Burst waveform is excellent test signal for testing:
I have generated a continuous track of bursts with center frequency sweeping from 10Hz to 200Hz through 4 minute interval and uploaded a copy as 44.1kHz 16bit mono wave file:
https://dl.dropboxusercontent.com/s/advf4c75c4keqof/swept%20bursts%2010Hz-200Hz%204min.wav?dl=1&token_hash=AAFfz_TjpnizazdzfkfNXMOcXhYO38vIv8Z8v5zHoARyaw
As long sweep the spectrum at any point is easily resolved as a peak center frequency with side bands at 0.85f and 1.15 f:
Response recording of waveform is revealing of room interaction and distortion.
Waveform readily exercises driver excursion, and caution is advised in controlling volume at start of wave with initial use until familiar with system capability.
Slow sweep effectively energizes single room mode over any short interval of time.
In my room driving sub system with two subs each with 450 watts of available power, portions of track sound like diesel locomotive throttling up under load.
Perception of sound direction shifts with frequency.
I have generated a continuous track of bursts with center frequency sweeping from 10Hz to 200Hz through 4 minute interval and uploaded a copy as 44.1kHz 16bit mono wave file:
https://dl.dropboxusercontent.com/s/advf4c75c4keqof/swept%20bursts%2010Hz-200Hz%204min.wav?dl=1&token_hash=AAFfz_TjpnizazdzfkfNXMOcXhYO38vIv8Z8v5zHoARyaw
As long sweep the spectrum at any point is easily resolved as a peak center frequency with side bands at 0.85f and 1.15 f:
Response recording of waveform is revealing of room interaction and distortion.
Waveform readily exercises driver excursion, and caution is advised in controlling volume at start of wave with initial use until familiar with system capability.
Slow sweep effectively energizes single room mode over any short interval of time.
In my room driving sub system with two subs each with 450 watts of available power, portions of track sound like diesel locomotive throttling up under load.
Perception of sound direction shifts with frequency.
^
Nice. Here are bursts that vary the time between single bursts. Let's you hear room modes.
https://dl.dropboxusercontent.com/u/21936387/audio/test_signals/LF_TEST.zip
With my near field sub each burst is heard as a single event with no prolonged decay.
Nice. Here are bursts that vary the time between single bursts. Let's you hear room modes.
https://dl.dropboxusercontent.com/u/21936387/audio/test_signals/LF_TEST.zip
With my near field sub each burst is heard as a single event with no prolonged decay.
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Markus76,
I am surprised that nobody has asked what the driver is that is creating that flat response in your sub woofer. Is there some error correction going on in that implementation? I would say that this would fall into a reference speaker with this FR and decay plot. Tell us more please.
And Happy New Year to all, was off sailing and wasn't anywhere near the internet.
I am surprised that nobody has asked what the driver is that is creating that flat response in your sub woofer. Is there some error correction going on in that implementation? I would say that this would fall into a reference speaker with this FR and decay plot. Tell us more please.
And Happy New Year to all, was off sailing and wasn't anywhere near the internet.
I asked, he did not really respond.
And as far as nearfield is concerned, it's unclear to me just how "near" this is?
Like 1/3m or less?? I work in inches so the metric units except for meters seem not so clear to me.
What was referenced was another forum where the person used an entire wall as a single baffle with multiple LF drivers across the surface...
The results seem too good to be true having measured many speakers and drivers. I expect a boatload of DSP based error correction at minimum. I have to admit I am unfamiliar with what HT is doing in this area.
And as far as nearfield is concerned, it's unclear to me just how "near" this is?
Like 1/3m or less?? I work in inches so the metric units except for meters seem not so clear to me.
What was referenced was another forum where the person used an entire wall as a single baffle with multiple LF drivers across the surface...
The results seem too good to be true having measured many speakers and drivers. I expect a boatload of DSP based error correction at minimum. I have to admit I am unfamiliar with what HT is doing in this area.
Bear,
I agree with you that the FR and the decay plot on that speaker is beyond anything I have seen that was not using massive correction to get that flat a response. I also don't for a second believe that most speakers even nearfield would have anything like that response plot. That is not just some speaker placed in a box and getting that +/- 1db without being something special. Considering that it is supposedly no smoothing something smells here.
Just remember that a meter is almost the same as a yard. 39.4" vs 36"
I agree with you that the FR and the decay plot on that speaker is beyond anything I have seen that was not using massive correction to get that flat a response. I also don't for a second believe that most speakers even nearfield would have anything like that response plot. That is not just some speaker placed in a box and getting that +/- 1db without being something special. Considering that it is supposedly no smoothing something smells here.
Just remember that a meter is almost the same as a yard. 39.4" vs 36"
Bear, I did respond and all the information is there. What else do you want to know? There're no secrets surrounding near field sub. Put it as close as possibe to your ears (around 1ft), lift the low end if you want to and you're done.
The damped SBA is documented in this PDF. It's in German. You can try Google Translate to translate it.
There is no "boatload of DSP based error correction at minimum". SBA is similar to a DBA: Double Bass Array (DBA) - The modern bass concept!
Measure the frequency response of your sub in 1ft distance. What frequency response do you get?
markus, the "SBA" is the same system you linked to earlier. It has multiple woofers on a large front wall. As I said nearly an IB arrangement that uses the entire front wall.
The "DBA" makes a claim that quite frankly I do not understand how it could possibly be correct. It may, but I do not know. Dr. Geddes might care to look at the DBA and comment?
I don't understand how the DBA, placed in a random room using the placement by the fraction of dimension specified would cause room nodes to not occur, and I am unclear how the delayed out of phase woofers on the back wall prevent room nodes or reflections either. Although that last bit seems both curious and worthy of more investigation.
What this has to do with you having a woofer a foot from your head, I'm lost on??
The "DBA" makes a claim that quite frankly I do not understand how it could possibly be correct. It may, but I do not know. Dr. Geddes might care to look at the DBA and comment?
I don't understand how the DBA, placed in a random room using the placement by the fraction of dimension specified would cause room nodes to not occur, and I am unclear how the delayed out of phase woofers on the back wall prevent room nodes or reflections either. Although that last bit seems both curious and worthy of more investigation.
What this has to do with you having a woofer a foot from your head, I'm lost on??
DBA and near field sub are two different approaches to get bass that is flat and free of modes into an acoustically small room. Something you considered "a funny idea".
Regarding how a DBA works this diagram might be helpful:
The front array creates a plane wave that travels through the room. The same plane wave is emitted at the back of the room exactly when the front wave arrives at the back array. This affectively cancels the front wave. This is active absorption.
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Bear
I have no doubt that the DBA works as claimed. But to me its massive overkill. It would be easy to implement for anyone who wants to throw ton's of dollars at a solution that is extremely hard to implement in real rooms. I just don't see the point. I get comparable results with a far far simpler and more practical approach.
By the way, I posted my Room Modes software on my web site. It most likely won't run for a couple hours yet (maybe more) as the code is having some trouble finding the right DLLs.
I have no doubt that the DBA works as claimed. But to me its massive overkill. It would be easy to implement for anyone who wants to throw ton's of dollars at a solution that is extremely hard to implement in real rooms. I just don't see the point. I get comparable results with a far far simpler and more practical approach.
By the way, I posted my Room Modes software on my web site. It most likely won't run for a couple hours yet (maybe more) as the code is having some trouble finding the right DLLs.
When do we get to see those impulse responses of your room that would prove your claim?
Thanks! I'll try it right away.
Markus
That would be on your side, but it still should not happen. I don't use those power packs (that I know of) so they should not be necessary. And if they are necessary, the installer should download them onto your computer.
I just ran the software off of my site and it worked fine. You do have to right click on each source to get it to work as something in the default load prevents it from showing up. The scales on the plot change by double clicking on the top dB number or the bottom one to move the scale up or down. The range is fixed for now.
The trouble with this kind of software is that it always works on the machine on which it was developed. It can take a while to figure out why it won't work on remote machines. My expertise is in number crunching not in web server administration.
That would be on your side, but it still should not happen. I don't use those power packs (that I know of) so they should not be necessary. And if they are necessary, the installer should download them onto your computer.
I just ran the software off of my site and it worked fine. You do have to right click on each source to get it to work as something in the default load prevents it from showing up. The scales on the plot change by double clicking on the top dB number or the bottom one to move the scale up or down. The range is fixed for now.
The trouble with this kind of software is that it always works on the machine on which it was developed. It can take a while to figure out why it won't work on remote machines. My expertise is in number crunching not in web server administration.
^
I've searched around but didn't find a download for v10 of those "Visual Basic Power Packs". I found v3 which is from 2008 (!), downloaded and installed it but no luck.
I think your app needs to provide it: Deploying Applications That Reference Visual Basic Power Packs
Edit: Found an installer for v10: http://go.microsoft.com/fwlink/?LinkID=145727&clcid=0x804
Nw I get this error message:
I've searched around but didn't find a download for v10 of those "Visual Basic Power Packs". I found v3 which is from 2008 (!), downloaded and installed it but no luck.
I think your app needs to provide it: Deploying Applications That Reference Visual Basic Power Packs
Edit: Found an installer for v10: http://go.microsoft.com/fwlink/?LinkID=145727&clcid=0x804
Nw I get this error message:
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The thing that convinced me to convert back to stereo bass is the many papers written by David Griesinger, formerly a top engineer at Lexicon. He talks about how the lower frequencies create more of a feeling of "envelopment" when the recording actually has stereo bass. He also talks about how the acoustics of most listening rooms effectively reduces separation at the lower frequencies, and shares a circuit that combats this somewhat effectively. Google his name and read his papers. He's one of the best out there IMO.
^
I've searched around but didn't find a download for v10 of those "Visual Basic Power Packs". I found v3 which is from 2008 (!), downloaded and installed it but no luck.
I think your app needs to provide it: Deploying Applications That Reference Visual Basic Power Packs
Edit: Found an installer for v10: http://go.microsoft.com/fwlink/?LinkID=145727&clcid=0x804
Nw I get this error message:
The last error is the one that I just fixed, at least on my end. I'll look into the VB power pack error as this should not be required. It may have snuck into the references.
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