Modifying the sound of a p pickup

[Aspine]

Hi all,

I've been using a revival sd curlee bass for a while now which I really like. It has a Dimarzio model P in it which I sometimes find too hot, i would like to modify it so it sits better in a band mix, rather than cut through so much. The bass is short/medium scale with a reversed P pickup closer to the bridge than a traditional precision bass. Being this close to the bridge, and being a model P, there is a huge amount of high midrange. It also has a series/parallel switch, of which I prefer series for the high frequency cut off, especially with the volume rolled back a bit. I also like parallel for the lower (smoother) output and flatter response but not for the highs.

As I would like to get a more traditional or balanced sound I considered swapping it for a vintage style pickup like the seymour duncan SPB-1, but I wonder if it will make much difference in this position and if I could just get the current pickup more balanced with different electronics. Currently has 500k volume and tone pots and a 203 (.022uf?) capacitor.

I would like to hear your experience, is it possible to reduce the output and high/mid response with for example 250k pots and a higher value capacitor or will a different pickup (and electronics) get me closer?

 

[sikamikanico]

Based on that description, I think you might like the sound of the pickup in parallel + use loading caps and maybe resistors to shape the resonant peak to taste.

switching the pickup in parallel moves the resonant peak up to a higher frequency, making the pickup sound flatter and brighter. A loading cap - which is a very low capacitance cap, in the range of hundreds and thousands pF (say 470-4700 pF) - would shift the resonant peak back down, but in discrete incremental steps. By picking the right capacitor value (or putting them on a selector switch) you could dial in the sound exactly at the frequency you like best.

You could also tailor the sound with resistors to tame the resonant peak, but you can also do that with a tone control pretty well. A 250K tone might help if you find the bass too bright with a 500K pot, but turning down 500K a little does already get you the 250K sound.

The value of the tone pot cap (the .02 uF one) doesn't kick in until you roll of your tone over about 2/3 off, so it probably won't matter much whether you change it or not, but you could mess with that too…

These passive components are very cheap (shipping costs more), and allow you to experiment with simple tools. Indeed, you can audition the caps with simple alligator clip leads. You may not even need to open up the bass if you have an instrument cable where the body of the jack can be unscrewed and pushed back to reveal the wires.

all other mods are more expensive, and results less predictable. I usually do my changes from simplest and cheapest to most expansive ones. Also, you could experiment with different strings, they have a major impact on the sound…

 

[Ricky Rioli]

I changed a Dimarzio Model P for a stock-wound Fralin . The difference was enormous.

The Model P worked really well with Daddario Pro Steels, which have plenty of top and bottom.

When I changed from steels to flats, though, there was no balance, just too much of a good thing and nothing else. With the Fralin I get a lovely open sound with plenty of bite (which is then controlled by the tone knob)

 

[DDawg]

Everything recommended above is great advice, but I think swapping the Model P for a vintage style P-pickup will get you closer to what you're after. Lots of great pickups to choose from including much less expensive ones as long as they're Alnico 5 and not over-wound. I've had similar experiences with the Model P, Split P and other ceramic magnet pickups just not delivering the P-bass tone I was after, but they sound great on a fretless.

 

[Derek Kay]

Post#2 gave the best solution for me.
No real cost, just time finding the right pots and components.

I think early DiMazio PUs had a reputation for harshness, but they're now classic.

If there is clearance, then lower the PUs and/or poles.
Adding extra shielding often helps if you're shifting everything.

 

[Aspine]

Thank you for the replies, that's some really good advice. I've never heard about the loading cap thing but I read into it and it seems like a very useful and easy mod. Im going to experiment with capacitors and a 250k volume pot to see if I can get it to taste, it's indeed a small investment and some different value parts could still be useful if I later decide to swap the pickup.

Just wondering how this works with resistors, if I understand correctly the loading cap acts as if you have a second tone control fixed at 0% with a higher cut off frequency than the tone control already there, so would the resistor (in series with the cap?) act as a tone pot rolled off to taste, letting a small amount of the high frequency still through?

 

[sikamikanico]

Just wondering how this works with resistors, if I understand correctly the loading cap acts as if you have a second tone control fixed at 0% with a higher cut off frequency than the tone control already there, so would the resistor (in series with the cap?) act as a tone pot rolled off to taste, letting a small amount of the high frequency still through?

good guess, but not quite… you're correct until the last comma, but the effect on sound is the opposite*

if you put a small resistor in series with the loading cap, it dampens the resonant peak. One thing that can happen with loading caps is that the sounds can get a little peaky (depends on other factors), so a small resistor can help take it down a notch. I currently have a 25k pot in series with the cap switch, and it works pretty well. I'd consider an even smaller pot. But, what also works similarly is a tone pot or a variable resistor (rheostat; basically a tone control without a cap) used at the top of the normal tone pot range (250k or 500k or whatever). They all produce a similar effect. So if you keep a traditional tone control, that should be enough…

*this is also what happens with a tone control… sound is often not darkest with tone control at 0, but more around 1… at 0, the new, lower resonant peak emerges, which can sound quite middy (depending on stuff like cap value)… reintroducing some resistance by moving the pot a smidge dampens the resonant peak…

 

[Deleted member 271037]

Normally when comparing P-bass pickups I would say the differences are marginal. In most cases simply changing the strings would make a LOT more difference! But that's assuming we are comparing two classic "vintage voiced" alnico P-bass pickups.

The DiMarzio Model P is a VERY different sounding pickup. Extremely hot output, extremely aggressive mids. It still sounds like a P-bass (as long as the pickup is installed in the P-bass position) but it's more like a "P-bass on steroids".

This is one of those cases where a pickup change will actually make a difference. Good or bad? That's purely a matter of personal taste.

A vintage style pickup like the SPB-1 will give you significantly lower output and a warmer tone with more "relaxed" mids. A P-bass will always be rather mid-forward though, but a vintage-style pickup less so than the Model P.

The SPB-1 is a great sounding pickup btw. A classic vintage P-bass tone for a reasonable price. There are lots of other options too of course but they're mostly tiny variations of the same theme. I mean they're all basically aiming for the same kinda tone. If one "vintage voiced" P-bass pickups sounded vastly different from other "vintage voiced" P-bass pickups it wouldn't actually have the classic, vintage P-bass tone, would it?

As for your pot/cap values...

For the classic P-bass tone I would use A250k (log/audio taper) for both volume and tone. Using B250k (linear) pots will make the tone control behave more like an on/off switch (although I guess linear could work for volume, it's a matter of taste).

Using a 500k volume pot can be ok with the Model P but it's far too bright/harsh for my taste on P-basses with "vintage" alnico pickups. Some people like it, but unless you want a very bright tone with lots of "zing" and string noise you will most likely be better off with A250k for both pots.

Personally I would definitely replace the .022 uF cap with .047. In my opinion the tone control doesn't really do enough on a P-bass with a .022 uF cap. In my world .022 is for humbucker equipped guitars. A .047 uF cap will give you a MUCH wider range of tones on a P-bass. I often go a step further an use a .068 uF cap on my P-basses, for a slightly darker/fatter tone when rolling off the tone. Vintage Fenders used .100 uF but that gets too dark, too fast, for my taste

The .022 uF cap is actually the dealbreaker for me with the EMG GZR solderless kits. I honestly don't understand why EMG use a .022 uF cap in a pickup kit they market VERY heavily as having an authentic "vintage" tone. Sorry EMG, but that's just not the case, unless you throw the wireless kit in the thrash and wire everything "old school" with vintage correct component values (the GZR pickup itself is very nice though, very similar to the SBP-1 but with SLIGHTLY more mids).

 

[Zooberwerx]

Would something like a ToneStyler be of any use in this situation?

Riis

 

[Aspine]

Based on that description, I think you might like the sound of the pickup in parallel + use loading caps and maybe resistors to shape the resonant peak to taste.

switching the pickup in parallel moves the resonant peak up to a higher frequency, making the pickup sound flatter and brighter. A loading cap - which is a very low capacitance cap, in the range of hundreds and thousands pF (say 470-4700 pF) - would shift the resonant peak back down, but in discrete incremental steps. By picking the right capacitor value (or putting them on a selector switch) you could dial in the sound exactly at the frequency you like best.

Thought I'd share the results. So I ordered a range of caps from 330 pf to .1uf and alligator clips. I started out experimenting with hooking up caps in the control cavity. First the loading caps for the "tone at full sound" and then adding different higher value caps in series for the "tone rolled off sound".

It was a bit of a compromise to find a good fit for both the series and parallel modes bit I ended up liking the sound best with the 470pf loading cap and a .033uf tone cap so I soldered them in. It turned out to be a really cheap and easy mod and I way prefer the sound now, I didn't bother swapping pots.
The parallel sound is less bright making it way more useful, in series it is still a bit agressive but rolling off the tone now makes a great deep sound.

I might still try a different pickup eventually but for now I'm really happy with the result so thanks again!