Best way to run subs a little hot? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 14 Old 05-19-2018, 06:04 AM - Thread Starter
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Best way to run subs a little hot?

I just finished calibrating my system with the Audyssey app. If I now want to run the subs a little "hot" is it best to adjust the trim in the Denon's AVR settings (It is currently -9.5db for the subs, I would make them -6.5db, so 3db increase) OR is it best to simply increase the gain a little bit on each subwoofer's amp directly.

Or maybe it doesn't matter either way?

Thanks!
Dan
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post #2 of 14 Old 05-19-2018, 06:11 AM
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Quote:
Originally Posted by dftkell View Post
I just finished calibrating my system with the Audyssey app. If I now want to run the subs a little "hot" is it best to adjust the trim in the Denon's AVR settings (It is currently -9.5db for the subs, I would make them -6.5db, so 3db increase) OR is it best to simply increase the gain a little bit on each subwoofer's amp directly.

Or maybe it doesn't matter either way?

Thanks!
Dan

Hi Dan,

For a modest increase of about 3db, putting you around -6, just using your AVR trim controls is fine. For anything more significant than that, I would recommend using the sub gains themselves. It is helpful to keep the AVR trims relatively low.

There is a detailed explanation of why this is a good idea in Section II of the Guide linked in my signature. The Guide also covers some other issues which may be of interest to you.

Regards,
Mike

GUIDE TO SUBWOOFER CALIBRATION AND BASS PREFERENCES

* The Guide linked above is a comprehensive guide to Audio & HT systems, including:
Speaker placements & Room treatments; HT calibration & Room EQ; Room gain; Bass
Preferences; Subwoofer Buyer's Guide: Sealed/ported; ID subs; Subwoofer placement.
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post #3 of 14 Old 05-19-2018, 06:18 AM - Thread Starter
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Originally Posted by mthomas47 View Post
Hi Dan,

For a modest increase of about 3db, putting you around -6, just using your AVR trim controls is fine. For anything more significant than that, I would recommend using the sub gains themselves. It is helpful to keep the AVR trims relatively low.

There is a detailed explanation of why this is a good idea in Section II of the Guide linked in my signature. The Guide also covers some other issues which may be of interest to you.

Regards,
Mike
Thanks Mike!
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post #4 of 14 Old 05-19-2018, 08:18 AM - Thread Starter
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Quote:
Originally Posted by mthomas47 View Post
Hi Dan,

For a modest increase of about 3db, putting you around -6, just using your AVR trim controls is fine. For anything more significant than that, I would recommend using the sub gains themselves. It is helpful to keep the AVR trims relatively low.

There is a detailed explanation of why this is a good idea in Section II of the Guide linked in my signature. The Guide also covers some other issues which may be of interest to you.

Regards,
Mike
Mike, another question if you don't mind. After running Audyssey, here is the response I'm getting from 10hz-200hz--no smoothing on the graph.

I have a dip around 65hz-70hz. My Dayton plate amps have a band of PEQ on each of them. Can I tweak and give a boost on the amp around 65hz to try to alleviate the dip after running Audyssey? Or are PEQ tweaks on the plate amp better to do before running Audyssey? Does it make a difference?

Thanks again,
Dan
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post #5 of 14 Old 05-19-2018, 08:31 AM
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Just run calibration so it gives up to 6db of adjustment while staying at least -3db in the AVR. So that translates to turning up the amp gains until you target -9 in the AVR post calibration.
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post #6 of 14 Old 05-19-2018, 09:06 AM - Thread Starter
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I fooled around a few different ways with one band of PEQ on each sub after Audyssey but it didn't make any significant difference so I'm going back to the way it was before when the subs had no PEQ filter on.
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post #7 of 14 Old 05-19-2018, 09:26 AM
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Originally Posted by dftkell View Post
Mike, another question if you don't mind. After running Audyssey, here is the response I'm getting from 10hz-200hz--no smoothing on the graph.

I have a dip around 65hz-70hz. My Dayton plate amps have a band of PEQ on each of them. Can I tweak and give a boost on the amp around 65hz to try to alleviate the dip after running Audyssey? Or are PEQ tweaks on the plate amp better to do before running Audyssey? Does it make a difference?

Thanks again,
Dan
Quote:
Originally Posted by dftkell View Post
I fooled around a few different ways with one band of PEQ on each sub after Audyssey but it didn't make any significant difference so I'm going back to the way it was before when the subs had no PEQ filter on.

Hi,

I think it may be pretty hard to pull-up that dip with PEQ. I would have suggested doing it after running Audyssey, but I have also seen some people have success using the PEQ first, so if you are in the mood to experiment some more, that may be worth a try.

I assume that this is not something you can fix with subwoofer placement? The good news is that our brains are pretty adept at not actually noticing dips in the frequency response unless they are very wide. For instance, the octave between 50Hz and 100Hz consists of 8 notes, and a dip between 60Hz and 70Hz would only be about 1 1/2 notes wide. Since each note has harmonics, odds are that you might not even be aware of any missing sound at that limited frequency.

Regards,
Mike

GUIDE TO SUBWOOFER CALIBRATION AND BASS PREFERENCES

* The Guide linked above is a comprehensive guide to Audio & HT systems, including:
Speaker placements & Room treatments; HT calibration & Room EQ; Room gain; Bass
Preferences; Subwoofer Buyer's Guide: Sealed/ported; ID subs; Subwoofer placement.

Last edited by mthomas47; 05-19-2018 at 09:29 AM.
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post #8 of 14 Old 05-19-2018, 09:32 AM
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^^ That is ~ 7-17db dip in the mid bass region. Other than that, it looks great. Try to post graph with 5db vertical scale. I would run measurement with the center channel + subs and see if the sub distance tweak helps bringing the dip up.
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post #9 of 14 Old 05-19-2018, 09:54 AM - Thread Starter
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Quote:
Originally Posted by mthomas47 View Post
Hi,

I think it may be pretty hard to pull-up that dip with PEQ. I would have suggested doing it after running Audyssey, but I have also seen some people have success using the PEQ first, so if you are in the mood to experiment some more, that may be worth a try.

I assume that this is not something you can fix with subwoofer placement? The good news is that our brains are pretty adept at not actually noticing dips in the frequency response unless they are very wide. For instance, the octave between 50Hz and 100Hz consists of 8 notes, and a dip between 60Hz and 70Hz would only be about 1 1/2 notes wide. Since each note has harmonics, odds are that you might not even be aware of any missing sound at that limited frequency.

Regards,
Mike


Right now, this is the best placement combination I could determine for two subs in my room. I’ve measured them in every practical combination I could think of. And I’ve ended up with one sub up front and center and the other behind the couch in the rear corner. The subs are DIY Sound Group Stonehenge ported 18’s. The second best combo I found was actually having both subs near field, together, firing right into the back of the couch. This front room/back room combo is slightly better though. The room is very irregular with multiple angles on the ceiling and an open staircase on the side. I’m pretty happy with what I was able to get through placement and measuring.

Thanks
Dan


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post #10 of 14 Old 05-19-2018, 10:01 AM - Thread Starter
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Quote:
Originally Posted by tvuong View Post
^^ That is ~ 7-17db dip in the mid bass region. Other than that, it looks great. Try to post graph with 5db vertical scale. I would run measurement with the center channel + subs and see if the sub distance tweak helps bringing the dip up.


I just packed up all my equipment. This was a marathon session last night and this morning of pushing these big subs around the room and measuring, moving, measuring, moving, etc. When I get motivated again, I’ll give it a shot. I just started using REW, so I’ll have to figure out how to scale like you’re referring.

Currently, the sub distance is set at 8.5 ft. Again, there is one behind and one in front. I kept them both at normal phase. I might try just adjusting the distance a bit for fun to see if that helps at all with the dip.

Thanks


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post #11 of 14 Old 05-24-2018, 09:06 AM - Thread Starter
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Originally Posted by tvuong View Post
^^ That is ~ 7-17db dip in the mid bass region. Other than that, it looks great. Try to post graph with 5db vertical scale. I would run measurement with the center channel + subs and see if the sub distance tweak helps bringing the dip up.
Tvuong,

I'm going to try a couple more tweaks and measurements in the next week or so. My first step is to try to adjust the sub distance and see what that does to the dip. Then, I'm going to see if adjusting the rear sub also helps the dip.

I'm new to REW. How do I post a graph with a 5db vertical scale? I've just been hitting measure and taking what comes out.

Thanks
Dan
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post #12 of 14 Old 05-24-2018, 03:25 PM
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Originally Posted by dftkell View Post
Mike, another question if you don't mind. After running Audyssey, here is the response I'm getting from 10hz-200hz--no smoothing on the graph.

I have a dip around 65hz-70hz. My Dayton plate amps have a band of PEQ on each of them. Can I tweak and give a boost on the amp around 65hz to try to alleviate the dip after running Audyssey? Or are PEQ tweaks on the plate amp better to do before running Audyssey? Does it make a difference?

Thanks again,
Dan
Is this measurement subs only or does it include a speaker? If it is sub+speaker, where is your crossover set?

I ask because you may be able to flatten out that dip with the Sub Distance Tweak if you are using a relatively low crossover (60-70hz).
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post #13 of 14 Old 05-24-2018, 05:34 PM - Thread Starter
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Is this measurement subs only or does it include a speaker? If it is sub+speaker, where is your crossover set?

I ask because you may be able to flatten out that dip with the Sub Distance Tweak if you are using a relatively low crossover (60-70hz).
It was my first time using REW. (I had used Fuzzmeasure in the past.) I believe it is a sub and speaker. The crossover is at 80hz for the LR speakers. I had also tried it at 60hz but that didn't make a significant different in FR.

This weekend I'm going to try adjusting the sub distance--increasing and decreasing--to see if that helps with the dip.

So you're saying if I'm going to adjust sub distance, I should lower the crossover to 60hz? It's not a problem, just want to confirm it.

Thanks!
Dan
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post #14 of 14 Old 05-25-2018, 12:27 PM
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Oh no, I'm not saying to lower your crossover, I was just saying that if your crossover was set around 60-70hz that the dip is most likely caused by the sub and speaker being out of phase with each other (a common occurrence with auto cal software).

Here is how to run the sub distance tweak:

  • Measure CC+subs (REW HDMI CH3)
  • Add to the sub distance setting (both subs equally if using an AVR with dual sub calibration) in 1' increments (on some AVRs you must make sure to back out of the distance setting menu before the new setting will take effect)
  • Re-measure
  • Repeat until you get the smoothest transition over the crossover
  • You can repeat the process with the L/R+sub, but will usually have to compromise the CC+subs to get them all fairly smooth (if you are primarily movies, balance the compromise in favor of CC+sub, if music the L/R+sub)
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