Don't understand this 'suggestion' from the Ampeg website:

[Al Kraft]

a steady sine wave can't transport any information in the sense of human communication, which is either speach or music.

If you're talking about an un-modulated carrier wave, I guess I might agree. However, a steady sine wave is a single tone and, if transmitted by an element/transducer that is designed for audio, will likely have some harmonic artifacts introduced by the element/transducer itself. That could sound musical and easily be mistaken for a whole note in 4/4 time.

The issues of phase coherence, phase cancellation, time phasing, etc. is interesting in theory and has a clear place among other important design considerations. However, in the real world (vice an an-echoic chamber or digital modeling program) it seems to me that the environment itself could cause you equal or bigger issues and a "bad design" might actually work in your favor in some odd acoustical environments.

Let me be clear, I'm not advocating for bad designs/lack of attention to details and hoping for odd venue acoustics to balance things out. We know that sounds can cancel sounds...there are popular products on the market that capitalize on that fact (e.g. noise cancelling headphones, optional radios in some vehicles). We also know that certain scientifically inadvisable situations can produce excellent acoustic outcomes (e.g. not every mixed cab set-up sounds awful, drums sounded great at Sound City Studios which were built in a factory space where Vox amps were once assembled).

I think there are some obvious black and white rules of the road in speaker design and then more than a few areas that lose their 18th decimal point significance out in the real world. The old expression "measure with a micrometer, mark it with chalk, and cut it with an ax" comes to mind. As with the EPA gas mileage estimates, YMMV!

 

[seamonkey]

In the FOH side of things with just about the same power and drivers they often use arrangement and delay of cabinets to steer the audio to the audience. Cardioid subs for example

I could see somebody accidentally coming up with the same but not wanting it or understanding why.
Modern amps have huge power and drivers more efficient that ever. Some manufacturers, not just Ampeg, could do better by educating their customers instead of falling on old thinking.

 

[JimmyM]

In the FOH side of things with just about the same power and drivers they often use arrangement and delay of cabinets to steer the audio to the audience. Cardioid subs for example

I could see somebody accidentally coming up with the same but not wanting it or understanding why.
Modern amps have huge power and drivers more efficient that ever. Some manufacturers, not just Ampeg, could do better by educating their customers instead of falling on old thinking.

Ampeg's fanbase, as well as most other amp makers' fanbase, don't want it. I know I don't, for sure. Don't get me wrong...I have a lot of respect for those who build more forward-thinking cabs, and I think they're great, but I've played through some as well as some of the best PA's in the business, and I like the sound of my cabs better and always ask sound techs to make them sound like my onstage rigs. The extra dispersion is nice, I will say, but not necessary to my way of life.

 

[rodl2005]

Oh for gawd sake...this thread. .....

Surely Shirley. ... it's like believing a car advert...
Shirley y'all take it all with a grain of salt. ..don't cha?
If ya don't like a brand. ..don't buy it. If you DO. ..Shirley you'd TRY it out 1st. ..
Plus. ..there a lot of collective E.E. brains on this forum. .
Imo...more than I've noticed at most M.E. co.s
Ask. ..and as with ALL Internet Q & A's go thru the answers and see which fits best. ..

 

[Downunderwonder]

Unfortunatelly it's not.
Relative phase shift tells nothing but relative phase of two systems at singular frequency point.
Group Delay tells something about the way how a bandwith is transfered.

A singular frquency point on it's own can't transfere any information.
While a bandwidth consideration for audio program material is the consideration on transfered (audio) information. That's a big difference 'science' folks do hard to understand.

As we as musicians don't play singular sine waves the group delay is more important to consider a distinct bandwidth.
On it's own group delay on a mono system does not matter to much but in stereo it does matter if left and right channel don't match.
Similar issues may happen if different bass cabs show noticeable deviations.


Sometimes there is no need to try to explain with science stuff.
If a EVM15L driver was mixed with a Hartke 410 aluminium drivers it's predictable the characterful voicing of the EVM 15L will strongly compete with linear sound of the 10" aluminium drivers.
Two totally different voicings that will not match and very likely refuse to be EQ'd to personal taste.

explain why my different brand mixed cabs have a slight blurriness that biamping takes away. I believe it is a slight difference in ''phase response'' but you may call it group delay.

 

[ThisBass]

explain why my different brand mixed cabs have a slight blurriness that biamping takes away. I believe it is a slight difference in ''phase response'' but you may call it group delay.

A slight blurriness may be caused by some none linear 'anomalies' to the signal that can't be corrected anymore by any EQ.
While some 'anomaly' to the signal caused only by phase (linear distortions) was completely correctable by some proper EQ adjustment.
Although group delay has something to do with phase but both must not be mixed up.
So it's invalid to mix up phase issues for group delay issues.
The effects to signals respectively a bandwidth is totally different.

edit,
you may want use a chorus pedal in stereo mode and feed the stereo signals to matching cabs. Set rate as low as possible and depdth to max. The only thing that will happen is the chorus effect is slightly audible at best. If phase anomalies was a reason for blurriness than the chorus should now cause lots of noticeable bluriness artefacts. You just will not notice any of this.

 

[ThisBass]

If you're talking about an un-modulated carrier wave, I guess I might agree. However, a steady sine wave is a single tone and, if transmitted by an element/transducer that is designed for audio, will likely have some harmonic artifacts introduced by the element/transducer itself. That could sound musical and easily be mistaken for a whole note in 4/4 time.

A couple of illustrations about the way how phase velocity can differ from signal (group) velocity.
Invalid Link Removed

"The idea of a group velocity distinct from a wave's phase velocity was first proposed by W.R. Hamilton in 1839, and the first full treatment was by Rayleigh in his "Theory of Sound" in 1877."

"The group velocity is often thought of as the velocity at which energy or information is conveyed along a wave. In most cases this is accurate, and the group velocity can be thought of as the signal velocity of the waveform."

In practice. With ampitude modulated RF frequency it's possible to carry information over very long distance cause the ionisphere layer reflects the wave back to earth ground and vice versa. As the HF carrier and the waveform travel in lossy media it comes to some anomalies.
The phase of the carrier travels with velocity that equals speed of light while the group velocity (which is the information, or the conveyed energy) is of considerably lower velocity. Around 1/2 to 2/3 of speed of light if I remember correctly.
As the decrease of group velocity depends on waveform bandwith there is also some dispersion anomalies that will cause distortion to the sound. In rough words the artefact could be described as frequency dependent distortion, or partial reverbaration.

Back to NF audio science,
Althogh no carrier present like with RF transfere there is still the phase curve of the NF system the signal information has to pass through (that naturally covers some bandwidth, no singular steady sine wave). As the phase curve of the system does not proceed linear versus frequency there will always happen some deviation to group delay. As long as there are no critical anomalies then some group delay issues don't matter. But it may matter if two different systems of different group delay characteristic shall reinforce a correlated signal.

For stereo monitoring cabs at studio recording this may mean an interference of spatiality if the matching cabs tend to show deviations for group delay. Although phase was still pretty good matching.
In high quality recording rooms the stereo monitors (or loaded drivers) are checked frequently and replaced if requiered. It's not an phase issue rather an group delay issue.

Not directly addressed to you my friend
I think you know that a very lot of different science disciplines use just similar mathematical tools like Fourier transform and Laplace transform and Informations and Systems Theory and Filter Theory as well and many other tools more to explain rather complex things.
I wonder the way how we can be so overbearing to explain with just phase.

 

[JimmyM]

Whether phasing or group delay or a combo of both, the results are the same...some notes are louder, some are quieter, some are normal. That doesn't take a rocket scientist to decipher. What are we arguing about again?

 

[ThisBass]

In the FOH side of things with just about the same power and drivers they often use arrangement and delay of cabinets to steer the audio to the audience. Cardioid subs for example

I could see somebody accidentally coming up with the same but not wanting it or understanding why.
Modern amps have huge power and drivers more efficient that ever. Some manufacturers, not just Ampeg, could do better by educating their customers instead of falling on old thinking.

Nice
meant as supplement how it works,
The back side loaded driver "sucks" the acoustic power pushed by the front loaded drivers and terminates the unwanted backward acoustic power as heat inside the amplifier that "powers" the back loaded driver.
Instead of "powering" the driver the amplifier is loaded back with some additional power coming off from the front amplifiers.

It just reminds me on a question I asked a professor when I was a student on university.
What happens with power that is pushed to a RF antenna at valleys of polar pattern?
Answer: The power runs back into the amplifier!

 

[Deleted member 165050]

If any,
a steady sine wave can't transport any information in the sense of human communication, which is either speach or music.
Then there is all kinds of daily noise which actually differs from speach and music.
Either way, independent of what kind of specrum shall be transfered,
a sine wave keeps no information in the sense of science of telecommunications and also keeps no information in the sense of science of information and systems theory.

A sine wave (steady or otherwise) carries two very important items of information. Frequency and amplitude. Both of which are meaningful in music. So very much useful information for human communication.

 

[ThisBass]

A sine wave (steady or otherwise) carries two very important items of information. Frequency and amplitude. Both of which are meaningful in music. So very much useful information for human communication.

a sine that is not steady in ampliude will already generate some additional spectrum at transients, probably not audible.
I wonder how you will convey information to another people by sending him nothing but a endless lasting steady sine. Electrical or acoustical does not matter.
You might als send a steady DC or even nothing.
Try to imagine following two situations.
Which type of 'signal' carries more of information.
A steady sine 1kHz 1 Volt that was started with beginning of evolution (or creation) process and still carries on nowadays and furthermore will carriy on till ..... or just even no signal nothing at all.

To send morse code is a totally different animal and has nothing to do with a steady sine.

 

[beans-on-toast]

What are we arguing about again?

How time alignment is like the road runner.

 

[Deleted member 165050]

Nope,
a sine that is not steady in ampliude will already generate some additional spectrum at transients, probably not audible.
I wonder how you will convey information to another people by sending him nothing but a endless lasting steady sine. Electrical or acoustical does not matter.
You might als send a steady DC or even nothing.

To send morse code is a totally different animal and has nothing to do with a steady sine.

There ain't no such thing as endless, and there is information in everything. Including sine waves in the human hearing range. I have one in my ears all the time.

 

[ThisBass]

There ain't no such thing as endless, and there is information in everything. Including sine waves in the human hearing range. I have one in my ears all the time.

Actually it's a hard nut for every on go student who want's to learn one or two things about any kind of science on university that a steady sine carries actually no information.
And actually there are a couple of physical (and also socially) phenomena that do the proof.

Try to imagine following situation,
a steady sine wave is switched to steady on in the morning at 8:00 and switched to off at 18:00. Every day at 12:00 you check the sine if the signal is on. You might do this procedure for more than 50 years but you know nothing but it's a sine.
May be in the evening the sine was used to send morse code to south africa every night.
Every night frequently switched from on to off just to transfere information by morse code.

After 50 years are gone you heard nothing but a steady sine but in the evening the sine was used to transport lots of information.

 

[Deleted member 165050]

Nope,
Actually it's a hard nut for every on go student who want's to learn one or two things about any kind of science on university that a steady sine carries actually no information.
And actually there are a couple of physical (and also socially) phenomena that do the proof.

You are incorrect. I've detailed two items of information every sine wave carries, and the presence or absence of a sine wave can indicate more in any number of circumstances. Oh and by the way continually saying "nope" to people is rude. But then I'm not really surprised.

Incidentally there is no apostrophe in "wants".

 

[drittal]

Incidentally there is no apostrophe in "wants".

Ever think English isn't his first language?

 

[ThisBass]

You are incorrect. I've detailed two items of information every sine wave carries, and the presence or absence of a sine wave can indicate more in any number of circumstances. Oh and by the way continually saying "nope" to people is rude. But then I'm not really surprised.

Incidentally there is no apostrophe in "wants".

Sorry but with this post I do hard to translate your words. You know English isn't my first language.
Some art projects use very slightly differing tones in amplitude and frequency that is not directly noticeable within listening in time space of an hour or two. It may happen that difference in sound is more noticable when listening to the 'show' the other day.

Those extrem sound collages don't hurt science nothing at all, even not cybernetics, I think artists contribute something to evolution (or creating) process of human sociality and even if the sound collage is 'strange', may be the artist wants to show something about cybernetics which is very essential for human development (or creation) on planet earth.

Hope I remember there is no apostrophe with wants.
Nope in posts above is deleted.

 

[Al Kraft]

Try to imachine following two situations.
Which type of 'signal' carries more of information.
A steady sine 1kHz 1 Volt that was started with beginning of evolution (or creation) process and still carries on nowadays and furthermore will carriy on till ..... or just even no signal nothing at all.

To me as an engineer, this not a technical question, but rather a philosophical one that I would address by adding the concept of context. In my hypothetical answer below "carries more information" is defined broadly as the presence or absence of the signal itself to directly contribute to or change the state of knowledge/awareness of that person relative to at least one single thing in their environment.

If the presence of a steady state audible sound indicated, for instance, something good (e.g. my refrigerator is running - admittedly not a perfect, pure sine wave, but it will help illustrate the point), then hearing it would indicate that all is well and, in our fictional example, my food/drink is cold. That to me is clearly useful information essentially transmitted by the presence of a noise I associate with a normal state. If my refrigerator was a silently operating device (at least relative to my ability to perceive sound), then the presence of any audible noise (like maybe a pure sine wave) could indicate that a malfunction had occurred and my food/drink was going to spoil...a potentially valuable piece of information.

It's an interesting thought question that reminds me of this one which I never get quite right: if a tree falls in woods and hits a mime, does anyone care?

 

[Al Kraft]

You know English isn't my first language.

Without a doubt your English is better than my German.

 

[Downunderwonder]

I can generate a sine of 50hz @ one volt RMS and play it just fine. What are you guys smoking?