Question about subwoofer upgrade

SteffMarinov

Active Member
That 140-160Hz dip is quite narrow so I doubt it's too audible.
Those subs look like they're running very hot though, that looks to be about 20dB?

Yes I thought (and heard) the same so I’ve corrected the house curve this afternoon to be closer to 10 dB. Couldn’t do much listening today but will check it out tomorrow.

I think in the next couple of weeks, if my neighbours don’t shoot me, I will experiment a little with trying to extend the subwoofer to about 120 to see if it’s gonna cover some of that dip, and also with individual subwoofer EQ before blending them and do another final EQ. Reason being, there’s still a good variance of the response, there’s one place in the room (about 7-8 feet forward and to the left) where the bass is like 7-8 dB louder… wasted energy and extra annoyance for the neighbours below.
 

Conrad

Moderator
Be careful chasing smooth bass throughout the room, it's not possible. There'll be peaks and nulls through the room and correcting them in one place will cause them in another.

Those variances will only be at specific frequencies so a peak at one frequency will have nulls at another. Unless you're going to EQ for your neighbours seats there's not much you can do.
 

SteffMarinov

Active Member
Fair points. I try to tune it for myself and just have in mind how does it sound throughout the room to know what volume I can listen to late at night, wouldn’t wanna have it ok at MLP and blasting a couple of metres away killing the neighbours at 11pm, that’s my motivation behind it.

Now the rabbit hole gets deeper unfortunately…
I’ve found in the last few days that:
If I do a steep house curve, with say 10db slope, I find it that the bass is tighter but I tend to feel I need to turn it down, which leads to the 60-100 Hz region looking quieter on the graph compared to the 100-500.
If I do a flat tune I get some mud which is probably due to the 45, 57 and 72hz triggering the room resonants
If I do the 30Hz - 100hz volume compare and base the house curve on that, I need to turn up the low range a lot and again it becomes overpowering…
It does tighten up a little if I roll off the subs at 15hz but at the moment it seems that whatever I do, I can’t really get it right… don’t get me wrong, it doesn’t sound bad by any means, I just know that theoretically it can sound great. I’m getting lost!
 

SteffMarinov

Active Member
At the moment I have it at
15-27hz at 72db sloping down to 100-500hz - 65db so about a 7db difference… am I missing something very obvious?
cant upload a screenshot at the moment but will get one tomorrow.
 

SteffMarinov

Active Member
Ok so here's a shot from today. Null problems aside, the difference between the subs' peak and the rest of the graph is about 10dB here.

May 21st S+M.jpg



However when I measure levels from the processor subs measure 20dB hotter than the rest??? Then if I have to turn them down, that messes up with the down slope which would meet the mains about 7-8 dB quieter at the XO point whereas now it slopes down. What am I doing wrong?
 

Conrad

Moderator
Yeah, it's tough. See my post here: Lyngdorf MP-40

If you look at the waterfall for your response you'll see there's lots of long decay times below ~50Hz. This leads to a bit of boominess and can give the impression of sluggish bass. It's the reason behind the myth that large subs are slow, because they can hit the frequencies that take a long time to decay that small subs can't. As you've seen, stick a HPF on the sub and you get all that speed and clarity back.

I would suggest changing your response a little. With REW EQ the response flat and confirm that.
Then, in the minidsp, add a filter: Low shelf, 30Hz, +6 gain, 0.5Q. That'll give you a nice rise in house curve that you can adjust. If you want it to cover more of the range, increase the frequency. If you want more low end, add gain (obviously don't go nuts or you'll run into the sub's limits).

That way you can adjust to taste without having to regenerate and reapply REW's eq.

Running a house curve from >100Hz is a LOT of bass. You're basically just turning the sub up by 10dB.

As for your levels difference, you'll be measuring the subs on the LFE channel. The LFE channel runs 10dB hotter than the mains channel. If your subs on the main channels are +10dB then they'll be +20 on the LFE.
 

SteffMarinov

Active Member
Great - thanks for all info and advice!

Here's the results, is that how it's supposed to look like?
That's as flat as I can get them
SUBS FLAT.jpg

Low shelf at 30 Hz:
SUBS LS 30Hz.jpg

Low shelf at 20Hz:
SUBS LS 20Hz.jpg

With the L+R:
SUBS+MAINS.jpg

I'm not 100% sure what to take for the mains' average because of those massive peaks and dips in the upper bass... But at least now the subs are a lot tidier and easier to change the curve, once again thanks for such a useful advice!

Edit: Crossover is at 100Hz here.
 

SteffMarinov

Active Member
I’ve just lowered them with 10dB from the minidsp so I can turn them up in the processor if I want to, it’s a lot easier
 

Conrad

Moderator
Maybe raise the frequency to 40Hz.
You can model it in REW or the minidsp to see what you're doing, just put it on a config that has no other EQ. The frequency is the centre point of the slope, so in this case it'll be +3dB.

If you can measure the mains (L, C, R, separately) without the sub, and the sub on the L channel (turn off the amp or disconnect the speaker), all with a timing reference, you can adjust the delays on the sub to improve the integration. If you can take those measurements and post your MDAT I can try and take a look.
 

SteffMarinov

Active Member
That’s awesome, thanks a lot again!

I will check the subs to mains integration although at the moment there’s just a very tiny dip at 100Hz, or do you think it might be affecting higher? That massive dip is there on both mains measured independently, it’s just room boundary interference (I think), and each speaker looks a bit flatter on its own. I’ll work a bit more on it tomorrow.
 

Conrad

Moderator
You might be able to smooth that dip with timing.

How large is your room? I’m surprised dual
15s aren’t hitting low teens.
 

SteffMarinov

Active Member
You might be able to smooth that dip with timing.

How large is your room? I’m surprised dual
15s aren’t hitting low teens.
Oh they are but I’ve put a high pass at 18Hz here. The room is about 4m x 6.5m I think.
 

SteffMarinov

Active Member
I usually have a noticeable bump at 11 Hz
 

Conrad

Moderator
Ok. That makes sense. Has that tightened up the rest of the sub range?
 

SteffMarinov

Active Member
Ok. That makes sense. Has that tightened up the rest of the sub range?
It did so a little with the EQ I had before - I’ll watch a bit like that and bring it down to 12-10Hz to see if it makes any difference.
 

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