The No.1 Website for Pro Audio
Should i consider a sub ? (REW data included)
Old 7th June 2018
  #31
Lives for gear
 
evosilica's Avatar
 

Quote:
Originally Posted by deedeeyeah View Post
true group delay occurs with any system other than a single broadband speaker,
No, it occurs on any speaker - without exception.

(Unless it's a hypothetical speaker that can reach down to DC / 0 Hz.)

Quote:
Originally Posted by deedeeyeah View Post
it's only possible to align (properly) for one frequency and for one position: frequencies below and a above the chosen frequency (all emitted by the sub) cannot be aligned at the same time.
You should only ever allign at the crossover frequency region. Everything else is going to create more problems than it solves.
And most importantily, you cannot get rid of low end group delay by time alligning. FIR filters are the only way to do it. Or designing a speaker that can reach down so low, that it's not an issue in the audible range anymore.
Old 7th June 2018
  #32
Lives for gear
 

Quote:
Originally Posted by evosilica View Post
No, it occurs on any speaker - without exception. (Unless it's a hypothetical speaker that can reach down to DC / 0 Hz.).
correct

Quote:
Originally Posted by evosilica View Post
You should only ever allign at the crossover frequency region. Everything else is going to create more problems than it solves.
And most importantily, you cannot get rid of low end group delay by time alligning. FIR filters are the only way to do it...
i'm not with you on the first part ('create more problems than it solves'), experienced enough and have the tools to do that and know how to use fir filters, but there are other reasons for (sometimes) not using them.
Old 7th June 2018
  #33
Gear Nut
 
Jpastor's Avatar
 

Quote:
Originally Posted by DanDan View Post
When treatment doesn't have any effect, one has to question the diagnosis. Is it the floor which is causing this dip?
I have seen GS claim quite good improvements in the floor dip using absorption, in the form of thick carpet with underlay. Blocking is another approach, or a combination of blocking and absorption. Some console manufacturers provided an otherwise unnecessary back all the way to the floor to block.

IMO when a sub is physically as coincident as possible with the rest of the speakers, I call that a full range speaker system.

DD
Hello DD, yes, like Jens said, the 120hz, is a SBIR form the floor for sure, because i've tried every way i can to put HH in the high pressure points at this frequency around the room, it had no effet, the only time my HH had effect on the dip, was when i put the resonator under the microphone. i'll try to pile up some carpet so see if i have any slight improvement. Although i thought that even thick carpet couldn't do anything on low frequencies, because they have almost not absorption capacity ?

this console doesn't have a back all the way to the floor. i did have great response on the 80/100 hz, when i shoved a bunch of tiny tuned HH under the console all the way against the wall (i treated the 80/100hz dip before the 120hz because these frequencies are more important for me, but now that i get to the 120, nothing will do, so it must be a different cause)
Old 7th June 2018
  #34
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by deedeeyeah View Post
i do sometimes... - hope you got to read the second part of my previous post added later and an additional post addressed to someone else): without mentioning it, it also explains that - although i know and appreciate what adding additional subs can do in terms of the overall eq response of a system - i mostly dislike the consequences in the phase domain.

ciao and over,

dd
What negative effects in regards to phase would a dual sub setup (assuming symetrical as the example in the other thread linked to) suffer from compared to a single sub?
Old 7th June 2018
  #35
Gear Guru
Sure?

May I ask, with total respect, how are you certain the SBIR dip is from the Floor? What test proved that? It is rare to find some problem caused by just one boundary, as all the others are really quite close and are all likely to play a part.
If it is mostly Floor Bounce, the place for your absorbers is on the floor half way between speakers and listener, not around the room. You have quite a big console blocking that floor bounce area. Perhaps the sound is making its way around and under your desk, but I am very doubtful. Could you post an .mdat with L, R, L+R measurements please?
I have noticed a few times people using absorptive traps as speaker stands.
TubeTraps, perhaps SoffiTraps. But interestingly V4 traps. This is simply a pretty massive simple box with long hole, slot, and a sliding strip to adjust the amount of opening, i.e. Helmholtz Frequency.
DD
Old 8th June 2018
  #36
Lives for gear
 

Quote:
Originally Posted by Jens Eklund View Post
What negative effects in regards to phase would a dual sub setup (assuming symetrical as the example in the other thread linked to) suffer from compared to a single sub?
basically 'cause spaced subs create inhomogenous patterns of energy compared to either a single sub or to specifically designed sub arrays.

now how large needs a studio to be for this to become effective, how wide the spacing, what happens with what kind of filters, what effect have traps, boundaries, could this be an advantage, when not etc.? - all very difficult to predict, tricky to measure, even worse to interpret and sometimes impossible to cure.

compared to hf, lf is a different animal imo...
Old 8th June 2018
  #37
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by deedeeyeah View Post
basically 'cause spaced subs create inhomogenous patterns of energy compared to either a single sub or to specifically designed sub arrays.

now how large needs a studio to be for this to become effective, how wide the spacing, what happens with what kind of filters, what effect have traps, boundaries, could this be an advantage, when not etc.? - all very difficult to predict, tricky to measure, even worse to interpret and sometimes impossible to cure.

compared to hf, lf is a different animal imo...
Two identical sources placed symmetrically in a symmetrical space will not cause any problem, quite the opposite, again;

Add a sub instead of even more bass trapping to even out freq response?

if not, everyone would use 2.1 systems instead of full range speakers …

Can I use a consumer grade home theatre sub for a music production/mixing in studio?
Old 8th June 2018
  #38
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by Jpastor View Post
Hello DD, yes, like Jens said, the 120hz, is a SBIR form the floor for sure, because i've tried every way i can to put HH in the high pressure points at this frequency around the room, it had no effet, the only time my HH had effect on the dip, was when i put the resonator under the microphone. i'll try to pile up some carpet so see if i have any slight improvement. Although i thought that even thick carpet couldn't do anything on low frequencies, because they have almost not absorption capacity ?

this console doesn't have a back all the way to the floor. i did have great response on the 80/100 hz, when i shoved a bunch of tiny tuned HH under the console all the way against the wall (i treated the 80/100hz dip before the 120hz because these frequencies are more important for me, but now that i get to the 120, nothing will do, so it must be a different cause)
I can only speak based on my own experience, but every time I´ve helped clients with existing rooms who’s looking for an “easy” improvement to their situation; installing two subs and a DSP (in order to be able to X-over freely, signal align and apply correction if needed) has always resulted in major improvement, especially in the troublesome 100-150 Hz range since there is almost always a dip in this range due to the floor bounce if using only mains (and actually often a bigger problem in well treated rooms since the only reflection vector left to interfere with the direct sound is the one related to the floor since this surface is seldom treated).

But I must stress that just because you have a dip in this range, it´s not the only possible cause. Modal nulls or SBIR related to other surfaces, due to inefficient treatment on related surfaces, might also be an issue. However, if properly treated; the floor bounce is pretty much the only possible cause.

If there´s a very large desk, it might “block” this reflection somewhat, but most of it will still diffract around this relatively small object compared to wavelength. But even if so; a large desk opens another can of worms so …
Old 8th June 2018
  #39
Moderator
 
Northward's Avatar
Quote:
Originally Posted by deedeeyeah View Post
i do sometimes... - hope you got to read the second part of my previous post added later and an additional post addressed to someone else): without mentioning it, it also explains that - although i know and appreciate what adding additional subs can do in terms of the overall eq response of a system - i mostly dislike the consequences in the phase domain.

ciao and over,

dd
The consequences in the Phase domain are negligible (a few degrees) to non-existent unless there is something wrong with the way you setup your system.

We basically only do dual subs systems. No DSP. Perfectly well aligned.

Mains aren't filtered though. Subs are added to full range signal, 70Hz down.
Attached Thumbnails
Should i consider a sub ? (REW data included)-20180411_200558.jpg  
Old 8th June 2018
  #40
Lives for gear
 
Jens Eklund's Avatar
I´ve never seen an Augspurger install with only one sub either:

https://www.google.se/search?q=augsp...w=1280&bih=800
Old 8th June 2018
  #41
Lives for gear
 

Quote:
Originally Posted by Northward View Post
The consequences in the Phase domain are negligible (a few degrees) to non-existent unless there is something wrong with the way you setup your system.

We basically only do dual subs systems. No DSP. Perfectly well aligned.

Mains aren't filtered though. Subs are added to full range signal, 70Hz down.
looking (and sure sounding) great!

get back to you...
Old 8th June 2018
  #42
Lives for gear
 

Quote:
Originally Posted by Jens Eklund View Post
I´ve never seen an Augspurger install with only one sub either:

https://www.google.se/search?q=augsp...w=1280&bih=800
i was referring to a sub array using two subs in an endfire setup that is getting associated with augspurger (for some reason i dunno)
Old 8th June 2018
  #43
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by deedeeyeah View Post
i was referring to a sub array using two subs in an endfire setup that is getting associated with augspurger (for some reason i dunno)
Not sure what you’re referring to, but my argument (that you seem to be disagreeing with, or am I wrong here?) is that there is no downside in using two subs (assuming symmetrical setup and normal subs as normally used in studios) compared to only one. Quite the opposite; there are upsides as shown in the other thread.
Old 8th June 2018
  #44
Moderator
 
Northward's Avatar
Quote:
Originally Posted by deedeeyeah View Post
looking (and sure sounding) great!

get back to you...
Well, I should mention that being able to work so closely with the engineers at ATC is very helpful in getting a system properly integrated so finely.

So lots of the credit goes to them and their incredible skills.
Old 8th June 2018
  #45
Gear Guru
Lovely

Jpastor.......LOL, in Gaelic JP a stór, would translate as JP darling.....

You can do this with sweeps and movement, but just to illustrate the other way.....
Fire up the Generator in REW Pink PN. Also the RTA or Spectrum, which shows the null better. Zoom and tweak to get a good clear dip. Now move the mic. If you can get the frequency of that null to shift upwards, you are probably moving towards the offending reflection.

DD
Old 8th June 2018
  #46
Gear Nut
 
Jpastor's Avatar
 

Quote:
Originally Posted by DanDan View Post
Jpastor.......LOL, in Gaelic JP a stór, would translate as JP darling.....

You can do this with sweeps and movement, but just to illustrate the other way.....
Fire up the Generator in REW Pink PN. Also the RTA or Spectrum, which shows the null better. Zoom and tweak to get a good clear dip. Now move the mic. If you can get the frequency of that null to shift upwards, you are probably moving towards the offending reflection.

DD

Hey DD, i'll do that this week end, i'm just done recapping all the psu's of the console, i'm going to get back to this 120hz and the subs now.


Quote:
Originally Posted by Northward View Post
Well, I should mention that being able to work so closely with the engineers at ATC is very helpful in getting a system properly integrated so finely.

So lots of the credit goes to them and their incredible skills.


Northward, i'm wondering, if it's not to indiscrete, are you from/in Belgium ?
Old 9th June 2018
  #47
Moderator
 
Northward's Avatar
Quote:
Originally Posted by Jpastor View Post
Northward, i'm wondering, if it's not to indiscrete, are you from/in Belgium ?
Based in Brussels. But working all over the place.
Old 9th June 2018
  #48
Lives for gear
 

Quote:
Originally Posted by Jens Eklund View Post
Not sure what you’re referring to, but my argument (that you seem to be disagreeing with, or am I wrong here?) is that there is no downside in using two subs (assuming symmetrical setup and normal subs as normally used in studios) compared to only one. Quite the opposite; there are upsides as shown in the other thread.
maybe confusion in threads, but yes, the dis-/advantages is what we seem to come from different sides.

Quote:
Originally Posted by Northward View Post
The consequences in the Phase domain are negligible (a few degrees) to non-existent unless there is something wrong with the way you setup your system.

We basically only do dual subs systems. No DSP. Perfectly well aligned.

Mains aren't filtered though. Subs are added to full range signal, 70Hz down.
the average gs's rooms cannot keep up with your (very well designed) rooms! many cannot even afford (multiple) sub(s) i assume...




ANYWAY - to both of you, maybe dan and whoever else may join us here:

in large HALLS, there is a 'huge problem' with spaced subs/multiple subs unless they get arrayed properly - in ROOMS, there is 'no problem'.

i assume we can all agree on that? if not, i'm out: i am very experienced in setting up, measuring, correcting large systems in live sound, far less in (mostly small) studios - if so:

how small/large needs a room/hall to be in order for this to become effective? longer than the wavelength of the lowest frequencies? or where's the 'threshold'? what other factors besides differences in spl levels, area to cover, damping/absorption/diffusion?

anybody with lots of/equal experience in both fields?

Last edited by deedeeyeah; 9th June 2018 at 11:25 AM.. Reason: typo
Old 9th June 2018
  #49
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by deedeeyeah View Post
ANYWAY - to both of you and whoever else may join us here:

in large HALLS, there is a 'huge problem' with spaced subs/multiple subs unless they get arrayed properly - in ROOMS, there is 'no problem'.
Well that's another story.

I thought we were discussing studio control rooms ...
Old 9th June 2018
  #50
Lives for gear
 

Quote:
Originally Posted by Jens Eklund View Post
Well that's another story.

I thought we were discussing studio control rooms ...
i get to setup temporary control rooms (with various amounts of 'control') in ball rooms, barns, castles, churches, hotels etc. every now and then: these places range from somewhere close to a control rooms to almost entirely being live venues, from small to large, heavily dampend/dry to very boomy/reverberant - hence my comments and questions....
Old 9th June 2018
  #51
Gear Guru
Topic

Hi ddy. I started as a Live Mixer, developed into Studios, then into Acoustics. So whaddyawannaknow!

PA systems in Halls try to deliver a reasonably similar sound to a large number of people. Has to be Mono then but.....
With hanging systems, line arrays, DSP, we might assuming things are improving, but I haven't heard proper bass at big gigs.
Also Delay stacks can only be aligned for small numbers of audiences, so really, does this actually work?
These comments suggest that all the speakers need to be together either stacked or hung. If multiple full range sources are necessary, then they need to address their own area. No coupling.
Studio CR is kinda the opposite, it's all about coupling and imaging perfectly, but luckily in a relatively small area.
LF sources can be beneficially (mis-) located to address modes and SBIR but ultimately most of us simply prefer them in coherent stacks.


I am curious as to whether there is a dominant floor bounce at play here.
Instinctively and with some experience, I would add LF without Xover. But if the subs are trying for the Floor bounce obviously it is vital to remove LF from the elevated woofer. Seems a waste of a speaker but easily tried if a Sub is brought in. Also if the floor bounce is confirmed, then there are the reported successes with large areas of thick carpet and underlay. Perhaps blocking. A hard back behind that desk, or a blocking wall underneath, plus absorption. I would be quite hopeful. But ultimately that LF roll off is troubling.
DD

Last edited by DanDan; 9th June 2018 at 04:09 PM..
Old 9th June 2018
  #52
Gear Nut
 
Jpastor's Avatar
 

Quote:
Originally Posted by Northward View Post
Based in Brussels. But working all over the place.
Cool, we have friends in common from Brussel then, i could tell from the picture you posted
Old 12th November 2018
  #53
Gear Nut
 
Jpastor's Avatar
 

Hey guys what's up ? i've been working yesterday on this 120hz dip, i've raised the speakers a bit more, fiddled here and there, got a really flat FR (ecept the 120 dip) between 45 and 300. All sounds good right ? well actually no, i've got a bit of a problem.

I've been working professionally as a music producer / mixer for 10 years now. i've my actual job and passion, and i can say that i trust my ears 100%, especially for analysing resonances and unpleasant sounds. Now here is the problem, my FR is flat in REW, but it doesn't sound flat at all with my ears. When i slowly sweep a sine, from 40hz to 1800hz, i hear resonnance between 150 and 330, then also at 800 etc... it makes the sounds really harsh and un-natural. As a test, i decided to do a little EQ on my studer 903, killing 3 resonances : result was magic, really sounded natural, round. I could hear my reference tracks perfectly (and of course whenever i would switch the EQ off, it sounded even worse than before).

i thought i may have a problem in the chain of recording, i tried a different mic, but everything seems to work normally. When i do a REW measurement with the correcting EQ on, it shows a FR not flat at all, but it sounds so much better. i'm almost wondering if my Focal twin 6 don't have a problem.

The treatment in my room really killed the decay, i think my waterfall graph and spectrograms are good. When i put the test EQ, i just lower the volume at the resonant frequency i detect with my ears when i sweep manually the sine.



What drives me insane is that my flat FR response sounds worse than when i do the EQ correction, and i can garanty it really sounds better with all my reference track, which i know by heart and have heard countless times. Am i insance or what ? anything that could cause that ?
Old 12th November 2018
  #54
Lives for gear
Flat is not the most important thing.

Can you post your last measurements?

What's going on here? "Flat response" sounds terrible!
Old 12th November 2018
  #55
Gear Nut
 
Jpastor's Avatar
 

ye i read that topic already. I don't think it's the same problem here, cause the FR curve after tuning looks really crippled, not just a slight slope. i've uploaded the 2 mdat right there :
Dropbox - with and without tning.mdat
Old 12th November 2018
  #56
Gear Nut
 
Jpastor's Avatar
 

i've just done more test :
- going manually from 30 hz to 3kHz
- listenning for each resonnance,
- correcting them as smoothly as possible with a basic equalizer.

i've to say my room is fully treted, i'm well aware you cannot correct acoustical problems with softwares, and as you've seen in this thread (and i've got another building thread) i've done a lot in term of speaker placement and absorption (the room is a full shell, 50 cm thick back wall, 70 cm deep super chunks in the corners, HH resonators to treat energy points in the room etc...).
Maybe i just don't like the sound of the Focals ? what kind of bothers me and my OCDness, is the fact that it's like REW doesn't hear the resonance the same as me. Is it because is measuring amplitude and not power ?

here is attached the quick EQ i did. Should i consider a DSP to fin tune the speakers like that ? actually i don't feel the need for a sub anymore with these resonance removed.
Attached Thumbnails
Should i consider a sub ? (REW data included)-capture-d-ecran-2018-11-12-14.40.15.png  
Old 15th November 2018
  #57
Gear Nut
 
Jpastor's Avatar
 

little update on that, i've bought a high end dsp (XTA DP 226), to do subtle eq on the speakers, i've listenned to hundreds of tracks i know by heart, and it all sounds exactly spot on, everywhere in the room. On the other thread, someone mentionned that maybe one of the driver on the focal was damaged and out of phase. i'm doing diffusors for the back wall now.
i've got to say, this dsp is a game changer, the difference may be quite subtle for normal people (my wife / friends) but it is giant for me. I do have to say again, my room is treated to death, it is basically a giant basstrap, but this last tuning was the icing on the cake.

still i find it odd that the REW curve is better with the resonance, maybe my old beat up cheap ECM800 isn't up for the task anymore, i'll check with another measurement mic.

edit : i've been reading a lot about house curves and such, i guess my fr was too flat and i was having this phenomenon of "harshness" in the mid and the high. Once i read "Northward" saying that FR was only a part of the game, and it's true. Basically what i did with my eq if tune the speaker for a softer house curve type FR, and now it really sounds amazing.
thanks to everyone who helped me.
📝 Reply
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
🖨️ Show Printable Version
✉️ Email this Page
🔍 Search thread
🎙️ View mentioned gear
Forum Jump
Forum Jump