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Another Wiring help request

tspallone

tspallone

Guest
Oct 13, 2011
341
171
Nanuet, NY
www.tomspallone.com
#1
I did search for this but couldn't find.

I just received a Belcat 2 Band Active EQ Preamp circuit.

I'm awaiting 2 Wilkinson J-type pickups.

The preamp is all pre-wired. It has a Master volume, 2 tones knobs (one for each pickup) and a blend knob.

The only thing I'm sure of is how to connect the battery.

Anyone know of a schematic to wire it so that each pickup can be controlled by it's own tone knob, the blend knob blends the pickups and the master volume controls the output level of the whole mess?

I contacted the seller of the preamp for it and they "sort of" explained it in broken english from chinese but, a picture is worth thousand words.

Thanks for any help.
 
#2
The only way that is going to work is if you put a resistor in series with each pickup to isolate the signal paths. This is going to drop a lot of output and darken things up, especially with the load of the other three pots from the blend and volume. I wouldn't bother with it, personally.

In any case, I'll draw a diagram when I get around to it.
 
#4
tspallone said:
So, you're saying the preamp is worthless? How else can it be wired? I just figured this is a standard for a four knob setup with two pickups.
Click to expand...

You're probably confusing something somewhere. Preamps very rarely have anything other than a single-ended input and output, which works over one signal after the blend pot. Tone controls are passive, and work independent of a preamp. Since they operate parallel to the signal path, if you want one on each pickup, you have to isolate the pickups by placing a resistance between them. This resistance will prevent the pickups and their tone pots from being parallel to each other, but it will also resist the flow of electrons from the pickups to wherever they are wired.

It sounds like what you want is a two band preamp and no passive tone controls.
 
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#5
This is active, no?
I just did a search and found a pic with a bunch of red wires all over the place.
Why didn't they even send a schematic diagram with it?
The only way you're going to get any help with this sort of unknown preamp is to get a schematic to post on here or else find someone else that has one.
No schematic? Unbelievable. I wouldn't toss it, yet.
 
#6
If its a two band preamp it has no "tone" knobs, it probably has bass and treble (active). The blend and the volume are the only "passive" controls. You would never want to hook up the bass and treble controls to different pickups independently.
You just need to find a diagram for wiring a master volume and blend, don't worry about the rest of the circuit as its already wired and your pickups won't go directly to either of the other controls.
 
#7
line6man said:
You're probably confusing something somewhere. Preamps very rarely have anything other than a single-ended input and output, which works over one signal after the blend pot. Tone controls are passive, and work independent of a preamp. Since they operate parallel to the signal path, if you want one on each pickup, you have to isolate the pickups by placing a resistance between them. This resistance will prevent the pickups and their tone pots from being parallel to each other, but it will also resist the flow of electrons from the pickups to wherever they are wired.

It sounds like what you want is a two band preamp and no passive tone controls.
Click to expand...

I'm thinking he has the pickups going to the blend control first, then a volume for master and EQ both on-board. In other words, blend as a passive and then to th preampfor tone and master volume adjustments.
 
#8
bumperbass said:
This is active, no?
I just did a search and found a pic with a bunch of red wires all over the place.
Why didn't they even send a schematic diagram with it?
The only way you're going to get any help with this sort of unknown preamp is to get a schematic to post on here or else find someone else that has one.
No schematic? Unbelievable. I wouldn't toss it, yet.
Click to expand...

Not too many manufacturers will readily provide schematics. They don't want their designs copied, and most people can't read them, anyway.

More useful is a wiring diagram with indicates the color code for the connections. From there, you can get the EQ pots wired and drop the preamp into any setup.
 
#9
That's what I meant...a wiring diagram. What kind of company would sell a preamp and not indicate where the pickups are wired? Heck, it sounds like the guy doesn't even know which is bass and which is treble, hence calling them 'tone controls'.
I figure the OP MUST have bought this second hand. Had to have, IMO. In that case, buyer beware!
I do hope he gets it working.
 
#10
bumperbass said:
That's what I meant...a wiring diagram. What kind of company would sell a preamp and not indicate where the pickups are wired? Heck, it sounds like the guy doesn't even know which is bass and which is treble, hence calling them 'tone controls'.
I figure the OP MUST have bought this second hand. Had to have, IMO. In that case, buyer beware!
I do hope he gets it working.
Click to expand...

The OP said that the preamp was prewired, and he knows how to connect the battery. That means there should only be an input and output. That means you can pick one wire to be the output and see if it makes noise when you connect it to an amp and touch the other wire, and if not, swap the two wires around so it does. Then wire normally with a VBT setup, or VB, or VBTT if you want the two passive tones plus the EQ.
 
#11
Good answer. Find out which is the output FIRST, then touchy feely till noise is heard, with all controls full clockwise. Find which outside lug is hot, then wire a pickup to it or leave it open to pick up noise, then he can find out which tone is doing what.
 
#12
After reading a couple of posts And then retreading the preamp description, it would appear that there is a bass boost/cut and a treble boost/cut and not 2 identical tone controls which, I assumed would be for each pickup as is the case on my other bass.

The picture did copy over but please see description below.

Yea, this thing came from china off eBay and it's new. One could search for it on eBay and see the picture if they had a mind to.

So NOW I'm thinking that, operationally, the volume and two tone (85hz and 7kz) both affect the combined signal of both pickups and the blends of course just alters the level of signal from each pickup.

Can I view it as a standard jazz configuration and just jump from one eq knob to the next as if it were one as in the standard jazz.?


HomeShipping & HandlingPayment PolicyReturn PolicyAbout Us

Belcat 2 Band Active EQ Preamp Circuit for Bass Pickup






Description

100% brand new
high quality and testing is fine
Item 100% like the picture shown
1 Volume + 2 Tone pots with balance volume
Balance volume for pickup
Volume: Master
Bass: +/- 12dB at 85Hz
Treble: +/- 12dB at 7KHz
Package included:
1 xBelcat 2 Band Active EQ Preamp Circuit for Bass Pickup
 
#13
I got it!!!!!!

I found wiring diagrams from Bartolini, Aguilar and Seymour Duncan and they all support each other in the same wiring configuration.

Thanks to all for the dialog.

The take away......I've only just recently got a bass with an onboard preamp. Have always been passive. I'm actually converting a Fretting Passive P into a Fretless Active J, hence the parts purchases. But based on this project and from all who've commented, It turns out that I was under the wrong impression by the way my current bass (Schecter Stilleto Custom 4) operated.
I was under the impression that there was a seperate tone control for EACH pickup!!!! Not So!!!! I came to this realization at 6am this morning and plugged in to check. Sure as Schit, with the blend panned both hard to "Neck" or hard to "Bridge". Both "tone" controls affected output. As I now realize, they are boost/cut at 2 differerent frequencies (85hz/7Khz) per pot.

NOW, I get it!!!! Cool. Thanks. Now where's that soldering iron?
 
#15
I'm curious myself. I'm still in shaping and sanding stage. I've basically cut the thing in half and have put a new (different wood) top on it. My "better mousetrap" idea of the type of wood will have to remain secret until I hear it and actually wish to share. It might just end up sounding like crap. But, if one doesn't try...... Actually waiting for pick-ups to arrive to determine location and cavity routing and such. A few more weeks before plugging in at this point.
 
#16
the wires go to the 6 post pot the two middle ones get the hot wires from your pickup and the black ones go to any of the pots backs as a ground. as you can tell there is an extra pot what I did was drilled a hole 7/8 of the way through the body of the guitar from the inside out and stopped before breaking through the other side in an angle like a Gibson or other side plug model then drilled out the hole for the jack. I used the 4 holes in the plate to mount the pots and places a 9v battery clip in the empty space under the pots to secure it down. the pot your looking for to hook the pickups to is the one that is all by its self with a red and a black wire only there is two jumpers there one black going to the opposite side and lower connector then another one going to ground hook up the hot side of your pickups to the middle two connectors one top one bottom this is the pot with the detent in it you will feel the click in the middle of turning the pot then all you have left is to hoop up a 9v battery or two if you prefer and find the places to put the preamp its self and the battery I found that the preamp fits right around where the neck pickup is there is a lot of room there as for the batteries well your just going to have to figure it out each one is different. if you prefer you can use two opf the batteries that work in your car alarm remote and just solder the two lines to it and it will work for a few months at a time just add a switch to turn them off when not using
 
#17
HI, This is my 1st post.mI got here whilst looking for info on a replacement pre-amp kit I just got off Ebay. A great site. (TB I mean). I'm pretty sure it the same as this Belcat kit. Anyho.. I've got myself a Warwick Rockbass. Really like it but the tone controls didnt work so I got a new kit. Still cant get any sound. ON my bass there are 2 thick white wires and two thin reds that come into the cavity from the MEC pick ups. It has the right set up for this kit (4 knobs, Bass , treble, blend and volume). I currently have the two red spliced into the red from the battery. I'm not sure if I need to connected the red and blacks from the battery clip to the jack as the kit is pre-wired and already connected to the jack. I have the two white wires from PUP's wired to the middle terminals of the blend as stated previous. Is this 'HOT' side. HELP please.
D
 

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