theory question about p-bass pickups

[FunkyKikuchiyo]

I know I already had a thread about p-bass pickups a while back, but this is a bit different, so bear with me...

I was looking at the specs at the SD website today, and I realized that their vintage P-bass pickup has a resonant peak measured at 11.6 kHz. This is way higher than I expected since most pickups seem to be between 5-8 kHz, at least according to their charts, J-bass pickups are around 9. P-Bass pickups always had more of a growl, so by my understanding of how resonant peak will play out in final tone, this seems a little counter intuitive. Of course it isn't the only thing important in forming the voice, but this stuck me as odd. I suppose they don't sound midrangey, having a high RP does tend to make a pickup more transparent to my ears, but that doesn't sound to me like a good explanation.

So, theory guys..... any ideas 1) why is it so much higher despite having a good amount of windings, and 2) why it doesn't sound (to me at least) like a high RP pickup?

Thanks for letting me waste your time.

[FunkyKikuchiyo]

No one seems too interested in this, but after some research I have a modest theory...

All of the SD readings are a bit on the high side, and if you go down the list there are lots of occasional outliers in the data set. It seems possible that if a pickup has a resonant peak at 4 kHz, it would also have peaks at the relating octaves, so also at 2 kHz and at 8 kHz. So, if you fudge the numbers and work with different octaves, you can put the p-bass at 5.8 while the j-bass is at 5.1 kHz, which seems a little more equitable to me. I'm using the figures for the respective vintage models, by the way.

Can anyone who has measured resonant peak confirm/deny this modest theory? If it is valid, would it make sense that a better comparison of resonant peak would be to adjust numbers to all exist in the same octave? It obviously wouldn't be a better figure than the actual resonant peak, but still useful I'd think.

[David King]

What i've read recently is that the higher resonant peak will actually sound a bit duller because our ears don't hear so well up there. If you put a peak in at 3-4kHz it will sound bright as hell because that's the annoying frequency that we can all still hear pretty well (most of us can anyway).
I'm not sure how well folks can detect pitch above 6k. It eventually starts sounding like white noise. I should read up on that.

http://www.noiseaddicts.com/2009/03/...-hearing-test/

[FunkyKikuchiyo]

Thanks for the link, David!

I've heard that about high peaks, too. That is why active pickups have such a flat response, they are wound so lightly.

But, look at the figures on the SD site: Seymour Duncan/Basslines

There are some real anomalies. It puts a Seth Lover neck model at 8.14 kHz, a five-two tele neck pickup at 10 kHz, a vintage '54 lead tele bridge at 9 kHz... those all sound too high to me.

On page 3 of this PDF, there are some numbers that seem to make much more sense and be in a range that is consistent with what (I think) I know about pickups. http://www.blueguitar.org/new/misc/gtr_lemme.pdf

One thing that makes that last one so plausible to me is that he is calculating for other capacitance.

[Joe Gwinn]

What i've read recently is that the higher resonant peak will actually sound a bit duller because our ears don't hear so well up there. If you put a peak in at 3-4kHz it will sound bright as hell because that's the annoying frequency that we can all still hear pretty well (most of us can anyway).
I'm not sure how well folks can detect pitch above 6k. It eventually starts sounding like white noise. I should read up on that.

Can you hear THIS? Musicians high frequency hearing test | NoiseAddicts music and audio blog

I heard nothing through the website test, but I can certainly hear 8 KHz through a stereo driven by an oscillator, so I would take the webtest with some salt.

[David Schwab]

That is why active pickups have such a flat response, they are wound so lightly.

That's a bit of a myth. Some active pickups might use low impedance coils, but for instance EMGs do not. They are wound like regular passive pickups.

The Duncan active bass pickups sound more low Z in comparison.

[David King]

Joe,
I think what you hear mostly seems to depend on your sound card and speakers. I could hear 8 and 10kHz but above that the sound of my hard drives and fan were too loud for the tiny built-in G4 tower speaker.

I can usually hear 16kHz if it's a clean sin wave but a lot of these software oscillators seem to modulate so it's more like a sawooth or square wave.

[Joe Gwinn]

Joe,
I think what you hear mostly seems to depend on your sound card and speakers. I could hear 8 and 10kHz but above that the sound of my hard drives and fan were too loud for the tiny built-in G4 tower speaker.

I can usually hear 16kHz if it's a clean sin wave but a lot of these software oscillators seem to modulate so it's more like a sawooth or square wave.

My computer is pretty quiet, and I have external powered speakers connected to the computer (a PPC Mac).

Anyway, my point was that the web test may be invalid, measuring the computer et al, not your ears.

[David Schwab]

I could hear 8 and 10kHz but above that the sound of my hard drives and fan were too loud for the tiny built-in G4 tower speaker.

Oh that thing is awful! You need to add some speakers to that G4. The audio system is actually very nice sounding.

[David King]

I know, I used to have the headphones out connected to a 1400W stewart amp and a 15" bass cab. When I got new mail the whole neighborhood knew.

[Mike Sulzer]

But, look at the figures on the SD site: Seymour Duncan/Basslines

I believe the SD resonant frequencies are those of the pickup alone, that is, without the effect of the cable capacitance. The actual resonances would be significantly lower. How much lower is a function of the pickup and the cable.

A resonance at frequency f does not imply resonances at harmonics or sub-harmonics. This is a pretty much just an LCR circuit.

Making a resonance too high in frequency puts it above the response of the (bass or guitar) speaker. It also puts it where the instrument might have less output and where some listeners might not hear so well. But the primary effect is the speaker. Both bass and guitar speakers are woofers and the responses fall very fast above some frequency, faster than can be made up for with a low Q resonance. For example, check the Eminence web site for lots of plots.