2 subs and oh man I give up....(music 2 channel)

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MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #60 on: 25 Aug 2020, 06:29 pm »
If you're not using EQ, then you have to find your happy balance (compromise) between overall level and the size of the peaks.  Measuring the mains by themselves is a must, so you know what the actual additive contribution of the subwoofers is.  The HT approach is to find the subwoofer settings that provide the maximum in phase contribution to the system, and then EQ down the peaks.  The "music" system approach is to just find the best compromise of overall level and minimizing objectionable peaks without EQ.  In a dedicated room, bass trapping is pretty normal practice irrespective of HT or music purposes.

There is one other thing that I've never heard anyone mention - there's a chance that you don't have a good placement option for a second subwoofer.  For example, I also have an open room, and I gave up running a second subwoofer in my system because the only spots I had available for the second sub resulted in destructive combing effects that I felt were clearly a net negative, no matter how I set the phase or crossover point.  The system simply sounded better with 1 subwoofer. 

Measure 1 sub at a time and measure the combined system results of each. 
Here are basic measurements I'd like to know if it were my system:
  • mains alone (or single main speaker if you prefer)
  • sub 1 alone
  • sub 2 alone
  • mains with sub 1
  • mains with sub 2
  • mains with sub 1 and sub 2

And you get to play with the crossover settings on each sub as you start to combine them with your mains.  This is just for 1 placement.  Aren't we having fun?  :thumb: Tuning bass with subwoofers is a real riot  :thumb:

Interesting you mentioned that as when Imoved the rear sub to the front right, the bass seemed good. When I moved the front left out of the corner and inside the right main there was more bass but it seems less sharp, softer attack. Which I thought was either crossing over too high or some phase issue.

I will try these that you mentioned.  :thumb:

ooheadsoo

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #61 on: 25 Aug 2020, 07:58 pm »
The good news is that you have a measurement system, so not as much guesswork involved.  My problems with the second sub were visible in the measurements - but you need baseline measurements so that you understand the impact of each individual subwoofer.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #62 on: 25 Aug 2020, 11:00 pm »
Ok so 4 quick sweeps.

Left sub (0 phase crossed at 38hz @12db slope - forward facing)


Right sub (0 phase crossed at 38hz @12db slope - right facing)



Left main


Right main


4 back to back sweeps of each speaker as they are set up now.


EDIT: I just realized I had fabric stuffed in the port of the Heresys when I was trying to blend them. Damn.

WGH

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #63 on: 25 Aug 2020, 11:39 pm »
Looks like the main speaker balance knob got bumped.  :icon_surprised:
I'll bet my old JBL L100 speakers have the same rock and roll 45 Hz hump and they sound great.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #64 on: 25 Aug 2020, 11:44 pm »
Looks like the main speaker balance knob got bumped.  :icon_surprised:
I'll bet my old JBL L100 speakers have the same rock and roll 45 Hz hump and they sound great.

Actually I don’t have a balance knob. I honestly can’t account
For the volume difference. Playing music music now and I can tell you there’s no 10db difference.

I have seen this on my sweeps so I wonder if the mic isn’t great or...

When running the left main (which has a side wall 3’ away I could detect pressure starting around 36 hz

ooheadsoo

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #65 on: 26 Aug 2020, 12:06 am »
Maybe your speakers are very directional.  If so, and the toe-in isn't symmetrical, it could show up as an issue in the measurements.  AFAIK, you probably want to do a gated sweep if you really want to see the speakers performance without room effects for troubleshooting purposes.  The subs actually look great except for the peak.  Since those are sealed subs and I'm assuming no weird EQ shenanigans, that has to be a room mode, not a sub design issue.

Tyson

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #66 on: 26 Aug 2020, 12:10 am »
Don't your subs have a built in EQ?  Most do, and they are useful for knocking down a peak like you are seeing.  The peak at 45 hz is clearly a room mode since it shows up on all your graphs.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #67 on: 26 Aug 2020, 12:13 am »
Maybe your speakers are very directional.  If so, and the toe-in isn't symmetrical, it could show up as an issue in the measurements.  AFAIK, you probably want to do a gated sweep if you really want to see the speakers performance without room effects for troubleshooting purposes.  The subs actually look great except for the peak.  Since those are sealed subs and I'm assuming no weird EQ shenanigans, that has to be a room mode, not a sub design issue.

Very directional. Like tiny moves to the toe in are audible.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #68 on: 26 Aug 2020, 12:14 am »
Don't your subs have a built in EQ?  Most do, and they are useful for knocking down a peak like you are seeing.  The peak at 45 hz is clearly a room mode since it shows up on all your graphs.

Yes both subs have a parametric eq. My question is if I’m crossing over at 38 then doesn’t that nullify the 44hz bump? I could see it going either way.

Mike-48

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #69 on: 26 Aug 2020, 12:18 am »
Yeah, very slightly different toe-in with respect to the measurement mic can cause the two speakers to look different, for sure.

Mike-48

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #70 on: 26 Aug 2020, 12:21 am »
Yes both subs have a parametric eq. My question is if I’m crossing over at 38 then doesn’t that nullify the 44hz bump? I could see it going either way.

If you're using a 12 db/octave crossover, it's down by 12 db an octave higher, i.e., at 76 Hz. It would be down only a few dB by 44 Hz.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #71 on: 26 Aug 2020, 12:21 am »
Yeah, very slightly different toe-in with respect to the measurement mic can cause the two speakers to look different, for sure.

Makes sense. Ok so at this point should I go and align the left main to the left sub (phase)? Or is therefore work I should do first? Should I maybe move the subs forward first?

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #72 on: 26 Aug 2020, 12:22 am »
If you're using a 12 db/octave crossover, it's down by 12 db an octave higher, i.e., at 76 Hz. It would be down only a few dB by 44 Hz.

Ahh, ok I will play with that.

ooheadsoo

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #73 on: 26 Aug 2020, 12:32 am »
based on your measurements, i still think your mains are trailing off around 100hz. Just saying...

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #74 on: 26 Aug 2020, 12:35 am »
based on your measurements, i still think your mains are trailing off around 100hz. Just saying...
I don’t disagree. Should I set the subs to 100 and see what damage I can do?  :wink:

Edit: set to 100 and sure sound better to me. Can’t run sweeps until tomorrow but I will try it :thumb:

Mike-48

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #75 on: 26 Aug 2020, 05:53 pm »
Makes sense. Ok so at this point should I go and align the left main to the left sub (phase)? Or is therefore work I should do first? Should I maybe move the subs forward first?

I guess I'd do the phase alignment -- then you will know what the overall FR really looks like. That will allow you to play with the crossover and level of the sub to improve it if necessary. The crossover settings may affect the phase a little; the level should not.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #76 on: 26 Aug 2020, 07:04 pm »
I guess I'd do the phase alignment -- then you will know what the overall FR really looks like. That will allow you to play with the crossover and level of the sub to improve it if necessary. The crossover settings may affect the phase a little; the level should not.

I'm hoping to do that this afternoon.  :thumb:

ooheadsoo

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #77 on: 26 Aug 2020, 07:59 pm »
I may be wrong, but I think the phase adjustment depends on the crossover point.  I'd pick crossover first and adjust phase to maximize the spl within the crossover region.

Mike-48

Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #78 on: 26 Aug 2020, 08:16 pm »
I may be wrong, but I think the phase adjustment depends on the crossover point.  I'd pick crossover first and adjust phase to maximize the spl within the crossover region.

Absolutely true. Unfortunately, it's also a chicken-and-egg thing. You can't see (or hear) how well a crossover frequency is performing until you get the phase right. So I'd suggest starting with a plausible xover point, optimizing the phase, and then making changes as needed.

In my system, changing the xover point a little (from 80 Hz to 65 Hz) made very little difference to the phase setting -- less than the 5-degree resolution my preamp uses to set it. There's no guarantee that's true for everyone, or for larger changes, but made me think that getting the phase right for the current of speaker positions is a good starting point. Then find a crossover frequency you like, then see if the optimal phase setting has changed.

MONKEYWICKEDMONKEY

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Re: 2 subs and oh man I give up....(music 2 channel)
« Reply #79 on: 27 Aug 2020, 12:17 am »
To summarize mine & others' posts, there are three main ways to adjust phase of the subs relative to mains. I've tried all three. All need to be done one channel (R or L + associated sub) at a time.

   
  • Reverse wires so a main is out of phase, then while playing a tone at the crossover frequency, adjust phase for the null (as heard at the main listening position). Less fun, but more accurate. Issues: You need to have a tone available at that specific frequency. And unless your sub has remote control, you need to be in two places at once (at the sub to adjust phase, in the listening chair to hear the null).[/li
Just tried this. Basically listened to where the tone was lowest in volume as I moved the phase knob. Then I left it there. I have to say if I did it right then I’m
Kind of shocked how far off of 0 the phase is.
It never completely cancelled but the volume did dip half or more. Going to leave it here and listen for a while but wanted to confirm I did what was spec’d.