Bass frequency/waterfall plots: what they mean to rigs

[svtb15]

thanks.. wow that is alot smaller than i thought it might be.. cool

http://www.talkbass.com/forum/showthread.php?t=508659

 

[greenboy]

Incidentally, over the years I've seen tons of dataplots from bass guitar but they are often not representing but a single moment in a note's envelope, which is pretty much useless unless you have a whole bunch of those slices to compare. Actually I've seen more waterfall plots of bass guitar notes way back in the early days of digidesign sample editing - pre-internet - than I have in recent years.

But one standard-scale-length bass platform really sticks in mind as one that can actually make a lot of fundamental on lower pitched strings and their lowest notes, and that was a Basslab L-Bow:

It seemed uncanny how little regard for string gauge one had to have to downtune one of these puppies and not only have a lot of articulation - from plenty of mid- and high-partial content - but also a big honkin' fundamental.

 

[Hoover]

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If I'm reading this correctly, the amplitude of the 1st harmonic is swelling to a fairly high level a full 2.5 seconds after the note is struck?

While an evolving envelope doesn't surprise me for a stopped note on a fretless fingerboard, the fact that it's that delayed is pretty enlightening...there, my friends, is your "MWAH"!

 

[OldogNewTrick]

cool thread !

thanks Charlie and greenboy !

Ever been a sucker for this!
I posted this pic sometime ago, cant find the post anymore tho.

IME it is extremely difficult to produce consist results. Hard as I tried to plug exactly at the same position, with the same attack and obviously settings, the plots showed a lot of variance.

One thing consistent tho was that every plot showed the fundamental to be of approx. the same energy as the 1st harmonic.....

Again congrats, Charlie, cool plots, never could get them as nice as yours...

 

[greenboy]

If I'm reading this correctly, the amplitude of the 1st harmonic is swelling to a fairly high level a full 2.5 seconds after the note is struck?

While an evolving envelope doesn't surprise me for a stopped note on a fretless fingerboard, the fact that it's that delayed is pretty enlightening...there, my friends, is your "MWAH"!

Hey Hoover,

Yeah, that's some of it. But fretted basses exhibit some content changes too. Bass bodies and actually the entire string suspension system they provide actually act as acoustic filters and transformers of the content provided by string vibration. They can't CREATE energy, but they can by way of various resonances soak energy in various ranges or excite it in others.

 

[seamonkey]

One option for sound sources is sample libraries.
There's a free (donationware) direct recorded bass lib here:
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"DirectBass"
Several articulations, and pickup combinations.

 

[4Mal]

Good point. On further review, I should probably just borrow a fretted Fender to keep the methodology completely consistent.

when ?

you got your choice of ...

MIA Active Deluxe with rounds, string through
MIJ 62 RI Audere, rounds, Vintage Vibe split coils
MIJ 62 RI Duncan SJB1's TIJF's
MIJ 75 RI Vintage Vibe slight Overwind, Chrome flats

 

[greenboy]

One of several samples from this:

It's a time-averaged sample of a low B (B0). Think of it as taking all the waterfall data and removing the ability to see what envelopes individual partials make over a period of time, instead just showing the AVERAGE levels of each during that same period of time.

 

[greenboy]

Here's another from the BASSLAB L-Bow, this one of low F#0 - a fourth below low B:

While the 2nd, 3rd, and 4th partials are all more powerful than the 23.12 Hz fundamental, it still makes a huge one considering how much upper content this bass provides even for these low pitches.

 

[davio]

Impressive, but what do you play it through that'll reproduce the 23.12 Hz fundamental?

 

[zac2944]

OK GB, how exactly would one use this data in cab design? If I may be so blunt, what exactly are you getting at here.

To me these plots illustrated just how much of a low bass note's energy is contained within the 2nd fundamental and above. Therefore, if your cab can accurately produce everything in this area you should have a pretty true sounding low end. OTOH, if you want to reproduce the fundamental it won't be easy. For something like that BassLab low B, forget about it.

It would be interesting to see the harmonic content of some higher notes on bass. Looking at the BassLab low B there isn't much 3.5k and from Passinwind's graphs things die off even earlier. This could shed some light on the mid vs. tweeter conversation.

 

[greenboy]

Impressive, but what do you play it through that'll reproduce the 23.12 Hz fundamental?

To reproduce it in the same proportion as the instrument can deliver, you need speakers and power above and beyond what you can find in commercial Basscabdom - regardless of manufacturer claims.

This is the conundrum. How far do you go in design (and schleppage the player has to deal with) just to reproduce accurately the fundamental of a low B0 - let alone a F#0 - at performance levels? And how much further would you then go to compenate for the ears' horrible lack of sensitivity at lower frequencies? See the Equal Loudness Contour to see how many more dB you need at 30 Hz to seem as loud as an equal signal at 100 Hz.

 

[davio]

Are you saying this is the next step for installed venue PAs?

 

[greenboy]

{...} OTOH, if you want to reproduce the fundamental it won't be easy. For something like that BassLab low B, forget about it.

Actually there are quite a few dB between the fundamental and the octave overtone, even so. But to reproduce that same balance between the two you need a system that is essentially FLAT throughout the bass regions - and that's BEFORE you attempt to compensate for the ear's lack of sensitivity down there ; }

It would be interesting to see the harmonic content of some higher notes on bass. Looking at the BassLab low B there isn't much 3.5k {...} This could shed some light on the mid vs. tweeter conversation.

I've got some samples of higher notes. But realize that any sufficiently flexible string has the potential to make say 16 to 32 partials from the natural overtone series. So,

B0: 30.87 Hz
* 16 = 493.2 Hz
* 32 = 987.84 Hz

C5 (24th fret of a six-string bass's C string): 523.26 Hz
* 16 = 8372.16 Hz
* 32 = 16744.32 Hz

Any content above the open strings' 16th-32nd partial figures partials is string and instrument noise, and inharmonics from the string not being ideally flexible; it tends to also act like a bar.

And as you go up the neck closer and closer to the bridge, there tends to be less true natural overtone content as for the length of the sounding string there is less flexibility. You could easily set a limit for useful content for a high C string to 8000 Hz and not be missing anything from the string's natural harmonics, really. And that's on a really efficient string platform like the Basslab instrument. 5000-6000 Hz is more than enough for most instruments.

 

[greenboy]

Here's a six-string Basslab bass's open high C3 (130.81 Hz):

 

[greenboy]

Here's a breakdown of the natural overtone series I posted in another thread awhile back...



Any note is comprised of a fundamental and the harmonics derived from it. This is called the natural overtone series. With an electric bass string the overtones come from vibrations of subdivisions of the string. Each overtone is a multiple of the fundamental frequency.

If that fundamental is low A below a five-string's low B (27.5 Hz), the first few harmonics are:

27.5 * 2 = 055.0 Hz (octave up; open A on standard bass)
27.5 * 3 = 082.5 Hz (1 octave and a perfect fifth up)
27.5 * 4 = 110.0 Hz (2 octaves up)
27.5 * 5 = 137.5 Hz (2 octaves and a major 3rd up approximately)
27.5 * 6 = 165.0 Hz (2 octaves and a perfect fifth upapproximately)
27.5 * 7 = 192.5 Hz (2 octaves and a dominant seventh up approximately)
27.5 * 8 = 220.0 Hz (3 octaves up)
...and so on

The characteristic tone of any instrument is defined by the changing balance of various overtones that wax and wane during its duration. An electric bass's lower notes typically have less fundamental energy than the amount of energy the next few overtones above it display. The reproduction of this note through an amplification system further changes this distribution/balance, and due to psychoacoustics I won't get into here, it's not necessary that the fundamental be fully represented as long as the overtones above are decently portrayed. The ear senses the spacing between overtones and understands and "hears" the missing or only-partially represented overtone.

This is especially relevant for instruments that play very low pitches, since sound reproduction systems usually cannot adequately represent these lower fundamentals.


Thanks to Michael Furstner at Invalid Link Removed for allowing use of the use of the overtone series image, and be sure to check out his site!

 

[KJung]

I actually did the graphs. I used an EMU 1820M sound card, my DIY tube line driver, which measures ruler-flat, as the front end, and WaveLab 4.0 to do the waterfall graphs.

Massively cool! Thanks to you and Greenboy!

Subscribed!

 

[Thor]

Ima gonna tag along too ...

 

[BartmanPDX]

This is real cool stuff, greenboy and Charlie! I'll be lurking . . .

Charlie: It might be really cool to try this with the Steinberger XL-2, which has such an unusually focused tone. I don't know when I can get it up to you, but you're welcome to borrow it some time to try something like this -- I'd be really curious to see the results. A Reverend could be fun too.

 

[rbonner]

Say guys, I think we need to back up here a second. When we compare the Standup Bass with the Bass Guitar we see a considerable difference in the relationship from the fundamental to the first harmonic.

I used to play THE BASS in an orchestra type situation and not a Jazz Scenario like Charlie is doing, but I still have considerable experience with the instrument.

When we look at the two waterfalls, what I see is the failing of the Bass Guitar to reproduce the standup basses fundamental note.

In my opinion instead of accepting the BASS GUITAR's note as gospel and the way things are, we need to figure out how to CORRECT the bass guitar to get its signal closer to the standup's signal.

Why are they different? Well sure scale length is some of the factor in sustain, but the string is resonating at the correct frequency in both instances... Green and others have noted that the sustain is different between the EUB and the BG. I'm curious if this EUB is a hollow body construction miced or is it a solid body with pickups Charlie?

Lets say it is a conventional bass with string micing. The sustain and fabulous tone in an Upright Bass is derived from the combination of the body (amplifier) and bridge (pickup)

It by far is more efficient than the BODY, BRIDGE and pickup of an electric bass.

SO many people BLOW OFF the body material used in making an EB, and changes in the BEEF of a heavy bridge structure to a resonant body.

Those of us who have had the priviledge of playing a Hofner Beatle Bass or other hollow body bass like an EB-2 or even my old Apollo bass would notice that they had a different tone to them than a Jazz or a Precision. The problem still is the "SCALE OF THE BODY"

Even the differences between an ES-335 Gibson compared to a Les Paul or an SG.

But there is a lot of BASS involved when you are wheeling around a 60# or more String Bass. OK I might be dribbling here, stay with me.

Instead of trying to duplicate and reproduce the Electric Bass, we need to try and reproduce the Stand Up Bass. SO in my opinion we need to correct this deficiency of the fundamental and we need to boost this in our reproduction.

While Bill Fitzmaurice is saying that we're hearing the second harmonic and the brain fills it in, I'm saying we need to correct for the instrument and boost the fundamental to make up for this deficiency.

The advantage we have with an Electric Bass is the signal chain. We have EQ's, amplifiers, compressors, clippers, limiters and reproducers and tuned cabinets...

What I think needs to happen is correct the deficiency in the fundamental without boosting the harmonics. I think by doing this we could possibly avoid the output sounding BOOMY. BUT if we just crank up the lows, we boost everything and the mids also come up and we still have our relationship problem.

BUt now that we know what our signal looks like, we need to get out to the OUTPUT at the speaker mic it there with a full range mic and keep working until we are closer to the Stand Up Basses output.

Does this make any sence? BOB