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Forum: Audio theory, Setup and Chat   07-30-2014, 06:21 PM
Replies: 14
Views: 308
Posted By Okv
This is how movie sound can improve

Movie sound can be improved significantly, and it is not Atmos or other new technology that will deliver this.
As for music, the true limitations of sound quality is the production - how the sound...
Forum: DIY Speakers and Subs   07-13-2014, 01:38 PM
Replies: 144
Views: 4,980
Posted By Okv
If you look at the graphs you can see that they...

If you look at the graphs you can see that they start to look kind of erratic and does not have a smooth roll-off below 20hz.
If the IR-window is increased there is more detail to get out of this,...
Forum: DIY Speakers and Subs   07-13-2014, 10:18 AM
Replies: 144
Views: 4,980
Posted By Okv
This is noise.

This is noise.
Forum: DIY Speakers and Subs   07-13-2014, 09:30 AM
Replies: 144
Views: 4,980
Posted By Okv
This one was relatively easy, I know the answer.....

This one was relatively easy, I know the answer..

First, the response velocity vs pressure can be different at different frequencies due to room interaction and boundaries, even when measuring...
Forum: DIY Speakers and Subs   07-13-2014, 09:19 AM
Replies: 144
Views: 4,980
Posted By Okv
It may be difficult to see, but the frequency...

It may be difficult to see, but the frequency response measurement using sine sweep also has all time information necessary to fully predict what will happen when any signal is reproduced.

If you...
Forum: DIY Speakers and Subs   07-12-2014, 01:48 PM
Replies: 144
Views: 4,980
Posted By Okv
Any software for measurement can of course be...

Any software for measurement can of course be used.
REW is the most used and it has also become a very complete and easy to set-up software tool for acoustic measurements.

A smaller driver will...
Forum: DIY Speakers and Subs   07-12-2014, 01:38 PM
Replies: 144
Views: 4,980
Posted By Okv
Measuring with a sine sweep will give you...

Measuring with a sine sweep will give you information about the system in the time domain also, you can analyze the signal like any other measurement, you can look at decay and so on.
It does not...
Forum: DIY Speakers and Subs   07-12-2014, 10:29 AM
Replies: 144
Views: 4,980
Posted By Okv
Quick attempt to answer some of your questions. ...

Quick attempt to answer some of your questions.

Use REW, and instead of connecting the usual microphone, just connect the driver.
A line level input is fine.
No HDMI necessary.
(This is...
Forum: DIY Speakers and Subs   07-11-2014, 10:47 AM
Replies: 144
Views: 4,980
Posted By Okv
Just a quick comment on this; At low...

Just a quick comment on this;
At low frequencies it does not matter what direction the acoustic port has, or the driver, it will radiate in an omnipolar pattern like a sphere, and the actual sound...
Forum: DIY Speakers and Subs   07-11-2014, 10:37 AM
Replies: 144
Views: 4,980
Posted By Okv
Thank you for the kind words about my subwoofer...

Thank you for the kind words about my subwoofer design, the subwoofers used in the measurement uses the same principle but looks quite different, more like an ordinary ported subwoofer from the...
Forum: DIY Speakers and Subs   07-10-2014, 06:33 PM
Replies: 144
Views: 4,980
Posted By Okv
Near-field is defined as where the distance is...

Near-field is defined as where the distance is close compared to the wavelength, so, in that perspective, everything is nearfield.
Here I call it near-field when measuring closer than around 0.5m...
Forum: DIY Speakers and Subs   07-10-2014, 06:02 PM
Replies: 144
Views: 4,980
Posted By Okv
The purpose of measuring velocity is to analyze...

The purpose of measuring velocity is to analyze and come up with rules for configuration of subwoofer systems indoor, so measurements are done indoor.

For checking and finding out more on the...
Forum: DIY Speakers and Subs   07-10-2014, 05:44 PM
Replies: 144
Views: 4,980
Posted By Okv
Port and driver facing towards listening...

Port and driver facing towards listening position, I used this subwoofer because the port is close to the driver and easy to block.
So the driver and the port faces the measurement device, and this...
Forum: DIY Speakers and Subs   07-10-2014, 01:50 PM
Replies: 144
Views: 4,980
Posted By Okv
Thank you, much of this is quite heavy stuff, it...

Thank you, much of this is quite heavy stuff, it is good to see that someone is still reading.
Forum: Receivers, Amps, and Processors   07-10-2014, 01:44 PM
Replies: 2,818
Views: 94,957
Posted By Okv
There seems to be a lot of focus on ceiling...

There seems to be a lot of focus on ceiling speakers and speaker configurations.

But I believe the greatest benefit is that it is easier to produce better soundtracks, and they are independent of...
Forum: DIY Speakers and Subs   07-09-2014, 04:17 PM
Replies: 144
Views: 4,980
Posted By Okv
Measurement does not need to be accurate as long...

Measurement does not need to be accurate as long as it is consistent so that it is possible to make measurements that can be compared to each other.
The measurement results shows that the sound...
Forum: DIY Speakers and Subs   07-09-2014, 11:26 AM
Replies: 144
Views: 4,980
Posted By Okv
There is really no magic mystery around this, the...

There is really no magic mystery around this, the theory behind it is well known and described and the practical implementation I found to work well enough is simple - just use a bass driver with no...
Forum: DIY Speakers and Subs   07-09-2014, 11:13 AM
Replies: 144
Views: 4,980
Posted By Okv
I believe your observation is correct, but the...

I believe your observation is correct, but the theory is wrong.
Once you move away from the port the sound field is similar to sealed, because both are small acoustic radiators at low frequencies. ...
Forum: DIY Speakers and Subs   07-08-2014, 10:18 AM
Replies: 144
Views: 4,980
Posted By Okv
Instead of the microphone you connect the...

Instead of the microphone you connect the velocity meter.
In REW the signal is treated just like an ordinary measurement with ordinary microphone.

Your questions got me thinking it may actually...
Forum: DIY Speakers and Subs   07-08-2014, 09:41 AM
Replies: 144
Views: 4,980
Posted By Okv
Look for graphs with "0deg" in the name in the...

Look for graphs with "0deg" in the name in the legend, this is a velocity measurement.

Velocity is measured in distance per time unit, as in m/s or ft/sec, but here it is represented in dB, which...
Forum: DIY Speakers and Subs   07-07-2014, 06:04 PM
Replies: 144
Views: 4,980
Posted By Okv
This looks like a great idea?

This looks like a great idea?
Forum: DIY Speakers and Subs   07-07-2014, 06:03 PM
Replies: 144
Views: 4,980
Posted By Okv
(I may have mentioned, if so, it is buried in...

(I may have mentioned, if so, it is buried in this or some other thread..)

I made a velocity measurement device out of a retired lf driver, I had some laying around, destroyed 2, and now I have 2...
Forum: DIY Speakers and Subs   07-07-2014, 01:53 PM
Replies: 144
Views: 4,980
Posted By Okv
Just some comments to the plots above: The...

Just some comments to the plots above:

The velocity normalized shows that velocity for a given spl is exactly the same for both configurations open or closed port, for near field and listening...
Forum: DIY Speakers and Subs   07-07-2014, 01:43 PM
Replies: 144
Views: 4,980
Posted By Okv
Comparing near field to lp1, however, is...

Comparing near field to lp1, however, is something quite different, we see that the velocity is much larger near field, for same spl: ...
Forum: DIY Speakers and Subs   07-07-2014, 01:41 PM
Replies: 144
Views: 4,980
Posted By Okv
No, once you move away from the close proximity...

No, once you move away from the close proximity of the port (where velocity can be very large, 10..30m/s), there is no difference:

Near field, one of my Compact Horn Subwoofers, open and closed...
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