Okay, this is documenting my upgrade of a Cirrus preamp with a Millennium preamp. This is an Option if you buy a Cirrus. I've gotten a Peavey G-Bass. It also has a Cirrus preamp, but since it only has a single pickup, there is an EXTRA Knob, the Pickup Blend. From what I've seen, it looks like I just have to remove it, and I'm golden! Other than that caveat, the upgrade would be the same for a G-Bass or a Cirrus.
Here is the preamp as it arrived:
The Midrange control has to be sepperated, and rotated 90 Deg. The board is perferated, and it separates cleanly and easily.
Here is the Mid-Control in place:
It needs a screw to hold it in place. It was NOT included.
But not to dispare! I used a mounting screw from an electrical outlet! It's a bit long, but it works fine!
Just to get an idea of how this was going to look, I sat the NEW Preamp on top of the controls...
What's with the 5th knob though?
Okay, so the millennium preamp is Preped! Now to get the Old Cirrus preamp out! First we need to get the knobs off...
There is a set-screw in each of these knobs. 1/4 turn and off they came! (Love those Sparkles!)
There is a 7/16" nut holding each of the controls in place. I used a 3/8" drive socket without a ratchet, and they came off easily.
Next, I needed to get into the cavity, and remove the old Cirrus preamp. There are 4 Phillips head screws.
Remove those, and there you are! The Mighty Cirrus Preamp! (Destined for the TRASH!)
I carefully lifted the old preamp out, so that I could identify (and DOCUMENT!) what wires I had to deal with, and where they attached to the preamp.
Here is the front of the Cirrus preamp. I can see the 6 mounting points for the pickup blend control (Either side of GR-03). It is just vacant. This leads me to believe that all I have to do is REMOVE the pickup blend control from the Millennium preamp, and I'm in business!
There are 3 groups of wires going to the preamp. From left to right, the batteries(Skinny Red & Black wires), the pickups(Gray sheathing and a red wire), and the output jack(Black sheathing).
Here's the battery connections, skinny red & black single wires. They are marked + & - on the board. They are the ONLY things that are marked! This is the Front of the preamp.
Here's the pickups connections. 3 wires total. The Black & White wires are together in a gray sheathing, and the Red wire is alone. This is the Back of the preamp.
The output jack connects very closely to the battery connection on the front of the preamp. Inside the black sheathing is a Red & 2 Black wires.
If you are upgrading a single pickup bass, such as the G-Bass, you must remove the Pickup Blend control. (Unless you want to drill a hole, I suppose...) If you're upgrading a 2 Pickup Bass, such as a Cirrus, or a Gv, then SKIP this Step. (Unless you like 50/50 blend, and don't mind an empty hole on your bass) Getting this off was kinda tricky. there are 3 soldered points on each side. I ended up with the board in my hand, thumb on the control shaft, and Pinky on the board, applying some resistance, and moving from one of the three soldered points to the next. It slowly started moving, and then pulled out. I turned the board around for the other 3 points, and it was out cleanly.
Next step was to swap the wires. I decided to do one group at a time, instead of removing everything, and then HOPE I get everything right. (A good project manager always breaks Big Projects into smaller projects!
) I started with the pickup wires on the rear of the preamp. I used an old string envelope to protect the bass, and to write notes on. These wires came out very easy. I applied a slight pull on each wire as I applied heat from the soldering iron on the other side. Very simple technique.
Here is the Millennium preamp with the pickup wires attached. The new preamp has Clean holes to solder in. I put each wire into it's place, and bent the end of the wire to keep it in place. I added a bit of flux, and carefully soldered each wire into place.
Next I turned the preamps over. I made notes of the wiring locations on another string envelope.
I decided to do the battery connections. I removed them from the Cirrus preamp, and transfered them to the Millennium, as I did with the previous connections.
Last, we have the output jack wires to replace. Remove & replace as we have been doing.
Hold On here! The Red wire from the Batteries is supposed to connect to the black resistor. It is in the wrong location!
Red wire should be in the hole to the left...
Easy fix though!
Okay, the electronics are swapped! And this control cavity is a great candidate for copper shielding! But that is beyond the scope of this project...(A good project manager avoids Scope Creep!)
That's it for today. Make sure you clean up, and dispose of all un-needed items. Like the Cirrus preamp!
I still need to mount the preamp, which will require reaming the Mid-Controller hole a bit. I will also need a Larger mounting nut, also Not Included, and a set of knobs, to accommodate the stacked controls of the sweepable mids. I think I'll call Peavey tomorrow, and see what they have in Black for the Millenium.
More to follow!