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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
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Summary of Contents for Seventh Circle Audio D11
- Page 1 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.
- Page 2 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.
- Page 3 Assembly 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 sales@seventhcircleaudio.com we’ll ship replacement parts ASAP.
- Page 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.
- Page 5 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. 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.
- Page 6 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.
- Page 7 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.
- Page 8 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.
- Page 9 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.
- Page 10 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.
- Page 11 22. Before going on to initial power-up, carefully check your work. Make sure you haven't created any solder bridges between pads, or between a pad and the ground plane. Initial Power-Up and Testing. 23. Again, carefully check your work. Make sure you've got the right resistors in the right locations.
- Page 12 Jumper Settings 29. Jumper J1 as shown to make CONN1 drive both outputs until a plug is inserted into CONN2. Jumper J2 as shown to make CONN2 drive both outputs until a plug is inserted into CONN1. 31. Jumper BOTH J1 and J2 for regular operation: INPUT 1 to OUTPUT 1 only and INPUT 2 to OUTPUT 2 only.
- Page 13 32. Jumper across J1 and J2 as shown to pass the instrument signal straight through from CONN1 to CONN2 and vice versa. Signals at either CONN1 or CONN2 will also drive both outputs. 33. Jumper J3 as shown to ground the instrument shield at CONN1 directly to CGND.
- Page 14 Output Transformer Option The D11 can accept either CineMag or Jensen mic level splitter transformers as an alternative to the coupling capacitors included with the kit. Either or both channels can be transformer coupled; it’s not necessary to mount transformers on both channels. Transformers can provide isolated outputs for connecting to other preamp chassis or for re-amping.
- Page 15 40. Install 100uf / 50V capacitors at C15 and / or C16 41. Remove / do not install capacitors at C9, C10 and / or C19, C20 42. Install suitable transformers at T1 and / or T2 Congratulations! You've got a working D11 module!
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