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installing single coil in active bass

I

iggy

Jan 3, 2006
227
28
#1
Maybe someone can tell me the "rules" of installing pickups. Can i install single coil pups in an active bass and will that make my bass buzz like a son of a "b". Or should the pickups be hum-cancelling if they're to be installed in an active bass?
 
#2
single coils hum. thats that. if you have a good preamp, it might not hum as much as with a cheap preamp, but it will still be there. i have 5 string i built with 2 emg j long pickups. these are ultra quiet, but they still hum a tiny bit through headphones. i have also noticed this in another bass with emg p-j pickups. boosting the highs accentuates this, cutting them diminishes it. so a preamp CAN help to remove some of the hum, but a single coil will still have noise. i have not used a single coil that is as quiet as an equal build quality humbucker. in my experience, an exposed pole piece, unshielded single coil is VERY noisey!! while a sealed, sheilded single coil(emg, duncan, bartolini) is very quiet.
 
#3
iggy said:
Maybe someone can tell me the "rules" of installing pickups. Can i install single coil pups in an active bass and will that make my bass buzz like a son of a "b". Or should the pickups be hum-cancelling if they're to be installed in an active bass?
Click to expand...

FWIW:

I'm guessing you may find something of use in the Bass Tone Glossary.

There are active single coils pups in active basses and they don't hum. If you boost trebles on anything you're likely to get noise. If you boost gain on a pup that makes noise you will get more noise. If you cut gain then you'd get less noise. Depending on how you set controls, in theory you could actually get less noise from installing noisey pups in conjunction with a preamp then without one.

Some passive true singles coils are quieter than some passive HB's, especially when volumes are matched.

There are internal and external sources of noise that require different solutions. If noise is a primary concern, then install active pickups as they are fairly impervious to both sources.
 
#5
Whether an instrument is active or passive won't matter so far as hum is concerned. A preamp doesn't add or subtract anything except to boost the signal it receives from the pickups. Keeping unwanted noise from the pickups is the key to letting the baby sleep soundly. Single coils seem to have the inherent ability of finding and retaining interference outside of a plucked string.
I have a project p/j passive bass that, before I shielded it, frustrated me to no end with the noise it produced. At 1st I used aluminum duct tape which might have helped a little. Then I ripped that out once I got copper foil tape. BIG difference. I use a carvin j99 single coil in the bridge position and it's dead quiet solo'd, which, even in my stock Carvin lb70p w/ the j99 in the neck postion produces some hum.
The pup cavities are not shielded in the Carvin bass.
My project p/j is shielded through out. I also have an active Yamaha bb605 that had 2 stock yamaha single coils, that even after doing the same shielding as in the project p/j, had annoying hum when soloing either pup. I dropped in a set of Carvin h50n humbuckers and now it's dead quiet.
Why the carvin j99 is quieter in the project bass than Carvins own bass is beyond me except for the pup cavity shielding.
 
#9
efe_gallagher said:
I don't think it will have unbearable levels of hum, but anything would help since I'll be playing it with my dead-silent Stingray.
What is this dummy-coil you speaketh of, L6-Man? :ninja:
Click to expand...

A dummy coil is usually a pickup with no magnets in it, such that it will not transduce the movement of the strings to electrical energy, but will provide a source of 60Hz hum at equal amplitude and 180 degree phase difference from the audible pickup. By common mode rejection, the hum from each pickup cancels the other out, since at any given time, one pickup is on the positive cycle while the other is on the negative cycle, at equal amplitude.

It's the same concept as a humbucker, except one of the coils does not have an audible output, only picking up hum.
 
#11
SGD Lutherie said:
Dummy coils suck the life out of a pickup unless they are summed actively. You are better off with some type of hum canceling pickup.
Click to expand...

My personal experience, though quite limited, was that the impedance drop only decreased the volume, but I definitely agree that it's only really worth doing if you buffer the pickups.

Humbuckers are certainly a better choice. The tone should come close to that of whatever single coil you want to replace, if you get a good pickup.
 
#12
SGD Lutherie said:
Dummy coils suck the life out of a pickup unless they are summed actively. You are better off with some type of hum canceling pickup.
Click to expand...

line6man said:
My personal experience, though quite limited, was that the impedance drop only decreased the volume, but I definitely agree that it's only really worth doing if you buffer the pickups.
Humbuckers are certainly a better choice. The tone should come close to that of whatever single coil you want to replace, if you get a good pickup.
Click to expand...

Well, since this is going against a Stingray and I'm making it active because of the volume differences (I know, I know, a P is probably hotter than the Stingray, but I'm talking about switching that -15Db switch/input on my amp every time I change basses). I have heard wonders about the Lindy (Or was it Nordstrand?) 50's P humbucker, but I'm not going for a vintage tone really, so I don't think I'd like that pickup sound :hiding:
I think I will try this dummy coil if the active Quarter Pounder + Aguilar pre-amp turns out to be way louder than my Seymour PU/pre-amp'd Ray... Or maybe I'll change the pre-amp on my Stingray? You can never go wrong with LOUDER! :bassist:
 
#17
efe_gallagher said:
I don't think it will have unbearable levels of hum,
Click to expand...

With a single coil pickup and even with a lot of shielding you are at the mercy of your environment when it comes to hum. If there is a strong stray 60Hz field you will hear it. True magnetic shielding is so hard to do that it is seldom done in instruments though some pickups claim to have it. The pickups in my active jazz are dual (aka, dummy) coil designs and they do not have the life sucked out of them but then pickup tone is a personal thing and a 3 band preamp gives you back more than the dual coil takes away, IMO. I am quite happy with them compared to what I get when playing single coil jazzes in stores. Another option is to look for a "split coil" design that fits your bass. Trouble is you have a non-standard pickup by today's standards so there may not be any available in the right form factor. The later P pickup is a split coil and there are quite a few jazz pickups that are split coils even though they are still in the traditional jazz form factor. They are effectively end to end instead of side by side humbuckers though they do not have the "hot" humbucker output.

Ken
 
#18
khutch said:
The pickups in my active jazz are dual (aka, dummy) coil designs and they do not have the life sucked out of them but then pickup tone is a personal thing and a 3 band preamp gives you back more than the dual coil takes away, IMO.
Click to expand...

Are they stacks or do they have a non string sensing dummy coil separate from the pickup?

Stacks are not the same as a dummy coil. If you want to hear the affect of a dummy coil, connect a pickup to your bass that's not in the bass. You can connect it parallel to the output.

The bottom coil in a stack does sense the strings, so it is contributing something. But it's also out of phase in the low frequencies, so they tend to be over wound, such as the example above. The Duncan stack is 28.3K, but will have similar output to a non overwound pickup.

The best dummy coil setups have the dummy buffered along with the string sensing coil so that the dummy is not adversely affecting the tone of the main pickup.
 
#19
Trevorus said:
Don't forget shielding, and proper grounding practices. They can make an improvement on most noisy situations.
Click to expand...

+1, Live downtown and was always getting the radio station in my jazz. Shielded the cavity and pup routes - cut it down but did not eliminate. Ended up wrapping the pup's with the copper as well and that pretty much quieted them down.

However, if pup's are hot may be less effective. Tried it on my pal's strat with the Hot 50's and don't think anything will quiet them down...
David
 

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