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Discussion Starter · #1 ·
I have a Yahama 8" 120-Watt Powered Subwoofer and I'd appreciate some modification advice in "tightening up" the sound.


It's hard to describe the sound. I would go with "airy" and "hollow", meaning that it sounds like the bass is not crisp but unfocused. It does not sound "floppy".


Can anyone reccommend some simple modifications (and I'd appreciate a link to any products) I can do? I think this sub could be solid if I could tighten the sound up a bit.


Right now, I need to keep this sub. I have a better sub, but currently it's much too big and too loud for my current living situation. So please, only advice on how to modify this sub!
 

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If it is in a corner. please move it to a center of a wall! Maybe 1/3 of the wall. In any case do not use it on a corner. Second, you would need a parametric eq. BFD, by behringer, is a nice one. That would let you cut the frequencies which are more pronounced with your sub, either because room modes or the inherent design of the small Yamaha.


That's about it.


Oh, here is a link: http://www.alegriaaudio.com/behringe...troyer_pro.htm
 

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Have you developed a frequency response curve for your low frequencies? If not, get a Radio Shack SPL meter and some test tones (Stryke has a basstone test disc that is easy to use or you can download testtones from the web and make your own disc). That may help diagnosis the problem.
 

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Discussion Starter · #5 ·
Quote:
Originally posted by Roger Q
Have you developed a frequency response curve for your low frequencies? If not, get a Radio Shack SPL meter and some test tones (Stryke has a basstone test disc that is easy to use or you can download testtones from the web and make your own disc). That may help diagnosis the problem.
Could you please point me in the direction of a site? Thanks!
 

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Subwoofer cabinet integrity might be contributing to what you're hearing (audible cabinet vibratiion.)


I've been running a Velodyne Servo 1200 for many years with two 18-inch concrete pavers floating on five rubber feet on top of it. THe pavers mass-load the cabinet and that really quiets-down the cabinet chatter contributing to clearer, tighter bass.


I also position my sub on the same plane as my front channel speakers, between the center speaker and one of the two front L/R speakers, away from the walls or a corner.


When using the Radio Shack SPL meter be aware that the recommended C-weighting, which includes bass frequencies (the A-weighted response does not), is not truely flat below 100 Hz. There are conversion charts online that let you interpret flat response from the actual response you'll read from the RS SPL meter.


Here's an article from the SVS website that has a conversion list at the bottom:

http://www.svsubwoofers.com/faq_rscomp.htm
 

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They both work but the analog version set on "slow" response easier to use in my opinion.
 

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"Hollow" bass is usually attributed to a bump aroun the 31.5-hz - 50hz region. This also makes the bass sound muddy and lose.


Also take heed of the corner advise. If it is in a corner. Get it away from there and put it 1/3 of the width of the room (divide the width by 1/3 and place sub on either side measured from the side wall).
 

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Discussion Starter · #10 ·
Quote:
Originally posted by Figgie
"Hollow" bass is usually attributed to a bump aroun the 31.5-hz - 50hz region. This also makes the bass sound muddy and lose.
How would one fix this problem?
 

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Quote:
Originally posted by bpape
Parametric EQ.
This is correct or so can room treatment. Easiest is EQ BUT it is not the be all end all solution. if the bump in freq is to big.


A good solution is the behringer Ultrapro curve 2496. Built in 61 band RTA with 31 band EQ. Can be put to process the signal in the digital domain or analog.


Price is around $300 USD.
 

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Before doing anything, make sure the sub level is not calibrated too high. Most subs get their levels set by ear, and they tend to be 6 dB-12 dB too hot. A smallish 8" cone will be working hard if it's set too loud, and it will sound strained and loose. If you don't have enough output, you may actually want to put the sub in a corner so you can turn the level down, limit excursion, and still get the same amount of bass; only cleaner.


Experiment, and have fun with the process.
 

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Here is a technique I found helpful. It does require the use of the SPL meter and the Analog meter is definitely easier to use and interpret than the digital meter. Place your sub at your listening position and then either using Pink Noise or test tones, you can move the SPL meter to potential sub locations and see what the level is at that point. You will find that as mentioned above, the corners have boosted responses that cause the bottom end to sound unnatural. Choosing one of the more neutral positions should help a lot. If EQ is still needed, it will be a lot less than if you just try to brute force the changes with a parametric equalizer. There are also PC based Audio spectrum analyzer programs out there and one of the best is Smaartlive. You can download a 30 day demo at this site. http://www.siasoft.com/

A real important factor when using any analyzer or audio measurement tool is your microphone as its response may color the data you are trying to take. If you can use the mic in the Radio Shack SPL meter, that may be a reasonable mic to get information with. I just don't remember whether there is a jack to get allow it to be connected to another instrument. The key here is understanding what is happening with your room and sub before you start applying fixes. Your ear is telling you it doesn't sound natural, now collect the info to determine what needs to be changed.

..Doyle
 

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When using the RS SPL meter connected to a RTA as the above post suggest, does one still need to use the correction factors? I guess it depends on where in the SPL meter the error occurs...the microphone, the circuitry downstream?
 

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Here is where it gets a little dicey. There is a lot of debate on the internet about the accuracy of the RS meter. Many feel that it falls off pretty bad below 20Hz but that it is relatively accurate between 32 and 2KHz and in trouble above 10KHz. Relatively accurate would be less than a +/- error of 1or 2 db. Addressing the original poster's problem, he probably has something that could be a 4-6 db hump or hole. That is something you should be able to see with the RS meter. You are not going to get your system tweeked to +/- 1 or 2 db. The physics of the room will prevent that. This is a situation where you are looking for a major problem and then addressing that problem. As a result, I would start out with no correction factors and just look at what I have got when I pink the room. Move my Sub around and look at it again. Moving the sub 6-10 inches can have a big effect on a listening position. The same goes for the listening position. Sometimes it needs to move forward or backward in a room slightly to achieve the best sound. Smaller rooms tend to be a bit more sensitive because you don't have the option of having the speakers more in the open.


..Doyle
 

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does anyone know which test tones or track #s to use on the stryke cd?

i've read that sign waves can damage sub drivers, do you limit the durration of each test?

any further help in using this disk with rs meter would be helpful. is there a tutorial out there on the web somewhere?

thanks,

eric
 

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Eric,

Here is a link to the Stryke CD with frequencies and track numbers.
http://www.stryke.com/pics/back.jpg


For a sub you are typically interested in the frequencies below 100Hz. As far as Sine Waves being damaging to a sub, the problem is not the sine wave but the amount of power you are putting into the sub. The real danger in damaging speakers is to have an amplifier that cannot deliver the power and as a result, the amp begins to clip or flatten the waveforms which in turn generates a large amount of high frequency harmonics which can be above the hearing range and you do not even know you are overdriving your speaker until it stops working. For these tests that we are talking about you don't need a lot of level. The RS meter is very sensitive and you can probably do most of your testing at an SPL of 60-80 db max which is well below power damaging levels. (sort of between an average home and the sound of an automobile. Many speakers put out 89-90 db SPL at an input power of only 1 watt so it doesn't take a lot of power to do this testing. The RS meter will read an ambient number when you start increasing the sensitivity and as long as you get a signal that is up over that level by maybe one range you should be able to get the information you are looking for. Each of the tones on the Stryker disk is 30 seconds long and I would start high and go low as you aren't going to get much of an indication when you get down to 10Hz. Play the tracks and write down the data. You can plot it on a graph if you like (use Excel or some spreadsheet program). Remember that db are logs so both axis should be log scales.


wfujosh,

First suggestion is give us a name or nickname as wfujosh is too hard to remember.


With regard to swapping speakers, I wouldn't swap anything until I understood the problem. If a friend has another sub that he wants to bring over and try, I would say go for it but I sure wouldn't buy another sub until I understood what was going on with the one I have.


..Doyle
 
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