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Post by igorzep on Sept 3, 2014 16:57:08 GMT -5
Yellow is the response of the loudspeaker with natural roll-off. F3 is about 58Hz. 58Hz is not quite close to 80. Do it with real THX speaker with F3@80Hz... Orange shows the sum of the roll-off and electrical crossover. The net effect is that just the slope increases. The -6 dB point moves very little. What about phase? Then... draw the sum of sub+speaker. |
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Post by bluescale on Sept 4, 2014 10:45:04 GMT -5
I ran out of steam last night, so I didn't get nearly as much testing done as I wanted (I still owe Chuck some data on what the loudness compensation is doing). Apparently I'm not 18 anymore, and can't pull multiple all-nighters without consequence  . That said, I did retest the crossover anomaly, because it was behaving just too troublesome to leave alone. Good news, folks. After doing a factory reset, the new tests look much better. I don't know if something strange was going on in the XMC-1, or if user error was involved in the first set of tests, but here's what happens to the sub and the main channel as I adjust xover and slope: Crossover set at 120, Low Pass Filter Slope = 24dB/octave:  Crossover set at 120, Low Pass Filter Slope = 12dB/octave:  Crossover set at 80, Low Pass Filter Slope = 24dB/octave:  Crossover set at 80, Low Pass Filter Slope = 12dB/octave:  Crossover set at 40, Low Pass Filter Slope = 24dB/octave:  Crossover set at 40, Low Pass Filter Slope = 12dB/octave:  Chuck Elliot and igorzep - Can you two confirm for me that this looks like we'd expect? It looks good to me, but you guys obviously know this stuff better than I do. |
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Post by igorzep on Sept 4, 2014 14:22:29 GMT -5
bluescale, looks much better than before. The exact dB @ crossover point is hard to read as there is a slight level difference between the sub and the speaker. But it look like -3dB everywhere. I'd expect -6dB for 4th order slope...Took a look at the graph again, it is -6dB for 4th order slope, so - it is the correct one.
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Post by Chuck Elliot on Sept 4, 2014 15:19:10 GMT -5
Yes, those look much better it terms of shape, but being only 3DB down at the crossover it also shows that they are not LR filters! I wonder why the 120Hx 12dB is dead on, while the others have drifted down a bit?  |
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Post by Chuck Elliot on Sept 4, 2014 15:27:04 GMT -5
58Hz is not quite close to 80. Do it with real THX speaker with F3@80Hz... What about phase? Then... draw the sum of sub+speaker. I'm not sure what you are talking about regarding THX. THX doesn't mandate the F3(-3dB) point of the certified speaker. My program will do both phase and total output graphs. It assumes a "perfect sub". Since it is geared to LR crossovers, at this point, I'm not sure that drawings will add anything the bluescale's stuff. |
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Post by igorzep on Sept 4, 2014 16:27:55 GMT -5
THX doesn't mandate the F3(-3dB) point of the certified speaker. It does. The standard is: Q=0.707, F3=80Hz for both satellite speaker and BM crossover high-pass (sum is LR4 high pass with F6=80Hz). Also mandates LR4 subwoofer low-pass with F6=80Hz. Perfect match. |
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Post by Chuck Elliot on Sept 4, 2014 16:39:25 GMT -5
THX doesn't mandate the F3(-3dB) point of the certified speaker. It does. The standard is: Q=0.707, F3=80Hz for both satellite speaker and BM crossover high-pass (sum is LR4 high pass with F6=80Hz). Also mandates LR4 subwoofer low-pass with F6=80Hz. Perfect match. I can see this for satellite speakers, but mains??? Got a link? |
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Post by igorzep on Sept 4, 2014 16:54:22 GMT -5
Mains are the satellites  As everything bass-managed. I don't have a link... THX doesn't share their specs for free  But you can check specs for any THX certified speaker, and also see the crossover slopes on any SSP or AVR in THX BM mode. They are always the same. |
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Post by Chuck Elliot on Sept 4, 2014 17:56:04 GMT -5
Mains are the satellites As everything bass-managed. I don't have a link... THX doesn't share their specs for free But you can check specs for any THX certified speaker, and also see the crossover slopes on any SSP or AVR in THX BM mode. They are always the same. You have enlightened me. I was not aware of this aspect of THX. Thanks! I never payed too much attention to THX deeming it more of a marketing tool than a innovation. |
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bootman
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Post by bootman on Sept 4, 2014 19:48:04 GMT -5
These do look much better.
Great job Bluescale.
Awesome work!
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Post by smfins on Sept 4, 2014 21:53:27 GMT -5
Id like it and expect it to do better,but there is much more to what xt32 does other than levels and distance. To me the job xt32 does on bass management is phenomenal! I just don't want dirac to be something similar to what audyssey multi eq was doing.
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bootman
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Post by bootman on Sept 4, 2014 21:59:03 GMT -5
Id like it and expect it to do better,but there is much more to what xt32 does other than levels and distance. To me the job xt32 does on bass management is phenomenal! I just don't want dirac to be something similar to what audyssey multi eq was doing. Are you talking about SubEQ HT? |
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Post by bluescale on Sept 4, 2014 22:44:11 GMT -5
The exact dB @ crossover point is hard to read as there is a slight level difference between the sub and the speaker I'm glad you mentioned that, as I noticed the slight level difference as well. I don't think it makes a practical difference, but it certainly is strange. I would have expected them to identical. This level difference was present before and after the factory reset. |
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Post by sahmen on Sept 4, 2014 22:54:38 GMT -5
The exact dB @ crossover point is hard to read as there is a slight level difference between the sub and the speaker I'm glad you mentioned that, as I noticed the slight level difference as well. I don't think it makes a practical difference, but it certainly is strange. I would have expected them to identical. This level difference was present before and after the factory reset. So Blue: How would you explain what these graphs demonstrate to a layman with zero expertise in REWing and other methods of advanced Sub EQing? I am particularly interested in understanding in practical terms how helpful this approach has been in addressing the questions surrounding dual-mono sub configuration that have been the major preoccupation of this thread, that is, if addressing those questions is what is intended in these exercises... Thanks. |
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Post by bluescale on Sept 4, 2014 22:55:59 GMT -5
Yes, those look much better it terms of shape, but being only 3DB down at the crossover it also shows that they are not LR filters! I wonder why the 120Hx 12dB is dead on, while the others have drifted down a bit? When you say dead on, do you mean that the two slopes meet at the crossover point? If so, 120/12 actually crosses at about 114, not 120. |
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Post by bluescale on Sept 4, 2014 23:24:53 GMT -5
So Blue: How would you explain what these graphs demonstrate to a layman with zero expertise in REWing and other methods of advanced Sub EQing? I am particularly interested in understanding in practical terms how helpful this approach has been in addressing the questions surrounding dual-mono sub configuration that have been the major preoccupation of this thread, that is, if addressing those questions is what is intended in these exercises... Thanks. I'm not sure I'm the best person to explain everything in these graphs. I'm more like a trained monkey who's been shown how to do a few tricks. I do my tricks, and the smart people help me figure out what it means. What these graphs are meant to show is what the XMC-1 is doing as far as bass management. What I'm trying to show is the relationship of the signal sent to the subwoofer and the signal sent to the channel speaker (in this case my front left channel). The sub is the line starting high on the left, and then sloping down sharply shortly before the crossover point. The channel speaker is the line starting low on the left, an then sloping up steeply before leveling off shortly after the crossover point. All these measurements are taken at the soundcard rather than using a mic. This allows us to view the pure signal before my room and speakers have a chance to mess things up at all. As far as addressing the dual mono questions, this has absolutely nothing to do with it. I merely stumbled across what looked like a problem with the slopes, and decided to poke a little harder. Fortunately, poking revealed that things are working more or less correctly. It just looks like a factory reset was needed to get things on track. I'm not sure if that answers your questions or not. If you've got more, or if I missed the mark, keep asking. I'll answer what I can, and folks like Chuck Elliot and igorzep know a lot more than me, and in my experience, have been very willing to chime in. I'm learning what I can from them. |
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Post by Chuck Elliot on Sept 4, 2014 23:29:30 GMT -5
Yes, those look much better it terms of shape, but being only 3DB down at the crossover it also shows that they are not LR filters! I wonder why the 120Hx 12dB is dead on, while the others have drifted down a bit? When you say dead on, do you mean that the two slopes meet at the crossover point? If so, 120/12 actually crosses at about 114, not 120. "Dead On" may be a misnomer, but it is the closest of the graphs. What I don't like is the variation. This is done in the DSP so there are no differing analog components. They all should be "Dead On". I also would like to know why these all appear to be Butterworth filters and not LR? I wish Emotiva would reply in this thread. Much appreciate your work in this thread bluescale! |
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Post by bluescale on Sept 4, 2014 23:41:19 GMT -5
I also would like to know why these all appear to be Butterworth filters and not LR? Can you explain the practical differences between the two? What makes Linkwitz–Riley crossovers superior to Butterworth? Like I said, I'm still learning about this stuff . |
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Post by sahmen on Sept 4, 2014 23:57:32 GMT -5
So Blue: How would you explain what these graphs demonstrate to a layman with zero expertise in REWing and other methods of advanced Sub EQing? I am particularly interested in understanding in practical terms how helpful this approach has been in addressing the questions surrounding dual-mono sub configuration that have been the major preoccupation of this thread, that is, if addressing those questions is what is intended in these exercises... Thanks. I'm not sure I'm the best person to explain everything in these graphs. I'm more like a trained monkey who's been shown how to do a few tricks. I do my tricks, and the smart people help me figure out what it means. What these graphs are meant to show is what the XMC-1 is doing as far as bass management. What I'm trying to show is the relationship of the signal sent to the subwoofer and the signal sent to the channel speaker (in this case my front left channel). The sub is the line starting high on the left, and then sloping down sharply shortly before the crossover point. The channel speaker is the line starting low on the left, an then sloping up steeply before leveling off shortly after the crossover point. All these measurements are taken at the soundcard rather than using a mic. This allows us to view the pure signal before my room and speakers have a chance to mess things up at all. As far as addressing the dual mono questions, this has absolutely nothing to do with it. I merely stumbled across what looked like a problem with the slopes, and decided to poke a little harder. Fortunately, poking revealed that things are working more or less correctly. It just looks like a factory reset was needed to get things on track. I'm not sure if that answers your questions or not. If you've got more, or if I missed the mark, keep asking. I'll answer what I can, and folks like Chuck Elliot and igorzep know a lot more than me, and in my experience, have been very willing to chime in. I'm learning what I can from them. Thanks for the explanation, even if it has only been helpful in showing me how off-the-mark my questions were, and what a complicated learning curve I have still got to confront in understanding these sub configuration/eq issues. Keep doing what you are doing, I am not going to ask anymore questions until I run into something more pertinent. Thanks again, though |
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Post by Chuck Elliot on Sept 5, 2014 0:52:49 GMT -5
I also would like to know why these all appear to be Butterworth filters and not LR? Can you explain the practical differences between the two? What makes Linkwitz–Riley crossovers superior to Butterworth? Like I said, I'm still learning about this stuff . LR filters sum flat at the crossover point with each side low/hi having the same phase. -6dB + -6dB = .5 + .5 = 1 BW filters sum with a 3 dB bump at the crossover point and aren't in phase. -3db + -3dB = .707 + .707 = 1.414 |
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. That said, I did retest the crossover anomaly, because it was behaving just too troublesome to leave alone. Good news, folks. After doing a factory reset, the new tests look much better. I don't know if something strange was going on in the XMC-1, or if user error was involved in the first set of tests, but here's what happens to the sub and the main channel as I adjust xover and slope:
As everything bass-managed. I don't have a link... THX doesn't share their specs for free 
But you can check specs for any THX certified speaker, and also see the crossover slopes on any SSP or AVR in THX BM mode. They are always the same.
