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jeffslife
Joined: 17 Apr 2010
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| Posted: Sat Mar 29, 2014 1:49 pm Post subject: how do I get the rumble out of my subs ? |
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My subs sound great at high volume and especially when pushed. The issue I have is when I have them turned up to the point where they sound so good at higher volume levels there is a low (light) rumble at points in the movie where there really shouldn't be. They are crossed at 50 hz.Thanks.
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Nashou66
Joined: 12 Jan 2007
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jeffslife
Joined: 17 Apr 2010
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| Posted: Sat Mar 29, 2014 3:08 pm Post subject: |
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DIY subs sealed. I originally built them for my van, They are wired in series in an 8 ohm load running about 200 watts. I have noticed in several movies ( especially horror movies) that there is a low end rumble seemingly almost constantly throughout the movie. I can turn the subs down and then I cant hear it but then the subs don't "shine" when I want them to. Anyone wanna invent a 2 stage amp for me ?
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jeffslife
Joined: 17 Apr 2010
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| Posted: Sat Mar 29, 2014 3:25 pm Post subject: |
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While on the subject of subs, I was thinking that my riser is a big heavy wooden sealed box. It wouldn't be that hard to cut a hole in the side or back and mount a sub. Bad idea ?
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CIR Engineering
Joined: 25 Aug 2008
Posts: 4269
Location: Chicago USA & Berlin Germany
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| Posted: Sat Mar 29, 2014 5:32 pm Post subject: |
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| jeffslife wrote: | | DIY subs sealed. I originally built them for my van, They are wired in series in an 8 ohm load running about 200 watts. I have noticed in several movies ( especially horror movies) that there is a low end rumble seemingly almost constantly throughout the movie. I can turn the subs down and then I cant hear it but then the subs don't "shine" when I want them to. Anyone wanna invent a 2 stage amp for me ? |
It's a little strange to run speakers in series. The second speaker won't get as much power as the first and the load will doubled to 16 ohms. I'd run them parallel, though this won't address your thread question. Parallel will also drop the load to 4 ohms.
When you set a system to reference volume than everything will sound correct as you have found. When you lower the volume down from reference the frequency response won't be linear between all the speakers. This is why base gets boomy and dialog becomes difficult to hear.
I don't normally like to use them, but your 9.9 has some settings in it that are designed to help compensate for this dynamically with respect to volume level. You could give that a try. I don't remember what they call the features on the 9.9, but you can enable them for low volume times.
craigr
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Nashou66
Joined: 12 Jan 2007
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Location: West Seneca NY
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| Posted: Sat Mar 29, 2014 6:07 pm Post subject: |
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With out some graphs its hard to say what your hearing. it might be your subs distorting. And some times Amps made for speakers are not the best for Sub's . The soundtrack engineers usually boost the LFE by 3-6 dbs from what I have heard on some research and what others have said.
But you really should try REW . It will give you a visual and the correct response of your speakers, subs and room.
Nashou
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jeffslife
Joined: 17 Apr 2010
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| Posted: Sat Mar 29, 2014 9:11 pm Post subject: |
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The subs are 4 ohm subs (car audio) that's why I wired them in series to get a 8 ohm load. I am using a class D sub amp but it don't like a 2 ohm load. OR a 4 ohm load for that matter.
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Last edited by jeffslife on Sun Mar 30, 2014 9:57 pm; edited 1 time in total
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jeffslife
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| Posted: Sun Mar 30, 2014 3:28 pm Post subject: |
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OK Nash, how much would this REW cost ? What would I need to buy ? I would consider it if it wasn't too horribly complicated. I really don't want to spend 2 weeks learning a software program. I am not all that great with personal computers in the first place. If it would even help me I am not so sure. I am not familiar with most of the technical jargon. I understand the basics and used to do amazing things in car audio but it was Nothing compared to all the issues that arise in Home theatre. Plus in car audio you had controls in every aspect of the set up.
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jeffslife
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| Posted: Sun Mar 30, 2014 11:57 pm Post subject: |
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So I cut back on the output level to the subs went -6 decibels and opened up the volume on the amps a little and its pretty close. I need to give my ears a rest and go at it a little later, I cant find my audio test disc either that aint helping, but its a lot closer.
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draganm
Joined: 08 Mar 2006
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Location: Colorado
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| Posted: Mon Mar 31, 2014 4:35 pm Post subject: |
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isn't the frequency response from pretty much any source cut-off below 20Hz? If that's true then I would expect commercial sub manufacturers to add rumble filter to remove and sub-20Hz "noise" from getting to a sub. A quick search shows there is some validity to this and I'm guessing Jeff you didn't add anything like this ?
http://sound.westhost.com/project99.htm
| Quote: | Frequencies below 20Hz are usually not able to be reproduced, and with the exception of synthesisers and pipe organs, are not a wanted part of the audio spectrum. This is especially troublesome with phono systems, since many of the vinyl discs you treasure (or wish to transcribe to CD) will be warped to some degree. Any warp in a vinyl disc will cause large outputs in the subsonic region, typically well below 20Hz.
For example, a 33 1/3 RPM album with a single warped section will create a signal in the pickup at 0.55 Hz (33.3 RPM / 60 = 0.555 Hz). This is a signal that will cause significant cone movement, but is undesirable in the extreme. Not only will vented subs be completely unable to handle such a signal linearly, but sealed subs will also be stressed. Large amounts of available power will be wasted trying to reproduce a signal that was never intended to be there in the first place.
To be effective, a subsonic filter has to be very steep - this allows all wanted frequencies to get through, and rejects those that will only cause problems.At least one circuit that the I know of uses a method of summing the channels below 140Hz, and although this is effective in removing the low frequency rumble (or sub-rumble in this case) component, it causes frequency response aberrations that (IMO) are not acceptable. The subsonic frequencies generated by record warp are by nature out of phase. The mono component of a vinyl disc is lateral, whereas warp signals are vertical. Stereo signals are at 45° The summing method was examined in great detail before deciding that it should not be used if the overall frequency response of the disc is to be preserved.
Please note that PCBs are available for this project (Revision-B boards available from 12 Jan 09). |
http://www.rythmikaudio.com/faq.html#rumble_filter
| Quote: | What is the purpose of rumble filter?
The rumble filter is a 3rd order high pass filter with corner frequency at 20 Hz to provide a steep roll-off below 20 Hz. It is useful when playing LP records, or when there is unwanted subsonic signals in both movies and music that makes the cone move in and out wildly without making audible audible sound. When it is on, it changes the roll-off of sealed subwoofers from 2nd order to 5th order, and vented subwoofers from 4th to 7th order.
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ecrabb
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| Posted: Mon Mar 31, 2014 9:47 pm Post subject: |
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| draganm wrote: | | isn't the frequency response from pretty much any source cut-off below 20Hz? |
Absolutely not! Both of the links you posted are music-centric, and both allude to where the real value of a "rumble filter" is, which is with vinyl. While it was generally pretty true that there wasn't much content below 20hz in music, it isn't so true any more. From newer stuff like Daft Punk, Blue Man Group, Nine Inch Nails, to even some older stuff like pipe organ and synth jazz, there's plenty of music with content below 20hz if you go looking for it.
With movies, there are plenty with sub-20hz energy, and they add significantly to the experience. Now, most subs - especially of the bandpass variety - roll off pretty quickly after 30hz, and most commercial subs don't have usable in-room output down in the 20hz range.
| draganm wrote: | | If that's true then I would expect commercial sub manufacturers to add rumble filter to remove and sub-20Hz "noise" from getting to a sub. A quick search shows there is some validity to this and I'm guessing Jeff you didn't add anything like this ? |
Some subs do have a "sub-sonic" filter on them, essentially a steep (like 18 or 24db/octave) high-pass filter at 20 or 25hz. Many do not though, and they just happen to roll off around 30hz.
I'm not sure what was happening in Jeff's system, but since turning them down 6dB yielded an improvement, it's probably not a stretch to imagine they were just running too hot. Residential rooms are HUGE compared to cars, and require significantly more power and cone area to reproduce SPLs and frequency response even remotely in the ballpark with what you can do in a car. A car is a CAKEWALK compared to a treated theater. Throw a single sealed 12-inch sub and 150 watts in a car and you can get SPL and extension that far exceeds what any of us would ever need even as enthusiasts. Quadruple that, and you'll just be getting started in the "enthusiast" category for even a small treated dedicated theater room.
I'm running dual 15-inch subs in like 2- or 2.25 cuft sealed cabinets, with 500w of dedicated class D amplification to each. With this system, I'd say I'm just at what I'd consider sort of the entry level to serious bass for home theater. It isn't just about max SPL or "blowing people out of the room". It's deep, deep, tactile bass that makes things feel real; it makes you part of the movie. It's immersion.
SC
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CIR Engineering
Joined: 25 Aug 2008
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| Posted: Mon Mar 31, 2014 10:29 pm Post subject: |
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| ecrabb wrote: | I'm running dual 15-inch subs in like 2- or 2.25 cuft sealed cabinets, with 500w of dedicated class D amplification to each. With this system, I'd say I'm just at what I'd consider sort of the entry level to serious bass for home theater. It isn't just about max SPL or "blowing people out of the room". It's deep, deep, tactile bass that makes things feel real; it makes you part of the movie. It's immersion.
SC |
I bought four Paradigm Servo 15's from a client a few years back at a really low price (he upgraded to Velodyne). I sold two and kept two so that I wound up getting the speakers for free and making some money... I should have kept all four.
I think Jeff was running the subs too hot as well. I find that the rumble and boominess are usually caused by two much "high" frequency base and not enough o the low end base. Setting the cross over to 50 or 60Hz can help, but you need punch below that to have base with impact that isn't boomy.
craigr
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Nashou66
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ecrabb
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| Posted: Tue Apr 01, 2014 4:28 am Post subject: |
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| Nashou66 wrote: | SVS, it is all I am saying  |
Chill, SVS fanboy!
SC
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AnalogRocks
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| Posted: Tue Apr 01, 2014 4:35 am Post subject: |
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| CIR Engineering wrote: | | ecrabb wrote: | I'm running dual 15-inch subs in like 2- or 2.25 cuft sealed cabinets, with 500w of dedicated class D amplification to each. With this system, I'd say I'm just at what I'd consider sort of the entry level to serious bass for home theater. It isn't just about max SPL or "blowing people out of the room". It's deep, deep, tactile bass that makes things feel real; it makes you part of the movie. It's immersion.
SC |
I bought four Paradigm Servo 15's from a client a few years back at a really low price (he upgraded to Velodyne). I sold two and kept two so that I wound up getting the speakers for free and making some money... I should have kept all four.
I think Jeff was running the subs too hot as well. I find that the rumble and boominess are usually caused by two much "high" frequency base and not enough o the low end base. Setting the cross over to 50 or 60Hz can help, but you need punch below that to have base with impact that isn't boomy.
craigr |
I auditioned a Servo 15 once. The store I was at got complaints from the plaza next door LOL A woman came over and said the dust was falling from her ceiling tiles. The plaza was a good 50 feet from the A/V store. Excellent subs!
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jeffslife
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| Posted: Tue Apr 01, 2014 4:56 am Post subject: |
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Put in Real Steel tonite and played with it for awhile, It aint perfect but its getting closer. I like that word, immersion. Yes sir I do.
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Nashou66
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Jeremy112
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| Posted: Tue Apr 01, 2014 3:31 pm Post subject: |
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I use both of my 10" subs frequency cut off option, to eliminate any bass over 30hz, seeing as my main speakers can easily go down that low, I saw no reason to make the subs boomy. With the frequencies cut off, they only reproduce sound in the 24hz-30hz range. Not a lot of room, but I use the subs strictly for that low low bass, why waste it out on boomy bass that people think is the "real" bass.
I also agree that you are probably just pushing you subs too hard for what they are capable of. Perhaps you should make a new DIY sub with a better box design and amplifier, it would be worth it if you want to try and improve your bass reproduction in the system. As crabb said, a good sub is what makes a movie, so it might be worth the time to change out your current subs if you aren't happy with how they sound.
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