microphonic pickups from wiring?

[C-5KO]

Is it possible for pups to become microphonic through incorrect wiring?

I just had some Nords install in one of my basses, and now all my pickups are microphonic.

Actually this project, has them along side with installed barts. So I have 4 pickups. 2 neck, 2 bridge that are affected.

They are wired through two pots Volume stacked Blend for Barts, Volume stacked Blend for Nords.

Since the barts were fine previous to the installation, I'm hoping that it has to do with wiring, and that the poles in all four pickups have become lose or something.

The pots don't seem to be affected.

 

[luknfur]

Is it possible for pups to become microphonic through incorrect wiring?

I just had some Nords install in one of my basses, and now all my pickups are microphonic.

Actually this project, has them along side with installed barts. So I have 4 pickups. 2 neck, 2 bridge that are affected.

They are wired through two pots Volume stacked Blend for Barts, Volume stacked Blend for Nords.

Since the barts were fine previous to the installation, I'm hoping that it has to do with wiring, and that the poles in all four pickups have become lose or something.

The pots don't seem to be affected.

FWIW:

my guess is it's a wiring issue but phase not microphonic and to my knowledge microphonics has nothing to do with how a pups wired into a harness. If you don't get squeals, feedback, or the like, it's probably phase - sounding hollow, weak, tinny. You can run the Nord alone and rule it out. If the pup seemed solid when you installed it, it probably is.

 

[C-5KO]

FWIW:

my guess is it's a wiring issue but phase not microphonic and to my knowledge microphonics has nothing to do with how a pups wired into a harness. If you don't get squeals, feedback, or the like, it's probably phase - sounding hollow, weak, tinny. You can run the Nord alone and rule it out. If the pup seemed solid when you installed it, it probably is.

It's odd though. No squeals, or feedback. But they definately pickup up any sort of contact with the pickup covers (tapping on them, even sliding my finger across the covers). So I don't think they're phasing. The pickups also sound "normal", no thinness or weakness. Which led me to believe they're microphonic.

This sort of has me worried. If the microphonic characteristics are not from any sort of wiring errors, it possibly means that the tech who installed them damaged all four pickups?

Using the active/passive switch, as well as the series/parallel switches does not to seem affect the microphonics (they're still there). Pickup blends the same also, still there.

help.

edit: just talked to the tech. he seems to think it's the pre? :-/ Is it possible it's a cold solder joint? I know that it may produce some funny things, along with noise? But microphonic?

 

[luknfur]

It's odd though. No squeals, or feedback. But they definately pickup up any sort of contact with the pickup covers (tapping on them, even sliding my finger across the covers). So I don't think they're phasing. The pickups also sound "normal", no thinness or weakness. Which led me to believe they're microphonic.

This sort of has me worried. If the microphonic characteristics are not from any sort of wiring errors, it possibly means that the tech who installed them damaged all four pickups?

Using the active/passive switch, as well as the series/parallel switches does not to seem affect the microphonics (they're still there). Pickup blends the same also, still there.

help.

edit: just talked to the tech. he seems to think it's the pre? :-/ Is it possible it's a cold solder joint? I know that it may produce some funny things, along with noise? But microphonic?

FWIW:

I suppose it could be an impedence issue with a pre and all those pups. I don't recall you saying anything about a pre previously.

Unlikely the Nords have been damaged. If you can throw the pups 180 degrees out of phase, an out of phase issue would be obvious once move away from 180 degrees.

Again just run the Nords to the jack. If they're not microphonic any more, they're fine and it's somewhere other than the pups (assuming something hasn't changed in the Barts since they worked).

 

[C-5KO]

FWIW:

I suppose it could be an impedence issue with a pre and all those pups. I don't recall you saying anything about a pre previously.

Unlikely the Nords have been damaged. If you can throw the pups 180 degrees out of phase, an out of phase issue would be obvious once move away from 180 degrees.

Again just run the Nords to the jack. If they're not microphonic any more, they're fine and it's somewhere other than the pups (assuming something hasn't changed in the Barts since they worked).

Actually, I didn't think it was the pre. Only because, switching to passive, I'm assuming bypassed the pre, and in passive mode, they still would be microphonic.

I'm thinking it has to do with him wiring the Volume after the pre. He mentioned this when I picked up the bass. For some reason, he said it had to be wired with the Volume controls last, after the pre, and not before the pre.

 

[ldervish]

It is highly unlikely that all 4 pups went bad at the same time, IMO the problem is how each set is hooked into the circuit. I'm also not sure 'microphonic' is the right term for what is happening, ISTM that it is a matter of signal from all 4 being output at the same time. Do I have that right?

I don't see how you could possibly have two separate signals (one from each pair of pups) out of the pre to each vol, nor do I see why the vol has to be after the pre.

Have you talked with the tech people who support the preamp? They may be able to help isolate one part of the circuit from another, perhaps by adding a couple diodes, or even give you a 'custom' wiring diagram.

 

[C-5KO]

It is highly unlikely that all 4 pups went bad at the same time, IMO the problem is how each set is hooked into the circuit. I'm also not sure 'microphonic' is the right term for what is happening, ISTM that it is a matter of signal from all 4 being output at the same time. Do I have that right?

This is what I thought (hoped). Here are the part I gave him, and what I asked for:

The original Barts (2 J's), the new Nords (2 J's), the orignal pre (Bart), 2 switches for series/parallel, and 2 knobs stacked Volume/Blends.

I asked for the Nords to be installed along side the Barts. Each Volume/Blend would control each pair of pickups (Bart pair and Nord pair). I also asked for series/parallel on each pair of pickups.

The symptoms are definately microphonic, from what I've heard of others' descriptions. Any tapping, or even touching of the pickups produces a thumpy sound. Even sliding my fingers across the pups causes a friction-like sound. No feedback or squealing though. It happens with any of the pups. I can isolate each one individually and tap on it, or have them all going at once, and get the tapping sound.

I don't see how you could possibly have two separate signals (one from each pair of pups) out of the pre to each vol, nor do I see why the vol has to be after the pre.

Ok. Thinking about this, you're right! How can he have wired separate volumes after the pre for each set of pickups? The pre wouldn't be able to split the signal.

Now I'm really confused. According to Audere (in a similar thread) he things that microphonics may be caused by poor insulation on the wires, or the insulation breaking down.

http://www.talkbass.com/forum/showthread.php?t=268672

I'm going to mention this to the tech also. BUT again, I'd say it's unlikely that the insulation has broken down in all four pickups.

 

[Audere]

Putting in a new pickup can not damage the internal insulation for the other pickups. Ok - I can think of some ways but it would be almost impossible.

How is your tech mounting the pickups - most techs use foam etc to push the pickups upward against the mounting screws. In other words, the pickups are held down by the screws against the foam. If your foam is to "soft/springy" then the pickups will move relative to the "fixed" string thereby becoming microphonic.

 

[ldervish]

How about this: add a SPDT switch. Have your tech wire each pair of pups in normal configuration (except there is no Tone pot) with its own Blend, Vol and S/P switch. Run the output from each of those to the ends of the new spdt, and the center of the spdt then feeds the input of the pre. Everything will be controlled as you want it, vol blend and s/p BEFORE the pre, and the spdt selecting either the Barts portion or the Nords portion.

Then you can deal with the microphonics, or whatever is happening with that. BTW, my own passive pups do exactly what you describe, if I tap them or rub my fingernail on the cover. I thought it was normal. If it's not, I'd like to know that.

 

[Audere]

It would be normal to hear your interactions with the pickup

I was assuming in this case it must be really loud.

In general, moving the pickup relative to fixed strings is identical to moving the strings relative to a fixed pickup.

In reality both move during playing but the pickups normally move less.

With an Audere preamp the passive switch is a real passive mode - it totally removes the preamp from the circuit.

 

[C-5KO]

Putting in a new pickup can not damage the internal insulation for the other pickups. Ok - I can think of some ways but it would be almost impossible.

How is your tech mounting the pickups - most techs use foam etc to push the pickups upward against the mounting screws. In other words, the pickups are held down by the screws against the foam. If your foam is to "soft/springy" then the pickups will move relative to the "fixed" string thereby becoming microphonic.

I thought it would be a bit of a stretch to have all the insulation go bad. I'm not sure how the Nords are mounted, but the Barts are still using the original foam. Nothing about the Barts should have changed.

I did drop of the bass back to him today. He thought that it might be possible to have one of the wires from the pickup be microphonic. I've never heard of this before.... does that make sense?

I did forget to mention that he added copper foil shielding also.

Anyways, after dropping it off, we were both scratching our head a little.

 

[C-5KO]

How about this: add a SPDT switch. Have your tech wire each pair of pups in normal configuration (except there is no Tone pot) with its own Blend, Vol and S/P switch. Run the output from each of those to the ends of the new spdt, and the center of the spdt then feeds the input of the pre. Everything will be controlled as you want it, vol blend and s/p BEFORE the pre, and the spdt selecting either the Barts portion or the Nords portion.

Interesting idea, but I don't have space for any more switches. Would that set-up allow for both the Barts and Nords to be present at the same time? I figured a double pole switch would only allow Barts or Nords. What I would like to do, is mess around with different combos of Barts and Nords. ie: Bart bridge + Nord neck, Bart neck + Nord bridge, etc.

Then you can deal with the microphonics, or whatever is happening with that. BTW, my own passive pups do exactly what you describe, if I tap them or rub my fingernail on the cover. I thought it was normal. If it's not, I'd like to know that.

Hmmmm.... I couldn't really say on if I think you're is normal or not. I know though, compared to my other basses, this is really loud! I tried to record with it, and the thumping can be as loud as the notes themselves. Even switching between bridge and neck pups with my right hand can be heard - my thumb lifting off one, and then moving to the others.

I figured that "normal" was what the barts sounded like before. Thinking about this whole thing: what's changed about the Bart configuration - series parallel switch, fact that he had to rewire it to accomodate the other pickups somehow, and the added shielding to all the cavities. Logically one would think that it has to do with one of these events, no?

 

[ldervish]

Would that set-up allow for both the Barts and Nords to be present at the same time? I figured a double pole switch would only allow Barts or Nords.

In the setup I described, only Barts OR Nords. You could use an on-on-on (commonly used as a pickup selector) for B/Both/N though.

What I would like to do, is mess around with different combos of Barts and Nords. ie: Bart bridge + Nord neck, Bart neck + Nord bridge, etc.

That is completely different from what I thought you were trying to do, and much more complex. I don't really have the inclination to try and draw something like that out, but off the top of my head, I think you would need some multi-position switches (like the 5 or 6 position rotaries but maybe not that many contacts). Lots of possibilities here. Don't know if it can be done with S/P switching either. Need more coffee.

Another thought on the microphonics - Luknfur could be onto something, what with adding two more inductors (pickup coils) into the circuit plus the pre electronics. I don't know enough electronics to figure it out, but there are many really knowledgeable people around who could say "yes", "no" or "maybe".

I hope you keep us filled in, I'm interested to see how this project ends up.

 

[steveb98]

Microphonic pickup like some of the old tele pickups is from loose winding of the pickups. Microphonic pickups you could crank the volume and sing into the pickup and it would come out the amp. The cure was to pot the pickups in wax, so wire couldn't vibrate.

I seriously doubt a Nordie is microphonic they are machine wound. If one was Cary would be glad to replace it. I would say your wiring or soldering is bad. I had Nordie's put in my bass and sounded good but the hum was bad. I needed some other work and had the bass rewired and it sounds amazing now. More output and quiet as can be.

i would start checking or replacing the wiring.

 

[C-5KO]

Microphonic pickup like some of the old tele pickups is from loose winding of the pickups. Microphonic pickups you could crank the volume and sing into the pickup and it would come out the amp. The cure was to pot the pickups in wax, so wire couldn't vibrate.

I seriously doubt a Nordie is microphonic they are machine wound. If one was Cary would be glad to replace it. I would say your wiring or soldering is bad. I had Nordie's put in my bass and sounded good but the hum was bad. I needed some other work and had the bass rewired and it sounds amazing now. More output and quiet as can be.

i would start checking or replacing the wiring.

Yeah. I have complete faith in the Nord going into my bass.

Here's a quick update after talking to the tech:

He believes that the pickup pairs, are picking up each others signal. He sort of explained it to me, and a bit of it was over my head, but I think I got the general idea.

With the Barts off, and the Nords on, it seemed as if the Nords were microphonic, and vice versa. The way he explained it was like this: tapping on the Nords, the Barts, would actually be picking up the tapping vibration, even though they're not present in the signal. And the magnetic field from the Barts is influencing the Nords.

Since the Barts are not physically mounted to the Nords, they will move somewhat. This vibration (from the tapping), and the Bart's magnetic field, is being picked up by the Nords, and hence the microphonics.

It seemed to make sense to me, even with my limited knowledge of magnets. I'm hoping he's on the right track here. He believes that if we isolate as much movement between the separate pairs (Bart bridge/Nord bridge, Bart neck/Nord neck) it should reduce the amount of microphonics happening. He's suggesting a thin piece of double sided tape between the pairs. And possible gluing the Nords more solidly within the covers.

Comments?

 

[Audere]

He believes that the pickup pairs, are picking up each others signal...

With the Barts off, and the Nords on, it seemed as if the Nords were microphonic, and vice versa. The way he explained it was like this: tapping on the Nords, the Barts, would actually be picking up the tapping vibration, even though they're not present in the signal. And the magnetic field from the Barts is influencing the Nords.

This is valid

Since the Barts are not physically mounted to the Nords, they will move somewhat. This vibration (from the tapping), and the Bart's magnetic field, is being picked up by the Nords, and hence the microphonics.

Valid

...He believes that if we isolate as much movement between the separate pairs (Bart bridge/Nord bridge, Bart neck/Nord neck) it should reduce the amount of microphonics happening.

Valid but

He's suggesting a thin piece of double sided tape between the pairs.

OK - if the pickups move relative to the either each other or to the string(s) then it will be microphonic. If the magnetic field between the 2 pickups is stronger than the magnetic field connection to the string then fixing the 2 pickups relative to each other will be more important than the interaction to the string. Normally the string is coupled better to each pickup than the coupling between 2 pickups - but did you put these 2 pickups close to each other? If you did then the 2 fields might need to be separated (try using 2 separated sheets of steel)... or fixed together (the tape idea). FYI - they will sound different in the 2 approaches and different than stand alone versions of the pickups.

And possible gluing the Nords more solidly within the covers.

Maybe

But you might also consider that moving a magnet relative to the strings will move the strings which will...

IMO I think you just want to increase the rigidity of Bart at X to body and Nord at X to body assuming the pickups are not close together.

 

[C-5KO]

Great!

Ok, I'll suggest the steel plates. The pickups are mounted directly beside each other, in their respective bridge and neck positions.

Thanks for the FYI. I did notice that the Barts were darker, and the Bart bridge pup definately had more bit to it. I can't comment on any change in the Nords, as this is the first time having them in this bass. I can comment on how great they sound. Soloing the Bart bridge, and Nord bridge was killer. The original volume pots were 500k, and these are 250k which may account for the darker sounding Barts.

OT: Thanks for the knob info. He's sort of backed up now, but I think I'll try to get an order in for September sometime.

 

[Audere]

If the pickups are directly next to each other I think the 2 steel plates might be create a larger problem

Here is the theory

Right now pickup #1 interacts with pickup #2 by "stray" magnetic fields - stray is not exactly a good description here

If we can isolate pickup #1 from #2 by closing the magnetic path of PU #1 before it gets to the 2nd pickup then the interaction will stop. The magnetic field travels the easiest path. Steel is a much easier path than air/wood by factors of 100s of times.

If we put 1 sheet between the pickup (BAD) then the both pickups would nicely couple to the common path.

If we put 2 sheets separated by a gap the idea is each sheet would pull the field through it and not though the 2nd sheet or the 2nd pickup structure which is farther away.

But 2 sheets right next to each is unlikely to be a winning combination.

Go back to fixing the 2 pickups together...