Hey Jens,

thanks for the response. With one sub I was thinking about putting two GIK Monster Bass Traps in the front corners (against the side walls as the offset window makes placing stuff a bit complicated in the right corner). Do you think I could cut that down to two 244-absorbers or the like if I add a second sub?
I do have the obvious SBIR-dips in the 80Hz region. So I'd have to cross over above that. Should I place the subs at 1/4 and 3/4 to cancel SBIR-dips on the subs or is this "taken care of" by the coupling of the subs?
And how about the 0.0.1 at 68Hz which is also my 2.0.0? Do you think it would be sufficient to put two Monster Bass Traps on the ceiling against the front wall above the speakers and another two at the back wall against the ceiling?

OT: Any ideas how I could even out L-R-ballance in the 200-300 Hz region (right side has window, left side concrete wall...)?

Cheers, Peer

I don´t see a reason to cut back on treatment. Treat as much area with as thick treatment as possible (to a sane limit naturally, but 0,5-0,6 m is not overkill, at least not for rear wall. 0,3 -0,4 m might be enough for sidewalls).

If ready made products are too expensive to do the job; build it yourself. It´s not rocket science, especially if not pressure based absorbers but just broadband velocity based absorbers.

As for the other questions, you really need to experiment and measure to know for sure.

Hey jens those visualizations in the link look great, i was wondering what you used to make them?

https://www.falstad.com/ripple/

Thank you.

Hey guys,

I have an issue that I think is probably related to this thread.

My room is 6m wide by 4.25m deep. I have 3 windows spaced equally along one of the long sides. My desk and speakers and located at that side of the room, shooting back towards the other long side of the room. I was recommended this setup by a pro acoustician, because although it goes against the “aim speakers down the length of the room” theory, the concern was a lack of symmetry due to the windows.

Anyway, I digress.

The room is moderately treated. It is both a writing/tracking and “rough” mixing room, so the sound doesn’t want to be completely dead, but as free of anyone frequency dips as possible. I have corner bass traps floor to ceiling in each corner of the room. Deep absorbers directly behind the two speakers, bass traps on the back wall, 12 absorbers on the ceiling, absorbers and diffusers on the side walls. So it’s pretty well treated but not scientifically nailed down. All GIK stuff.

It is also a wood floor (on top of concrete).

Only other thing to mention is that the computer monitor is directly between the two speakers, about 2 feet behind the computer monitor there is a window.

I have been working in my room now for 9 months using Genelec 8341 speakers, and although it sounds decent, I do find that I’m lacking clarity in the bass end. Plenty of thud but not much note, if that makes sense. I have used the GLM software but it’s making it all sound a bit lifeless.

So I’m wondering if I should be focusing my attention on:

1) different speakers. The Genelecs get rave reviews pretty much everywhere you read, but I’m not convinced they’re working in my room.

2) adding a Genelec sub / subs to help bring back some of those low frequencies.

3) more room treatment. The only areas I could realistically focus on without completely butchering my room would be the “soffits”. Currently they are just right angles, so some bass traps could potentially go in there. Other options for treatment could be the floor (more rugs) and also the window behind the computer monitor (possible first reflection point?) which I could potentially cover with a deep / bass absorber.

Would love to get some opinions on what people think would be the best route forward for me?

Thanks in advance!

I have some treatment in place now - nowhere near as much as you would want in a single use mixing room, but a compromise that seems to make sense for my room. Pictures and measurements are here. There are two Tri Traps against the back wall / ceiling that are not in the picture.

With this data, do you think a second sub would be good? The single sub seems to perform worse then the O110s between 50 and 200Hz, but the 0-1-0-mode is not the main issue. I put the tops on the floor at 1/4 and 3/4 from the side wall to have a quick impression, but got severe dips similar to the centered single sub.

Cheers, Peer

GLM aims for flat which can make things a bit boring. However, you can have GLM use a "house curve" (not the house music) to bring up the bass somewhat.

Or manually reduce any attenuation in the bass by 1-2 dB.

With GLM, you can save and recall any settings so play with a few.

The "thud but not much note" bass is probably a combination of holes in the bass + slow decay.

Can you measure your room and post the Room EQ Wizard .mdat?

Hi guys !


So guys, maybe some of you could chime in with some advice.

We have treated our room with my quite modest knowledge I gathered by reading this and other boards for years, and after we set everything up we decided to go with dual subs. The weakest point of the room is that we didn't have space due to the heating system in the building to put more than 8'' traping on the backwall, sidewalls in the front half of the room are treated with 12'' traps floor to ceiling, celing is treated with 12'' traps completely, sidewalls on the back half of the room are 8'' bass traps, covered by slats in binnary sequence, and we made a pair QRD diffusers installed in the backwall, also front corners have 24'' deep superchunks.

We got PSI A21m 8'' monitors, and after some playing, testing etc we got two SVS SB1000 12'' sealed subwoofers with variable phase knob on them, I read that Carl Tatz recommends subs with variable phase for the best possible result.

We got pretty flat response in the room with PSI's only, but the low end while being flat-ish, was kinda diminsihed, I guess it's because of thin walls and the fact that the right side of the room was all windows that we sealed.

I was lifting the low shelf up on the RME UFX+ EQ main out, and while that was doing ok results, it was compromising the speakers headroom thus giving us more THD in lows like bellow 100hz while playing loud, and we are doing bass heavy music, and of course everyone wants to hear it as loud as possible, we couldn't do that with 170W speakers and compromised headroom, for example the sub-bass on the song Mask Off by Future was falling appart very quickly as we were turning up the volume, on the other hand, Bruno Mars - 24K magic and all of well balanced pop music sounded clean as it can be even close to clipping.

We don't have any dedicated DSP device, I calibrated both speakers and subs to 75db on C weighting SPL meter and I'm high passing the PSI's from RME's Total Mix EQ @ 60hz 24db/oct, I'm still experimentig with the LPF crossover on the subs integrated LPF, because I don't have db/oct control on RME's EQ LP Filter, I just have the Q for LPF, and even we got SB1000's because of their variable phase, for now they sound the best with the phase intact. The subs are running in stereo and are front corner loaded, I would try to place them 1/4 and 3/4 width of the room, but PSI's are mounted on big stands touching the front wall and there's no space for subs to be placed there, and I wouldn't like to loose "good" PSI only response...

While I understand FR graphs, and kinda understand waterfalls and spectograms, I don't really understand phase and GD graphs...

High end should be ignored, first of all it's measured with both speakers in the same time for comparasion (how else could I measure what both subs are doing?), I guess that's why this phase trickery is going on in the PSI only phase response, second I most definitely didn't take measures with the mic put in the exact center between speakers, I didn't use any precise tools, so every sweep I did was showing different high end response, and third it's ECM8000 with generic calibration file... Also I kept the Air Conditioner on, because it's hell of a hot in here....

So, I'm pretty satisfied with the FR with subs, I would just want to fill that hole around @130hz a bit more if possible, at least a db of two, without using EQ for that. The only EQ move, beside HPF and LPF obviously, is knocking out a nasty mod @25hz on subs.

So red is PSI only, Green PSI + Subs.

Thanks

If you're worried about the delay in the low end, you might try out FIR Designer as I think it can correct that and give you flat(ter) phase.

Hi Johan!

I would if I understood what I am looking at and what should I listen for. ������������������

Seems that I shown results with 1/6 oct smoothing for "+ subs" setup, I'll correct that tomorrow.

But seems to me that A21ms only (red) Gd graph is worse than A21m+Subs (green) Gd graph, how's that possible?

Doesn't look that way to me. Phase is flatter, isn't it?

BTW: Don't forget that low distortion in the low end is important, too.

How's that ? What's I'm mising out on this GD graph ? I see on the red that it has that swing to -200ms @20hz, and the rest of the graph is kinda the same, with this over 50ms figure @25hz falling to zero until 100hz on both of them ? Is that swing desirable so you say it's better, what am I missing ?

Why not run the subs in mono and try readjusting the phase.

I don’t think that they will do the multi-sub magic mode cancellation thing if they aren’t receiving the same information.

Also, you can do 1/4 wavelength from any boundary or multiple boundaries. You can also try them in opposite corners, and centered on opposite walls.

https://www.gikacoustics.com/room-se...wo-subwoofers/

Was thinking about that, will give it a shot tomorrow ! Thanks

I learned a lot from this thread. Thank you! It shifted my approach to dealing with the low end of my room. With just one sub my results are so much better than I could have achieved without a sub. I could perhaps get even better results with more subs but one has taken me a long way already:
Genelec 8351 - Anyone else using these?

Figured I would add this, even though it’s probably already been said.


Delay is so important for multiple subs.

Unless you can position your subs so that they are exactly the same distance from your ears then you will get a huge suck out at the crossover frequency.

DSP or very slow and careful adjustment of position is essential.

What about the group delay when using multiple subs (say 2 in the front or even 4)?
Doesn‘t it increase tremendously?

Depends on how far away they are. If all the drivers are exactly the same distance from your ears then no delay should be necessary, but what are the chances that that’s the spot where they will have the best response?

One really irritating thing about using high delay is if you do any composition (Especially with software instruments) you can’t monitor through your mains. Also if there is a sync issue with any video you’re watching it can make the problem worse or cover up a problem that otherwise would have been evident.

Humans allegedly can compensate for 20ms of delay without impacting musicality too much.

I’m just learning about this stuff.

Imo if one treats his/her room well enough with a sufficient amount of porous absorbents, I really do not see any need for multiple subs. And it‘s even a lot cheaper. All the space needed for multiple subwoofer arrangements (like 4 at the front and 4 at the rear wall) could be used more efficiently by entire front or rear wall treatment. Which then helps with higher frequencies, too, which the subs do not affect anymore.

In a small room you would need to treat 2ft-3ft all around to deal with SBIR.
And then you have to figure out how to bring back some life into space so its not anechoic. And on top of that depending on ratios you still may need some EQ to bring down modal peaks.

How many people with home studios do you think are willing to go to those lengths? You literally might end up in a space that only one person can maneuver in.

So if you can't go to those lengths what can you do? Multisubwoofer use is just another option to help deal with Nulls created by SBIR which are always present in a control room with speakers on stands

Would this still work with a cardioid sub such as the Me Geithain Basis range?

https://www.me-geithain.de/en/aktiv-subwoofer.html

Also with regards the DSP is it mostly just for time alignment?

I've got a Crookwood monitor control with bass management so it does my crossover in there which I can adjust and I can mute and even solo the sub from the controller so I'd like to be able to keep this functionality.
Obviously it sends the subs and speakers to their own output. Is it possible to just run these outputs into the DSP to align them or is there more to it?

I noticed the Danley DSP is 4 in 8 out so I'm hoping the answer is yes.
A friend of mine works very closely with Danley, so I'm fairly sure they will have one I can borrow to test it out.
I thought I'd ask first though in case it's not even worth trying.

how the hell did you cross over and positioned them?

Carefully?

Most people recommend taping a grid on the floor, labeling each position, and measuring each sub at each location. Can also be extended into 3 dimensions with spacers.

When using multiple subs it may be useful to measure 1 sub and then 2 subs together and fine tuning with all subs and monitors running full range.

Figuring out what order to do DSP is hard. I’ve heard crossover -> EQ -> Delay.

Although intuitively it seems like it would be best to do delay first, I will leave that to someone more familiar with the subject.

delay comes last as filters affect phase - and you don't necessarily need a grid if you have a basic understanding of the nodes and how multiples subs interact in terms of phase...

Thanks! I needed a grid, because my walls are not all the same materials so REW predictions didn't end up being all that accurate.

If your room is completely soundproof and rectangular then a calculator should do it!

Say you have that room with 3ft all around and are placing subwoofers...

Would you negate the benefits of modal control by placing the sub in front of a wall of treatment?

When placing a dual side-firing subwoofer on a wall, how much insulation would you need to carve out to make room for it?

How important is line of sight? In other words, is it an issue to fire your sub though an absorber if the absorber doesn't absorb that low (should pass straight through eh?)

What would be a good, transparent DSP for 4 subwoofers + 2 mains? I want to do the setup that SteveGTR suggested and be able to adjust it with the DSP. I guess it would need at least 6 outputs.

I'm looking for something in the $600-$1500 range.

Some brands won't work for me: Trinnov would be great but it is very expensive for my budget. Same with Danley. MiniDSP has bad reputation because there seems to be a "hiss" in some units, randomly, the only unit that would work is MiniDSP SHD and it only has 4 outputs. And Behringer, according with this thread, sounds not very good.

EDIT: In case this may help someone, I decided to buy a DBX Driverack VENU360. Although newer units seem to have some problems in the DAC (according to a review in audiosciencereview), if the used input is the analog it works nicely. The reasons to choose this unit is that it seems superior to the Behringer and MinDSP, and it has an auto-eq, let's see if it works with this setup (or better said, if I'm able to configure it!).

To the point: Will adding two subs help with decay times at all? (in reference to the attatched waterfall graph/MDAT)


My room is getting close to the point of being ready for a sub or two.

Some or most of you may have already seen my thread Pseudo soffit mount for monitors - questions

Being a Bass Head, I am okay with the bump in the low end that shows in the graph below - I can always tame that down with the correction, or at least thats in the tentative plan. When I mix, I tend to over-do it with the low end even still with these readings.

With all the trapping I've done so far, I'm curious what can be done in terms of improving low end a bit more. Particularly what can be referenced to in the waterfall graph regarding decay times.

I would think that more energy would make decay times worse, but the idea of two subs is to have one phase cancel the modes? This will of course positively affect frequency response, but what about ringing/decay

Utilizing Trinnov to integrate the subs is also in the plan FYI

I read this long thread two times, this is very interesting. There is something I don't think was discussed, or I missed it:
Does using subwoofers also help when the listening position is too close to the centre in a small room (which results in a lack of low frequencies)?