wiring help for a bass guitar

[mytt88]

Hi guys. I have a custom bass project I am building and I have hit a snag in my plans.

I need to know if something like a circuit board exists to combine 10 wires into a single output.
It's to conect a polyphonic pickup (2 coils per string on a five string bass) to one input on an active preamp.

Appologies if that makes little sense bu

 

[Gryd3]

Depends how you want the signal treated.
You can connect them all in parallel and use optional resistors but that would hinder the individual pickups. You can also connect them in series..
Alternatively, you can use active components to 'mix' the signals together, but this would require a power source. Either a battery in the guitar, or a power jack on the guitar. (Using external power could also introduce ground loops and noise if not done carefully/correctly.
It is very easy for the wiring in a guitar to pick up external interference.

 

[mytt88]

I have attached an image if it helps.

I'd rather not use a power source and have it as compact as possible. Easiest way is best as I have no experience. I want even combined signals so I believe in series?

Thanks

 

[Gryd3]

Well... Here's the part where I say there is no answer.
Series or Parallel will provide you with different sounds. Simpler pickups can be wired to switches to be able to toggle between a series / parallel setup.

I am a little unsure how those pickups are wired. I see 11 conductors. 5 Top, 5 bottom, and one on the right?
From the initial look, it appears as though the coils could possibly be internally connected in parallel which means there is only one answer for you.
Can you provide more details on the pickup? If the coils are not internally connected to a common lead, then you have the option of connecting them in series.

My brother made a guitar so I understand there are some differences, but I am not much of a guitar guy so I can't advise you on if series or parallel would be more ideal for your desired sound. Your going to have to do some research into this if your pickup will allow you to connect it in either series or parallel.
Here's a resource to get you started: http://www.guitarnuts.com/wiring/serpar.php
remember this is the internet so try to get more resources read to ensure they all make common points and that you understand it before you commit to anything.

 

[mytt88]

It's a 10 coil polyphonic (Wal style) pickup, with each coils having 2 tags for outputs and one larger tag to ground out the internal shielding of the pickup, Is that the kind of information you need?

http://www.acguitars.co.uk/acg_admin/wordpress/basses/pickups/
If you could go here and look at the mc pickups that is what I have. what I need is something similar to the ACG IB1 interface board he mentions. I have no idea what it is but I need something that does the same thing.

Again thanks for your help

 

[mytt88]

An audio mixer circuit combines the outputs of many microphones. It can be used with less gain to combine the outputs of the coils in your pickup. It is fairly simple.
Get an audio electronics guy to make you one

I think this is what I might need?

 

[Gryd3]

It's a 10 coil polyphonic (Wal style) pickup, with each coils having 2 tags for outputs and one larger tag to ground out the internal shielding of the pickup, Is that the kind of information you need?

This is exactly the information I need.

The MC Series Multi-Coil Pickups have two coils per string. In a 4 string pickup there are 8 poles, 2 per string, where each pair of coils is wired in series as a humbucker. In other words each string has its own dual coil humbucking pickup.

The individual outputs from each string feed an ACG IB1 interface board, which mixes them electronically. The multiple coils and electronic mixing reduces the interaction between the strings coil signals, since there is no cross-feeding between string signals as with traditional pickups, where the same magnet systems and coils are used for all strings.
This leads to improved dynamics and far greater clarity over the entire range of the bass.

but the link you provided have me slightly better details


Keep in mind what you are doing, and what is in the description are two completely different approaches.
The board described will mix the signals together and prevent the coils from interfering with each other. This is only to a certain extent though because the pickup contains pairs of coils connected in series, and no board will compensate for that. What the described board does is mix the signal from each pair preventing the pairs from interfering with each other. This sounds like an 'active' device and would need power but would give you a signal free of interference from the other coils.
You are after a 'passive' solution because you do not want a power source to be involved.

You can connect the coil pairs in series or parallel, this is entirely up to you. You can make it selectable, but will need a switch that can toggle at least 5 poles which may be pricey. Otherwise you wire it and forget about it.
Here are your options:
Series connection. This would result in all of your coils being connected in series. (Top of one terminal would be connected to the bottom of the next. Repeat to connect the top of each pair of coils to the bottom of the one next to it. The two left over at either end will be sent to the amp)
Parallel connection. This would result in 5 pairs of series coils all connected in parallel. (Top terminal would be connected to the top terminal for all other coils. Bottom terminal would be connected to the bottom terminal for all other coils. Top and Bottom would be sent to the amp)

Optional slightly experimental method.
This is the same as the Parallel method, but a small value resistor is added for each pair of coils... This method will reduce, but not eliminate the drawback of parallel wiring at the expense of a weaker signal making your guitar quieter. This is only suggested if you were willing or able to experiment with the setup.

 

[Gryd3]

An audio mixer circuit combines the outputs of many microphones. It can be used with less gain to combine the outputs of the coils in your pickup. It is fairly simple.
Get an audio electronics guy to make you one

I think this is what I might need?

This is more of the experimental method I have mentioned.
Again, passive or active.
Passive will use resistors to reduce the signal from feeding back to other coils but not prevent it. This will reduce overall signal strength.
Active will use things like opamps to isolate the pairs of coils before mixing the output. This will provide you with a stronger signal strength.

 

[KrisBlueNZ]

OK, as Gryd3 says, your options are limited if you go passive. You can either connect all five pickups in series, in which case you will get a fairly high output impedance, or you can connect them in parallel, with or without a series resistor for each pickup, in which case you get a lower output impedance and a significant reduction of signal level.

Output impedance is significant because of the capacitance in the cable from your bass to your amp (or pedal or whatever). The impedance of the pickup forms a "pole" with the cable capacitance and this causes attenuation of higher frequencies and the high-frequency components of fast transients. The higher the pickup impedance, the worse this effect becomes. This can be noticeable if you use very bright strings, or slap and pop.

The best option is always active circuitry, but of course that requires power. It can be made to have pretty low current consumption, so you'll get days of continuous operation from a small 9V battery, or you can pass the supply voltage to the bass via the cable - either using a stereo cable, or by merging the signal and the supply voltage onto a single signal line.

The big advantages of active circuitry involve buffering the signals to reduce their impedance, so cable capacitance becomes irrelevant. The signal amplitude can also be boosted, and custom tailored responses can be added on individual strings. I would stick with keeping all pickups in phase and avoiding filtering, but amplitudes can be adjusted.

This is an area where the opportunities for experimentation are almost unlimited, and strong opinions can be formed on the basis of placebo effect and confirmation bias. Google some relevant keywords and you'll probably see what I mean - try some keywords like active bass multiple coil pickup impedance buffer response processing mixed phase transient.