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Post by thezone on Sept 30, 2020 4:02:02 GMT -5
This installment highlights the preferred locations for a two subwoofer setup. This is where I "want" the subs to be in a perfect world. As shown in the plan the subs are inboard of the Front Left and Right main speakers, under the tv. The attached plots are with no correction, no PEQ, but where the two subs are measured together there is delay added to one of them, which happens to be S2. S2 and S1 are at the top of the plan. The first two plots are of each subwoofer individually. The third plot is both together with some delay on S2. Notice the boosted bass below 40Hz with both subs together, but also notice some loss of SPL on both sides of the 50Hz peak. I've done enough testing to know that there are other locations and combinations that work better, but wanted to share this scenario first. I played a little with PEQ and was able to reduce the peak around 50Hz but chose not to confuse things. I want to show all the different combinations, this combo and the others to follow, without corrections before delving into any type of correction other than delay. For what its worth, I have my S1 in the same spot as you ( configured only for bass management) and my S2 in the right rear corner behind the MLP ( configured only for LFE). I find this works amazingly well. |
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ttocs
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Post by ttocs on Sept 30, 2020 9:06:25 GMT -5
This installment highlights the preferred locations for a two subwoofer setup. This is where I "want" the subs to be in a perfect world. As shown in the plan the subs are inboard of the Front Left and Right main speakers, under the tv. The attached plots are with no correction, no PEQ, but where the two subs are measured together there is delay added to one of them, which happens to be S2. S2 and S1 are at the top of the plan. The first two plots are of each subwoofer individually. The third plot is both together with some delay on S2. Notice the boosted bass below 40Hz with both subs together, but also notice some loss of SPL on both sides of the 50Hz peak. I've done enough testing to know that there are other locations and combinations that work better, but wanted to share this scenario first. I played a little with PEQ and was able to reduce the peak around 50Hz but chose not to confuse things. I want to show all the different combinations, this combo and the others to follow, without corrections before delving into any type of correction other than delay. How does this compare to having S2 where it is, and S1 back by the refrigerator? I have not remeasured since discovering my mistake in doing measurements using the REW output 4-LFE which starts to roll off above 100Hz. Now I'm using output 1-L so can see how the subs perform up to their maximum frequency. This gives me complete information so I can decide to continue using all the subs for LFE only and the Fronts for Bass Management, or maybe use one sub for Bass Management and the others for LFE, either way I want as much info to make an informed decision. I will measure all the previous sub locations I've tried in the past using the current method so it's a good baseline. I really like having LFE only separated. And even though the Fronts are outstanding for Bass Management, I may want to dedicate subwoofer(s) just for that duty as well, assuming the subs are as capable as the Fronts in doing so. |
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ttocs
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Post by ttocs on Sept 30, 2020 9:18:10 GMT -5
This installment highlights the preferred locations for a two subwoofer setup. This is where I "want" the subs to be in a perfect world. As shown in the plan the subs are inboard of the Front Left and Right main speakers, under the tv. The attached plots are with no correction, no PEQ, but where the two subs are measured together there is delay added to one of them, which happens to be S2. S2 and S1 are at the top of the plan. For what its worth, I have my S1 in the same spot as you ( configured only for bass management) and my S2 in the right rear corner behind the MLP ( configured only for LFE). I find this works amazingly well. I've been planning out the strategy for doing all the combinations I can come up with, and your suggestion is one of them. For example, one combo is with S1 and S2 in the locations as seen in the plan above, and adding my smaller Rel in the spot between the Front Right and Right Width. This location has measured well when checking it with the mic-crawl, and also with all three subs stacked, and finally with only the Rel. Unfortunately, the design of the Sumiko subs, being a down firing driver and front firing passive doesn't measure well when it's only one Sumiko - S1 or S2. But the Rel, being a down firing driver only, measures pretty well on its own in that spot. The next installment that I'll post today is with the Rel, S3, in that spot and S1 and S2 in the spots shown above. |
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Post by marcl on Sept 30, 2020 9:47:28 GMT -5
How does this compare to having S2 where it is, and S1 back by the refrigerator? I have not remeasured since discovering my mistake in doing measurements using the REW output 4-LFE which starts to roll off above 100Hz. Now I'm using output 1-L so can see how the subs perform up to their maximum frequency. This gives me complete information so I can decide to continue using all the subs for LFE only and the Fronts for Bass Management, or maybe use one sub for Bass Management and the others for LFE, either way I want as much info to make an informed decision. I will measure all the previous sub locations I've tried in the past using the current method so it's a good baseline. I really like having LFE only separated. And even though the Fronts are outstanding for Bass Management, I may want to dedicate subwoofer(s) just for that duty as well, assuming the subs are as capable as the Fronts in doing so. Cool. Looking forward to the new results. As you know, my expectation is that the front/rear placement will do a better job of reducing peaks and filling in nulls .... but the data will tell the tale! Regarding using the fronts for bass management, I went for the best of both worlds. I split the L/R fronts and combine them to the miniDSP Input 2, while the Center Sub output goes to miniDSP Input 1. I put a 35Hz LPF on the front end of Input 2 so that for bass management the subs only play below the range of the Magnepan 3.7 fronts. Added benefit of this arrangement is that when Dirac sweeps the left and right fronts, it sees the full response including the subs below 35Hz. Astute miniDSP wranglers will note that the Plugin has a Parametric EQ Filter on the Input, not a Crossover. No problem! I used the Biquad Calculator included in the Plugin to create the coefficients for a 35Hz LR 48db/octave LPF and pasted them into four of the Advanced Biquad filters in the input filter block. You even have one filter left if you'd like to do some PEQ.  |
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ttocs
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Post by ttocs on Sept 30, 2020 10:26:59 GMT -5
I have not remeasured since discovering my mistake in doing measurements using the REW output 4-LFE which starts to roll off above 100Hz. Now I'm using output 1-L so can see how the subs perform up to their maximum frequency. This gives me complete information so I can decide to continue using all the subs for LFE only and the Fronts for Bass Management, or maybe use one sub for Bass Management and the others for LFE, either way I want as much info to make an informed decision. I will measure all the previous sub locations I've tried in the past using the current method so it's a good baseline. I really like having LFE only separated. And even though the Fronts are outstanding for Bass Management, I may want to dedicate subwoofer(s) just for that duty as well, assuming the subs are as capable as the Fronts in doing so. Cool. Looking forward to the new results. As you know, my expectation is that the front/rear placement will do a better job of reducing peaks and filling in nulls .... but the data will tell the tale! Regarding using the fronts for bass management, I went for the best of both worlds. I split the L/R fronts and combine them to the miniDSP Input 2, while the Center Sub output goes to miniDSP Input 1. I put a 35Hz LPF on the front end of Input 2 so that for bass management the subs only play below the range of the Magnepan 3.7 fronts. Added benefit of this arrangement is that when Dirac sweeps the left and right fronts, it sees the full response including the subs below 35Hz. Astute miniDSP wranglers will note that the Plugin has a Parametric EQ Filter on the Input, not a Crossover. No problem! I used the Biquad Calculator included in the Plugin to create the coefficients for a 35Hz LR 48db/octave LPF and pasted them into four of the Advanced Biquad filters in the input filter block. You even have one filter left if you'd like to do some PEQ. I'm basically a hack when it comes to PEQ, learning as I go, so anything related to Biquad Filters is currently above my head - so I will need to learn up this stuff. |
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Post by megash0n on Sept 30, 2020 10:51:01 GMT -5
Cool. Looking forward to the new results. As you know, my expectation is that the front/rear placement will do a better job of reducing peaks and filling in nulls .... but the data will tell the tale! Regarding using the fronts for bass management, I went for the best of both worlds. I split the L/R fronts and combine them to the miniDSP Input 2, while the Center Sub output goes to miniDSP Input 1. I put a 35Hz LPF on the front end of Input 2 so that for bass management the subs only play below the range of the Magnepan 3.7 fronts. Added benefit of this arrangement is that when Dirac sweeps the left and right fronts, it sees the full response including the subs below 35Hz. Astute miniDSP wranglers will note that the Plugin has a Parametric EQ Filter on the Input, not a Crossover. No problem! I used the Biquad Calculator included in the Plugin to create the coefficients for a 35Hz LR 48db/octave LPF and pasted them into four of the Advanced Biquad filters in the input filter block. You even have one filter left if you'd like to do some PEQ. I'm basically a hack when it comes to PEQ, learning as I go, so anything related to Biquad Filters is currently above my head - so I will need to learn up this stuff. I know I've mentioned it before, and probably too many times, but MSO will give you the biquads to import into the MiniDSP. It only takes a few minutes to mess around with different variables to see the impact of them. Then, you can let it crunch math for 30 mins on the scenario you like the best. I did a handful of tests inverting one sub, adding all pass filters, etc etc. What I did with mine was to allow it to attenuate but not boost any frequency. My goal using MSO was to get the "best" integration of the subs together, then let Dirac do its thing. It would be worth checking out just to see something different. |
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Post by marcl on Sept 30, 2020 12:53:36 GMT -5
I'm basically a hack when it comes to PEQ, learning as I go, so anything related to Biquad Filters is currently above my head - so I will need to learn up this stuff. I know I've mentioned it before, and probably too many times, but MSO will give you the biquads to import into the MiniDSP. It only takes a few minutes to mess around with different variables to see the impact of them. Then, you can let it crunch math for 30 mins on the scenario you like the best. I did a handful of tests inverting one sub, adding all pass filters, etc etc. What I did with mine was to allow it to attenuate but not boost any frequency. My goal using MSO was to get the "best" integration of the subs together, then let Dirac do its thing. It would be worth checking out just to see something different. I understand. But my point here is the idea of using fronts for bass management (rather than just subs) and then using an input on the miniDSP to give the fronts the subs below their operating range. One could use MSO, regular PEQ, or Dirac with this scenario. But the point of it is to give best response for bass management (not LFE) for the small speakers. |
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Post by marcl on Sept 30, 2020 13:40:00 GMT -5
A couple notes on using Room EQ Wizard (REW) to measure subwoofer response. 1 - Highly recommended to read Austin Jerry's tutorial on REW and specifically how to use it with an HDMI output to measure response in a multichannel setup. Note a couple things: You can only measure up to 7.1. You can't measure Atmos top channels or wides, etc. You can't measure separate subwoofer outputs directly (Left, Center, Right). www.minidsp.com/support/community-powered-tutorials/295-minidsp-tutorials-by-austinjerry2 - Once you configure your computer to output up to 7.1 channels from REW to your sound output device, you need to be aware of which output routes to which speaker. Here's a screen shot of the REW Measurement screen and my selection of outputs from JRiver Media Center which in turn outputs to the HDMI 1 input on my XMC-2.  3 - For your speakers configured as Small, sending signals to their outputs will give you the response of that speaker plus the bass which is passed on to Bass Management below the configured crossover frequency for that speaker. Bass Management can be handled by one or more subwoofers if they are configured as Mono or Dual Mono. In this case bass below the crossover for each Small speaker will go to the subs, and you will see the combined result in the REW frequency response plot. If you have no subs - or you only have the Center Sub and it is set to LFE - then you must have some speakers set to Large for Bass Management to work. For example, if you have just a Center Sub set to LFE and your Front speakers set to Large, then bass from Small speakers will go to the Front speakers, and NO bass from the Fronts or Small speakers will go to the sub. Note also that Dirac does not measure this way. It measures the subs and other speakers separately and corrects them separately. This is the only way you can see the actual combined result of Dirac correcting the small speakers and the speakers used for Bass Management. 4 - Output #4 in REW says "LFE". This means that this output will always look like the ".1" channel of a multichannel source to the processor. The processor will see this and treat it as though it's the .1 from a 5.1 or 7.1 or 5.1.4 source. It's assumed to be LFE - Low Frequency Effect - and the processor will allow it to play up to 100Hz, and then it will roll off at either 12 or 24db/octave above 100Hz, depending on the Crossover Slope setting in your Preset. The processor will also increase the level of this output +10db because the spec for the .1 channel requires this. The response of Output #4 will be +10db higher than the other channels as measured by REW. 5 - If you are using one or more subs set to Mono or Dual Mono for Bass Management, and you want to measure the full response of the subs available for Bass Management, NO NOT use REW Output #4. Output #4 will always roll off above 100Hz irrespective of your subs' actual response. If you're crossing over small speakers at 150, 200 or even 250Hz you will want to see how your subs respond at those higher frequencies. To measure the sub response available for Bass Management, select a Small speaker (Center, for example) and set its crossover frequency to the maximum 200Hz. Then TURN OFF the Small speaker's amplifier, and measure that speaker's channel (Output #3 for the Center speaker in this example). With the Small speaker's amp turned off and the crossover set to 200Hz, only the subwoofers used for Bass Management will play. The response of the subs measured this way will accurately reflect their frequency response, and they will NOT be boosted +10db as the .1 LFE signal from Output #4. 6 - If you are not using subs for Bass Management and have at least one pair of speakers configured as Large (so either no subs configured, or just the Center Sub as LFE) then measuring the Large speaker's output will let you see how it responds in the Bass Management range. If you have no subs configured, and you measure Output #4, then the LFE signal will be sent to your Large speakers. The LFE signal will still be treated as LFE, and so it will roll off at 100Hz at either 12 or 24db/octave. And it will be boosted +10db. This will be the case, even though the LFE is being played through the Large speakers and not subwoofers. 7 - A final note .... the crossover settings on Small speakers have nothing to do with the LFE signal. LFE signal always rolls off at 100Hz irrespective of any other crossover settings. LFE signal is only affected by the Crosssover Slope setting which is either 12 or 24db/octave, and is the same for all speakers in a Preset. For example, if you set the crossover on all your Small speakers to 80Hz, the LFE signal will still play up to 100Hz. |
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Post by ttocs on Sept 30, 2020 14:35:22 GMT -5
marcl EXCELLENT !Very, very, excellent synopsis! Thank you very much! It was a post you made a little while back where you started talking about Output #4 in REW being truly only LFE and how the frequency rolls off over 100Hz that got me thinking about this. But it really didn't hit home for me until a week or so ago, and everything changed for the better. I was starting to wonder why my subs were not capable of going over 120Hz, and also wondering why the bass was so strong down low vs how weak the upper frequencies were. So now this is how I test the subwoofers, using an output for a Small speaker with the Small speaker's amplifier turned off so only the subwoofer makes sound. Part of the reason I started this thread is for instruction like this because there doesn't seem to be a source for this kind of information coupled with How-To. I'm planning on making some videos, short videos, demonstrating nifty information such as what you pointed out. So many videos show the big picture but lack some of the minutia that can be, in my case, critical to being able to setup the measurement scheme with success. It's like what I discovered last week with the UMIK-1 microphones being set for a 18dB sensitivity and also being limited to a max SPL that disallows being able to test at high volume. Once I set mine for 12dB sensitivity it's like the whole world of testing opened up.
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Post by marcl on Sept 30, 2020 15:31:47 GMT -5
marcl EXCELLENT !Very, very, excellent synopsis! Thank you very much! It was a post you made a little while back where you started talking about Output #4 in REW being truly only LFE and how the frequency rolls off over 100Hz that got me thinking about this. But it really didn't hit home for me until a week or so ago, and everything changed for the better. I was starting to wonder why my subs were not capable of going over 120Hz, and also wondering why the bass was so strong down low vs how weak the upper frequencies were. So now this is how I test the subwoofers, using an output for a Small speaker with the Small speaker's amplifier turned off so only the subwoofer makes sound. Part of the reason I started this thread is for instruction like this because there doesn't seem to be a source for this kind of information coupled with How-To. I'm planning on making some videos, short videos, demonstrating nifty information such as what you pointed out. So many videos show the big picture but lack some of the minutia that can be, in my case, critical to being able to setup the measurement scheme with success. It's like what I discovered last week with the UMIK-1 microphones being set for a 18dB sensitivity and also being limited to a max SPL that disallows being able to test at high volume. Once I set mine for 12dB sensitivity it's like the whole world of testing opened up. :-) It literally took me 8 years to figure it out. I don't know why it was so hard. Just want to save some folks some effort. |
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Post by DYohn on Sept 30, 2020 17:27:45 GMT -5
Have you tried this position?  |
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Post by ttocs on Sept 30, 2020 17:35:48 GMT -5
I'm basically a hack when it comes to PEQ, learning as I go, so anything related to Biquad Filters is currently above my head - so I will need to learn up this stuff. I know I've mentioned it before, and probably too many times, but MSO will give you the biquads to import into the MiniDSP. It only takes a few minutes to mess around with different variables to see the impact of them. Then, you can let it crunch math for 30 mins on the scenario you like the best. I did a handful of tests inverting one sub, adding all pass filters, etc etc. What I did with mine was to allow it to attenuate but not boost any frequency. My goal using MSO was to get the "best" integration of the subs together, then let Dirac do its thing. It would be worth checking out just to see something different. Thanks, and I may use MSO at some point. But first up is finding the best combos and locations for the sub(s) before any consideration is given to correction. Once the best scenarios have been determined is when correction will be done on possibly several of those scenarios, because I suspect that a successfully corrected scenario may not be predictable so I'll need more than one to choose from. I'm prepared for a possibly lengthy journey, and that's alright, because as I used to say when traveling around the Country on my motorcycle with a tent and sleeping bag - The destination may be the excuse, but it's all about the journey. |
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Post by ttocs on Sept 30, 2020 17:50:58 GMT -5
Have you tried this position? Yes, but not during this series using the methods now being employed. It was a while ago, and it wasn't too bad, but there's another consideration with that spot, and that's the fact that the Martin Logan has dual woofers - front and rear firing. When I tested the subwoofer there a while ago I didn't test the ML to see if the bass was worse with the sub possibly in the way. I do plan to test the sub in that spot again - and run ARC on the ML's to see their result. |
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Post by megash0n on Sept 30, 2020 18:56:00 GMT -5
I know I've mentioned it before, and probably too many times, but MSO will give you the biquads to import into the MiniDSP. It only takes a few minutes to mess around with different variables to see the impact of them. Then, you can let it crunch math for 30 mins on the scenario you like the best. I did a handful of tests inverting one sub, adding all pass filters, etc etc. What I did with mine was to allow it to attenuate but not boost any frequency. My goal using MSO was to get the "best" integration of the subs together, then let Dirac do its thing. It would be worth checking out just to see something different. Thanks, and I may use MSO at some point. But first up is finding the best combos and locations for the sub(s) before any consideration is given to correction. Once the best scenarios have been determined is when correction will be done on possibly several of those scenarios, because I suspect that a successfully corrected scenario may not be predictable so I'll need more than one to choose from. I'm prepared for a possibly lengthy journey, and that's alright, because as I used to say when traveling around the Country on my motorcycle with a tent and sleeping bag - The destination may be the excuse, but it's all about the journey. Fair enough. I also found it pretty helpful to get a quick configuration on integration when I was testing different spots. Kinda shortened my testing in a sense. |
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Post by thezone on Sept 30, 2020 21:10:19 GMT -5
Hi marcl, Can I please ask where you got this information from? It's not in the XMC-2 manual. Not saying your incorrect but I was looking for this information and could not find it. If you are correct then thanks for the info! 7 - A final note .... the crossover settings on Small speakers have nothing to do with the LFE signal. LFE signal always rolls off at 100Hz irrespective of any other crossover settings. LFE signal is only affected by the Crosssover Slope setting which is either 12 or 24db/octave, and is the same for all speakers in a Preset. For example, if you set the crossover on all your Small speakers to 80Hz, the LFE signal will still play up to 100Hz. |
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ttocs
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Post by ttocs on Sept 30, 2020 22:52:40 GMT -5
00929ACD This uses all three subwoofers. Delay is used on S2 and S3. Here's the plan with S3 (Rel 10" down firing) added to the group next to the Right Width speaker at position C.   S1 in Position D  S2 in Position A   S3 in Position C   S1, S2, and S3 combined. The overall SPL is higher pretty much all the way across. That dip near 70Hz is still a problem.   |
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Post by marcl on Oct 1, 2020 7:11:59 GMT -5
Hi marcl, Can I please ask where you got this information from? It's not in the XMC-2 manual. Not saying your incorrect but I was looking for this information and could not find it. If you are correct then thanks for the info! 7 - A final note .... the crossover settings on Small speakers have nothing to do with the LFE signal. LFE signal always rolls off at 100Hz irrespective of any other crossover settings. LFE signal is only affected by the Crosssover Slope setting which is either 12 or 24db/octave, and is the same for all speakers in a Preset. For example, if you set the crossover on all your Small speakers to 80Hz, the LFE signal will still play up to 100Hz. Correct, it's not in the manual. I determined all of this with testing and then confirmed in correspondence with someone from Emotiva. I expect this is how other processors work too, though they may not have the LFE-only option like we do for the Center Sub. |
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Post by marcl on Oct 1, 2020 7:15:50 GMT -5
00929ACD This uses all three subwoofers. Delay is used on S2 and S3. For each Here's the plan with S3 (Rel 10" down firing) added to the group next to the Right Width speaker at position C.  S1 in Position D S2 in Position A  S3 in Position C  S1, S2, and S3 combined. The overall SPL is higher pretty much all the way across. That dip near 70Hz is still a problem.  Can you guess my next move? S2 to position H  |
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Post by megash0n on Oct 1, 2020 7:52:43 GMT -5
00929ACD This uses all three subwoofers. Delay is used on S2 and S3. For each Here's the plan with S3 (Rel 10" down firing) added to the group next to the Right Width speaker at position C.  S1 in Position D S2 in Position A  S3 in Position C  S1, S2, and S3 combined. The overall SPL is higher pretty much all the way across. That dip near 70Hz is still a problem.  Cab you guess my next move? S2 to position H is that a check or checkmate? |
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ttocs
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Post by ttocs on Oct 1, 2020 8:13:45 GMT -5
Am I just a Pawn in your dastardly scheme?
Actually, S2 to H does make sense. I've been trying to figure out the most efficient method of ordering the combinations, but in the end, it not worth trying.
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