"WAVES" the faked fundamental via higher harmonics method?

Status
Not open for further replies.
Jump to Latest
#41
Well... it's clear as mud as to what is happening in the analog world WRT this... when I say the analog world, again my thinking is as to the
effect of higher levels of low order distortion in terms of making things sound "warmer"/"richer/"fatter" above the bass frequencies. In the digital domain it looks pretty "simple" (ha ha) to put together the requisite filters for missing tone bass, operating in nearly real-time to produce the bass freq effect(s).

Having read a bunch of the papers now, it is fabulously interesting.

I'm giving serious thought to putting together some organ pipes that do the magic relationships for one seriously thunderous note... the only problem is that an octave up from 20Hz is still a pretty BIG pipe... heh. But you could make a one note bass wonder with a few signal generators. 😀 Maybe I'll dork with that. Would be a really neat demo!


Btw, is anyone aware of a standalone hardware box that was made to create the missing bass fundamental??
 
Last edited:
#42
bear said:
Btw, is anyone aware of a standalone hardware box that was made to create the missing bass fundamental??
Click to expand...
Bear,

The DBX Sub-harmonic Synthesizer did just that. I don't know if it is still available as a stand alone unit, but it is a feature available for use on the DBX DriveRackPA, which cost about the same as the original rack units.
They were also available to fill one or more slots in the DBX rack/PSU units, the slot fillers were quite a lot cheaper than the 19" rack units since they only had an edge connector and no PSU. They were cool, you could have 2 noise gates, 2 compressors and 2 Sub-harmonic Synthesizers for one tour, and switch them out to any combination needed for the next tour, using just two spring loaded screws you could twist out the unit with a coin. Funny, a 5.25" 19" rack was small for six devices back then, now 32 channel digital mixers with all those effects (and more) available on each channel cost less and are smaller and lighter.

The DBX Sub-harmonic Synthesizer is awesome for making tiny drums sound huge, and bigger drums sound mammoth, but for use on the entire sub output of a PA it makes weird artifacts- adding a sub harmonic to vocals (even with the crossover set to 100 Hz) makes them sound like "Jabba the Hut" from Star Wars 😀 .

I experimented with it one time when micing up a "too small" native American hand drum, but when the singing came in had to cut it out in a hurry 😉.

Art
 
Last edited:
#43
No, the DBX subharmonic did the contrary of what is being discussed here. It did actually generate and add the subharmonic content (even whenthere was none of it present originally). Altough I must admit that this is fun on really beefy playback systems it is also very taxing.
What is being discussed here is quite the contrary of the DBX thingie: Psychoacoustically causing the impression of having the low bass content without actually reproducing it.

Bear: As you are now able to read the AES papers I'd like to hint you to soemthing invented by Philips. They used a high-mass high Qts driver that is basically producing one-note bass but with quite good efficiency. But they somewhat modulate the one-note signal fed to this driver with the actual bass signal faking the LF content to some degree.

As always: The "real thing" is much more interesting than those tricks IMO but it comes at a cost of course.

Regards

Charles
 
#44
There was something for the car audio market. Can't remember much about it except that all the hardware forms are unobtainium this side of the Atlantic. Peavey's IPR DSP amps have it built-in, which is cool, but I want it as a 1U rack-mount device. Those Peavey amps are also pretty difficult to get hold of.

It can't be that difficult to DIY.

Chris
 
#45
phase_accurate said:
No, the DBX subharmonic did the contrary of what is being discussed here. It did actually generate and add the subharmonic content (even whenthere was none of it present originally). Altough I must admit that this is fun on really beefy playback systems it is also very taxing.
What is being discussed here is quite the contrary of the DBX thingie: Psychoacoustically causing the impression of having the low bass content without actually reproducing it.
Click to expand...
Charles,

The DBX Subharmonic Synthesizer was the answer to Bear's question:

"Btw, is anyone aware of a standalone hardware box that was made to create the missing bass fundamental??"

You are correct that what had previously been discussed were methods to emulate a missing fundamental using upper harmonics (Waves, MaxxBass, etc.) which suggest, but do not create, a "missing fundamental".

Carry on 🙂.

Art
 
Last edited:
#46
bear said:
Well... it's clear as mud as to what is happening in the analog world WRT this... when I say the analog world, again my thinking is as to the
effect of higher levels of low order distortion in terms of making things sound "warmer"/"richer/"fatter" above the bass frequencies. In the digital domain it looks pretty "simple" (ha ha) to put together the requisite filters for missing tone bass, operating in nearly real-time to produce the bass freq effect(s).
Click to expand...
In the analogue world its exactly the same as in the digital world.

bear said:
Btw, is anyone aware of a standalone hardware box that was made to create the missing bass fundamental??
Click to expand...
It will cost just a few bucks to make one.
I can give you the details of an AES paper on how to do it, if you want.
 
#49
Looks like the Rolls doesn't use the "missing fundamental" technique:

"THE ROLLS SONIC EXCITER - SCE PROCESSING
The human ear can detect a frequency range of roughly 20Hz to 20kHz. However, the frequency response
that a normal speaker can effectively reproduce is much, much less. Additionally, speakers add distortion
and phase changes that make the sound quite different from that of the original material.
A sonic exciter restores clarit y and presence to the processed signal by correcting phase changes and
harmonic struct ure differences. In other words, it puts the components of the sound back where they
belong.
All of this magic is done by the use of all-pass filtering, frequency compensated gain adjustment, and
compensated frequency domain delay. What this means to you is the elements of your sound are fanned out
like a deck of cards, making each sound more audible and distinct, reducing the need for high volume and
radical equalizer adjustment.
THE ROLLS SUB-OCTAVE SYNTHESIZER
Specially designed circuitr y for the sole purpose of adding ultra low-end to the sound is included in the
RP221. The Sub-Octave Synthesizer divides the low frequency portion of the signal (the frequencies below
the crossover point) in half, providing an extreme bass sound."

The PPI stuff does - the description of operation seems a bit unclear, but I've not read the mfrs pdf yet. It might be fun to dork with - could be cool on simple TV playback... 😀

_-_-

thanks for the search on the PPI, I found them myself, but my search did not turn these units up (wrong search terms...)
 
#50
bear said:
Looks like the Rolls doesn't use the "missing fundamental" technique:

1)"THE ROLLS SONIC EXCITER - SCE PROCESSING
The human ear can detect a frequency range of roughly 20Hz to 20kHz. However, the frequency response
that a normal speaker can effectively reproduce is much, much less. Additionally, speakers add distortion
and phase changes that make the sound quite different from that of the original material.
A sonic exciter restores clarit y and presence to the processed signal by correcting phase changes and
harmonic struct ure differences. In other words, it puts the components of the sound back where they
belong.
All of this magic is done by the use of all-pass filtering, frequency compensated gain adjustment, and
compensated frequency domain delay. What this means to you is the elements of your sound are fanned out
like a deck of cards, making each sound more audible and distinct, reducing the need for high volume and
radical equalizer adjustment.
2)THE ROLLS SUB-OCTAVE SYNTHESIZER
Specially designed circuitr y for the sole purpose of adding ultra low-end to the sound is included in the
RP221. The Sub-Octave Synthesizer divides the low frequency portion of the signal (the frequencies below
the crossover point) in half, providing an extreme bass sound."

3)The PPI stuff does - the description of operation seems a bit unclear, but I've not read the mfrs pdf yet. It might be fun to dork with - could be cool on simple TV playback... 😀
Click to expand...
Bear,
1) Sounds like a description of FIR filters.
2) Sound like a description of the DBX Sub-harmonic Synthesizer.
3) Don't know what PPI is, been dealing with the aftermath of hurricane Matthew for too many hours to look it up.

Power went out a few minutes after a tree branch fell from about 60 feet and pierced the roof a few feet right of my computer. It was loud. It had no missing fundamentals, but the "crack" noise predominated.

Power resumed about 28 hours later, days sooner than expected considering how many blown transformers and downed power lines all over.

Good night,
Art
 
#51
bear said:
Sure milkshake - but frankly I do not see a way that this can be done easily in analog.

The level control of the desired harmonics is non-trivial, iirc that is the fly in the ointment part.

_-_-
Click to expand...

The "difficult" part is actually the distortion section. Only if you need equal loudness is gain important. In the attached pictures you see the MaxxBass pluginn, you can adjust the filters cutoff frequency, slope, direct and processed sound levels to taste.

Distortion is "the difficult part" because you need equal amounts of distortion at all signal levels, even better is to use something that has higher distortion as levels decrease. This is unlike "normal" tube circuitry where distortion increases as levels get higher.
There are 3 circuits that come to mind for the distortion device:
A full wave rectifier
An externally hosted image should be here but it was not working when we last tested it.

This produces only even harmonics and is level independent.

A full wave integrator
An externally hosted image should be here but it was not working when we last tested it.

This produces all harmonics and is level independent.

A diode crossover clipper
sat7.gif

This produces more distortion as signal levels decrease.
Here tube diodes are best as they have no "threshold voltage", germanium and schottky work fine to.

I'll assume the people here know how to make filters and mixers.
 

Attachments

  • Waves Maxxbass high.png
    Waves Maxxbass high.png
    127.1 KB · Views: 139
  • Waves Maxxbass low.png
    Waves Maxxbass low.png
    124.2 KB · Views: 153
#52
Yes, if you read the papers they show that these methods are not sufficiently "good"... they're discussed in some detail. Anyhow at ~$50USD for one of these commercial DSP based boxes, it's hardly worth the effort to try the diode clipping methods.

I see you have a computer plug in... the graphs are interesting 😀
Of course it looks boosted (the Maxxbass output), but presumably you did that to make it easier to see?? Looks like that from the sliders... thanks for this!

----------------------

PPI = Precision Power the link a few posts up shows them on ebay...
 
#53
What is sufficiently good? No audible difference between original and processed sound, that's not going to happen, not in analogue, not in digital.
But you can certainly get a subjectively "better" low frequency performance for small speakers.
And in mixing you can get more bass without actual more bass frequencies, it does work but you can always hear a difference.

This is diyaudio so why not try it?

I indeed put the sliders so that its easy to see what is happening in the pluginn.
 
#54
weltersys said:
are correct that what had previously been discussed were methods to emulate a missing fundamental using upper harmonics (Waves, MaxxBass, etc.) which suggest, but do not create, a "missing fundamental".

Carry on 🙂.

Art
Click to expand...
weltersys' helpful logical clarification, correct or not, deserves further logical consideration.

Bear's quest looks different when you look at it from the "worm's eye view" which is the point of view of faithfully reproducing instruments. It is true that various circuits can insert or remove a missing fundamental or can create harmonics or remove sub-harmonics. And this can be attempted when you have the full bandwidth signal recording in your hands or when you have the already-processed harmonizer version.

In most of these instances, to work correctly, the circuit would have to know what instrument is playing and decide if something is missing or something has been falsely added. Doing the harmonic trickery without identifying the instrument and separating it out, can't lead to clean sound. Some instruments caught up in the processing just don't have any bass missing.

I don't know if enough is known about the perceptual illusion to say how your brain addresses the identification question when your brain is doing the processing. I do know enough about human perception to know it is quite possible the brain is doing its job correctly*, something no DSP can remotely achieve today.

Ben
*McCollough colour-form after-effect
 
Last edited:
#56
Well, no, I'm not looking from only the point of view of faithfully reproducing instruments.
That's certainly of interest.

The aspect that is most intriguing to me is that this phenomenon has been fairly well studied, reduced to practice, and while there is no particularly good reason that it should work, it does. But there is more in my mind, and that relates to more than bass... but perhaps I ought to start a separate thread to discuss. I've brought it up in previous posts, but while it may have a possible psychoacoustic relationship to the "missing fundamental" it's not the same.

For the missing fundamental, I'm most curious and see it as having some potential applications personally - things that have little to do with accurate reproduction, and more with fun with sound! 😀

The idea of utilizing the missing fundamental in a way that maintains true fidelity to the source is interesting too...

...it's all fascinating to me.

-------------------

phase-accurate, thanks for the link looks like another "good read"... (the file thickens!)


-----------

milkshake, sure an analog version would be interesting. but since the papers seem to rather clearly indicate that the analog methods were discarded for various reasons, I'm not sure what the benefit to revisiting when there are <$100USD boxes in DSP that do the trick now?

_-_-

PS. I've had the Waves demo CD/DVD from years back, and tried it out then, it is VERY impressive, pumping out fairly fat/big sound from relatively small speakers. Can't speak to accuracy/fidelity only to the fact that in their demo it was not subtle and was rather surprising. Not going to trade my BEAR Labs Quadripole subs in, not yet... (otoh if I could get "missing fundamental" down into the near subsonic region, the 12Hz and up to ~25Hz with a "box" that might be worth the price of admission... but I'd not want energy down there that was actually not in the source either).
 
#57
The Rolls is an octave divider (like the DBX or PCA from Audio Control).

Of these three, the PCA sounds the best.

The PPI is a Waves unit.

It sounds like it has deep bass, but lacks the visceral feel of deep bass.

Waves is an old pipe organ trick, play the 3rd and 5th interval when playing a piece written for a 16' organ on your 8' instrument.
 
#58
djk said:
It sounds like it has deep bass, but lacks the visceral feel of deep bass.
Click to expand...
This may be hard to follow but... it sounds best because your mind is creating the percept and your mind is doing the listening.

See post #22 for clarification of what's going on perceptually.

Or read Helmholtz on "unconscious guess" perception.

https://en.wikipedia.org/wiki/Unconscious_inference

B.
 
Last edited:
#60
bear said:
The aspect that is most intriguing to me is that this phenomenon has been fairly well studied, reduced to practice, and while there is no particularly good reason that it should work, it does.
Click to expand...

This deserves its own thread.

Pitch detection is well studied. In very simplistic terms, its has to do with the distance of the harmonics. In case of the missing fundamental the harmonics are half the distance (logarithmic) than the actual lowest frequency.

Piano's and guitars for instance have a stretched tuning, but still sound perfectly in tune, if tuned by ear.
 
Status
Not open for further replies.
Top Bottom