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Klipsch SUB-12 Subwoofer (1 Viewer)

BraveHeart123

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I need to know if SUB-12 ouputs sound within its operating fequency range i.e. 24-120 Hz OR does it output those frequencies at their peak within the operating range and still outputs frequencies greater than 120 Hz with some upper limit???
I need to know if 120 Hz is a straight brick wall or it slopes to some upper limit which it does output but not at peak??
 

Robert_J

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It is definitely not a brick wall but that is determined by the slope of the crossover on your receiver. Most are 12db/octave.
24hz is probably a subsonic filter of 12db/octave also combined with the 18db/octave slope you automatically get with a ported sub below tuning frequency.
 

BraveHeart123

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Hi Robert. Um using Yamaha RX-V3900 and have no clue as to what crossover slope my AVR is using. Also please explain what 12 db per octave is. I know slope concept but um not fully clear. Dont mind my immaturity in HT world :)
 

Robert_J

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Crossovers are commonly referred to as 1st order (6db / octave), 2nd order (12db / octave), 3rd order (18 db / octave) and so on. Let's say your receiver uses a 2nd order crossover at 100hz for the sub. 1/2 of the crossover is called the low pass. That means everything from 100hz and LOWER is allowed to pass. If you measured the output at 200hz (1 octave above 100hz) then it will be 12db lower than at 100hz. If you measured at 400hz (2 octaves above 100hz) then it would be 24db lower than at 100hz (2 * 12 = 24).
The other half of the crossover is called the high pass. That means everything from 100hz and HIGHER is allowed to pass. If you measured the output at 50hz (1 octave below 100hz) then it will be 12db lower than 100hz. If you measured at 25hz (2 octave below 100hz) then it would be 24db lower than at 100hz (2 * 12 = 24).
Here's another explanation - http://slumz.boxden.com/f359/guide-crossovers-916853/
 

BraveHeart123

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I am a bit confused here. My avr offers various crossover frequencies (40 / 60 / 80 / 90 / 100 / 120) hz and I use 90 hz as the crossover point. Let's assume RX-V3900 uses 12db/octave slope. So, if I measure the SPL at 45 Hz, one octave below the xo point 90 hz, will it be 12db lower than at 90 hz?? At the same time, what will be the SPL if I measure the same at 180 hz i.e. one octave above xo point of 90 hz??? What happens at exactly 90 hz, what will the SPL be???
I need to understand this fully so I can adjust proper PEQ settings to boost or attenuate certain frequencies at their dips or spikes, respectively.
 

Robert_J

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The sub crossover in your receiver is a LOW PASS filter. It allows everything below 90hz to pass freely. If you measured at 180hz then it will be 12db lower than at 90hz.
The opposite is true on the receiver's HIGH PASS filter going to the speakers. That's where if you measured at 45hz, it would be 12db lower than 90hz.
Depending on how the crossover is designed, at 90hz, there should be no change on either side of the crossover. But in most cases, there is a dip at the exact crossover point as both the speakers and sub will be playing at that frequency. More drivers equals louder so they dip it a little to compensate. Look at the graph in my link.
I need to understand this fully so I can adjust proper PEQ settings to boost or attenuate certain frequencies at their dips or spikes, respectively.
You don't need to understand it but to do that but I'll help you as much as it takes. You shouldn't boost frequencies as a guideline. Cutting peaks is preferred.
 

BraveHeart123

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But how can we measure SPL at 40 Hz on mains when the crossover is set at 90 hz? It will route 40 Hz to the sub. What I am logically painting crossover region is that it's like a pyramid which has slopes on either side. Wouldn't the slopes need to be boosted up to make it flat OR does it require to clip the highest point of pyramid and lower the gain???
 

Robert_J

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From the link above. In that design, they left a dip at 1 khz because 2 different drivers would be working in that area and will naturally boost the output. Other times you can overlap frequencies. In fact, there is no end the different combinations of crossover points and slopes that you can choose when designing a system.
Cyan = 6dB/octave
Red = 12dB/octave
Green = 18dB/octave
Violet = 24dB/octave
a6b3fa7d_4ue9l4y.gif
 

BraveHeart123

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I am still confused. I got the logic how frequencies behave octave to octave. Lemme rephrase my question. I run YPAO on my AVR and select PEQ also in auto setup, YPAO sets my mains (Yamaha NS-7900 2-way towers ... not so great but not bad at all) as large. After the auto setup completes including the PEQ settings, I manually set my mains to SMALL and set the xo to 90 Hz and for center and sats, I set xo to 120 Hz.PEQ sets 3 values Band/Gain, Frequency/Gain, and Q/Gain on all the 5 channels + the subwoofer. The tiny graphs for each channel show response curves which have dips at certain frequencies and at some points there are spikes. So, what do I do? Can you pls explain what effect do these 3 PEQ values have on sound and what exactly is their purpose?
 

BraveHeart123

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Thanx. Its a great document and I get it how PEQ parameters work. That leads me to another question. How to find out which frequency or band I need to boost or cut? I need some heavy thud in bare knuckle fight scenes e.g. (Bourne Identity - The 2 minute scene in which Jason Bourne gets a ride to his appartment in Paris in Marie's car, and there is this scene in which the other assasisn breaks in through the glass door). How do I figure out which frequencies are in play when they dispatch bare knuckle jabs at each other so I can adjust them? I need beefed up heavy sound of punches.
 

Robert_J

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How to find out which frequency or band I need to boost or cut?
I created my own test disc with sine waves matching the frequencies on the PEQ spreadsheet ( http://www.pvconsultants.com/audio/eq/peq.htm ). I used a Radio Shack analog SPL meter and measured the SPL of each frequency. Make sure the meter is EXACTLY in the listening position. I put it on a tripod in my favorite seat and make sure it is at ear level, pointed up at a 45 degree angle.
Once the SPL of each frequency is measured and entered into the spreadsheet, apply the correction factor and look at the graph. You want to cut the frequencies at have peaks. You rarely want to boost any valleys.
I need some heavy thud in bare knuckle fight scenes e.g. (Bourne Identity - The 2 minute scene in which Jason Bourne gets a ride to his appartment in Paris in Marie's car, and there is this scene in which the other assasisn breaks in through the glass door).
I know that scene but you don't use that as a reference unless you have heard it on a reference system. Once your bass is calibrated using the method above, you will hear it as the director intended.
 

BraveHeart123

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Hi Robert thanx for the valueable info. I played around with the PEQ settings using some of my reference movies and noticed considerable difference in sound. It really opened up the sound stage engulfing the audience from all sides + I can hear sounds which were never there due to incorrect settings on AVR. There is still some defficiency in the mid range, which I think I can fix by tinkering with relevant frequencies. I need some info on the following;
1. Do I need to apply PEQ settings first and then calibrate the system using Avia especially channel levels (I do have RS analog SPL meter) OR the other way around???
2. Can you provide some reference tones for each channel so I can properly adjust the culprit frequencies???
 

Robert_J

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1. Yes, you get a flat response first before setting levels. Otherwise, the wide frequency band of the calibration signal will set the level at a peak frequency.
2. I've only used PEQ on my sub. I used a random sine wave generator I downloaded to create my test disc. My AVR applies a 3 band EQ in addition to setting levels when running the MCACC calibration. With relatively flat speakers, I have no need to use any external EQ or additional calibration.
 

BraveHeart123

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Hi Robert, I'm again lost here. Was trying to fiddle with frequencies (120-500) hz to get solid upper bass but to no luck. I am unable to plot the frequency graph in excel sheet using AVIA disc and RS Analog SPL meter. The frequency sweep in subwoofer setup section is a bit too fast to capture MANUALLY. It drops from 200 Hz to 20 Hz so fast, that I can't look at the SPL meter and the LCD at the same time to know what the SPL reading is on the meter at a particular frequency.
1. Am I doing it correctly OR is there any other way?:confused:
2. The frequnecy sweep section uses all the channels one by one with subwoofer i.e. it sends (200 hz - 20 hz) signal to the relevant channel plus the subwoofer at the same time. Now how do I know if I have to set PEQ for the subwoofer or the concerned channel??? e.g. If front right main channel + subwoofer are undergoing frequency sweep test and I have set the crossover on AVR at 80 hz and if I notice a spike at 110 hz, should I set PEQ for the subwoofer OR the front right channel??
3. My klipsch SUB-12 uses 24db/octave slope in the crossover region and has a frequency response of 24hz-120hz. I dial the crossover to its max on the sub to bypass sub crossover and set 80 hz on AVR for the front mains and 120 hz for center and surrounds. My question is......Does doing so nullify the crossover region slope of 24db/octave of the subwoofer and instead use 12 db/octave crossover slope of AVR??? Coz if 24db/octave slope of subwoofer is still employed, then it is a 24db drop at 160hz which is huge and I may never be able to get that thump.
Need your help.
 

Robert_J

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I am unable to plot the frequency graph in excel sheet using AVIA disc and RS Analog SPL meter.
I never mentioned using Avia to plot the frequency response. It is used to set levels. I used software to create a test disc to match the frequencies of the PEQ spreadsheet. Google sine wave generator software and you will find over 700,000 hits and most are downloads.
Now how do I know if I have to set PEQ for the subwoofer or the concerned channel???
The PEQ spreadsheet is for the sub only. You may need a real time analyzer to see which frequency is being played.
3. Technically no. The crossover slope is 12db/octave until it reaches the 160hz (where it is set at the sub). Then it is 36db/octave (24db/octave + 12db/octave).
 

BraveHeart123

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So, if i get a sine wave generator software and create all frequncies I want and burn them on a disc, will I be able to direct them to one specific channel at a time to check the response in a 5.1 setup??? Is there any option to do that??
which sine wave software do u use?
which type should I burn to (Audio CD / Data CD / Data DVD) and in which format i.e. wave file or what?
 

Robert_J

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Again, my receiver's MCACC automatically analyzes my speakers and applied a 3 band EQ as needed on them. I am only giving you suggestions for the sub.
Pick one that is free and will create .wav files. Burn them as an audio CD. I like to use 10 seconds of sound and 20 seconds of silence. Sine waves will heat up an amp and sub quickly so you need to give it rest between each track and that's what the silence does.
If you look enough, I'll bet you can find a program that will create tracks for 5.1 or at least a DVD authoring program that will allow you to save individual tracks to a channel. But that is something I've never had a reason to look for.
 

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