DIY Sub(s) integration with AVR included REW charts

avnewbee

Active Member
Hi All,

I'm after some advise or thoughts....

I've been using my DIY LAB12 subs for a couple of years now and I thought I would order a Minidsp to try and see if I can tune the subs and better integrate them.

my current setup:

Main LCR: Kef Reference 103.2
Rears: JBL Control 1 Pro
Atmos: CA Min22
AVR: Sony STR-DN1080
Subs: 2x DIY Eminence LAB12 Sealed
Sub amp: Behringer NX3000

Don't get me wrong they sound great for movies and provide the extra LFE that I don't get from my mains alone. But....I do find for music I enjoy listening to the Kefs in 2ch stereo (full range - no xo) as opposed to with the subs. my AVR might be to blame as i cant seem to find a mode that allows me to play 2ch plus subs. I have to use one of the surround options or if i play music via the AVR's built in spotify then I can select music mode which works well. But this music mode is not available if i play music from my HTPC or FireTV.

Whilst i'm waiting for the minidsp to arrive i ran some rew sweeps with my UMIK 1 mic to see where i'm at currently with my setup.

Please see image below:

sweep.jpg


From the graph you can see the kefs in 2ch stereo provide almost as much spl if not more than with the subs below 60hz.

The Sony AVR calibration utility has set the subs to +3db and the Behringer nx3000 gain controls are only set to 12oclock. So I know I can manually adjust for much higher spl from the subs but it would be too much for my small man cave.

Which by the way is a basement (converted celler) about 3.8m x 3.5m x 2m high.

I am looking to use the minidsp to help clean up the response and help provide more quality bass as opposed to just boosting and potentially overloading my small room. I'm also wondering if i should put a hi cut in to loose the frequencies below 15hz. or would that drastically affect LFE movie content?

Any thoughts? or am i just messing with something that doesn't really require anything?
 

Conrad

Moderator
The scale is slightly misleading. If you change it to the standard 5dB increments you'll see that the subs are working well <25Hz. The Kefs are going low, sure, but it looks fairly uncontrolled with a big 10dB peak at 40Hz. They drop off under 25Hz and are 6dB down at 10Hz, that's a big difference.

Plus, by sharing the load across the amp and sub amps, and reducing the work the Kef drivers are doing you'll be clearing up the midrange and lowering distortion.
 

avnewbee

Active Member
The scale is slightly misleading. If you change it to the standard 5dB increments you'll see that the subs are working well <25Hz. The Kefs are going low, sure, but it looks fairly uncontrolled with a big 10dB peak at 40Hz. They drop off under 25Hz and are 6dB down at 10Hz, that's a big difference.

Plus, by sharing the load across the amp and sub amps, and reducing the work the Kef drivers are doing you'll be clearing up the midrange and lowering distortion.
Yeah tbh I wasn't sure if the response from the subs was substantial enough considering the time and investment to make them. But I understand what your saying about offloading the load from the mains. Also means I can play them louder with less distortion.

I think the peak at 45hz is a room mode? Particularly as it's there regardless of which speaker is used. I did use an online room mode calculator and it also suggested I would get one at 45hz for my room dimensions.

Hopefully it's something I can smooth out with the minidsp. Aswell as putting in a house curve.

Do you think I should cut off frequencies below 10 or 15hz? Or is there substantial LFE content at those frequencies?
 

Conrad

Moderator
Yeah tbh I wasn't sure if the response from the subs was substantial enough considering the time and investment to make them. But I understand what your saying about offloading the load from the mains. Also means I can play them louder with less distortion.
It only looks like they're not doing much because of that massive room mode. The mains will still be helping below the crossover, but without much effort.

I think the peak at 45hz is a room mode? Particularly as it's there regardless of which speaker is used. I did use an online room mode calculator and it also suggested I would get one at 45hz for my room dimensions.
Yup, it's a mode. It's common in average sized UK rooms to have modes in the 40Hz region.

Hopefully it's something I can smooth out with the minidsp. Aswell as putting in a house curve.
Using REW's time alignment tool will help you manage the integration of the subs with the mains through the crossover region. It's tough when you have a big peak like that which the EQ on the mains doesn't take care of. Will you only be running the subs through the minidsp or the mains as well?

Do you think I should cut off frequencies below 10 or 15hz? Or is there substantial LFE content at those frequencies?
It depends on who you ask. If your subs can cope with content in the low teens then I wouldn't bother. If they start to distort or you're worried about them, add a high pass.

If you're planning on using BEQ then that'll give you a lot more content lower down.
 

avnewbee

Active Member
Will you only be running the subs through the minidsp or the mains as well?
Just the subs through the minidsp. The mains will be through the avr and crossed over at 80hz.

But are you suggesting that I won't be able to smooth out the 40hz room mode because of no eq on the mains? If so any solutions for the mains as my sony avr doesn't have any built in eq settings. Should I xo them higher at 120hz maybe?
 

Conrad

Moderator
All a crossover is is a high pass on the mains, so if you have lumps and bumps and modes on your response before the crossover, they'll still be there on the response when the crossover is applied, but they'll follow the curve. So where a mode might be at +6 on the un-crossed-over response, it'll be at 0 at the -6 point, where it should be at -6.

All it means is you'll have a lot more energy in the 40-50Hz region than you should have, even with the crossover. You'll be able to take it out of the subs, but without EQ it'll still be in the mains. You might have to over EQ the subs to compensate.

It's not not-doable, it just might take you a bit more effort. Crossing higher might help, steeper would be better if you have that option? Does the Sony not have any EQ at all? Even my old STR940 has some basic tone controls.
 

avnewbee

Active Member
so i tried the basic bass/treble eq on the sony and all it did was bring the wide range of bass frequency response down by upto max 10db.

I'll have to see if putting a higher mains crossover in and the combination of using the sony eq will help. might mean alot more of the lower frequency range will be crossed over to the subs than i originally anticipated but if it works and provides an overall improvement in sound then great.

this is a current chart at 5db spl increments of each set of speakers and combined, at the AVR calibrated level.

i do find i enjoy both musc and movie lfe content more by adding a further 10db gain to the subs.

1623106854967.png
 

Conrad

Moderator
It's common to add some boost to the sub from where an auto-eq process sets it. With a minidsp you can add a house curve which allows you to boost on the low end of the sub meaning that you don't overwhelm the midbass and integration, but you get the extra output that you need to perceive the lower frequencies to be the same level as the higher frequencies (due to our ears sensitivity).
 

avnewbee

Active Member
It's common to add some boost to the sub from where an auto-eq process sets it. With a minidsp you can add a house curve which allows you to boost on the low end of the sub meaning that you don't overwhelm the midbass and integration, but you get the extra output that you need to perceive the lower frequencies to be the same level as the higher frequencies (due to our ears sensitivity).
Yeah that's what I was hoping to do.

Failing that I suppose when I upgrade my avr next I'll look for one with Audessy xt32 calibration software. Am I right in thinking that it has a peq that would allow me to iron the room modes?
 

Conrad

Moderator
I think you can brute force PEQs in XT32 with 3rd party software (ratbudyssey) but it should take care of the modes for you anyway.

Alternatively look at something with Dirac and compare the outcomes with XT32.
 

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