Balancing outputs of 2 pickups beyond the help of height adjustment

focusbob

focusbob

Jan 28, 2019
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#1
I recently learned through experience that a vintage p-bass pickup has substantially higher output than a vintage j-bass pickup. And, that this difference (as indicated by 10.5k vs 7.5k dc resistance) is so great that the two pickups' outputs cannot be matched via pickup height adjustment (i.e., with the j-pickup too close to the strings and the p-pickup receded as far into the body as physics will allow, the imbalance remains albeit less so). I'm wondering what I can do, perhaps via electronics, to balance the outputs of these two pickups without replacing one of them (I quite like the sound of each individually)? Note, I would like to have at least the option of passive electronics, with balanced outputs between pickups.

The bass is an ibanez mezzo srmd200k and the pickups are fender avri. I have the stock (active 2 band eq + volume and balance pots) electronics in place, though I am open to any suggestions that would alter this setup (changing the electronics, at least adding a passive/active switch, was the long term plan anyway). I have a nice soldering iron and a penchant for modifications :)
 
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#3
focusbob said:
I recently learned through experience that a vintage p-bass pickup has substantially higher output than a vintage j-bass pickup. And, that this difference (as indicated by 10.5k vs 7.5k dc resistance) is so great that the two pickups' outputs cannot be matched via pickup height adjustment (i.e., with the j-pickup too close to the strings and the p-pickup receded as far into the body as physics will allow, the imbalance remains albeit less so). I'm wondering what I can do, perhaps via electronics, to balance the outputs of these two pickups without replacing one of them (I quite like the sound of each individually)? Note, I would like to have at least the option of passive electronics, with balanced outputs between pickups.

The bass is an ibanez mezzo srmd200k and the pickups are fender avri. I have the stock (active 2 band eq + volume and balance pots) electronics in place, though I am open to any suggestions that would alter this setup (changing the electronics, at least adding a passive/active switch, was the long term plan anyway). I have a nice soldering iron and a penchant for modifications :)
Click to expand...

Hello. To my understanding, the premise is flawed: that, all other things being equal, there is a reliable correlation between a pickup's DCR and its perceived output volume.

But whether or no, in this example not all other things are equal. :)

What is at work here mainly is the position of each pickup relative to the neck and bridge. For the purpose of greater output volume, the P pickup's position is advantageous compared to the J pickup's position, assuming that dominant low frequency output is desirable and a basis for the measure of "output".

Either of these devices might work for you:

Snaxster said:
In a recent thread we discussed something similar:

Who makes a passive Ceramic 5 String PJ set? (Hot output)

I said that a Bartolini AGDB/918-2 could be used. @ctmullins suggested an EMG PA2.
Click to expand...
 
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#4
The best solution is to wind the P pickup with less turns and/or more on the J. That fixes two problems:

1) It gets the pickups' sensitivities in the same ballpark when soloed, and.....

2) It gets their impedances closer, so that when you have both of them on, you're hearing roughly equal proportions of both.

Both of these things involve compromises, but a PJ bass (using 2 pickups that weren't really designed to work welll with each other starts off as a compromise, so you're working with an interesting set of tradeoffs whatever you do.

By the way, the Dimarzio P and J are pretty close in impedance to each other - they're a pretty good set of pickups for a PJ.
 
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#5
micguy said:
Both of these things involve compromises, but a PJ bass (using 2 pickups that weren't really designed to work welll with each other starts off as a compromise, so you're working with an interesting set of tradeoffs whatever you do.
Click to expand...

Thanks, I'm not interested in swapping out the pickups though (nor unwinding the p, which I don't think you were suggesting).
 
#7
Snaxster said:
Hello. To my understanding, the premise is flawed: that, all other things being equal, there is a reliable correlation between a pickup's DCR and its perceived output volume
Click to expand...

If the construction is similar, dc resistance can provide a useful comparison, in my opinion, but regardless, I would wager that if I knew the inductance of each pickup it would demonstrate that the p has higher output than then the j. I have a lot of experience with electric guitar (that is, as opposed to electric bass) pickups and the difference in output between bridge and neck positions is nowhere near what I am experiencing. It may be a factor but it is not the main factor, in my opinion.

Thanks for the active electronics suggestions, I think I'm leaning more towards a solution that would also work with the pickups in 'active mode' (with the active eq engaged). I could add resistance to the p pickup (eg using a trimpot as suggested above), but I'm concerned about changing the tone of the pickup by doing so (cutting high end, muffling it). It may be time for me to look more into treble bleed circuits...
 
#8
Domespeed said:
You could reduce the output of the P with a trim pot. That's the easiest way that comes to my mind.
Click to expand...

That might be the way to go, thanks; my only concern is that it will roll off high end like a volume pot does. Id like to have a 'full on' setting for the p pickup tone-wise. I guess I should look into treble bleed circuits...
 
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#9
focusbob said:
If the construction is similar, dc resistance can provide a useful comparison, in my opinion, but regardless, I would wager that if I knew the inductance of each pickup it would demonstrate that the p has higher output than then the j. I have a lot of experience with electric guitar (that is, as opposed to electric bass) pickups and the difference in output between bridge and neck positions is nowhere near what I am experiencing. It may be a factor but it is not the main factor, in my opinion.

Thanks for the active electronics suggestions, I think I'm leaning more towards a solution that would also work with the pickups in 'active mode' (with the active eq engaged). I could add resistance to the p pickup (eg using a trimpot as suggested above), but I'm concerned about changing the tone of the pickup by doing so (cutting high end, muffling it). It may be time for me to look more into treble bleed circuits...
Click to expand...

You got it. I think that both of those solutions will work in active mode. I know that the Bartolini one is designed to do so.

Related is my next comment in the thread I quoted:

Snaxster said:
With this approach, you don't need to know the point within the Pensa preamp for adding a trim. Instead, you would add the new circuit between the Pensa preamp's output and the jack.
Click to expand...
 
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#11
One way to fix your problem is to put the J pickup by the neck, and move the P pickup closer to the bridge. :cool:

Seriously. You said you had a "penchant for modifications"!

Okay, that may not be practical. The only other option that comes to mind is something active with gain adjustments, such as a MixPot / noll electronic .
 
#12
focusbob said:
That might be the way to go, thanks; my only concern is that it will roll off high end like a volume pot does. Id like to have a 'full on' setting for the p pickup tone-wise. I guess I should look into treble bleed circuits...
Click to expand...

I am quite sure that if you use a 500k or even 1meg trim pot, there will be no audible change in the sound of the pickup.
It will be turned down only slightly anyway.

I did this a couple of times and for me it's good enough :)
 
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#14
run away.gif
Precisely why I like basses with one pickup. Any more than two knobs and I get confused and grumpy,
 
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#16
My favourite mod in PJ combinations in recent times is wiring the P from serial to parallel.

That way, the output of the two pickups becomes very comparable (you can even have the J louder than the P if it's close to the strings).

I didn't mention this before because you like the way the pickups sound now.

Indeed the parallel P becomes very trebly at first. I am using a capacitor of 1nF wired in parallel to the pickup which brings down the resonant frequency to where it was before.
And just turning down the tone knob (or treble if active) a bit will let it sound like before... only lower in volume.

The biggest change in sound of this mod is the combination of both pickups.
So if you like that sound the way it is now this mod probably isn't for you.
 
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#17
The cheapest and easiest solution (tho not necessarily best) is to add a resistor/trimpot. Because it's cheap, I'd try that first, let your ears decide if it works for you. Perhaps you can make that switchable too, to get a "pure" P sound when you want/need.

I'd also consider two volume controls, to fine-tune the mix between the pickups. I always find passive blend a bit tricky to navigate. I think linear taper pots might blend better.

But if you were going to replace electronics anyway, I'd also look into active mixing solutions. But if I understand how exactly they work, they might not allow for an active/passive switch.
 
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