Input via the CHI chorus input header Pin 2 is signal pin is ground But this can be and is in the suggested design connected directly to the pre amp output via LK1 If you want to use CHI as a separate input you must remove LK1 Output via the CHO chorus output header Pin 2 is the signal pin is ground 3 Vox filter network Input via one of four inputs F4U M8U M4L amp MBL Each of these inputs represent the connection that was made on the original VP 330 F4U being Female 4 Upper M8L being Male 8 lower etc If you have an old string machine with a split keyboard and two available footages these inputs are the ones to use It is these I used on my own RS 101 upgrade project The four inputs are accessed by their own headers Again pin 2 is the signal input and pin 1 is ground The output of the Vox filter network is available from the VOX header Pin 2 being
3. the front panel so that you just have the board again Get the LED and find the cathode Make sure the cathode of the LED will go into the square pad pin 1 on the board Carefully bend the LED s legs at a point 6mm away from the plastic body of the LED The legs should be bent by 90 degrees so that the legs are pointing straight down Check to see if they fit into the board The bottom of the LED s body should fit just flush to the board edge Fit the LED to the board but do not solder it in at this stage Let its legs poke through there s no need to cut them down yet Now fit the front panel again to the board and tighten the pot nuts You should find that the board now fits snugly into position and the LED should be just poking out of its hole neatly albeit loosely Align the LED if it isn t quite straight and then solder it trimming its leads nice and short afterwards The three switches These are made by Multicomp part numbers IMSIT2B4M7RE for the two SPDT and 1MD1T2B4M7RE for the single DPDT With panel removed once again you can now fit the switches The PCB mountable switches should fit tightly into their respective holes on the board Indeed they ll probably work for short time without soldering them so don t forget to do so Make sure the switch body is flat against the board Now refit the front panel and make sure the round switch barrel fits into its hole in the front panel Now solder all the pins on each of the switc
4. 36 220K R57 R27 R58 R50 R26 R59 R88 R31 R45 R24 R56 R82 330K R30 R33 390K R52 470K R29 10K x 8 resistor pack 9 pin single in line SIL package RN1 Capacitors 100nF axial multilayer ceramic C25 C27 C47 C49 C76 C23 C53 C39 C6 C7 C9 C73 C28 C54 C38 C5 C8 C87 C10 C72 C88 C70 C52 C48 C37 C71 C51 C36 C50 C75 C74 C24 C77 C26 33pF 2 5mm COG ceramic C40 C84 C85 100pF 2 5mm COG ceramic C2 C14 470pF 2 5mm COG ceramic C13 1n5 polyester C61 C62 3n3 polyester C35 C22 C34 C21 3n9 polyester C58 C44 C60 C46 8n2 polyester C81 C83 C66 C68 12nF polyester C63 C64 C78 C79 15nF polyester C3 18nF polyester C55 C56 C42 C41 A47nF polyester C33 C19 C20 C32 56nF polyester C31 C30 C18 C17 C12 100nF polyester Cl 680nF polyester C16 C15 C69 C4 luF polyester C89 C29 C11 10uF 35V electrolytic C91 C92 10uF 16V non polarised elect C86 C90 Non polarised capacitors can sometimes be called bipolar Unlike ordinary polarised electrolytic capacitors they can be put into the board any way around Both 8n2 and 3n9 may be difficult to find from your normal parts supplier There are places on Ebay that sell both values usually the old green cased mylar capacitors and these seem easy enough to get However provision on the board has been made to substitute two smaller value capacitors instead which when combined make up a close approximation of the required val
5. LEDs and Switches If you are using the recommended Alpha pots then they can support the PCB with specially manufactured pot brackets You may not normally need any further support for the board although I do tend to use the rear pair of mounting holes and attach these to threaded hex spacers which then attach to the bottom panel of the case When constructing the board fit the pot brackets to the pots by the nuts and washers supplied with the pots Now fit them into the appropriate holes in the PCB But only solder the three or six pins that connect to the pot Do not solder the pot bracket at this stage When you have soldered all the pots you can fit the board to your front panel Position the PCB at right angles to the panel the pot s own pins will hold it fairly rigid for now Then you can solder each of the brackets This will give you a very strong support and not stress the pot connections The Alpha pots are labelled with an A B or C suffix For example 50KB or 1OKC Alpha and ALPS use the key A log B linear and C reverse log So a 47KB is a 50 kilohm linear pot The single board mounted LED must be fitted carefully if you are using the directly mounted technique Although this sounds fiddly it s actually quite easy and it reduces wiring interference and possible errors A close up of the LED This should light up when the power is on You can chose any colour you wish but I tend to like either green or yellow Remove
6. Oakley Sound Systems Human Voice Module PCB Issue 1 Builder s Guide V1 0 5 Tony Allgood Oakley Sound Systems CARLISLE United Kingdom Introduction This is the Builder s Guide for the issue 1 Human Voice Module HVM from Oakley Sound This document contains a basic introduction to the circuit board and a full parts list for the components needed to populate the board or boards For the User Manual which contains an overview of the unit and goes into some detail regarding the operation of the module please visit the main project webpage at http www oakleysound com hvm htm For general information regarding where to get parts and suggested part numbers please see our useful Parts Guide at the project webpage or http www oakleysound com parts pdf For general information on how to build our modules including circuit board population mounting front panel components and making up board interconnects please see our generic Construction Guide at the project webpage or http www oakleysound com construct pdf This is an early version of the documentation If you do find any errors even silly little ones please do let me know either directly by e mail or via the forum eReO Se R41 case c4 FELS E A completed issue 1 HVM circuit board awaiting its case The Oakley Sound Human Voice Module The HVM does not have any built in power supply It is expected that the circuit board be powered from a regulated split supp
7. ansformer is not what I recommend when using an external wall wart Therefore I prefer to use plastic framed chassis mounted sockets for my rack projects This allows the case to be grounded via the power supply and keep the sleeve terminals of all the sockets locally isolated from the case Grounding the sockets must therefore be done via a short wire link back to either the PSU s main ground star point which is not so easily done on the RPSU if both four way headers are being used or the main HVM PCB Input Socket The two way header named INPUT should be wired so that pin 1 goes to the ring of the input socket and pin 2 goes to the tip The sleeve or ground of the input socket connects to the sleeve of the output socket Output Socket The three way header named OUT should be wired so that pin 1 connects to the tip of the output socket and pin 3 goes to the ring The sleeve or ground of the output socket connects to pin 2 of the OUT header 12 Other I O Options The HVM is designed to be very flexible It has four main circuit parts and all are available with individual inputs and outputs should you wish to use them I cannot go into every possible combination since I will leave this to the builder of the unit to decide However I will give a quick run down of what is available and a description of the slightly cryptic nomenclature of the headers on the board It is advisable that if you are planning on some cunning interfacing
8. hes including the two securing pins to the front That completes the soldering of the front panel components 10 Power Supply Power is admitted onto the board using the usual Oakley power system That is a single four way 0 156 3 96mm MTA or Molex KK header For the rack projects I am recommending the Molex system over the MTA simply because the tool needed to make the interconnects is much cheaper It is also possible to solder the crimp terminals used in the KK system It is of course quite possible to solder your power leads straight onto the board The board is protected against reverse polarity with a couple of diodes Note that these diodes work by shorting out your power supply in the event of a reversal Because of this they should not be relied on if the reversal continues for a long time as this will stress both the diodes and the power supply The diodes are simply there to save the board s ICs from certain death in the event of the power being inadvertently reversed during testing There is no overvoltage protection to be careful not to put anything over 17V into the board The pin out for the power connector PSU Pinl 12V to 17V Pin2 Ground 0V Pin3 Ground 0V Pin4 12V to 17V Pin 1 is indicated by the little diagonal on the header s legend Both ground connections need not be connected to your power supply However you do most certainly need at least one of them either pin 2 or pin 3 will do if you using
9. ly of 12V to 17V Power is admitted onto the board via a four way 0 156 2 96mm header of MTA or KK type The module is designed to be powered by our own Rack Power Supply Unit RPSU or any other split rail compatible supply such as the Oakley PSU The benefits of using the RPSU is its small size and ability to take a variety of different AC power sources Because of the inherent dangers of using a component level mains transformer in your project I recommend that you use an external low voltage AC source such as that obtained from a wallwart or line lump The RPSU can then be fed from a low voltage alternating current supply so all the high voltages are kept inside the wallwart or line lump The User Manual for the RPSU will go into more detail of the various options for powering your unit A single RPSU should be capable of driving both the HVM and SE330 should both projects be built into the same case The board size is 198mm width x 131mm depth Power consumption of the HVM with no audio passing through it is 80mA at 15V Re a 7 AL s Tiir The power header on the HVM board This is a 0 156 3 96mm Molex KK This is similar to the MTA156 type connector that we normally use on our MOTM compatible modules but the two are not interchangeable However the KK is cheaper and only requires a cheap crimper to make the leads Parts List For general information regarding where to get parts and suggested part numbe
10. o one pin usually labelled with dot or a line A close up of the wire link that joins the FBO and EQI headers Modifications The HVM is configured to work well with line level signals like those coming from a mixing desk s auxiliary outputs It can also be plugged into most synthesiser outputs including modulars with no issues However you may wish to use the HVM on an output that is weaker than normal Like for example an older machine like the Logan String Melody In this case it is a good idea to increase the input sensitivity The easiest way of doing this is to change the value of R6 This sets the gain of the post input level amplifier Doubling the value of R6 to say 33K will double the sensitivity of the input If you find the volume level too low when used in the Vox mode then you can increase the value of R81 Currently it s at 10K Increasing it to 22K will double the gain of the filter network summing amp based around U 13a and produce an increase in Vox volume However I have chosen 10K for a reason the Vox mode s filter networks do produce some very large increases in signal level at certain specific frequencies which may distort the signal Feel free to experiment though If you do make some interesting changes to the circuit do let the Oakley community know via our friendly online forum at Muffwigglers I for one am always interested to hear what people do with their Oakley Sound projects Mounting the Pots
11. return postage costs If you have a comment about this user guide or have a found a mistake in it then please do let me know But please do not contact me or Paul Darlow directly with questions about sourcing components or general fault finding Honestly we would love to help but we do not have the time to help everyone individually by e mail Last but not least can I say a big thank you to all of you who helped and inspired me Thanks especially to all those nice people on Muff s Forum and the Synth diy and Analogue Heaven mailing lists Tony Allgood at Oakley Sound Cumbria UK March 2013 updated August 2013 No part of this document may be copied by whatever means without my permission 14
12. rs please see our useful Parts Guide at the project webpage or http www oakleysound com parts pdf The components are grouped into values the order of the component names is of no particular consequence A quick note on European part descriptions R is shorthand for ohm K is shorthand for kilo ohm R is shorthand for ohm So 22R is 22 ohm 1K5 is 1 500 ohms or 1 5 kilohms For capacitors luF one microfarad 1000nF one thousand nanofarad To prevent loss of the small as the decimal point a convention of inserting the unit in its place is used eg 4R7 is a 4 7 ohm 4K7 is a 4700 ohm resistor 6n8 is a 6 8 nF capacitor Resistors All resistors 5 or better 0 25W types Those items marked with 1 need to be 1 metal film or better 0 25W metal film resistors For the sake of clarity it is recommended to make all resistors 1 metal film types 47R R70 R69 110R R94 220R R23 R20 220R 1 R107 R106 R34 R35 1K R74 R103 R66 R73 R108 R38 R100 R44 R41 1K2 R28 R25 R83 R51 R89 R64 R32 2K2 R16 R61 3K3 R113 4K7 R93 R105 10K R77 R79 R110 R60 R78 R67 R49 R80 R17 R48 R65 R109 R68 R104 R96 R95 R81 R47 10K 1 R1 R4 R11 R14 15K R3 R6 22K R91 R92 R18 R62 22K 1 R7 R8 R9 R10 27K R37 R99 R40 R72 R76 R102 R43 33K R12 R5 R2 R15 68K R55 R87 R84 R86 R54 R53 R85 100K R90 R13 R63 R19 R21 R22 R46 R97 100K 1 R111 R112 180K R71 R101 R39 R75 R98 R42 R
13. the signal and pin being ground Alternatively the outputs from both Vox and Chorus filter networks can be obtained from the wet dry mixer output header FBO The CHO VOX switch will then determine the choice of filter heard and the wet dry pot will also allow for the pre amplifier s output to be mixed in 13 4 Parametric equaliser Input is available via the EQI equaliser input header Pin 2 is the signal pin 1 is ground Output is available via the HVM s main balanced output OUT Pin 1 is hot tip pin 2 is ground sleeve and pin 3 is cold ring Final Comments If you have any problems with the module an excellent source of support is the Oakley Sound Forum at Muffwiggler com Paul Darlow and I are on this group as well as many other users and builders of Oakley modules I d love to hear about what you have done with your module Please do post pictures of your finished module at the Oakley Sound forum on Muffwigglers And if you can t get your project to work then Oakley Sound Systems are able to offer a get you working service If you wish to take up this service please e mail me Tony Allgood at my contact e mail address found on the website I can service either fully populated PCBs or whole modules You will be charged for all postage costs any parts used and my time at 25GBP per hour Most faults can be found and fixed within one hour and I normally return modules within a week The minimum charge is 25GBP plus
14. ue 1n5 polyester C68 C66 C83 C81 6n8 polyester C67 C65 C82 C80 560pF 5mm ceramic or polystyrene C46 C44 C60 C58 3n3 polyester C45 C43 C59 C57 Discrete Semiconductors 1N4004 diode D1 D2 Green or yellow 3mm LED ON Integrated Circuits OPA2134PA U1 U3 U8 U12 U14 U17 TLO72 U2 U4 U5 U6 U7 U9 U10 U11 U13 U15 U16 IC sockets are recommended You need seventeen 8 pin DIL sockets Pots All pots 16mm Alpha or Alps types 10K log dual gang FREQUENCY 10K reverse log Q 47K linear LEVEL OUTPUT GAIN WET DRY Six Alpha pot brackets Six knobs to suit Switches SPDT toggle PCB mounted CHO VOX UPR LWR DPDT toggle PCB mounted FOOTAGE Interconnects 4 way 3 96mm Molex KK or MTA header PSU 2 way 0 1 Molex KK or MTA header INPUT 3 way 0 1 Molex KK or MTA header OUT Other interconnects may be required if you intend to use the HVM differently to the suggested design Wire Links These are to be fitted if you are building the suggested design Use a small piece of uninsulated wire like a resistor wire clipping Link out LK1 This connects the pre amp output to the chorus filter network Link pin 2 of FBO to pin 2 of EQI Pin 2 is the round pin on each header This connects the output of the wet dry balance circuit to the input of the parametric equaliser A close up of the resistor network This is eight resistors in one package manufactured so that one end of all the resistors are tied t
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