| Jazz Looping Pedalboard /\ | ||
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The Copeland 6dc+ is an active hexaphonic pickup designed to fit in the same slot as a normal PAF-style humbucker. Inside the body are 12 magnets, 12 coils, and 6 transistor preamps. The bottom of the pickup is a circuit board with terminals for +9V and Gnd inputs and six audio outputs, one for each string.
I get regular emails from people asking about this pickup, which I installed in the Ibanez AR-250 for use with the Jazz Looping Pedalboard. In 2002, I bought it from Rick Copeland, who used to have a web site at "tubeamps.com". His web site disappeared sometime in 2003, and I don't know what's up with him. I hope he is OK and still making these things because they are great; but at the moment, there doesn't seem to be any way to get one.
Despite the Copeland's unavailability, I am going to describe my wiring since it might be helpful to those using other pickups like the OS Music Technology pickups.
I wired the guitar with a stereo output jack with one output for the guitar effects chain and one for the bass chain. A toggle switch on the guitar controls which strings from the hex pickup get sent to which outputs. I use the cable from my Chapman Stick to split the 1/4" stereo output into two mono 1/4" plugs for the pedalboard. The guitar plug goes into the Dano tuner and the bass plug goes into the EQ before the Chili Dog octave pedal. The toggle switch selects between three operating modes:
The Copeland pickup's transistor preamps each have a series output resistor so you can easily mix different strings just by shorting the output terminals together:
Copeland Hex Pickup +--------+ |Hi E +---+ | | | |B +---o | | | |G +---o------> Top 4 strings | | | |D +---+ | | |A +---o------> Bottom 2 strings | | | |Lo E +---+ +-+---+--+ | | +9V Gnd
At first I just wired these two outputs to a DPDT toggle switch with three positions. The switch's connections map looked like this:
+------+ +------+ +------+ | o o | | o o | | o o | | | | | | | | | | | o o | | o o | | o o | | | | | | | | | | | o o | | o o | | o o | +------+ +------+ +------+
So the connections in the three modes looked like this:
6-String Guitar Mode
Hex Pickup
+--------+
|Hi E +---+ +-----------------+
| | | /o-----+----------+ Tone & Vol Pots +---> Guitar Output
|B +---+---o | +-----------------+
| | | o----(----+
|G +---+ | |
| | | | |
|D +---+ | |
| | /o-----+ |
|A +---+---o | +-----------------+
| | | o---------+------+ Tone & Vol Pots |---> Bass Output
|Lo E +---+ +-----------------+
+--------+
Split Mode
Hex Pickup
+--------+
|Hi E +---+ +-----------------+
| | | /o-----+----------+ Tone & Vol Pots +---> Guitar Output
|B +---+---o | +-----------------+
| | | o----(----+
|G +---+ | |
| | | | |
|D +---+ | |
| | o-----+ |
|A +---+---o | +-----------------+
| | | \o---------+------+ Tone & Vol Pots |---> Bass Output
|Lo E +---+ +-----------------+
+--------+
6-String Bass Mode
Hex Pickup
+--------+
|Hi E +---+ +-----------------+
| | | o-----+----------+ Tone & Vol Pots +---> Guitar Output
|B +---+---o | +-----------------+
| | | \o----(----+
|G +---+ | |
| | | | |
|D +---+ | |
| | o-----+ |
|A +---+---o | +-----------------+
| | | \o---------+------+ Tone & Vol Pots |---> Bass Output
|Lo E +---+ +-----------------+
+--------+
There is a problem with the above approach: the signal levels change when you switch between split mode and either of the other modes. When you short together the hex pickup outputs, you are creating an "averaging" mixer: the shorted output gives you the average of the individual string outputs. As a result, the more strings you add to the mixer, the lower the output level gets. This is particularly noticeable when switching from split mode to bass mode, where you change from average-of-two to average-of-six. The pure bass output is so much quieter it is unusable without adding some kind of gain externally.
To get around this problem, I added additional trimpots to ground which get switched into the circuit to lower the output level when you are in split mode. This required the use of a 4PDT toggle switch with a connection scheme like two of the aforementioned DPDT switches:
+------------+ +------------+ +------------+ | o o o o | | o o o o | | o o o o | | | | | | | | | | | | | | o o o o | | o o o o | | o o o o | | | | | | | | | | | | | | o o o o | | o o o o | | o o o o | +------------+ +------------+ +------------+
The idea is that we want to lower the guitar output and the bass output levels when we are in split mode, but not lower the guitar output when we're in guitar mode or the bass output when we're in bass mode. With the 4PDT switch, we can connect things such that the guitar-side trimpot is connected in both split mode and bass mode (we don't mind if the guitar-side trimpot is connected in bass mode, because the guitar output isn't connected to any pickups). Similarly, the bass-side trimpot is connected in split mode and guitar mode:
6-String Guitar Mode
(Bass trimpot is connected with no audible effect)
/o
+--o 50K Trimpot
Hex Pickup | o--/////----- Gnd
+--------+ |
|Hi E +---+ | +-----------------+
| | | /o-+---+----------+ Tone & Vol Pots +---> Guitar Output
|B +---+---o | +-----------------+
| | | o----(----+
|G +---+ | |
| | | | |
|D +---+ | |
| | /o-----+ |
|A +---+---o | +-----------------+
| | | o-+-------+------+ Tone & Vol Pots |---> Bass Output
|Lo E +---+ | +-----------------+
+--------+ |
| /o--/////----- Gnd
+--o 50K Trimpot
o
Split Mode
(Guitar & bass trimpots are both connected, reducing level of
guitar and bass outputs)
o
+--o 50K Trimpot
Hex Pickup | \o--/////----- Gnd
+--------+ |
|Hi E +---+ | +-----------------+
| | | /o-+---+----------+ Tone & Vol Pots +---> Guitar Output
|B +---+---o | +-----------------+
| | | o----(----+
|G +---+ | |
| | | | |
|D +---+ | |
| | o-----+ |
|A +---+---o | +-----------------+
| | | \o-+-------+------+ Tone & Vol Pots |---> Bass Output
|Lo E +---+ | +-----------------+
+--------+ |
| /o--/////----- Gnd
+--o 50K Trimpot
o
6-String Bass Mode
(Guitar trimpot is connected with no audible effect)
o
+--o 50K Trimpot
Hex Pickup | \o--/////----- Gnd
+--------+ |
|Hi E +---+ | +-----------------+
| | | o-+---+----------+ Tone & Vol Pots +---> Guitar Output
|B +---+---o | +-----------------+
| | | \o----(----+
|G +---+ | |
| | | | |
|D +---+ | |
| | o-----+ |
|A +---+---o | +-----------------+
| | | \o-+-------+------+ Tone & Vol Pots |---> Bass Output
|Lo E +---+ | +-----------------+
+--------+ |
| o--/////----- Gnd
+--o 50K Trimpot
\o
With the trimpots, we can adjust the levels as desired. I opted to make the guitar a little bit louder in guitar mode than in split mode, so my guitar solos would be a bit louder than the looped bass + chords accompaniments over which they are played.
Here are photos showing the completed wiring:
Guitar Wiring |
Closeup showing trimpots glued to 4PDT toggle |
The 9V battery powers the active Copeland hex pickup; power to the pickup is switched on and off with a push-pull switch on the guitar tone pot.
I think this wiring scheme would be useful for hex pickups other than the Copeland; basically in any case where an averaging mixer is used.
Olle Svensson from OS Music Technology makes hex pickups with a hex distortion circuit built in! I just received a custom pickup from him very similar to the Copeland, but it appears to have better isolation between strings. I will post some pics and sound samples once I get it mounted in a guitar for real testing.
Musician/educator Paul Rubenstein is now making some hex pickups.
Ultramagnetics is now making some hex pickups. I haven't tried these yet.
I've experimented a little bit with modifying a regular humbucker for split usage. Go here.
I don't think a bridge-mounted Roland GK-2a-type hex pickup would work very well for this application because the Chili Dog bounces octaves quite a bit if you try to drive it from bridge pickup. I got the Copeland specifically so I could use it in the neck position.
