Author Topic: Why Nobody Buys Sound Cards Anymore  (Read 6906 times)

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Offline b_force

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #75 on: November 06, 2018, 03:24:59 pm »
The major problem is intermodulation distortion produced by the speaker drivers themselves and especially with the bass driver.  This is minimized by limiting displacement which is not difficult for higher frequency drivers but a major problem at low frequencies.  The reason bass-reflex designs are so helpful is that they minimize driver displacement at resonance which is exactly the procedure I use for tuning during construction.  All that it takes is an audio signal generator, multimeter, and enclosure design which allows adjustment.
Well, in fact a bass-reflex system is actually more likely to introduce more non-linear distortion

See; https://www.klippel.de/fileadmin/_migrated/content_uploads/Loudspeaker_Nonlinearities%E2%80%93Causes_Parameters_Symptoms_01.pdf
Page 16 (if you look around the web you will find similar findings)

Still, Floyd Toole (Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms) basically has proved that all these effects are less important on the "priority list".
Or in other words, bad directivity and room acoustics are much more significant that just a little bit of extra distortion.
Of course all within limits.

But in general, yes more excursion means more distortion. Mostly due too non-lineair effects in the suspension and magnetic field.
So for the same air volume displacement, it is always better to take a bigger woofer.
Although with a proper driver design (especially the motor) that isn't always that black and white.
A bad designed 12" will perform less than a very well designed 8".
(a side note, a good designed speaker isn't always more expensive)

Btw, signal generators and multimeters are old fashioned.
Just get a laptop, smartphone or PC with a decent soundcard.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline John B

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #76 on: November 06, 2018, 09:21:01 pm »
I'm still running a MOTU firewire interface for audio and music production purposes. I use a Scarlett interface on the PC as an audio out and headphone preamp.

What is interesting in this conversation is that audio interfaces are compromises in themselves. So while you may look at motherboard based sound hardware as being an all-in-one compromise, an audio engineer may look at an interface as being an all-in-one compromise. That is, the interface is a mix of ADCs/DACs and preamps. If you want to spend big bucks and get the absolute best in each area, you have to buy them separately.

It's not audiophoolery either. For example the headphone preamp in my MOTU isn't that powerful, so I have a separate multi channel headphone amp for driving 250 ohm headphones. Having said that, a high end interface is plenty for professional quality recordings.
 

Offline b_force

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #77 on: November 06, 2018, 10:13:27 pm »
I'm still running a MOTU firewire interface for audio and music production purposes. I use a Scarlett interface on the PC as an audio out and headphone preamp.

What is interesting in this conversation is that audio interfaces are compromises in themselves. So while you may look at motherboard based sound hardware as being an all-in-one compromise, an audio engineer may look at an interface as being an all-in-one compromise. That is, the interface is a mix of ADCs/DACs and preamps. If you want to spend big bucks and get the absolute best in each area, you have to buy them separately.

It's not audiophoolery either. For example the headphone preamp in my MOTU isn't that powerful, so I have a separate multi channel headphone amp for driving 250 ohm headphones. Having said that, a high end interface is plenty for professional quality recordings.
That is correct, some headphones are difficult to drive.

Also for professional recordings or professional PA systems (so mixers etc) you really need to have a decent SNR.
If you have a pretty sensitive headphone you can sometimes easily hear the noise.

Interfaces and sounds-cards nowadays are actually pretty good.
Like said before, even the onboard soundcards are better than top of the line CD-players 10-15 years ago.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline John B

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #78 on: November 07, 2018, 12:48:19 am »
Speaking of distortion, I have noticed with the MOTU interface that there is noticeable distortion when sampling a simple sine wave. This is sampling at 24bits/48kHz.

I've made sure that the distortion isn't present in the original signal. The distortion takes the form of noticeable harmonics of the fundamental frequency, especially the 5th 7th and 9th harmonic.

It's not noticeable with a complex signal, but obvious and audible with a simple sine wave. Never figured out whether it was user error, or just limitations on the hardware itself.
 

Offline b_force

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #79 on: November 07, 2018, 12:54:30 am »
Speaking of distortion, I have noticed with the MOTU interface that there is noticeable distortion when sampling a simple sine wave. This is sampling at 24bits/48kHz.

I've made sure that the distortion isn't present in the original signal. The distortion takes the form of noticeable harmonics of the fundamental frequency, especially the 5th 7th and 9th harmonic.

It's not noticeable with a complex signal, but obvious and audible with a simple sine wave. Never figured out whether it was user error, or just limitations on the hardware itself.
Sounds more like a samplerate conversion somewhere that didn't really went well.
Don't know what system you're using, but in Windows just check your settings.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline John B

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #80 on: November 07, 2018, 01:09:31 am »
Speaking of distortion, I have noticed with the MOTU interface that there is noticeable distortion when sampling a simple sine wave. This is sampling at 24bits/48kHz.

I've made sure that the distortion isn't present in the original signal. The distortion takes the form of noticeable harmonics of the fundamental frequency, especially the 5th 7th and 9th harmonic.

It's not noticeable with a complex signal, but obvious and audible with a simple sine wave. Never figured out whether it was user error, or just limitations on the hardware itself.
Sounds more like a samplerate conversion somewhere that didn't really went well.
Don't know what system you're using, but in Windows just check your settings.

Similar kind of sound as a bad resampling algorithm. Except in this case the audible distortion is present in both recorded form, and through the interface's internal routing, ie input straight to output. I use Reaper on a Mac, but it doesn't seem to be a relevant factor in this case. I think.
 

Offline b_force

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #81 on: November 07, 2018, 01:20:19 pm »
Speaking of distortion, I have noticed with the MOTU interface that there is noticeable distortion when sampling a simple sine wave. This is sampling at 24bits/48kHz.

I've made sure that the distortion isn't present in the original signal. The distortion takes the form of noticeable harmonics of the fundamental frequency, especially the 5th 7th and 9th harmonic.

It's not noticeable with a complex signal, but obvious and audible with a simple sine wave. Never figured out whether it was user error, or just limitations on the hardware itself.
Sounds more like a samplerate conversion somewhere that didn't really went well.
Don't know what system you're using, but in Windows just check your settings.

Similar kind of sound as a bad resampling algorithm. Except in this case the audible distortion is present in both recorded form, and through the interface's internal routing, ie input straight to output. I use Reaper on a Mac, but it doesn't seem to be a relevant factor in this case. I think.
What I was trying to say is that the samplerate has to match the samplerate of the audio file on some interfaces.
If you're talking about just a loopback (it won't even go into your pc) than there is obviously something else wrong in circuit.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline David Hess

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Re: Why Nobody Buys Sound Cards Anymore
« Reply #82 on: November 13, 2018, 02:25:15 am »
The major problem is intermodulation distortion produced by the speaker drivers themselves and especially with the bass driver.  This is minimized by limiting displacement which is not difficult for higher frequency drivers but a major problem at low frequencies.  The reason bass-reflex designs are so helpful is that they minimize driver displacement at resonance which is exactly the procedure I use for tuning during construction.  All that it takes is an audio signal generator, multimeter, and enclosure design which allows adjustment.

Well, in fact a bass-reflex system is actually more likely to introduce more non-linear distortion

See; https://www.klippel.de/fileadmin/_migrated/content_uploads/Loudspeaker_Nonlinearities%E2%80%93Causes_Parameters_Symptoms_01.pdf
Page 16 (if you look around the web you will find similar findings)

Bass-reflex adds other distortion mechanisms but lowers the overwhelming non-linear distortion from the driver by minimizing displacement.

Quote
Still, Floyd Toole (Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms) basically has proved that all these effects are less important on the "priority list".
Or in other words, bad directivity and room acoustics are much more significant that just a little bit of extra distortion.
Of course all within limits.

In my experience the non-linear bass distortion is overwhelming for high fidelity material.

Quote
But in general, yes more excursion means more distortion. Mostly due too non-lineair effects in the suspension and magnetic field.

Page 17 of the PDF you linked discusses the major contribution from the doppler effect.  A bass-reflex design improves this by minimizing cone movement but using a good crossover is also important.

Quote
Btw, signal generators and multimeters are old fashioned.
Just get a laptop, smartphone or PC with a decent soundcard.

Why make it complicated when it can be simple?  Tuning a bass-reflex design requires only a signal generator, resistor, and multimeter.  The port is adjusted to null the speaker resonance producing two smaller resonances on either side.
 


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