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post #541 of 757 Old 11-02-2013, 06:14 PM - Thread Starter
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Just found out that REW eq has option to select the target software that is going to be used to equalize and plot the graph accordingly. Therefore, I selected MiniDSP in eq option and graphed it again. Here is the result. Sorry about previous graph.

Good part is that I managed to get the graph match target with only 2 filters and still no -ve filters :-)

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post #542 of 757 Old 11-03-2013, 12:55 AM
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Can you explain a bit more? Are you suggesting that
1 - take spl at 80 (cross over point) of subs only.
2 - take spl of Mid, Left, Right speakers only.

Make sure subs spl match speakers spl at 80 and beyond 80?

In a flat curve, speakers and subs are at the same level i.e. all frequencies in subs passband and those in the speakers passband should read the same SPL. In HC/HKC, subs' response should be at the same level with mains at the crossover frequency and start to rise the lower you go in the spectrum. It should keep rising till 30Hz where you should peg the curve and then it should be flat from 30Hz and below making it look like a plateau.
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Originally Posted by SherazNJ View Post

Just found out that REW eq has option to select the target software that is going to be used to equalize and plot the graph accordingly. Therefore, I selected MiniDSP in eq option and graphed it again. Here is the result. Sorry about previous graph.

Good part is that I managed to get the graph match target with only 2 filters and still no -ve filters :-)

In your final plot as given above, you can see your response is at the same level from 30Hz and below compared to 100Hz and above. Which is going to sound like a weak HC/HKC. That is so coz you applied negative gains, your response from 30Hz and below compared with 100Hz and above are at the same level.

Raise the gains on the sub.

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post #543 of 757 Old 11-03-2013, 11:07 AM - Thread Starter
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In your final plot as given above, you can see your response is at the same level from 30Hz and below compared to 100Hz and above. Which is going to sound like a weak HC/HKC. That is so coz you applied negative gains, your response from 30Hz and below compared with 100Hz and above are at the same level.

I was only focusing on 30-80hz. I thought that as long as we have 10 db diff from 30 as highest point and 80 as lowest. Now it seems like that even after cross-over point, 30hz should be higher than crossover point. Looking at my graph without any eq, it is flat. Logic dictates that we raise at 30hz which will give a 10db diff and will be higher even after cross-over but then its against the rule that we shouldn't apply +ve gains.

Other option (that I was using) is to reduce gain from 30 till 80. But then it will bring 30 to same level around 100 (passed cross-over). Unless I apply a gain filter around 30, it won't be possible to get a slope where 30 is ALWAYS higher than any frequency above it (40,50,200).

How is increasing gain is going to help? Even if I increase gain and then re-calibrate, Audyssey is going to flat out the curve.
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post #544 of 757 Old 11-03-2013, 12:47 PM
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How is increasing gain is going to help? Even if I increase gain and then re-calibrate, Audyssey is going to flat out the curve.

All this exercise is done after running audyssey. Moreover, you've applied correct filters. Just raise the gain knobs on subs. It will lift your entire house curve from 80Hz and below. That's it.

The negative gains you applied must have brought down the SPL of your subs relative to mains near the crossover region. By raising the gains on the subs, you will bring the SPL of your subs near crossover region back to where it was before. Only this time your lower bass will read higher SPL coz raising the gain lifts up the entire HC as it is.

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post #545 of 757 Old 11-03-2013, 01:00 PM - Thread Starter
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It took me a little longer to understand the need of increasing sub trim. Since the cross-over is set to 80, audessey will not raise the frequency above 80. Therefore, if we increase sub trim, it will be applied below 80 and that will bring the lower frequency higher. Is my understanding correct?

I increased sub trim level from default audyssey (3.5) to 6db more (9.5db). Is there any issue increasing sub trim that much? I can always increase gain on subs a bit more to bring default audyssey 3.5 to -3 and then increase sub trim to another 6 db.
Here is the result with eq.

Hz Level Diff
25 93 -
80 80 13
100 83.7 9.3
117 86 7

First graph is with low limit so you can see the diff closely and 2nd one is with recommended limit (20-130).

Here is are the graphs.

Low Liimit


High Limit
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post #546 of 757 Old 11-03-2013, 01:07 PM
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It took me a little longer to understand the need of increasing sub trim. Since the cross-over is set to 80, audessey will not raise the frequency above 80. Therefore, if we increase sub trim, it will be applied below 80 and that will bring the lower frequency higher. Is my understanding correct?

Yes.
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I increased sub trim level from default audyssey (3.5) to 6db more (9.5db). Is there any issue increasing sub trim that much? I can always increase gain on subs a bit more to bring default audyssey 3.5 to -3 and then increase sub trim to another 6 db.

Don't increase the sub trim level in AVR. Raise the gain on the subs bring the SPL back to where it was. Only then you would experience the full effect of HC.
People who use Audyssey and even the Audyssey guide do not recommend raising the gain on the sub itself after running audyssey as audyssey has no visibility to that. But, I've tried it and this works.

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post #547 of 757 Old 11-03-2013, 01:20 PM - Thread Starter
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Originally Posted by braveheart123 View Post

Yes.
Don't increase the sub trim level in AVR. Raise the gain on the subs bring the SPL back to where it was. Only then you would experience the full effect of HC.
People who use Audyssey and even the Audyssey guide do not recommend raising the gain on the sub itself after running audyssey as audyssey has no visibility to that. But, I've tried it and this works.
Ok but how does the graph look now? Is this the desired result? This time 30hz is around 13 db higher from cross-over point and around 9.3 db higher from the rest after cross-over. If this is the desired result then I know the target and can easily work with gain on sub after turning sub trim in avr. Its just a matter of increasing gain know from mid point to 2 p.m. :-).

Out of curiosity, why is it better to increase gain on sub as compared to avr sub trim?
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post #548 of 757 Old 11-03-2013, 01:25 PM
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Ok but how does the graph look now? Is this the desired result? This time 30hz is around 13 db higher from cross-over point and around 9.3 db higher from the rest after cross-over. If this is the desired result then I know the target and can easily work with gain on sub after turning sub trim in avr. Its just a matter of increasing gain know from mid point to 2 p.m. :-).

13dB HC is huge but it's all personal preference. Normally 7-8dB is enough. Onnly your ears will tell you how it sounds. I think it's a lil too hot down low. But your hearing will reveal the final outcome. I can visualize your rib cage flex big time now wink.gif

If it is too strong; reduce the negative gains.

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post #549 of 757 Old 11-03-2013, 01:49 PM - Thread Starter
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Originally Posted by braveheart123 View Post

13dB HC is huge but it's all personal preference. Normally 7-8dB is enough. Onnly your ears will tell you how it sounds. I think it's a lil too hot down low. But your hearing will reveal the final outcome. I can visualize your rib cage flex big time now wink.gif

If it is too strong; reduce the negative gains.

Tomorrow my friend tomorrow (that is if it gets here). Can you also plz address this
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Out of curiosity, why is it better to increase gain on sub as compared to avr sub trim?
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post #550 of 757 Old 11-03-2013, 07:17 PM
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That's coz Dynamic EQ maintains the perceived loudness of bass frequencies, which you may or may not like at your reference volume. I'd say do not go beyond 00 on sub trim level in the avr; rather control it from the gain knobs on a sub.

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post #551 of 757 Old 11-04-2013, 08:42 AM - Thread Starter
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It took me a little longer to understand the need of increasing sub trim. Since the cross-over is set to 80, audessey will not raise the frequency above 80. Therefore, if we increase sub trim, it will be applied below 80 and that will bring the lower frequency higher. Is my understanding correct?
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Yes.

If that's correct then shoudn't we increase gain in avr? If we increase gain in subs, avr wouldn't know about it and won't apply the cross-over cut to it which will increase whole graph (not hz below 80). But, if we were to increase sub trim in avr, it will still have to apply cross-over and therefore we are going to have higher hz below 80.
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post #552 of 757 Old 11-04-2013, 09:01 AM
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If that's correct then shoudn't we increase gain in avr? If we increase gain in subs, avr wouldn't know about it and won't apply the cross-over cut to it which will increase whole graph (not hz below 80). But, if we were to increase sub trim in avr, it will still have to apply cross-over and therefore we are going to have higher hz below 80.

When miniDSP is in the sound chain; the subs will get an already processed signal (House Curve / Hard Knee Curve) by miniDSP and whatever gain is applied on the subs themselves, will be amplified as it is.

The initial bass management will be done in avr, so minDSP will get the signal below the crossover point whatever that may be.

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post #553 of 757 Old 11-06-2013, 08:32 AM - Thread Starter
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I received miniDSP and playing along with it. Braveheart noticed that the graph around 30 hz is at same heigth as around 100 hz and we needed to boost lower side of graph up. He recommended to increase gain on subs after calibration. Now something very beautiful happened. I had gain knob to 12:00 (little right to 0 degrees) to make sure I get closest to 0 in sub trim in avr. After calibration it was .5 in avr trim. I was happy with that. I took REW reading and then increased gain knob on subs (not in avr) to one notch up. Took REW reading. Guess what ?????????? I ended up having a beautiful house curve :-). No dsp was introduced yet. I wanted to have around 8 db of diff in b/w 30 and 100. So I increased gain knob a bit more and it worked. But later I realized that my subs started to bottom out on scenes with loud bass. Does anyone know why????

If I set gain knob on subs to 2 notches from middle and calibrate, subs don't bottom out (most likely avr is suppressing it). But, if I change gain knob after calibration, subs bottom out on loud bass scene. Any idea why? There is a sweet spot (very close to one notch) where it won't but why is it happening in the first place? My graph readings come around 95 db for 30 hz and 86db around 80 hz and around 89 around 100hz.
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post #554 of 757 Old 11-06-2013, 09:26 AM
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Quote:
Originally Posted by SherazNJ View Post

I received miniDSP and playing along with it. Braveheart noticed that the graph around 30 hz is at same heigth as around 100 hz and we needed to boost lower side of graph up. He recommended to increase gain on subs after calibration. Now something very beautiful happened. I had gain knob to 12:00 (little right to 0 degrees) to make sure I get closest to 0 in sub trim in avr. After calibration it was .5 in avr trim. I was happy with that. I took REW reading and then increased gain knob on subs (not in avr) to one notch up. Took REW reading. Guess what ?????????? I ended up having a beautiful house curve :-). No dsp was introduced yet. I wanted to have around 8 db of diff in b/w 30 and 100. So I increased gain knob a bit more and it worked. But later I realized that my subs started to bottom out on scenes with loud bass. Does anyone know why????

If I set gain knob on subs to 2 notches from middle and calibrate, subs don't bottom out (most likely avr is suppressing it). But, if I change gain knob after calibration, subs bottom out on loud bass scene. Any idea why? There is a sweet spot (very close to one notch) where it won't but why is it happening in the first place? My graph readings come around 95 db for 30 hz and 86db around 80 hz and around 89 around 100hz.

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post #555 of 757 Old 11-06-2013, 09:39 AM - Thread Starter
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just remember that using boost to effect a House Curve will use headroom. The more boost you use, the more headroom it will eat up. Your subs will start to compress and distort at lower Master Volume Control settings. I'm just sayin'... be careful.


But craig, I'm not using boost from DSP. There is no equalization. Are you saying that any type of boost other than one coming from avr sub trim can cause this issue?
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post #556 of 757 Old 11-06-2013, 10:26 AM
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Can you post the graph which shows natural house curve after audyssey?
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My graph readings come around 95 db for 30 hz and 86db around 80 hz

11dB is huge. Insert DSP in the sound chain, reduce the house curve by 3-4dB using a single wide-band filter. You should be able to avoid subs bottoming out even with increased gain.

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post #557 of 757 Old 11-06-2013, 11:00 AM - Thread Starter
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Originally Posted by braveheart123 View Post

Can you post the graph which shows natural house curve after audyssey?
11dB is huge. Insert DSP in the sound chain, reduce the house curve by 3-4dB using a single wide-band filter. You should be able to avoid subs bottoming out even with increased gain.

I"ll post when I get home. The reason I have this diff is not because I want that big of a difference but because I wanted 30hz about 6 db higher than 100 hz based on your recommendation
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In your final plot as given above, you can see your response is at the same level from 30Hz and below compared to 100Hz and above. Which is going to sound like a weak HC/HKC. That is so coz you applied negative gains, your response from 30Hz and below compared with 100Hz and above are at the same level.

Raise the gains on the sub.

As I understood, 30 hz and below (down to 20) should be higher as compared to not only 80 but 100 as well. Hard-knee curve has a I believe 8db diff (I don't excatly remember) but then I also have to keep in mind that 30hz and below is higher than 100 hz and above.
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post #558 of 757 Old 11-06-2013, 11:08 AM
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How come you have a HC like response without using miniDSP all of a sudden, when you earlier had flat FR?

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post #559 of 757 Old 11-06-2013, 11:14 AM - Thread Starter
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Originally Posted by braveheart123 View Post

How come you have a HC like response without using miniDSP all of a sudden, when you earlier had flat FR?

By increasing sub gain. First calibrate with Audyssey and then increase sub gain from subs (not avr) and it increases the gain at the lower side.
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post #560 of 757 Old 11-06-2013, 11:22 AM
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By increasing sub gain. First calibrate with Audyssey and then increase sub gain from subs (not avr) and it increases the gain at the lower side.

That's what caused your subs to bottom out. As I said earlier also; raise the gain on the subs after dialling a house curve using minDSP. Also all this exercise is to be done after running audyssey.

Even now with the increased gain on subs; simply add miniDSP and reduce the House Curve by 3-4dB from 30-80Hz and you should be able to get ride of this problem.

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post #561 of 757 Old 11-06-2013, 11:41 AM - Thread Starter
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Originally Posted by braveheart123 View Post

That's what caused your subs to bottom out. As I said earlier also; raise the gain on the subs after dialling a house curve using minDSP. Also all this exercise is to be done after running audyssey.

Even now with the increased gain on subs; simply add miniDSP and reduce the House Curve by 3-4dB from 30-80Hz and you should be able to get ride of this problem.

I'm making sure to do all that after Audyssey. A bit confusing. What's the point to increase gain in sub after miniDSP? I was raising sub before miniDSP in chain so that I could have higher reading in low frequency and then I could use miniDSP to tilt the higher frequency to match the target curve. I wish I had access to my laptop right now but I'll use paint to draw a graph to make a point. Please don't take these as actual readings. These are primarilty to understand the point.



As you can see that increasing gain only increased the lower frequencies and ended up giving me a house curve (almost). Then I used miniDSP to match the hard-knee curven. I had to use only one -ve filter to do that.
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post #562 of 757 Old 11-06-2013, 11:50 AM
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The test tone recorded in AVR for setting subwoofer levels is not for lower frequencies only. It's a wide-band pink noise covering 40Hz-80Hz band. Some receivers use 30Hz-80Hz band limited pink noise. I hope you can now read between the lines why your subs were bottoming out when you increased the gain.

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post #563 of 757 Old 11-06-2013, 12:03 PM - Thread Starter
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can you plz explain the purpose of this when we already have a house curve?
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raise the gain on the subs after dialling a house curve using minDSP
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post #564 of 757 Old 11-06-2013, 01:34 PM
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Read post # 544 and 552 in this thread

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The best EQ is no EQ ...

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post #565 of 757 Old 11-06-2013, 01:59 PM - Thread Starter
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Originally Posted by braveheart123 View Post

Read post # 544 and 552 in this thread

ok I think I got it. I"ll apply hard-knee curve in minidsp without any change in sub gain first. That will produce the curve. Then increasing gain on subs will lift up the curve from 80Hz and below.
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post #566 of 757 Old 11-06-2013, 04:45 PM
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Originally Posted by SherazNJ View Post


But craig, I'm not using boost from DSP. There is no equalization. Are you saying that any type of boost other than one coming from avr sub trim can cause this issue?

Boost... is boost... is boost. It doesn't matter if you add the boost with the AVR's subwoofer trim, or you use Audyssey DEQ, or you set a House Curve with the miniDSP or you raise the gain of the amp on the subwoofer, or you simply turn up the Master Volume Control, if you increase the signal level anywhere in the chain, you eventually reach the limits of the sub driver. The following graph is your sub from the PSA website. It demonstrates the limits of your subs:



You can see that as you increase the signal level, you eventually reach the point where you don't get the same amount of output increase as the amount of signal increase. In the top graph, (yellow), 5 dB of signal has been added, but only about 2 to 3 dB of additional output was realized from about 30 Hz down. This phenomenon is known as "compression." If you were to add another 5 dB of signal, you would get even less additional output. Eventually you reach a point where additional input results in ZERO additional output.


The following graph is not your sub, but I post this graph for demonstration purposes. The sub is the SVS PB13 Ultra in 15 Hz tune. It shows the distortion levels at 3 different signal levels.



In this graph, you can see that the distortion increases dramatically when the maximum output of the sub is approached, especially as the frequency approaches the port tune. Below port tune, the distortion goes "off the charts" because the driver is no longer "loaded" by the port. Your subs are not as capable as the SVS PB13 Ultra, (they have neither the output nor the extension), and they likely reach the point of high distortion well before the Ultra. This is likely the "bottoming" noise you're hearing from your subs with excessive output below port tune.

I said before, if you add boost, no matter where that boost comes from, you reduce headroom and increase distortion. Based on the compression graph of your subs, it looks like you have about 103 dB of output capability at 30 Hz and 97 dB at 20 Hz. Adding the 2nd sub should provide an additional 3 to 6 dB of output at those frequencies. If you go above that, you'll be introducing compression and distortion. With room gain, your subwoofer system should be capable of about 112 dB at 30 Hz, (estimated), and about 106 dB at 20 Hz, (estimated.) When calibrated for "flat" response, you should be at the limits of your subs with Master Volume Control settings of about -9 at 20 Hz and -3 at 30 Hz. If you boost the response at those frequencies by 10 dB, you'll want to limit the MVC settings to about -19 to -13. That is not a compromise I, (personally), would make, but feel free to set up your system however you chose.

Craig

PS. You can see the Data-Bass power compression and distortion graphs for your subs here: http://www.data-bass.com/data?page=system&id=88&mset=95 The power compression graph shows exactly what I described... add another 5 dB of input signal and you get ZERO additional output. The distortion graphs show that the distortion starts to rise dramatically at about 25 Hz. At 110 dB and 20 Hz, the THD is about 28%!!!

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post #567 of 757 Old 11-06-2013, 07:47 PM - Thread Starter
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Quote:
Originally Posted by craig john View Post

Boost... is boost... is boost. It doesn't matter if you add the boost with the AVR's subwoofer trim, or you use Audyssey DEQ, or you set a House Curve with the miniDSP or you raise the gain of the amp on the subwoofer, or you simply turn up the Master Volume Control, if you increase the signal level anywhere in the chain, you eventually reach the limits of the sub driver. The following graph is your sub from the PSA website. It demonstrates the limits of your subs:



You can see that as you increase the signal level, you eventually reach the point where you don't get the same amount of output increase as the amount of signal increase. In the top graph, (yellow), 5 dB of signal has been added, but only about 2 to 3 dB of additional output was realized from about 30 Hz down. This phenomenon is known as "compression." If you were to add another 5 dB of signal, you would get even less additional output. Eventually you reach a point where additional input results in ZERO additional output.


The following graph is not your sub, but I post this graph for demonstration purposes. The sub is the SVS PB13 Ultra in 15 Hz tune. It shows the distortion levels at 3 different signal levels.



In this graph, you can see that the distortion increases dramatically when the maximum output of the sub is approached, especially as the frequency approaches the port tune. Below port tune, the distortion goes "off the charts" because the driver is no longer "loaded" by the port. Your subs are not as capable as the SVS PB13 Ultra, (they have neither the output nor the extension), and they likely reach the point of high distortion well before the Ultra. This is likely the "bottoming" noise you're hearing from your subs with excessive output below port tune.

I said before, if you add boost, no matter where that boost comes from, you reduce headroom and increase distortion. Based on the compression graph of your subs, it looks like you have about 103 dB of output capability at 30 Hz and 97 dB at 20 Hz. Adding the 2nd sub should provide an additional 3 to 6 dB of output at those frequencies. If you go above that, you'll be introducing compression and distortion. With room gain, your subwoofer system should be capable of about 112 dB at 30 Hz, (estimated), and about 106 dB at 20 Hz, (estimated.) When calibrated for "flat" response, you should be at the limits of your subs with Master Volume Control settings of about -9 at 20 Hz and -3 at 30 Hz. If you boost the response at those frequencies by 10 dB, you'll want to limit the MVC settings to about -19 to -13. That is not a compromise I, (personally), would make, but feel free to set up your system however you chose.

Craig

PS. You can see the Data-Bass power compression and distortion graphs for your subs here: http://www.data-bass.com/data?page=system&id=88&mset=95 The power compression graph shows exactly what I described... add another 5 dB of input signal and you get ZERO additional output. The distortion graphs show that the distortion starts to rise dramatically at about 25 Hz. At 110 dB and 20 Hz, the THD is about 28%!!!

Craig,
Thanks for all the info. Only one point wasnt clear to me.
Quote:
When calibrated for "flat" response, you should be at the limits of your subs with Master Volume Control settings of about -9 at 20 Hz and -3 at 30 Hz. If you boost the response at those frequencies by 10 dB, you'll want to limit the MVC settings to about -19 to -13.
If I understood correctly, at flat curve response, if I turn MVC volume to -9 and take REW reading, it shouldn't be over the limit @20hz (estimated 106 db) and @30 shoudn't be over the limit (112db)??
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here comes the graphs. All graph readings where taken at -10 MVC.

Black: original without any gain changing or miniDSP
Green: no dsp included bet. Increased gain on sub to 1 notch (1 p.m.)
Red: Hard-knee graph using miniDSP.

I tried different combination and increasing gain on sub first gave best result.

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post #569 of 757 Old 11-06-2013, 08:42 PM
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Are these graphs with subs only or speakers+subs?

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post #570 of 757 Old 11-06-2013, 08:56 PM
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I would not run a house curve with your setup...for one your room offers very little room gain and you do not have enough subwoofage to effectively accomplish this feat at reference levels. When you boost the sub 30hz area of the curve 3db, then you lose 3db of headroom everywhere else...basically you effictively cut the amp power in half.
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