Official Rythmik Audio Subwoofer thread - Page 283

Originally Posted by Eldiablos 
:I have a FV15HP and I noticed that flapping issue while watching Dredd at the classroom scene. I have mine set to 14hz extension high damper. What's the negative of setting the damper to low?

Originally Posted by rsmt2000 

just wondering what is the cut off for someone to got to FV15H as opposed to LV12 in terms of room size. Also vice versa when can some one know that LV12 is good enough and any thing more is an over kill?

Originally Posted by Rythmik 



I need to explain a bit more on the excursion plot. It is a plot that when you apply signals of equal magnitude to the subwoofer, the excursion the driver will experience at various frequency points. The above is the excursion plot for 1 port mode with extension filter set to 14hz high damping. The output above 13hz is useful and the output below 13hz is just not so good. All speakers driver has excursion limit. It is equivalent to drawing a horizontal line to this plot. What is means out if there is an alternating signals of 8hz and 18hz, the 8hz signal will drive the subwoofer into over excursion when the excursion at 18hz can only achieve -6db down (which is half excursion or 1/4 of power, or reducing the capability of a 600WRMS power amp to the like of a 150WRMS amp). It is not good because all you hear is over-excursion and with 18hz not even driven to its full potential. Next look at the same 1 port mode, but 14hz low damping.



Again let us draw a horizontal line to this plot. Now if we have an alternating 8hz and 18hz signals, the18hz can now be played at full excursion potential. That is the main difference between low damping and high damping on FV15HP. It is subtle, but very important to understand. I have every concern that a roomEQ program will change our low damping curve into something like the high damping curve. It is very much like you want to put in salt and pepper to the soup and the chef comes out and give you a funny look: "don't change my soup, it is just right".

Now LV12 series does not have this flexibility and therefore, I set the lowest extension of something like the above (14hz low damping) so it is almost fool proof. But FV15HP is a higher end model and I want to keep in as flexible. The14hz high damping setting, even though is more vulnerable to over-excursion when the subsonic signal hits, has better group delay, and therefore better for some application. For instance, if the sound track already use subsonic filter to curtail excursion, a 14hz high damping can sound better because 14hz low damping can cut down subsonic signal even further down. The problem is there is no common agreement where subsonic filtering should be applied (there used to be, but some studios become creative and just started doing things differently).


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Originally Posted by mikepos 

do I have to worry about driver damage?

Originally Posted by Rythmik 

...I have every concern that a roomEQ program will change our low damping curve into something like the high damping curve... "don't change my soup, it is just right".
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Originally Posted by Rythmik 



I need to explain a bit more on the excursion plot. It is a plot that when you apply signals of equal magnitude to the subwoofer, the excursion the driver will experience at various frequency points. The above is the excursion plot for 1 port mode with extension filter set to 14hz high damping. The output above 13hz is useful and the output below 13hz is just not so good. All speakers driver has excursion limit. It is equivalent to drawing a horizontal line to this plot. What is means out if there is an alternating signals of 8hz and 18hz, the 8hz signal will drive the subwoofer into over excursion when the excursion at 18hz can only achieve -6db down (which is half excursion or 1/4 of power, or reducing the capability of a 600WRMS power amp to the like of a 150WRMS amp). It is not good because all you hear is over-excursion and with 18hz not even driven to its full potential. Next look at the same 1 port mode, but 14hz low damping.



Again let us draw a horizontal line to this plot. Now if we have an alternating 8hz and 18hz signals, the18hz can now be played at full excursion potential. That is the main difference between low damping and high damping on FV15HP. It is subtle, but very important to understand. I have every concern that a roomEQ program will change our low damping curve into something like the high damping curve. It is very much like you want to put in salt and pepper to the soup and the chef comes out and give you a funny look: "don't change my soup, it is just right".

Now LV12 series does not have this flexibility and therefore, I set the lowest extension of something like the above (14hz low damping) so it is almost fool proof. But FV15HP is a higher end model and I want to keep in as flexible. The14hz high damping setting, even though is more vulnerable to over-excursion when the subsonic signal hits, has better group delay, and therefore better for some application. For instance, if the sound track already use subsonic filter to curtail excursion, a 14hz high damping can sound better because 14hz low damping can cut down subsonic signal even further down. The problem is there is no common agreement where subsonic filtering should be applied (there used to be, but some studios become creative and just started doing things differently).


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Originally Posted by mikepos 

So is the flapping sound overexcursion? I heard that on the video where the guys played 10Hz and recorded the blanket moving from the air movement. Will that damage the driver? It sound like it would. I got it when I played a 10-19Hz signal but not nearly like the guys got on that video, it seems dangerous to me... so if I run high damping one port and 14Hz, and do get hit with a low signal that occasionally, do I just have to put up with the sound on the rare occasion it happens or do I have to worry about driver damage?

Originally Posted by Rythmik 

But FV15HP is a higher end model and I want to keep in as flexible. The14hz high damping setting, even though is more vulnerable to over-excursion when the subsonic signal hits, has better group delay, and therefore better for some application. For instance, if the sound track already use subsonic filter to curtail excursion, a 14hz high damping can sound better because 14hz low damping can cut down subsonic signal even further down. The problem is there is no common agreement where subsonic filtering should be applied (there used to be, but some studios become creative and just started doing things differently).

Originally Posted by woody777 

My FV15HP has tons of air movement and the loud flapping at 20Hz and moderate volumes.

Originally Posted by Skylinestar 

Could you please play this 20Hz test tone audio track (I got it from Brian) on -20dB master volume?
WARNING from Brian: Do NOT play it for more than 10 seconds continuously.
20hz_mono.zip 188k .zip file
Do you hear any flapping port noise?
I have this problem before. The problem was the port is leaking air. The faulty unit is replaced with a new unit. Problem solved.

Originally Posted by woody777 


Interesting information, Brian. I don't know the video mikepos is referencing, but that sounds exactly like the issue I've been having. My FV15HP has tons of air movement and the loud flapping at 20Hz and moderate volumes. I am an Audyssey user. I wonder if it's possible to unplug the sub, run Audyssey, then plug the sub back in. Any EQing could be done on the sub itself. This is obviously not an ideal work around (I think Audyssey is fantastic for the most part), but maybe a possibility to use Audyssey and keep it from messing with the sub.

Originally Posted by Rythmik 

^^^
Steve, do you already have F12? Or are you thinking the possibility of getting A370PEQ3 to go with OB (before A370PEQ become available again in Apr) . If you don't care about limiter function and you don't use LFE inputs (as it will mess up the FR), then you can just replace the servo board and it will work with GR OB drivers.

Originally Posted by Bill Fitzmaurice 

You have to worry about driver damage. What you're hearing is your sub's way of telling you "Don't Do That!". Your options are to change the tuning, turn it down, or add another sub, so that you can go as low and loud as you want to. If you're serious about your bass you should have two anyway, to smooth room modes.

Originally Posted by woody777 


Interesting information, Brian. I don't know the video mikepos is referencing, but that sounds exactly like the issue I've been having. My FV15HP has tons of air movement and the loud flapping at 20Hz and moderate volumes. I am an Audyssey user. I wonder if it's possible to unplug the sub, run Audyssey, then plug the sub back in. Any EQing could be done on the sub itself. This is obviously not an ideal work around (I think Audyssey is fantastic for the most part), but maybe a possibility to use Audyssey and keep it from messing with the sub.

Originally Posted by Rythmik 

That is correct.

Originally Posted by Rythmik 

Please send me the pdf version after you are done. It will help other customers.

Originally Posted by Smigro 

Just thought I would pop back in and say hello to new owners. I have had my FV15HP with the 550 amp for the last couple months now and this things rocks. After getting the Emotiva CMX module to get rid of the hum in my amp I am guessing that was caused by DC offset I have had zero issues with my sub.

I couple weeks ago I decided to put in The Hurt Locker and man that opening scene with the bomb blast is crazy. I seriously think I watched it over and over again about 10 times and amount of pressurization in my room was unreal. So does anyone else have certain scenes or movies overall that like to use when wanting some bass in da face.

Originally Posted by JT78681 

So far I really haven't come across anything that tops WOW chapter 5 for serious bass.

Originally Posted by Rythmik 

Woody,

I will check on Saturday when I got to Denver. I check the weather: no snow on Saturday. I wish I would bring my family for a ski. But the downside for that is it will take away my 2 working days plus a few more days of sore and ache