Experimental Basses (Has anyone done this)

[Drewbacca]

noob question: what is fundamental?

+1256397480580236589740


???

 

[allotabass]

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[spode master]

LOL, I guess you really don't like piezos.

Piezos are fine for the correct application. I just don't think I can "get there from here."

Maybe if the Piezo was actually mounted to the center of the string would it be useful, but it would be problematic at best.

Piezo Core Strings anyone?

 

[spode master]

noob question: what is fundamental?

Fundamental is the primary tone that is produced by the string vibrating on your bass.

For a 5 string low B its arround 31Hz

A 4 string low E is around 40HZish

most of what is picked up because of where the pickup is located on the instrument is the second harmonic of the open string notes 62Hz and 80Hz.

It is also better at picking up the higher fretted note fundamentals. Because of reasons stated earlier.

 

[mongo2]

Piezo Core Strings anyone?

Run out and patent that one.

 

[ehque]

Piezos pick up all frequencies, not just the "second harmonic". In fact, even normal mag pickups pick up a LOT of the fundamental.

A piezo running into a gentle slope EQ will give you the STRONG fundamental signal you are craving. maybe a 3 or 6 db per octave slope will do (the difference between white noise and pink noise).

The reason why you don't hear a lot of fundamental is more to do with the rig rather than the bass. You can plug a 41Hz sine wave into most bass rigs and not hear much, me thinks.

 

[spode master]

Piezos pick up all frequencies, not just the "second harmonic". In fact, even normal mag pickups pick up a LOT of the fundamental.

A piezo running into a gentle slope EQ will give you the STRONG fundamental signal you are craving. maybe a 3 or 6 db per octave slope will do (the difference between white noise and pink noise).

The reason why you don't hear a lot of fundamental is more to do with the rig rather than the bass. You can plug a 41Hz sine wave into most bass rigs and not hear much, me thinks.

ehque I will refer you back to the pickup simulator applet that I linked at the begining of the thread.

There is infact a 6dB per octave roll of. DUE TO PICKUP PLACEMENT. I have a prototype single integrator, summed with a highpass filter to give a 6dB octave boost for my Alembic. (Back Burner at the moment)

I know that electromagnetic pickups and Piezos both can pickup low fundamental.

The placement requirements of a piezo do not lend themselves to being a good Low bass pickup on a solid body instrument.

I am well aware of what type of rigs are required to reproduce sub bass.

Here are a couple of things I have built.

http://www.talkbass.com/forum/showthread.php?t=469734

There is a significant lack of fundamental especially from the Ibanez. It takes a lot of EQ to get things back into equalibrium.

And then theres the Equal Loudness hearing curves...

Antone-

 

[knuckle_head]

The biggest issue isn't placement. The relationship of fundamental in relation to harmonic content is a string issue.

You get most of your fundamental on attack. When resolving a plucked string 'blooms' - meaning that sympathetic vibration (overtones) overtakes the fundamental.

Individual piezos are your best bet in presenting everything a string has to offer. It doesn't vary its presentation as a static magnetic pickup does when fretting, it CAN be individually EQd (but you REALLY don't want to do that), and if buffered correctly gives an absolutely true presentation of what your strings present.

FWIW - EQs accentuate specific frequencies. If you bump up 30 Hz to get more out of your B, you also bet that same bump on your C, D, E, etc. You no longer have a true presentation. If it ain't coming out of the bass with all settings flat then you need to reconfigure or replace the pickups. EQ is nearly always best handles outside of the bass anyway - proper tool for the job and all.

It looks like you have a couple of isobaric cabs - good call. Inefficiency aside, they have awesome bass presentation. I am an ELF/INFRA guy...

EDIT; piezos will 'Get you from here' - I have two sub-basses with GraphTech piezos out there and scoped them before they left. It is indeed all there.

Something to consider doing - if you use VERY loose strings you will shift the harmonic content dramatically in the direction you want to go. That with piezos will give you your best shot IMO.

Second edit; If you are compelled to EQ to get the most from your setup I'd suggest giving a full range signal to the cabs that can carry the sonic weight, and send a low pass signal to the subs only. If the fundamental of E and below is what you want to hear then pump only 50 Hz and below through the subs - you can play with fundamental/harmonics relationships with volume knobs at that point. Cut only EQ is always a better bet than opamps and bumping up specific frequencies.

 

[yodedude2]

be advised i have no idea what i'm talking about.

what if you used piezos & mag pickups, with split outputs. then, run the piezos through a low pass filter/crossover set at, say 70 or 80 Hz...how about that??? later, ron

 

[Baryonyx]

Come on where are all of the experimental, and fusion players?

As a fusion player I wouldn't want to touch this idea. It's an exercise in instrument theory that just sounds like it would be a dog egg in practice.

 

[spode master]

The biggest issue isn't placement. The relationship of fundamental in relation to harmonic content is a string issue.

You get most of your fundamental on attack. When resolving a plucked string 'blooms' - meaning that sympathetic vibration (overtones) overtakes the fundamental.

Individual piezos are your best bet in presenting everything a string has to offer. It doesn't vary its presentation as a static magnetic pickup does when fretting, it CAN be individually EQd (but you REALLY don't want to do that), and if buffered correctly gives an absolutely true presentation of what your strings present.

FWIW - EQs accentuate specific frequencies. If you bump up 30 Hz to get more out of your B, you also bet that same bump on your C, D, E, etc. You no longer have a true presentation. If it ain't coming out of the bass with all settings flat then you need to reconfigure or replace the pickups. EQ is nearly always best handles outside of the bass anyway - proper tool for the job and all.

It looks like you have a couple of isobaric cabs - good call. Inefficiency aside, they have awesome bass presentation. I am an ELF/INFRA guy...

EDIT; piezos will 'Get you from here' - I have two sub-basses with GraphTech piezos out there and scoped them before they left. It is indeed all there.

Something to consider doing - if you use VERY loose strings you will shift the harmonic content dramatically in the direction you want to go. That with piezos will give you your best shot IMO.

Second edit; If you are compelled to EQ to get the most from your setup I'd suggest giving a full range signal to the cabs that can carry the sonic weight, and send a low pass signal to the subs only. If the fundamental of E and below is what you want to hear then pump only 50 Hz and below through the subs - you can play with fundamental/harmonics relationships with volume knobs at that point. Cut only EQ is always a better bet than opamps and bumping up specific frequencies.

Until you give me information that disprooves that the amount of fundamental energy is'nt dirrectly related to pickup position what you have to offer is hearsay.

I posted the link to the pickup simulator at the begining of my post.

The string is vibrating 1/2 wave from nut to bridge. The point where the peak of vibration occours (maximum signal strength) is 1/2 way between the nut and bridge that would be the 1/4 wave point. Think of the pickup as the feed point for a DiPole antenna.

If you can disproove it great. I think the concept of wave propagation is pretty solid.

I am going to clamp a pickup on my old bass neck and post the FFT results that should be conclusive enough.

Antone-

Its just a simple Sealed cabinet. Not Isobaric. That would weigh over 200lbs with those drivers.

 

[Sirius]

According to the simulator, if you have 4 negative polarity pickups (that and the frequency are the only things I messed with), you'll be getting close to what you want, all placed between the heel of the neck and the bridge. Now that would be a pretty messed up looking axe, but hey, you'd get some sound, ya?

Also, said simulator does not take into consideration ANY information about the pickup specs, just the number. Nor does it include natural resonace. Plus, just how sound is this guys math?

Just some pointers.

 

[spode master]

According to the simulator, if you have 4 negative polarity pickups (that and the frequency are the only things I messed with), you'll be getting close to what you want, all placed between the heel of the neck and the bridge. Now that would be a pretty messed up looking axe, but hey, you'd get some sound, ya?

Also, said simulator does not take into consideration ANY information about the pickup specs, just the number. Nor does it include natural resonace. Plus, just how sound is this guys math?

Just some pointers.

The more pickups you cram together you are going to have a lot of nulls and funny buisness but thats what happens even whe combining 2 pickups. I know you get more response normaly a large gain. I'll look at what your talking about and see what type of curve I get.

All pickups out of Phase is the same as all pickups in phase. Not really seing the response characteristic your talking about. You get more total signal level out, because of the sum of the pickup output, but it doesn't change the roll off slope.

Pickup up resonance has to do with LCR of the windings of the pickup, Q of the pickup resonace has to do with R of the pickup and the circuit you load it into.

This is different from one pickup design to another.

You would have to first know the LCR values of the pickup in question write the script to interperate that Data.
Most Pickup manufacturers do not post that sort of information.

I have found some places on the internet that have that specific info.

Trying to model body resonances would be way hard, so I won't even go there.

I'm not a coder, so I wouldn't know how to modify Tills pickup modeling script, but I'm sure he could if he was really motivated to.

Its still a very illuminating little applet.

Antone-

 

[knuckle_head]

Until you give me information that disprooves that the amount of fundamental energy is'nt dirrectly related to pickup position what you have to offer is hearsay.

I posted the link to the pickup simulator at the begining of my post.

The string is vibrating 1/2 wave from nut to bridge. The point where the peak of vibration occours (maximum signal strength) is 1/2 way between the nut and bridge that would be the 1/4 wave point. Think of the pickup as the feed point for a DiPole antenna.

If you can disproove it great. I think the concept of wave propagation is pretty solid.

I followed the link you provided - I am not suggesting the information is wrong.

Presentation/recording/amplification of the fundamental is directly related to pickup placement - the amount of fundamental in relation to harmonic content has nothing what-so-ever to do with pickups.

My 'scope hasn't the ability to record video or I could present my findings. This is where I came by my data for development of strings, and the information I posted earlier on the functionality of piezos. I currently have a 5 string bass that is tuned an octave beneath a grand piano - 13.75 Hz - the fundamental is half the first harmonic as sonic energy goes at that frequency. It's very consistent with standard E and A strings on a standard bass.

Dynamic pickup placement will serve you best - I've not seen a practical application of that to date. Consistent presentation is possible through piezos and does not disallow fretting.

 

[spode master]

The amount of fundamental in relation to harmonic content has nothing what-so-ever to do with pickups.

I totally agree pickup types have very little to how they pickup low bass, Different pickup types normally have the biggest differences in the HF side.

My 'scope hasn't the ability to record video or I could present my findings. This is where I came by my data for development of strings, and the information I posted earlier on the functionality of piezos. I currently have a 5 string bass that is tuned an octave beneath a grand piano - 13.75 Hz - the fundamental is half the first harmonic as sonic energy goes at that frequency. It's very consistent with standard E and A strings on a standard bass.

Dynamic pickup placement will serve you best - I've not seen a practical application of that to date. Consistent presentation is possible through piezos and does not disallow fretting.

Smart pickup system moves when you change position!?

The easiest way I can think of to measure the output is use a decent FFT (Spectrum analizer). Put it on hold Data and pluck a string.

I have noticed fundamental decay much quicker than 2nd harmonic also. But the Fundamental is never as great as the 2nd, until I applied EQ.

I have built a custom EQ slope. My Alembic Neck PUP starts its roll off around 70Hz, it seems to be a predictable 6dB per octave, so what I made is a circuit that boosts 6dB per octave bellow 70Hz.

It actually works well, except I think maybe the Z is to low and its effecting the Q of the filters in my aniversery electronics, so it looses a little of the sparkle on the top.

I have to re evaluate its sound once I increase the input impedance.

The one thing I don't like about the EQ boost is it can add more noise to the circuit.

I think a solid body piezo is in the same boat as it needs a correction EQ, especially since its in the bridge.

What do you play your 13.75Hz bass through!? The upshot of tunning their is you get a lot more 27.5Hz but the strings have to be sloppy. I tune to 27.5Hz to get the low A.

Another issue with placing the pickup up at the 1/4 wave point of the string is the second harmonic will be effectively nulled. But who cares when you get all that juicy fundamental. Thats what I signed up for anyway.

 

[mongo2]

But who cares when you get all that juicy fundamental. Thats what I signed up for anyway.

If all you want is pure fundamental then how about a synth that can generate a pure sine wave at the frequency with no harmonics at all?

 

[JAUQO III-X]

If all you want is pure fundamental then how about a synth that can generate a pure sine wave at the frequency with no harmonics at all?

 

[ehque]

If all you want is pure fundamental then how about a synth that can generate a pure sine wave at the frequency with no harmonics at all?

Precisely. What it seems is that you know a pickup doesn't pick up as strong a fundamental as the higher octaves, and the obvious solution is to buffer the piezo properly and put in a large sloping EQ, but you don't want to do that, but would rather build/design/install a pickup that gives you only the fundamental?

a pickup at the midpoint on a string also picks up all odd harmonics. how will you deal with that?

 

[knuckle_head]

The easiest way I can think of to measure the output is use a decent FFT (Spectrum analizer). Put it on hold Data and pluck a string.

I would agree - but I didn't have that tool at my disposal. I used a stand-alone oscilloscope just as you suggest.

I have noticed fundamental decay much quicker than 2nd harmonic also. But the Fundamental is never as great as the 2nd, until I applied EQ.

This is what I was getting at with my original post - the fundamental is most prevalent on attack. My using the word bloom in that post is perhaps incorrect. It takes more energy to strike a string for a full range note than it does to excite one in order to get harmonics from one (unless you're eeking out the harmonic at say the third or first frets).

I have built a custom EQ slope. My Alembic Neck PUP starts its roll off around 70Hz, it seems to be a predictable 6dB per octave, so what I made is a circuit that boosts 6dB per octave bellow 70Hz.

It actually works well, except I think maybe the Z is to low and its effecting the Q of the filters in my aniversery electronics, so it looses a little of the sparkle on the top.

I have to re evaluate its sound once I increase the input impedance.

The one thing I don't like about the EQ boost is it can add more noise to the circuit.

I think a solid body piezo is in the same boat as it needs a correction EQ, especially since its in the bridge.

If there were a way for you to both split your signal to let you get full program and your EQ'd program, and isolate the output string for string to apply this you could tone shape remarkably.

A piezo output is very dissimilar from a magnetic output. It passes along vibration data strictly. It is more reliable as a sound source IMO as a result. It need not be a thin lifeless sound if it is buffered properly, and the crystal is subject to as much of the vibrational energy as possible (adequate downward break angle pressure is key).

What do you play your 13.75Hz bass through!? The upshot of tunning their is you get a lot more 27.5Hz but the strings have to be sloppy. I tune to 27.5Hz to get the low A.

I've built my own cabs as well - I have a full range 1x10/1x12 on top of a single 15" sub. The sub's box is tuned to give me flat to 19 Hz. It doesn't present the fundamental at 13.75 Hz, but it's pretty impressive. I need to sell a few more basses to come by the INFRA cab I want - it will be capable of 8-10Hz on spec.

I mostly reference what I do on a Cafe Walter headphone amp and studio cans, but I am as limited by them as I am with my sub.

The 13.75 Hz A uses a .265" string - there is just shy of 32 pounds of tension on it and it isn't sloppy really. My standard 27.5 Hz A is a .135" on a very long scale so that I could maintain a similar tension.

Another issue with placing the pickup up at the 1/4 wave point of the string is the second harmonic will be effectively nulled. But who cares when you get all that juicy fundamental. Thats what I signed up for anyway.

Again, if it's possible to isolate the fundamental and then add it back into a full range program (to taste, no specific relationship), this is how I'd like to make use of what you're cooking up. I look forward to your progress with this - if there is a different and better way to get there from here I'd love to benefit from and make use of your successes.

Skip

 

[Human Bass]

If it helps, Alembic recommends neck-thru with ebony lamination to bump the fundalmental.