Tone management with hot P bass quarter pounder

[Brewsbrother]

I built a short-scale P bass with a SD hot Quarter Pounder, 500k pots, 0.067uf cap, and flat-wounds. I'm finding that the tone is too dark, deep,, and boomy when I play at jams, even with the tone set at 10. Any suggestions for brightening it up a tad?

 

[jeremy]

welcome to the forum!

how short scale? the duncan qp p bass pup is a thick loud pup for sure, but ive had gotten great tones with it in 34" scale basses. in a 30" scale, it could be dark depending on position of the pup, flats arent helping at all

 

[Seashore]

Try lowering the pickup a bit. Roundwound strings might also work well. I don't know how the "de-mud" mod would work on a bass but that might be another option, there are a few threads here on it - a tone cap in series with the pickup output. Or, put an EQ pedal first in the chain and shape to your heart's content.

 

[Chistopher]

You put a hot pickup into a short scale bass with flatwounds. All 3 of those things are gonna make your bass sound darker. Maybe put some roundwounds on it and it might be manageable, but I'd say it would probably be best to get another pickup entirely.

 

[Mincer]

Short of getting an EQ pedal to suck out some of those frequencies, I think it comes down to the pickup. Bass pickups generally get darker as they get hotter and louder. I'd go with something that is more vintage, like the Vintage P-Bass. Short scale, the tone cap and flats are just making it worse.

 

[jeremy]

i think the de-mud mod actually is a good idea.

is there a reason youre using flats?

 

[Clint 55]

You put a hot pickup into a short scale bass with flatwounds. All 3 of those things are gonna make your bass sound darker. Maybe put some roundwounds on it and it might be manageable, but I'd say it would probably be best to get another pickup entirely.

This. You combined all your spex to maximize darkness. Start by putting roundwounds on. If that isn't enough, get a cooler pickup.

 

[idsnowdog]

Try a 1 meg volume pot.

 

[jmendoza]

Easy fix,; drop the tone capacitor to half that value,; ,033 to ,022 uF
That will brighten it up and give some more tone control range.
I just did this with my Squire Bronco bass using the SCBP-1 vintage 1951 P Bass pickup from Seymour Duncan. .

 

[Chistopher]

Tone cap will not effect the signal with the tone control at max.

With rough SPICE calculations, a 500k pot at 10 with a 67 nF cap will have a corner frequency of no lower than 20kHz, with a 22 nF cap it will have a corner of 70kHz. Neither of those will be audible to humans.

Edit: misplaced zeros

 

[jmendoza]

Sorry to burst your calculations expectations but the tone cap does have an effect throughout the entire range of the tone pot. The cap is in series with the resistor/pot, so it is always part of the circuit and has an effect, regardless of the pots resistance. All you have to do is listen to the bass while turning the tone pot to its extremes; it is quite noticeable. If it had no effect, then I would not have noticed the change, which BTW, was significant. My problem with the bass, as stated above was I had too much high frequency roll off, even with the tone at maximum, so decreasing the capacitor value gave me less high frequency roll off at maximum tone(full Cw) The math below is backed by actual results; plus, your ears don't lie:

BTW Given T=RxC and 1/T=Freq
Example 250K (pot) x .022uf =.0055 seconds (T) 1/.0055= 182 Hertz, which is well withing the range of human hearing.

Recently, I added a tone control to my Herb Ellis ES-165, using a 500K audio taper pot and started out with a .015uF, which worked but I wanted more bass response so a .033uF was a better solution as it extended the range of the tone pot perfectly.

I like to select a capacitor value that gives good tone response throughout the range of the tone pot's rotation. If all the control is at one or the other extreme of the tone pots rotation, then you need to select a smaller, or larger cap to open up the effective range of the tone control.

 

[Chistopher]

The math below is backed by actual results; plus, your ears don't lie:

BTW Given T=RxC and 1/T=Freq
Example 250K (pot) x .022uf =.0055 seconds (T) 1/.0055= 182 Hertz, which is well withing the range of human hearing.

Hey man, if you look at your result it should be obvious that your numbers are either wrong or being interpreted incorrectly. In this case it's a mix of both. Your equation is in the time domain and is used for transient analysis. You need the 2pi to put it in the frequency domain, which yields 29 Hz. For either equation, what do you think those numbers represent? How does the math back your results? You didn't mention in your post. 182 Hz is the low range of a woman's voice, and 29 Hz is the fundamental of the low B on a bass.

The bass changes at the extreme end of a tone control because the tone cap is no longer isolated from the pickup, so it will lower the resonant peak. One of the few ways a passive system can "increase" a frequency's amplitude. It's also why the Woman Tone only happens at exactly 0 on the tone control.

I always pick a capacitor for each individual guitar, because the pickup's and the guitars internal wiring's LC values play a huge part in how the tone control operates.

I always enjoy talking about circuits, but don't challenge me if you don't understand the fundamentals. It is true that your ears don't lie, but that says nothing of what lies between them.