The basic flaw in the p-bass

[dkelley]

I have never heard any boost in lows or mids by rolling down the tone knob on any passive bass. But then again, I don't like choking the life out of my bass tone.

Then read up on filters. Passive pickups have a resonance frequency which is frequently louder than the rest of the audible range. That resonance frequency is lowered by adding capacitance to the circuit. It can also be altered by adding inductance.

 

[thiocyclist]

Then read up on filters. Passive pickups have a resonance frequency which is frequently louder than the rest of the audible range. That resonance frequency is lowered by adding capacitance to the circuit. It can also be altered by adding inductance.

THANK YOU

 

[isher1992]

That resonance frequency is lowered by adding capacitance to the circuit. It can also be altered by adding inductance.

This probably explains why I don't hear it, because my P-bass uses a 0.022 uF cap, which isn't that much.

So, I guess in theory by using the RC filter, if the sweep range happened to catch and match the resonant frequency of the pickup, that would explain why it would sound louder in that position of the sweep, because it would be cutting anything above it, if that makes any sense.

The easiest way to find out would be to calculate the frequency of an RC filter for whatever the resistance of the pot is in the position the boost can be heard, and see if that matches the resonant frequency of the pickup.

 

[thiocyclist]

My cap is .047 uF I believe, I suppose that could be part of it. I would think the effect is still there but less dramatic.

 

[chuck3]

It retunes the resonant frequency and that's why you can hear a boost when the resistance between the cap and circuit is minimal. I'll stop believing it when I stop hearing it. And I thought like you did for years until a year or two ago I began hearing this.

I play with the tone 100% rolled off a lot and I like it there. I never thought about it the way you are saying, but maybe that's why. I'm apart from my P basses for a week or so though but I'll try it next time.

 

[David Jayne]

I play with the tone 100% rolled off a lot and I like it there. I never thought about it the way you are saying, but maybe that's why. I'm apart from my P basses for a week or so though but I'll try it next time.

It really does work. I usually run the Tone on my P at about 50% . But when the music gets funky my default style is a busy muted 16ths (Rocco wannabe) thing and I have found that rolling the Tone way back causes this low mid bump which really makes it thump and pop in the mix. Works great on a P bass, not sure about others.

 

[thiocyclist]

Hm, the critics have gone silent.

This effect is on all passives I've tried it out (P Bass, Jazz, Ric). I don't know what it would do on a Stingray but if it had a passive tone control added perhaps it would be the same.

 

[bucephylus]

This is what amplifiers are for. They make things louder without giving the user tendinitis.

Playing hard and playing softly will result in a different timbre.

The different combinations of playing hard/soft with high/low action will result in different timbres, as well.

One isn't inherently better than the other. They're just different flavors.

Gee thanks! After playing for 45 years I was starting wonder what the amplifier was for. Glad you cleared that up for me.

 

[scotch]

Hm, the critics have gone silent.

...

Or grown bored & moved on with their lives? Seriously, this thread entered dead horse territory pages ago.

 

[taurus1]

Hm, the critics have gone silent.

This effect is on all passives I've tried it out (P Bass, Jazz, Ric). I don't know what it would do on a Stingray but if it had a passive tone control added perhaps it would be the same.

has anyone scoped this and put it on a graph to point out which frequencies are being "boosted" by pickup resonance, when manipulated by a passive filter?

 

[taurus1]

Hm, the critics have gone silent.

This effect is on all passives I've tried it out (P Bass, Jazz, Ric). I don't know what it would do on a Stingray but if it had a passive tone control added perhaps it would be the same.

ok, I just went and plugged in.
I don't think you're nuts anymore , there is a very slight, and I mean slight, "boost" in the low mids. hardly perceivable but it's there, I guess I never noticed before because I rarely turn the tone knob down past halfway.
it's not what I would describe as a mid boost though, it's lower than midrange on my bass.
it's not something I would deem that useful (for me at least) because it's so subtle and at a frequency too low to add articulation or anything useful to me at least.
is it actually the pups resonant frequency being boosted, or is it the capacitors performance causing it?

 

[thiocyclist]

Or grown bored & moved on with their lives? Seriously, this thread entered dead horse territory pages ago.

On the other hand, you're still reading and posting.

has anyone scoped this and put it on a graph to point out which frequencies are being "boosted" by pickup resonance, when manipulated by a passive filter?

I haven't but it'd be cool to see it. It's got to be circuit dependent but what I hear is low mids.

 

[thiocyclist]

is it actually the pups resonant frequency being boosted, or is it the capacitors performance causing it?

It's the whole circuit working together. It probably varies if you change any component of the circuit. The cap is retuning the pickup within the rest of the circuit.

 

[PawnBass]

You get more bass and less mids, now accurate mids, if a bigger cap is put in. I upped mine x5.

 

[johnk_10]

there's a slight to moderate bump at the pickup's resonant frequency. this chart shows what generally happens with a passive tone control with passive pickups (with different cap values rolled off). of course, each pickup's wind and resonant frequency will differ.:

 

[David Jayne]

However, if it's a passive circuit, there is no way anything can be boosted at all. Only cut, making room for other frequencies.

See, the problem is that in spite of how impossible it sounds, it does in fact happen. It's a resonance, and it results in an actual peak. In a passive circuit. Strange but true.

 

[David Jayne]

It's the whole circuit working together. It probably varies if you change any component of the circuit. The cap is retuning the pickup within the rest of the circuit.

This. It's an RLC circuit. These have a resonant peak which is determined by the values of the components.

 

[dkelley]

has anyone scoped this and put it on a graph to point out which frequencies are being "boosted" by pickup resonance, when manipulated by a passive filter?

Yes, it's been done before. I'm on my phone in bed LoL right now but there are published documents on the web and any pickup manufacturer or filter designer and any REAL audio engineer (many claim to be but aren't actual engineering graduates) can discuss the math involved. I used to be able to but have long forgotten the details.... I prefer to just play and trust what I learned without myself with how and why like when I was younger in university. ERM... yea sorry I'm tired lol

Anyhow... my boring monologue aside.... Passive filters are resonant too just like active filters but less efficient and versatile. One simple rule of ANY filter including passive is that a resonance frequency can be changed by adding components.

I'm not talking about making the pickup resonance louder or softer at the same frequency, I'm talking about changing the center frequency (pitch/note) of that resonance. Greater capacitance added will lower the frequency more. Less capacitance lowers it less. It's pretty cool!

Adding a pot changes the circuit dramatically so you don't really get the resonance being loudly audible and lowered in pitch until the tone control is turned nearly or fully off, which puts the capacitor fully in the circuit as a true filter.

 

[dkelley]

I see others beat me to it!

Glad I helped shine a light on tone controls and passive pickups.

PS... Crappy pickups tend to have little or no audible resonance peak which is why they're so dull to listen to. Active pickups also or at a very high frequency but for different reasons.

 

[taurus1]

Yes, it's been done before. I'm on my phone in bed LoL right now but there are published documents on the web and any pickup manufacturer or filter designer and any REAL audio engineer (many claim to be but aren't actual engineering graduates) can discuss the math involved. I used to be able to but have long forgotten the details.... I prefer to just play and trust what I learned without myself with how and why like when I was younger in university. ERM... yea sorry I'm tired lol

Anyhow... my boring monologue aside.... Passive filters are resonant too just like active filters but less efficient and versatile. One simple rule of ANY filter including passive is that a resonance frequency can be changed by adding components.

I'm not talking about making the pickup resonance louder or softer at the same frequency, I'm talking about changing the center frequency (pitch/note) of that resonance. Greater capacitance added will lower the frequency more. Less capacitance lowers it less. It's pretty cool!

Adding a pot changes the circuit dramatically so you don't really get the resonance being loudly audible and lowered in pitch until the tone control is turned nearly or fully off, which puts the capacitor fully in the circuit as a true filter.

I'm learning something, this thread took a turn for the better.
I'll be driving through Maple Ridge in about 8 hours on my way to play golf at Sandpiper in Harrison Mills.