First speaker to reproduce a 60hz sq wave

[Matt_Holland]

I don’t think anyone is doubting the problems with reproducing square waves from conventional speakers. We’re just keen to know how your device works and evidence of claims made.

Are you using multiple woofers, each dedicated to reproducing separate parts of the Fourier series of sine waves?

In case these questions were missed by the OP.

 

[mhardy6647]

I thought the trick to reproducing a square wave* with a transducer (loudspeaker) was keeping everything in phase... crossovers and phase are like fish and bicycles.

______________
* [EDIT] besides bandwidth and amplitude, of course.

 

[fpitas]

I thought the trick to reproducing a square wave with a transducer (loudspeaker) was keeping everything in phase... crossovers and phase are like fish and bicycles.

Yup. Phase coherent. These days it can be easily done with phase flattening, like with RePhase or various others. In our highly scientific listening tests, aided by some well-aged mead, it matters at low frequencies but was undetectable at the 800Hz crossover. My friend left it in for 800Hz anyways, just to be trendy

 

[MAB]

As I said elsewhere, the first odd harmonic is in the planar driver and so on up the chain. I can create the square wave with large. cone drivers. How? Clue is in the name.

I don't understand.
To get a decent square wave, you need the fundamental plus the first two harmonics to be reasonably aligned phase and amplitude.
For instance a simulation:

Note that the phase is more critical than the amplitude. Here is a square wave built from the first four series. I changed the phase only of the second, third and fourth terms to illustrate:

To demonstrate, I have a 10" Seas W26 woofer in a 25 liter sealed box that I just measured a square wave on:

I measured this nearfield with a UMIK. Use only a few PEQ to flatten the frequency response and remove the peak in the breakup mode of the woofer. I got this driver to produce reasonable square-wave from 125Hz to 500Hz as above.
Here is before and after PEQ:

It is rough, very rough... But enough to demonstrate...
Without PEQ, the driver cannot produce a credible square wave and has dramatic changes in the harmonics as the fundamental changes:

I played around with more extensive PEQ filters and got even better results. I am only EQ'ing the amplitude here, ignoring phase, and that is kind of the point.
So it would be good to understand what you are doing a bit better.

 

[Matt_Holland]

I am only EQ'ing the amplitude here, ignoring phase, and that is kind of the point.
So it would be good to understand what you are doing a bit better.

Cool! By flattening the SPL in the woofer breakup region are you automatically correcting phase? Or just reducing the effect of the phase swings inherent in the driver?
What does the square wave look like if you brick-wall low pass the driver before it starts breaking up?

 

[antcollinet]

1140 is the 19th harmonic but the 9th odd harmonic.

But 1140 isn't in your waveform. As I pointed out above the highest frequency shown in the recorded waveform is 420Hz.

 

[MAB]

Cool! By flattening the SPL in the woofer breakup region are you automatically correcting phase? Or just reducing the effect of the phase swings inherent in the driver?

Just SPL.
I imagine I am introducing additional phase issues.

What does the square wave look like if you brick-wall low pass the driver before it starts breaking up?

Decent
2kHz, 48dB/octave, no PEQ:

3kHz, 48dB/oct, no PEQ:

I do think all I am doing is mitigating the impacts of the misaligned amplitudes, but doing nothing for the phase:

You can even see why I have a reasonable chance of producing a square wave from 125Hz to 500Hz. By 500Hz, the third harmonic is going to be 60 degrees misaligned with the fundamental. In fact, the PEQ I applied actually makes the slope of the phase vs. freq slightly worse above 2kHz. All I did was reduce the amplitude peak. If my simple simulation above is true, flattening the phase, and the response across three octaves seems to be a criteria that would suggest a decent square wave.

By the way, showing that one frequency or series of multi-tones is correctly rendered is not sufficient. Even that W26 woofer has a few frequencies that even without PEQ produce good square waves for a given mic setup!

 

[antcollinet]

So - at the end of the day, square wave accuracy is just a measure of frequency response flatness, and phase.


And we are back to that old question - is phase shift audible. Because we sure as hell don't listen to square waves.

 

[voodooless]

So - at the end of the day, square wave accuracy is just a measure of frequency response flatness, and phase

Who would have thought..

… once again, no magic is needed. As Laplace fittingly noted:

Sir, I have no need of that hypothesis.

 

[thewas]

Cool! By flattening the SPL in the woofer breakup region are you automatically correcting phase?

Also in the region before as there a single driver behaves mostly like a minimum phase device, so correcting the amplitude automatically also corrects the phase-

And we are back to that old question - is phase shift audible. Because we sure as hell don't listen to square waves.

A better metric for audibility is the group delay and there exist enough research about the limits where it become audible.

 

[Hayabusa]

pump a 60hz sq wave into your speakers and see what you get.

This what I got.. Indeed, yours looks more symmetric.

 

[OldHvyMec]

I have 11 drivers in my full range speakers,

That explains a lot!

none of which duplicate any frequency range except within a very narrow 48db

And that explains the rest.

So you want to control the sub/bass and 1/3 of the mid range?

How many drivers are you going to add to the mix if it's 1KHZ <? 2? The same driver or
do you use a different driver type per? Sub, bass, MB coupler, low mid?

I've seen 1 khz boxes < and they were very expensive. Wilson maybe? Nothing new though.

I'd like to know how you're going to implement that 48 db slope on the monitor side?
OR are you saying if there are dual binding post toss the bass section in a 2 way bookshelf.
1 khz is pretty close in many models. Then implement your system? OR digital or analog
LP filter?

Regards

 

[audiofooled]

So - at the end of the day, square wave accuracy is just a measure of frequency response flatness, and phase.


And we are back to that old question - is phase shift audible. Because we sure as hell don't listen to square waves.

Well, mine aren't perfectly square, but can be rather pleasant to listen to. But I do listen to music occasionally

 

[mhardy6647]

So - at the end of the day, square wave accuracy is just a measure of frequency response flatness, and phase.


And we are back to that old question - is phase shift audible. Because we sure as hell don't listen to square waves.

Not as such, no...but I'd never argue that square waves aren't a useful model for hifi component performance.

 

[Absolute]

I've got to say that I'm not impressed by the information shared over 3 pages. I get the sense that this thread is an attempt to catfish us into being interested in something mysterious and profound that is so secret it can only be hinted about.

I don't like it. Not one bit.

 

[antcollinet]

Not as such, no...but I'd never argue that square waves aren't a useful model for hifi component performance.

Why?

It's not any more informative than a frequency/phase response measurement. Less so if anything.

 

[audiofooled]

I've got to say that I'm not impressed by the information shared over 3 pages. I get the sense that this thread is an attempt to catfish us into being interested in something mysterious and profound that is so secret it can only be hinted about.

I don't like it. Not one bit.

ASR is a tough crowd to impress. People would have questions, "shut up and take my money!" would be the last statement on the last page if it would ever happen.

Perhaps doing some market research was an honest intention but clickbaits aren't popular over here. It has been more than 24 hours now, has the OP left the building?

 

[fpitas]

I've got to say that I'm not impressed by the information shared over 3 pages. I get the sense that this thread is an attempt to catfish us into being interested in something mysterious and profound that is so secret it can only be hinted about.

I don't like it. Not one bit.

You may be right; but a lot of us remember or have heard previous examples, or even made our own, so any secret glamour dissipated pretty quickly.

 

[ampguy]

Forget the speaker business. Make it a signal generator!

 

[fpitas]

"shut up and take my money!" would be the last statement on the last page if it would ever happen