Seventh Circle Audio D11 Manuel utilisateur
The D11 provides a pair of independent, high-impedance instrument inputs for direct recording
of guitar and bass through any of our microphone preamp modules. Switchable input
impedance allows for optimal loading, and internal jumpers provide options for termination,
grounding, and signal pass-through. The D11 features a simple, all-discrete signal path with
flat frequency response from below 10Hz to beyond 200KHz. The D11 requires no trimming or
adjustments and is very easy to assemble.
Who Should Build This Kit?
The D11 is not difficult to build, but it is not intended for absolute beginners. You should have
built at least one project on a printed circuit board (PCB) before trying the D11. Sorry, but
soldering cables doesn’t count. If you’ve never built an electronic project of any kind, this is
probably not the one to start with. To guarantee success, make sure you have:
•The ability to make basic voltage and resistance measurements using a digital
multimeter (DMM).
•At least a rudimentary understanding of voltage, current, and resistance.
•Some experience soldering on printed circuit boards.
•The patience to follow instructions precisely and work carefully.
Essential Tools
Fine tipped 20-30 watt soldering iron w/ cleaning sponge (Hakko 936 or similar)
Eutectic (63/37) rosin core or “no clean” solder (.025” diameter is usually best)
Good-quality DMM
Small needle nose pliers Small
diagonal cutters
Phillips screwdriver (#1)
Highly Recommended Tools
Lead bender (Mouser 5166-801)
T-Handle wrench and 4-40 tap (Hanson 12001 and 8012)
MOLEX crimp tool (Waldom W-HT1919 or equivalent)
Magnifying glass
Optional Tools
Panavise w/ circuit board head
Oscilloscope
Signal generator
Work Area
Find a clean, flat, stable, well-lit surface on which to work. An anti-static mat is recommended
for this project. If you’re in a dry, static-prone environment, it’s highly recommended. The
importance of good lighting can’t be overstated. Component markings are tiny, and you’ll be
deciphering a lot of them.
Soldering Technique
Make sure your iron's tip is tinned properly, and keep it clean! The trick to making perfect
solder joints is to heat the joint quickly and thoroughly before applying the solder, and a
properly tinned and clean tip is essential for this. Apply enough solder to form a "fillet"
between the lead and the pad, a little mound of solder that smoothly transitions from the plane
of the board up to the lead, but don’t use too much. The finished joint should be smooth and
shiny, not rough or gritty looking.
If you've never soldered a board with plated-through holes, you might be surprised to discover
how difficult it can be to remove a component once you've soldered it in place. If you're using
solder wick to correct a mistake, be very careful not to overheat the pads, since they will
eventually delaminate and "lift". It's often better to sacrifice the component and remove its
leads individually, and start over with a new part. If for some reason you need to unsolder a
multipin component (like a rotary switch or integrated circuit), remove as much solder as you
can with solder wick or a solder sucker, and then use a small heat gun to heat all the leads
simultaneously. With care, you can remove the component without damaging the board.
Instruction Conventions
Text in orange indicates a step where extra care needs to be taken. Doing it wrong isn’t a
disaster, but it’ll need to be corrected.
Text in red indicates a step that must be done correctly. Doing it wrong will guarantee
improper operation, and probably damage components and/or the circuit board.
Assembly
1. Before you begin, carefully unpack the kit and examine the parts. Check the contents of
each small bag against the BOM to make sure all the parts have been included. If you
think something’s missing, please e-mail the details to [email protected] and
we’ll ship replacement parts ASAP.
2. Generally, the idea when "stuffing" or “populating” a circuit board by hand is to start with
the lowest profile parts, such as the resistors, and work your way up to the taller
components. In each step below, insert the components, flip the board onto your work
surface component-side down, and carefully solder and trim the leads. Use a piece of stiff
cardboard to hold the parts in place while you flip the board. First, orient the board as
shown.
3. Before installing the resistors and inductors, prepare the leads using small needle nose
pliers or a lead-forming tool as shown below. Whatever you do, don’t bend the leads at
the resistor body and force them into the board.This not only results in an ugly job, it
can damage the parts.
4. Insert the 1/4-watt resistors. Check the Bill of Materials (BOM) for help in reading the
resistor color bands. It's also a good idea to actually measure each resistor with your
DMM as you place it on the board, just in case you've read it incorrectly. Don't rely on the
photos for component placement. If the resistor value silk-screened on the board doesn't
agree with the value on the schematic or parts list, follow the schematic.
5. Next, add input chokes L1 and L2. These components help to reduce RF interference.
Inductors are not polarized and can be installed in either direction.
6. Install the ½ Watt resistors now.
7. Install the protection diodes D1 through D10. Diodes are polarized and must be
installed the right way round! The colored band on the diode matches the white band
on the silkscreen.
8. Add ceramic capacitors C1, C11, C22 and C25. These capacitors are not polarized and
can be installed in either direction, but pay close attention to the capacitor markings!
These parts look alike, but they are not interchangeable. Putting one in the wrong spot
will not prevent the module from passing signal, but it can seriously impair performance.
9. Install the 470nF film caps at C3 and C13. These parts are not polarized and can be
installed in either direction.
10. Add the 0.1” headers and shorting jumpers at J1 through J6. Install the headers with
the long pins up! The jumpers connect pin 1 of CONN1 and CONN2 to ground as
shown in the table above. Unless you encounter issues with ground loop hum, jumper
pins 2 and 3 on both headers as shown at right. A jumper must be installed at J1 to
complete the phantom power circuit.
11. Add electrolytic capacitors C2, C4, C5, C6, C12, C14, C23, C26, C27, C28. Electrolytic
capacitors are polarized and must be installed the right way round! Be absolutely
sure to observe the correct polarity when installing these parts. The negative leads of the
electrolytic caps are marked with a colored stripe. The positive pads on the circuit board
are marked with a small "+" sign.
12. Add electrolytic capacitors C7, C8, C17, and C18. Again, electrolytic capacitors are
polarized and must be installed the right way round!
13. Install transistors Q1 through Q6. Be sure to orient the transistors correctly! These
parts are not the same, and are not interchangeable. Align the flat side of the transistor
with the flat side of the silkscreen outline.
14. Carefully mount the 3-position toggle switches SW1 and SW2. Be sure they're seated flat
on the board before soldering the leads. You may find it easier to solder the first lead of
each switch while the board is component side up.
15. Add J7, the MOLEX power connector. Be sure to orient it as shown, with the locking tab
away from the edge of the board.
16. Place two fiber spacers under each ¼” jack
and solder the jacks to the board. The
spacers are only required to align the jacks
with the front panel holes and can be
removed after soldering if desired.
17. Carefully thread the mounting holes of CONN3 and CONN4 using one of the included 440
screws or a tap as shown. This makes installing the module in the chassis much easier.
Adding a drop of light machine oil to the tap or screw makes tapping the holes much
easier. Don’t drive the tap in all at once. Advance ¼ to ½ turn, and then back the tap out
to clear the hole of cuttings.
18. Add CONN3 and CONN4 to the board. Make sure they’re fully seated before soldering.
19. Using the hardware supplied, attach heat sinks to U1 and U2 and solder them in place.
Make sure to install the regulators correctly! These parts are not the same, and are
not interchangeable.
20. Install the bulk filter capacitors C21 and C24. Push them in firmly until they are fully
seated against the board. Again, electrolytic capacitors are polarized and must be
installed the right way round! Be absolutely sure to observe the correct polarity when
installing these parts.
21. Add electrolytic capacitors C9, C10, C19, and C20. These capacitors are not polarized
and can be installed in either direction.
