A Faster S.S. Head?

[okcrum]

This is not unlike the particle theory and wave theory duality that occurs in the analysis of light energy. It depends on how you look at the problem as to which solution makes sense in context.

Yep. You can work in either domain (time or freq), bearing in mind how they are related, and use the best tool for the job.

 

[agedhorse]

Linear Phase EQ - no phase shift, digital domain only:

[Invalid or Expired Link Removed]
Linear Phase EQ - Equalizer Plugin | Waves

A bet a few power amps with DSP also have this.

Is it a gimmick or does it matter? I'll say on some instruments like an acoustic guitar, it just sounds like a different acoustic guitar. Not an equalized guitar.

In DSP, if you are willing to accept some uniform delay (across the entire spectrum) then anything is possible. Specifically, it's possible to look ahead in RELATIVE time. This is how some fast DSP limiting operates without clicks and chirps.

I suspect (I am not a DSP coder or algorithm developer myself) that once you buy yourself a few mSec of (real) delay, real time no longer matters when calculating filter coefficients. You can essentially solve amplitude and correct for phase shift in tandem.

 

[seanm]

I have to agree with the OP, there are amps that feel fast and amps that feel slow. You might not like the terminology, but that is how they feel.

It isn't the bass, because I have noticed it on different rigs with the same bass. I don't think it is EQ, because my iAMP seems fast even with extreme EQs. Although I wasn't really listening for that at the time. So that has to be taken with a grain of salt.

You also don't have to play fast to notice it. Trust me, I am not a fast player

Fast or slow probably are the wrong words, but they immediately come to mind as strong images. It is hard to ignore them.

 

[David Jayne]

I submit that the term "bappy" should be permanently lodged in the Talkbass lexicon.

It's no "oomph" but I like it better than "mwah."

::: Applause :::

 

[chadds]

Cause we're talking about Bappage.

 

[DavePlaysBass]

Just to be clear, DavePlaysBass is not incorrect in estimating 2 ms filter delay in post #44. That's a lower limit, but delay can go as high as 20-25 ms depending on the filter design. All the numbers for phase delays in filters are dependent on the type and Q of filter chosen.

That is all.

If you have a single pole at 40Hz, the natural frequency is 251 radians which is a time response (tal) of 4ms (not 2ms, must have mis hit the calculator the first time). This is just a ball park estimate. Later in the post I state that the phase lag could be even greater depending on how the filter is designed.

A 4ms tal, means that if you hit it with a square wave, you will get a response that is 63% of the way there at 4ms, 86% of the way there at 8ms, and 95% of the way there at 12ms. Again this is an order of magnitude calculation.

Also remember music is not sine waves, shifting a sine wave 360 degrees is nothing. But phase shifting a time varying input by the same amount is a delay that may be audible.

 

[Bob Lee (QSC)]

Slew rate is measured in volts against seconds, look up the respective slew rates as thats the only thing that they will publish that refers to what you feel you hear.

No, it's not. "Slew rate" is not about delay.

"Fast" and "slow" are psychoacoustic impressions that probably relate to loudness, EQ, etc. Unless an amp has delay built into it (you'd pay extra for that), the signal goes through instantaneously, as far as what human perception can detect.

 

[Bob Lee (QSC)]

Group Delay is inaudible except on systems that are so poor that other factors would make them unlistenable. Oddiophiles get all worked up about group delay because it's obvious on a chart, but you can't hear it, so it doesn't matter.

What the OP is hearing is simply the differences in the frequency response of the systems. Those with more midrange presence in the 500-800 Hz range will seem 'faster', because the ear/brain is most sensitive in that range. Psychoacoustics, pure and simple.

All of the other explanations offered would have some merit if electronic devices were mechanical, operating at the speed of sound or a few multiples of that. But they don't. They work at speeds that approach that of light. That includes the reaction time of speakers. Even if by some manner an amp or speaker could be persuaded to run at half normal speed it would still be some 300 thousand times faster than the speed of sound.

+1

 

[R Baer]

Group Delay is inaudible except on systems that are so poor that other factors would make them unlistenable. Oddiophiles get all worked up about group delay because it's obvious on a chart, but you can't hear it, so it doesn't matter.

What the OP is hearing is simply the differences in the frequency response of the systems. Those with more midrange presence in the 500-800 Hz range will seem 'faster', because the ear/brain is most sensitive in that range. Psychoacoustics, pure and simple.

All of the other explanations offered would have some merit if electronic devices were mechanical, operating at the speed of sound or a few multiples of that. But they don't. They work at speeds that approach that of light. That includes the reaction time of speakers. Even if by some manner an amp or speaker could be persuaded to run at half normal speed it would still be some 300 thousand times faster than the speed of sound.

++1 I would bet if I set up a blind A/B listening test with a group of bassist and asked them to pick out the "amp with the faster response" almost everyone would pick the brighter amp, even if all I did was eq the same amp two different ways. It's a bit like the old belief that 10" drivers sound faster than 15" drivers.

 

[okcrum]

If you have a single pole at 40Hz, the natural frequency is 251 radians which is a time response (tal) of 4ms (not 2ms, must have mis hit the calculator the first time). This is just a ball park estimate. Later in the post I state that the phase lag could be even greater depending on how the filter is designed.

A 4ms tal, means that if you hit it with a square wave, you will get a response that is 63% of the way there at 4ms, 86% of the way there at 8ms, and 95% of the way there at 12ms. Again this is an order of magnitude calculation.

Also remember music is not sine waves, shifting a sine wave 360 degrees is nothing. But phase shifting a time varying input by the same amount is a delay that may be audible.

It's not really delay but rather the change in relative phase of the components of the complex waveform, in your example, a square wave that will be audible. If the example was a true time delay, the square wave would be undistorted.

 

[JHAz]

It's not really delay but rather the change in relative phase of the components of the complex waveform, in your example, a square wave that will be audible. If the example was a true time delay, the square wave would be undistorted.

Actually, as I understand it, and in my limited experience, unless you have multiple transducers with differing phase delays, relative phase is not particularly audible. There at least used to be a headphone site that showed the phase results of various phones they tested. Many headphones mangled square waves into utterly unrecognizable bizarre shapes. Still sounded like a square wave to me.

Whether it's a natural sound, or coming from a speaker, the relative phases of the different frequencies, since they all have different periods, are different in different locations relative to the source. When I step toward or away from a sound, it doesn't change, even though the relative phases have changed.

 

[billfitzmaurice]

Actually, as I understand it, and in my limited experience, unless you have multiple transducers with differing phase delays, relative phase is not particularly audible..

Close. It's totally inaudible. And a good thing, too, as every component in your amp, your speakers and anything else in the signal chain imparts some degree of phase shift. Phase only becomes an issue when you mix two sources with differing phase. An extreme case of what happens then can be heard when you use an effect called, of all things, a phasor.

 

[jnewmark]

Close. It's totally inaudible. And a good thing, too, as every component in your amp, your speakers and anything else in the signal chain imparts some degree of phase shift. Phase only becomes an issue when you mix two sources with differing phase. An extreme case of what happens then can be heard when you use an effect called, of all things, a phasor.

I'm surprised you did'nt make a Star Trek reference, like, " Set all PHASORS to stun !"

 

[agedhorse]

It's not really delay but rather the change in relative phase of the components of the complex waveform, in your example, a square wave that will be audible. If the example was a true time delay, the square wave would be undistorted.

and for bonus points, what is a "simple" square wave made up of?

 

[Windreaper]

and for bonus points, what is a "simple" square wave made up of?

Smartass engineers . Won't bother to answer that but will post a picture .

Link Removed

 

[agedhorse]

A square wave is a Fourier series composed of the sine wave fundamental plus an infinate summation of it's sine wave harmonics.

(in practice this requires infinate bandwidth, which is unobtanium.)

 

[Bob Lee (QSC)]

^ +1 Specifically, the odd-order harmonics.

 

[Windreaper]

Yup, additive synthesis works by "adding sinusoidal overtones together". Used to have a Kawai K5000 back in the day .

EDIT: Did some digging and found a really nice tutorial explaining the concept:

http://www.computermusicresource.com/squarewave.tutorial.html

 

[Bob Lee (QSC)]

Analog synthesizers are what got me interested in waveforms, harmonics, and Fourier series.

 

[gnjpowell]

I speculate the delay from the speaker to your ear is orders of magnitude greater Vs the delay through the amp... or any other piece of electronics or cables.....