Bill and Will's Synth
Tellun 867 Tuner & Headphone Monitor Construction

November 2008 -

In February of 2007, in the process of perusing Scott Juskiw's site foraging for mods we'd want to include when building our Synth Tec MOTM kits, we came across this module which we felt we'd absolutely need.  For our recording projects, tuning is of paramount importance because we're going to be blending electronic and acoustic instruments.  And, remembering my experiences from the olden days, I know tuning a synth can be quite difficult sometimes... so we decided to dive in.

The module has no PCB specifically designed for it.  Rather, it uses some of the Multi-Use Universal Buffer (MUUB) PCBs designed by Richard Brewster, Larry Hendry, and Scott Juskiw and available through Scott.  Specifically, one MUUB4 and two MUUB3s are needed. 

Also, two special ICs are used... one - the DJB-A440 Reference Oscillator is available only from Dave Brown and the other the MAX7401 which we also got from Dave.

As it turns out, we actually tune our pianos to A440.5.  That turns out to be the note that's the average between our Hammond, and glockenspiel, both of which are non-tunable.  We'll ask Dave if he can make a special Chip tuned to 440.5.

Table of Contents

This page has become really long, so here's a table of contents that we hope will make it easier to traverse:

Background - presents an explanation and Scott Juskiw's initial description of the module with a photo

Modifications - presents details of a possible modification

Parts - presents a Bill of Materials and notes about it

Panel - presents the MOTM format panel

Construction PCB 1 - MUUB4

Construction PCB 2 - MUUB3

Construction PCB 3 - MUUB3

PCB Connections - wiring the PCBs together

Panel Wiring

Set up / Testing

Background

Scott writes:

The TLN-867 Tuner & Headphone Monitor combines an A440 reference tone generator, a headphone amplifier, and a beat frequency indicator all in a 1U module. The A440 generator is none other than David Brown's excellent DJB-A440 Reference Oscillator, a super stable digital A440 tone generator.

No matter how large your synthesizer is, you don't need more than one A440 tone generator module. A dedicated A440 module would only have a single output jack which, IMHO, is a waste of an entire 1U panel. If, like me, you have just the one head with two ears on it (a mono head), then a headphone monitor is another useful module that you only need one of. Combining the two together makes even more sense should you want to tune your oscillators without sending the A440 tone to your output amp for everyone else to hear. Simply plug your oscillators into the headphone monitor and tune them to the internal A440 tone in complete privacy. The A440 tone has a dedicated volume control so it can be removed from the headphone mix entirely. This is useful for when you want to tune oscillators to some other frequency, or just for having a private mix of any two signals in your synthesizer.

The TLN-867 also features a handy beat frequency indicator with four LEDS that provide a visual indication of the frequency difference between the left and right inputs, or either the left or right input with the A440 reference tone. I just like blinky lights, what else can I say?

The panel controls are as follows:

• PHONES pot: Sets the level of the signal at the PHONES jack.
• A440 pot: Sets the level of the A440 tone sent to the headphone monitor.
• MODE switch: In the STEREO position, the signal at the LEFT jack goes to the left headphone speaker and the signal at the RIGHT jack goes to the right headphone speaker. In the MONO position, the signals at the LEFT and RIGHT inputs are summed and go to both headphone speakers. MONO mode is also handy for checking for phase cancellation between two signals.
• BEAT switch: Sets which two signals are applied to the beat frequency circuit. This is a three position switch. In the upper (LEFT) position, the signal at the LEFT jack and the A440 tone are used. In the lower (RIGHT) position, the signal at the RIGHT jack and the A440 tone are used. In the middle position (LEFT+RIGHT), the signals at the LEFT and RIGHT jacks are used.
• LEDs: The four LEDS are the output from the beat frequency circuit. They provide a visual indication of the frequency difference between the two inputs to the beat frequency circuit.
• LEFT jack: The input for the left channel.
• RIGHT jack: The input for the right channel.
• A440 jack: Output for the A440 tone (always 10Vpp).
• PHONES jack: Plug your headphones in here.Dedicated 1volt/octave input with military-spec 25ppm 0.1% summing resistor...

...You’ll need one MUUB-4 and two MUUB-3s to build the TLN-867. If you look at the pictures on the website, you’ll see the three boards mounted on the stooge brackets:

• Board #1: MUUB-4 (bottom), board #1: headphone amp, +5V power, power connector
• Board #2: MUUB-3 (top left), board #2: A440 (U3-U5), left comparator (U7), beat frequency indicator SA and SB signals (Q2, Q3, U9, U10)
• Board #3: MUUB-3, board #3 (top right): right comparator (U8), inverter for the A signal (Q3), beat frequency indicator driver (U11-U13)...

...Total current draw for the TLN-867 is 45 mA @+15V and 27 mA @-15V.

Schematics

Here's Scott's Schematics (click on the image to see a high-rez version):

Modifications

We tune our pianos, guitars, and other acoustic instruments to 440.5 - an average between our non-tunable instruments (Hammond organ is aprox A440.1 and the glockenspiel at aprox 440.8 or 9., etc.) so we asked Dave Brown about the possibility of having a DJB-A440 Reference Oscillator chip made to give a 440.5 reference tone.  Even better than we'd hoped, he programmed a chip so it gives both 440 and 440.5 hz outputs -  switchable by grounding "pin 7" of the chip.

Of this special-made chip, Dave wrote to us:

"Pin 5 is your output at 440 Hz
"Pin 5 shifts to 440.497 Hz when pin 7 is grounded."

We couldn't have hoped for better.

So we'll put an additional switch on the panel to toggle between the two values and we'll adjust some of the labeling accordingly.  Here's the modification worked into the schematic diagram - switch up = 440, switch down = 440.5:

Parts

Will and I have developed a parts-list / bill-of-materials in the form of an XL spreadsheet (as usual).  We want to thank Dave Brown for making two DJB400s for us one in Feb of 2007 which was the original and the new, modified one that has the 400.5 option.

We've used it this parts list to make our Mouser purchases and we are relatively confident in our specifications.

Click here to download our XL spreadsheet Parts List

Panel

We developed a Front Panel Express panel (FPD) based on Scott Juskiw's design but including the extra switch for the DJB-400 modification.  Click on the image below to download the FPD file.

Here's how it came from Front Panel Express:

Pre Construction Phase

Scott urges assembling the pcb brackets and the panel first.

Construction - PCB1

PCB 1 is built using an MUUB4 and is described in Scott's 867 User's guide section 5.1.  For detailed drawings of the MUUB4, click here.  We're going to chart out each step as we build it to make sure we get everything right.  (click on images to see a larger one)

images from Scott Juskiw

Whereas we are vigilant about orienting all the resistors, caps, etc. consistently so their values can be read easily (in case we need to trouble-shoot them later), we oriented the resistors with the "tolerance" stripe on the left (relative to the text on the pcb).  Why did we do it this way?  'Cause when we started out doing these builds, we thought the gold stripe is so pretty and easy to see... and we put it on the left - well - just because.  But now, we do it so all our modules are consistent with each other <shrug>.  You might want to do it the opposite way - with the "tolerance" stripe on the right - it kinda makes more sense.

Phase 1

All the stuff in Phase 1 gets soldered using "Organic" Solder.  At every break in the action, we wash the board off to get rid of the flux.

Jumpers

here's where they go - (click on image for larger one)

jumpers stuffed

jumpers done

Resistors

resistors stuffed

resistors done

Capacitors

caps are in

Misc

We're going to be sure to wash off the PCB at this point and let it dry well before we begin on the +5V reference circuit.

Special +5V Reference Section

OK - so there is a special +5V Reference circuit built into the lower left section of the MUUB4... down in those 25 little individual pads.  Here are Scott's photos of it:

We thought it out - here's how we think the best method for accomplishing the build:

here's where the three parts go - the LM78L05, the 100nF ceramic cap, and the 10uF electrolytic cap

1. stuff the 100nF ceramic cap - and, looking at the back of the PCB, bend the leads like this:

solder it in:

2. now stuff the 10uF electrolytic cap - and, looking at the back of the PCB, bend the leads like this:

solder it in:

trim it:

3. OK - now, bending the leads so they fit - stuff the LM78L05

looking at the back of the PCB, bend the leads like this:

solder it in:

4. so - now the leads on the back look like this (in white):

5. a touch of solder here:

6. time to wash this off - carefully - those couple leads that stretch off to the left aren't soldered into their specific shape.

Phase 2

The stuff in Phase 2 gets soldered using "No-Clean" Solder and the PCB doesn't get washed off from here on.

Wire jumpers

The last step in making that +5V Reference circuit is to put in the red 22ga wire...

Cut the Wire

Here's where it goes

On the underside, that long lead bends over to connect to the LM78L05 like this.

So, having soldered in the other end of the red wire, the long lead solders at these points.

Now the traces look like Scott's photo - we're done with the +5V Reference thing.

The +5V Reference thing all done.

And now for the very last step of the MUUB construction - the orange wire - well - we don't have orange 22ga wire... but we've got blue.

Cut the wire.

Here's where that blue orange wire goes.

There - solder it up

PCB1 all done

Construction - PCB2

PCB 2 is built using an MUUB3 and is described in Scott's 867 User's guide section 5.2.  For detailed drawings of the MUUB3, click here.  Scott's photos and diagrams make construction quite clear, but we're going to chart out each step as we build it to make sure we get everything right.  (click on images to see a larger one)

Building this PCB isn't for the faint-of-heart. But we've carefully worked out a method that makes it quite do-able.

  
images from Scott Juskiw

Phase 1

All the stuff in Phase 1 gets soldered using "Organic" Solder.  At every break in the action, we wash the board off to get rid of the flux.

Jumpers

First off, for quick reference, here's Scott Juskiw's diagrams of the jumpers in the "general" area of the PCB:

  
top and bottom

Top Solid Jumpers

OK - so this is tricky. Some jumpers are on the front. Some are on the back. Some need to be put in after other components are already present. Some are wire and so should be soldered in with no-clean solder as part of Phase 2.

We'll start with the solid jumpers on the front.

the red lines indicate where they go - (click on image for larger one) - the position of the IC sockets are shown by those black rectangles.

jumpers - we missed one, but put it in later - it's the one that should be in the top right of this photo and ends up being under R32.

Top Components

Scott's diagram of the top components in the general area

IC Sockets

We think it's a good thing to put the sockets in now 'cause it'll help determine where other things go.

Resistors

Take a look at the bigger picture by clicking on this one. Note that the leads of R4 and R6 are interwoven. Also note that one of the leads of R32 goes around a corner of one of the IC sockets - now the jumper that we missed is under R32.

note that R30's leads are bent so R30 leans off the board and leaves space for wire jumpers that get put in later.

Capacitors

Click for the bigger image - here's where the caps go on the front... more go on the back later.

caps are in

Transistors and Crystal

here's where the transistors go

  
Q1 - leads bent

  
Q1 - installed

  
Q2 - leads bent

Q2 - installed

  
X1 leads bent - X1 installed

Bottom Jumpers

here is Scott's diagram of the bottom jumpers.

looking at the PCB bottom, here are the pads that are soldered.

Bottom Jumpers

Here is where the bottom jumpers go (in bright blue). Some of their ends solder into open holes. Most of these are under IC sockets and therefore can't except long leads so we'll have to trim them before we solder. Others ends solder to pads that are already full.

Here they are soldered in / on.

Bottom Caps

here is Scott's diagram of the bottom components. These are all 100n caps.

here's where the caps go on the back (the red rectangles). Like the bottom jumpers, some of there leads solder into open holes and others solder to pads that are already full.  Again, these are all 100n.

Here they are soldered in - and you can see the jumpers better here too.

Phase 2

The stuff in Phase 2 gets soldered using "No-Clean" Solder and the PCB doesn't get washed off from here on.

Wire Jumpers

Top Wire Jumpers

Here's where the wires go.  Actually as we're building the pcb, we're going to use black wire where green is indicated on this diagram and green wire where yellow is indicated.

Here the wire jumpers are.  We made a couple little mistakes in the process, but we corrected them.  We decided to also solder on the top of the PCB the two wire jumpers shown in tan on the diagram of bottom wire jumpers below.  We decided to do this because we figured it would be easier to maneuver soldering from the bottom of the PCB. 

Bottom Wire Jumpers

Here's where the wires go.  Actually as we're building the pcb, we're going to use black wire where green is indicated on this diagram and green wire where tan is indicated.

But we did put these power jumpers on the bottom.

PCB2 all done

And now, back to work.

Construction - PCB3

PCB 3 is also built using an MUUB3 and is described in Scott's 867 User's guide section 5.3.  Again, for detailed drawings of the MUUB3, click here.  As with PCB2 Scott's photos and diagrams make construction quite clear, but we're going to chart out each step as we build it to make sure we get everything right.  (click on images to see a larger one)

Building this PCB isn't as complex as PCB2 but it's still a challenge. But following the same procedure as with PCB2, it's quite do-able.  His photo is missing a couple caps, but we got them straight.

  
images from Scott Juskiw

Phase 1

All the stuff in Phase 1 gets soldered using "Organic" Solder.  At every break in the action, we wash the board off to get rid of the flux.

Jumpers

First off, for quick reference, here's Scott Juskiw's diagrams of the jumpers in the "general" area of the PCB:

  
top and bottom

Top Solid Jumpers

OK - so again - some jumpers are on the front and some are on the back. Same deal as with PCB2.  And again, we'll start with the solid jumpers on the front.

the red lines indicate where they go - (click on image for larger one) - the position of the IC sockets are shown by those black rectangles.

jumpers in

Top Components

Scott's diagram of the top components in the general area

IC Sockets

Again, we put the sockets in now 'cause it helps determine where other things go.

Resistors

Take a look at the bigger picture by clicking on this one.

Capacitors

Click for the bigger image - here's where the caps go on the front... again - more go on the back later.

Transistor

here's where the transistor goes

Q3 installed

Bottom Jumpers

here is Scott's diagram of the bottom jumpers.

looking at the PCB bottom, here are the pads that are soldered.

Bottom Jumpers

Here is where the bottom jumpers go (in bright blue). Some of their ends solder into open holes. Most of these are under IC sockets and therefore can't except long leads so we'll have to trim them before we solder. Others ends solder to pads that are already full.

Bottom Caps

here is Scott's diagram of the bottom components. These are all 100n caps.

here's where the caps go on the back (the red rectangles). In the case of these caps, they solder into open holes, but the two lower ones are under the IC sockets and can't accept long leads.  Again, these are all 100n.

Phase 2

The stuff in Phase 2 gets soldered using "No-Clean" Solder and the PCB doesn't get washed off from here on.

Wire Jumpers

Top Wire Jumpers

Here's where the wires go.  Actually as we're building the pcb, we're going to use black wire where, on the diagram, yellow is indicated, white wire where the blue is indicated, and blue wire where orange is indicated.

Bottom Wire Jumpers

And here's the bottom wires.  Actually as we're building the pcb, we're going to use black wire where green is indicated, blue for the orange, green wire where the blue and yellow are indicated.

PCB3 all done

PCB Connections

Top Connections

OK - the next step is to make the connections between the PCBs.  This is described in Scott's 867 User's guide section 5.5.  This drawing illustrates these connections and Scott illustrates them as being on top.  We're going to make one of these on the back (the one illustrated by a green dashed line).

The wire indicated by the bright red line is the 2" length of 22ga hook-up that goes

• from PCB3
• to what Scott calls "R33 (input to inverter for A signal)."

Well - we figured it out, but you could do it just by counting the holes and comparing the pictures here.

The wire indicated by the bright blue line is the 2.5" length of 22ga hook-up that goes

• from PCB3 CB3 top hole
• to PCB2 U10 pin 1.

Here, two connections are illustrated with heavy light-grey lines. These are the coax connections. On each of these wires, the little white line illustrates the shield of the coax that gets soldered into PCB1. The little green line illustrates the "signal" center lead.

In this diagram, the upper coax is the 6" length that runs

• from PCB1 JC6 (the shield soldered into the left, ground hole and the "signal" lead soldered into the right hole)
• to PCB3 JA5 (the "signal" lead soldered into the right hole).

The lower coax is the 6.5" length that runs

• from PCB1 JD6 (again, the shield soldered into the left, ground hole and the "signal" lead soldered into the right hole)
• to PCB2 JA5 ("signal" lead soldered into the right hole).

The wire indicated by the dashed bright green line goes from PCB3 U11 pin 12 to board 2 U10 pin 6. Scott shows this on the top... but in reality, the holes are all taken up by a cap and a jumper although these don't show up in his photo of this connection. So we're going to put this wire on the bottom of the boards instead.

Bottom Connections

Next we'll do the bottom connections.  This is described in Scott's 867 User's guide section 5.4 "Power Considerations."

But first - the 1" long wire indicated by the bright green line that's left over from the last step...

• from PCB3 U11 pin 12
• to PCB2 U10 pin 6

And now the power lines.  There's no easy way to describe this - you just gotta click on the drawing, above, and look at the big version to see where everything goes. 

• The two blue wires connect the +5V supply to busses on the MUUB3s
• The two white wires supply +15V
• The two white wires supply -15V
• The grey is ground

Panel Wiring

Next is the wiring that's between the PCBs and the pots, switches, LEDs, and jacks on the panel. This is described in Scott's 867 User's guide section 5.6 "Panel Wiring."

Here are Scott Juskiw's Photos of these connections.  We're going to build ours from the top down.

  
images from Scott Juskiw

Top-most "A440" or "STD" pot

Set up / Testing

Use Notes