Fitzmaurice Subs for low F#

[Tenma4]

That's nothing new. A few years back, a car audio company called Phoenix Gold came out with a "rotary" servo motor sub called the Cyclone -
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I wonder if something like this could be adapted for use in a small venue as part of a bass rig... Hehe. Hm. Wonder if I could just build something like this...winding coils, adapting/modifying a frame, perhaps an existing motor... Anyone else want to dream?

 

[bgavin]

I have no interest in F# basses.
However, I have strong interest in synths and brass that go down that low.
Unlike the electric bass, the synth does indeed produce full signal strength at 23 Hz. Measured.

I have not measured an F# bass.
I have measured multiple 4-string basses and found fundamental amplitude equal to the 1st harmonic in all cases.
Although the fundamental period is short, the driver will respond to it.

If the F# bass performs similar to the other basses, it would also have a strong, brief fundamental at 23 Hz.
A 23 Hz fundamental at any appreciable power level will over excurse most cabs, including O15.

My comments are not about suitability for a particular bass, but the inappropriate use of an O15 at 23 Hz.
O15 is indeed a vented, direct radiator. It obeys all the physics laws applicable to vented boxes, and that includes rapid unloading below 50 Hz.

A high pass filter in 45 Hz range must be at least 4th order to protect the driver at high power.
Due to the values involved, this requires an active filter.

 

[alexclaber]

I have measured multiple 4-string basses and found fundamental amplitude equal to the 1st harmonic in all cases.
Although the fundamental period is short, the driver will respond to it.

If the F# bass performs similar to the other basses, it would also have a strong, brief fundamental at 23 Hz.

You can't assume that a string tuned almost an octave lower will demonstrate the same overtone balance as a normal low E - the scale length is far too short to support significant fundamental energy.

My comments are not about suitability for a particular bass, but the inappropriate use of an O15 at 23 Hz.
O15 is indeed a vented, direct radiator. It obeys all the physics laws applicable to vented boxes, and that includes rapid unloading below 50 Hz.

The O15 has a driver with far greater excursion limits than those usually used without problems for low F# tuned basses. If you don't have a highpass filter then distortion will be higher than ideal but as Xlim is almost double Xmax it'll still handle over 200W @ 23Hz without damage.

Alex

 

[spode master]

You can't assume that a string tuned almost an octave lower will demonstrate the same overtone balance as a normal low E - the scale length is far too short to support significant fundamental energy.
Alex

What is the information you have to support this statement?

 

[spode master]

That's nothing new. A few years back, a car audio company called Phoenix Gold came out with a "rotary" servo motor sub called the Cyclone -
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I remember reading a review in Car Audio & Electronics at the time and recall it putting out something like 120db @ 10Hz. This "sub" has since long been discontinued (unless they've put it back into production, unlikely). They were pricey at the time (anywhere from $700-$1k). I've always wanted to get my hands on a couple for some "experimentation". There's a pair on ebay for around $650 (Blast you bad economy! )

From my car audio experience in the past and getting into playing bass, there truly is nothing like feeling the sound. Hearing it is only half of the equation. Similar to saying, "This spaghetti tastes wonderful!", without the accompanying smell to enhance the flavor it really isn't that great. 40Hz and lower can easily trigger a resonant response in a building causing floors to vibrate with the sound, or even in the person listening for that matter.

I think Tom Danley originally worked on that with pheonix gold or who ever, but he says it was very poorly implemented, and he would like to disassociate with the final product.

 

[alexclaber]

What is the information you have to support this statement?

For now all I need is my ears - like other string instruments with equal length strings the harmonic balance shifts as you move up and down the registers to keep the tone broadly similar regardless of the register you're playing in. Whilst a piano maintains much more consistent harmonic balance and thus greater tonal variation through the registers, although the lower note lower harmonics are much diminished due to the lack of size of the sounding board - if a piano had magnetic or piezo pickups this near constancy in harmonic balance and thus huge tonal variation would be much more obvious.

One day I shall do some more in-depth analysis of this but right now I'm busy designing a crossover!

Alex

 

[spode master]

For now all I need is my ears - like other string instruments with equal length strings the harmonic balance shifts as you move up and down the registers to keep the tone broadly similar regardless of the register you're playing in. Whilst a piano maintains much more consistent harmonic balance and thus greater tonal variation through the registers, although the lower note lower harmonics are much diminished due to the lack of size of the sounding board - if a piano had magnetic or piezo pickups this near constancy in harmonic balance and thus huge tonal variation would be much more obvious.

One day I shall do some more in-depth analysis of this but right now I'm busy designing a crossover!

Alex

For different string tunnings I'm pretty sure that the Harmonic relationships stay they same as tension is the only thing thats changing.

If its the same string Same position, the pickup doesn't move, the mechanical wavelength of the string is fixed. At some point your going to get to loose a string and its going to chatter and stick to the pickup, or fall off the bridge or tuning peg.

Again, string wavelength relation ship/pitch is directly tied to string mass, length and tension.

Its not like the speed of sound through air which has a fairly stable propagation speed that varies with temperature, humidity, and altitude.

In air each note has its own wavelength.

On a string instrument, if you change the tension, or have multiple strings, multiple notes have the same mechanical wavelength.

On a standard EADG dig this each string has about the same mechanical wavelength, give or take a few mm for intonation.

We have a fixed 1/2 wavelength for the open strings. The biggest factor in picking up overtones is going to be, pickup placement, and string mass, perhaps the amount of finger oil buildup, flat Vs round etc. for string damping.

Once the vibration is converted to sound traveling through the air do acoustic wavelengths really come into play.

At least that's my personal interpretation of my own investigation, and observation.

Antone-

 

[alexclaber]

If the tone changes then the harmonic balance thus changes. Play enharmonic notes on different strings, tune up or down to get the note on different frets etc etc and the tone is different every time thus so too is the harmonic balance. A particularly big issue is string compliance - once strings get thick their behaviour is far from 'perfect'.

Alex

 

[spode master]

If the tone changes then the harmonic balance thus changes. Play enharmonic notes on different strings, tune up or down to get the note on different frets etc etc and the tone is different every time thus so too is the harmonic balance. A particularly big issue is string compliance - once strings get thick their behaviour is far from 'perfect'.

Alex

I think your talking about fretting and changing strings, as opposed to changing detuning an open string a few steps.

All of the over tones should track the fundamental, and keep the relative pickup characteristics just shifted to what the new tuning is.

 

[alexclaber]

I think your talking about fretting and changing strings, as opposed to changing detuning an open string a few steps.

All of the over tones should track the fundamental, and keep the relative pickup characteristics just shifted to what the new tuning is.

I'm talking about playing notes anywhere on a bass and how the string length, mass per unit length and stiffness affects the harmonic balance. And that's before the pickups get involved.

Alex

 

[knuckle_head]

You can't assume that a string tuned almost an octave lower will demonstrate the same overtone balance as a normal low E - the scale length is far too short to support significant fundamental energy

Actually you can assume that.

A string large enough to have decent tension at pitch will be damped to a degree, but if it's a good string of similar construction and materials to the balance of the set, and tension is reasonably balanced the harmonic content is indeed consistent.

 

[bgavin]

For now all I need is my ears

And we all know how accurate those are...

Self-delusion using the designer's ears is the same as judging the beauty of your own baby.
Nobody is going to call their baby ugly. No way, no how.



I'm not interested in a perpetual pissing contest with you and Greenboy.
However, neither of you will ever post any measurements to back up your hyperbole... there is only endless talk.
Excuses like "but right now I'm busy designing a crossover..." or "the dog ate my chart", don't count for much.
Any designer actually interested in his creation will be chomping at the bit to see how it performs.

You have both designed cabs that get a lot of bandwidth here, but with zero substantiation.
I even saw a thread with a member looking to find a builder. Unseen, unheard, and unmeasured.
Such is the power of hyperbole.

I stay out of the fEarful threads because they don't concern me nor Bill's designs.
However, armchair quarterbacking on a design (O15) that I support daily very much concerns me.

You are welcome to debate theory, strings and harmonics ad nauseum, but O15 still isn't designed for 23 Hz.
If the OP wants one of Bill's boxes intended for 23 Hz, he should do a big Tuba 36 or THT.

 

[alexclaber]

However, neither of you will ever post any measurements to back up your hyperbole... there is only endless talk.

I have already taken numerous measurements to test my designs and have posted some of them online - it isn't my problem if you fail to see them. But as I have said this evening I have been going through another iteration of crossover design, based on taking real and accurate measurements. Despite what you may think it isn't actually that easy to get useful and accurate measurements and the related design process is time consuming.

There is no hyperbole, it's simply a case of designing a cab properly, no short-cuts, whilst bearing in mind what really matters in the real-world.

The OP wanted a cab for low F#. That doesn't necessarily mean he wants a cab that can reproduce 23Hz accurately.

Alex

 

[greenboy]

I'm not interested in a perpetual pissing contest with you and Greenboy.

You seem to be. You take offense where none is given, seem to want to give offense by making your comments personal when there is no good reason not to just stick to discussion with either a neutral or even a friendly tone. Others who disagree on something even fiercely here manage not to carry that on forever with underlying hostility. You seem to have some deep-seated hate you want to express under the guise of some technical thing. You bring up my name especially when there is no call to. If you don't like me - resent me for some reason - keep it gone from HERE. It's YOUR problem and shouldn't be here.

Also you make one wonder if you don't have some commercial interest in a Bill Fitzmaurice-related enterprise.

 

[billfitzmaurice]

I'm talking about playing notes anywhere on a bass and how the string length, mass per unit length and stiffness affects the harmonic balance. And that's before the pickups get involved.

Alex

+1. The same note played on different strings sounds different, in part due to the altered harmonic content caused by the different vibrating lengths.

 

[spode master]

I'm talking about playing notes anywhere on a bass and how the string length, mass per unit length and stiffness affects the harmonic balance. And that's before the pickups get involved.

Alex

Well Ok yah thats a given, your harmonic relationships will always shift with the fundamental, and other characteristics of the string. The pickup will also effect that.

But you mentioned Detuning a string an octave. The harmonic content will shift relative to the detuning but should be close to identical to any tuning in between and its harmonic relationships.

 

[zagnut]

Nobody is going to call their baby ugly. No way, no how.

I will.

 

[Chef]

Alex; Greenboy; BGavin:

I'm done asking you to play nicely.
Personal attacks fo any nature are not permitted here, and all three of you have had reminders of this, several times, in this thread.

Closed.

 

[BassyBill]

After some discussion with amps mods:

Guys - please feel free to have a spirited debate about the merits and debits of tech specs compared to verbal descriptions of cab characteristics. The mods here believe you can strongly support your views either way without offending anyone. But please be advised that if you can't post on this topic whilst still respecting the right of other people to hold opinions of their own, you will not be able to take part without our intervention to make sure the rules of the forum are observed by all. Remember, tone is everything.

 

[SpankyPants]

In after the lock?