Thanks, @vinnydbass - good point. While I don't have two of the 0.0047, I do have a 0.01. Connect these two in series and I'd get 0.0032.
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Change a pickup's resonant frequency and tone with a loading capacitor
- Thread starter fermata
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Thanks, @vinnydbass - good point. While I don't have two of the 0.0047, I do have a 0.01. Connect these two in series and I'd get 0.0032.
Cool, I was deciding between .0033 and .0039, I found .0047 a touch too dark.
Sorry I'm late to this great discussion. I've been interested in this for a good while. There's an old video on my channel where I use a series of "loading" caps on a 12-throw rotary switch to make a very progressive treble cut for my P bass. Unlike a regular passive tone cut which is for the most part a resistive load and approx 6dB/octave, the caps give a 12dB/octave cut. More like an active filter. It is a really nice mod, but one that has to be tailored to your pickup.
This kinda makes me cringe, since it was shot on an old smart phone in my early days on YT, and has a few technical mistakes as well, but for the most part the info is fine. Also, it's not really anything like a tone-styler. I just named the video like that to get views from google. (Don't hate me. YT actually recommend this sort of thing for new channels.)
I also did something sort of similar with my Project Berocca bass. (Although I didn't make a specific video, IIRC.) Since I have a twin buffer blending set up in it, I have push-pull switches that change the capacitive and z loads on both pickups.
This kinda makes me cringe, since it was shot on an old smart phone in my early days on YT, and has a few technical mistakes as well, but for the most part the info is fine. Also, it's not really anything like a tone-styler. I just named the video like that to get views from google. (Don't hate me. YT actually recommend this sort of thing for new channels.)
I also did something sort of similar with my Project Berocca bass. (Although I didn't make a specific video, IIRC.) Since I have a twin buffer blending set up in it, I have push-pull switches that change the capacitive and z loads on both pickups.
@RobbieK - Great video. Don't apologize for it. Is that modeling clay? Wow, what a great way to hold things for soldering. Loved seeing the resonant frequencies plotted. My inner geek was grinning ear-to-ear.
This is an insightful and educational thread, I've learned quite a bit. Loading caps were never an area I've looked into. 
Threads like this is why I have been lurking around TB for a while. I guess I'll order some caps and start experimenting. More than likely I'll be starting small uf and see what I like. This is of course all subjective to my own taste and needs and I can stop all this pickup swapping.
Awesome! Thank you. What was “every 2nd position” … the resistor pairings?
Does resistor value matter, and what’s it actually doing please?
Got mine soldered in yesterday during re-shield job on the dumpster special aka "P-Yama". It's a 0.0047 uF, hoping it'll make the el-cheapo Wilkinson ceramic pickup sound a bit less harsh.
When I went to watch your video I realized I had book marked it years earlier with the intention of delving into the process.
I have a question for the smart minds here. I really like my mid-range and low-end tone on my bass but my top end is WAY too harsh/tinny. Would I be able to address the undesirable high end characteristics through the application of this approach?
I finally got some alone in the empty house (hooray!) to play without headphones. Trying to side-by-side with the other P-bass. That one is identical (pots, cap, strings) except it has a Fender Player Alnico 5 pickup. The modified ceramic pickup/wiring is definitely better than before, but wouldn't be mistaken for the Alnico pickup. Describing it requires me to use rather meaningless words like "less shrill, more throaty" than before, but still noticeably more cutting than the Alnico. Now with the Alnico tone at 100% and the ceramic at 50%, it's close enough that it might pass.
Overall, it was worth the effort. But did it make a $25 pickup sound like a $80 pickup? Not exactly. That wasn't really my goal, but it's all I have for a side-to-side comparison.
Something between 0.0047 and 0.01 might be a tad better, LOL. At least it's not expensive to try.
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@RobbieK I'm planning on using a push/pull to wiring a tone knob with two choices of caps (well tones in this case). I want to wire in parallel in an attempt to avoid the click when switching like I'm afraid may happen in fralin's wiring diagram. My wiring would be solder point 1 to left lug, hot from volume to center lug, .047 uf standard cap from solder point 1 to ground, and a second cap (.047?) from C1 to ground.
For clarity for lurkers, capacitors in parallel add values (short uncomplicated version), so pushed down the tone knob would be normal (cap1) and then pulled it would be additive (cap1 + cap2)
Based on your experience, what value should I use for the second additive cap? Will I still get a click when pulling up? I was thinking a second .047 uf just to give a rough total ~.1 uf and a wide range. that or a smaller cap to put the total around .75 uf. Mathmatically, the .1uf is more sweeping range, but I know the peaks would change. What are your thoughts?
Edit: for those wondering, you could actually go smaller. If you wired in series, then instead of adding you divide. Google Capacitance and series / parallel. I've used this trick of parallel or series to put the correct capacitance on an air conditioner when I didn't have the right part.
For clarity for lurkers, capacitors in parallel add values (short uncomplicated version), so pushed down the tone knob would be normal (cap1) and then pulled it would be additive (cap1 + cap2)
Based on your experience, what value should I use for the second additive cap? Will I still get a click when pulling up? I was thinking a second .047 uf just to give a rough total ~.1 uf and a wide range. that or a smaller cap to put the total around .75 uf. Mathmatically, the .1uf is more sweeping range, but I know the peaks would change. What are your thoughts?
Edit: for those wondering, you could actually go smaller. If you wired in series, then instead of adding you divide. Google Capacitance and series / parallel. I've used this trick of parallel or series to put the correct capacitance on an air conditioner when I didn't have the right part.
Here's some more info on loading caps to add to the already excellent info provided in this thread.
<br> <br> BassesByLeo <br> Est. 2009 • View topic - The Taming of the Climax/L-1500 Bass
The first post has plain simplified language and easy charts. Shows the effect on amplitude (strength) and resonant freq change for a common range of caps used as loading caps.
In a separate section, he explains and shows what happens when extra resistance is added/subtracted using a common range of pots we use. For example, changing a 250k volume pot to 500k.
In later posts, he goes into the simple-ish math to determine what freqs the caps are effecting.
<br> <br> BassesByLeo <br> Est. 2009 • View topic - The Taming of the Climax/L-1500 Bass
The first post has plain simplified language and easy charts. Shows the effect on amplitude (strength) and resonant freq change for a common range of caps used as loading caps.
In a separate section, he explains and shows what happens when extra resistance is added/subtracted using a common range of pots we use. For example, changing a 250k volume pot to 500k.
In later posts, he goes into the simple-ish math to determine what freqs the caps are effecting.
I've had pretty cool results on PJ basses by installing Rick style chokes on both pickups. Except I'm using larger value caps than Rickenbacker would so as to only remove a small amount of low end from either pickup.
When both pickups are on full volume, I can filter out a small amount of low end from the bridge pickup (again not as much as rickenbacker, im using 0.022uf in series with the bridge pup), the result being that I preserve the PJ tone without losing the volume of the solo'd Precision pickup. Very useful.
When both pickups are on full volume, I can filter out a small amount of low end from the bridge pickup (again not as much as rickenbacker, im using 0.022uf in series with the bridge pup), the result being that I preserve the PJ tone without losing the volume of the solo'd Precision pickup. Very useful.
@vinnydbass, it's an underappreciated idea for other two-pickup basses, especially for those who like Ric tones. Minor point: better not call it a "choke" as that word is already taken! 
[For someone who *does* want to approximate the effect of the Ric bass blocking cap (I don't know the real inductance numbers so these are approximate):
If I'm not mistaken, you'd want to keep the product LC the same (the inductance of the pickup x the capacitance of the bass blocking cap). So if the Ric bass blocking cap is .0047uF and the inductance of the Ric bridge pickup is 4H (measured at, say, 1kHz), and the J bridge pickup is 2.8H @ 1kHz, then the cap you would use on the J to approximate the same effect would be about .0047 * 4/2.8 = about .0068. Someone please correct me if I'm wrong.]
[For someone who *does* want to approximate the effect of the Ric bass blocking cap (I don't know the real inductance numbers so these are approximate):
If I'm not mistaken, you'd want to keep the product LC the same (the inductance of the pickup x the capacitance of the bass blocking cap). So if the Ric bass blocking cap is .0047uF and the inductance of the Ric bridge pickup is 4H (measured at, say, 1kHz), and the J bridge pickup is 2.8H @ 1kHz, then the cap you would use on the J to approximate the same effect would be about .0047 * 4/2.8 = about .0068. Someone please correct me if I'm wrong.]
@vinnydbass, it's an underappreciated idea for other two-pickup basses, especially for those who like Ric tones. Minor point: better not call it a "choke" as that word is already taken!
[For someone who *does* want to approximate the effect of the Ric bass blocking cap (I don't know the real inductance numbers so these are approximate):
If I'm not mistaken, you'd want to keep the product LC the same (the inductance of the pickup x the capacitance of the bass blocking cap). So if the Ric bass blocking cap is .0047uF and the inductance of the Ric bridge pickup is 4H (measured at, say, 1kHz), and the J bridge pickup is 2.8H @ 1kHz, then the cap you would use on the J to approximate the same effect would be about .0047 * 4/2.8 = about .0068. Someone please correct me if I'm wrong.]
At the frequency where that capacitor operates, the dc resistances are involved in the calculation, so it’s not that simple. I choose based on Spice simulations - I characterize the impedances of the pickups (which are a bit more complicated than you might think), then I simulate the whole circuit to figure out a value that I like.
It's been in use as a generic EE term to describe an inductor for the better part of a century.
The term choke is (and has been) used for an inductor,l for a very long time, but the part in question is a capacitor.
