Here is why you may want a pair of subs in your studio

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Stumbled on this a while ago, it was written by Carl Tatz for sound on sound. If you've ever measured the frequency response of your room, its very likely that you'll have encountered this deep null (often around 100hz-150hz). Its without doubt one of the biggest hurdles to overcome when working in "normal" rooms, and with nearfield/midfield monitors. It's not uncommon for some people to have nulls of more than 20dB at these frequencies.

https://carltatzdesign.com/downloads/elephant-room-article.pdf

Its obviously really important to have room treatment, and to really spend time optimising the position of your monitors (and subs) and listening position. I love sonarworks too, and the advice in this article has helped me smooth out my low end response (at listening position) a lot.
 
I might give Sonarworks a shot soon. I’ve been playing around with the placement of my sub and it’’s not a reference sub to begin with, but one from a random entertainment system. Where I had it originally I could just roll my chair back a foot and it was perfect, so I tried sticking it elsewhere so I wouldn’t have to roll back and I couldn’t hear it anymore, moved it to another spot and could hear bass building up along a wall, blah blah…

I think I’m just going to get bigger monitors to not have to utilize a sub at all.
 
The method you described is pretty good practice - to move around and adjust until it sounds and feels right. If you use a measurement mic, it can be even easier - you just leave the measurement mic in your listening position and move things around and measure and you can see exactly what’s going on. Better subs have adjustable crossovers and phase so you can pair them nicely with your existing monitors.

I think I’m just going to get bigger monitors to not have to utilize a sub at all.

The article I linked above basically explains why this is not a good way to go - it‘a likely much better for your low end to not rely on just bigger monitors - they’ll be subject to the same cancellations in the room as each other, so a lot of the extra low end the monitors is making will get cancelled out by room modes.

If you have a sub (or better, pair of subs), they can be positioned in a way that reduces the big dip the room will inevitably cause. Lots of high end monitoring systems are moving this way - check out how the likes of Kii, Amphion, Barefoot etc do things. Or often even popular 3 way systems like Neumann KH310 or ATC’s have high quality subs that can be positioned to suit the room they’re in.

Would totally recommend Sonarworks, and also Room EQ Wizard which is free. Even just to get a sense of what’s going on in your room and having a way of being able to move things and reliably tell if it’s better or worse or not is so valuable. Corrective EQ like this won’t fix cancellations in the room though, but I absolutely love how it helps and many many professional rooms these days are using some kind of EQ to improve the rooms performance.
 
In order to tune room acoustics at ~125 Hz using subwoofers, I assume he's implementing crossovers at ~150 Hz? Subwoofer crossovers >80 Hz create additional limitations since it introduces the potential of localization away from the main sound source. I'm guessing that's why he prescribes front-corner placement... and this limited choice in subwoofer placement location means you'd be limited in your ability to solve the stated issue of a dip at ~125 Hz... which means you need acoustic treatment.
 
Carl explains it better, but the biggest dips are from axial modes and many of the dimensions being multiples of themselves. Like speaker (and listening) height being around half of the ceiling height, listening position usually being centred. Around 100-120 is where several of these are multiples and interact with each other. Soffit mounting helps, but for most people there will be nearfields and/or midfields on stands. Even well designed rooms will have this issue to some degree, but they’ll try and reduce it from being too deep, and it seems usually at lower frequencies. I have corner traps, lots of bass traps around the room and a thick ceiling cloud but the positioning of the speakers is still critical to getting the best response.

This guy has designed and built some of the best studios on the planet, and the approach to use subs in this way is pretty common from lots of speaker manufacturers.

I can’t claim to know more about it or try to explain it better, but through experimenting with the position of my sub and speakers and adjusting phase on the sub, I was able to reduce my biggest null to within -3dB on sonarworks (using a sub with the crossover set to 85hz).

I’m definitely a bit stretched for space for a 2nd sub, but when I change my desk it’s definitely what i’ll do next.

Another cool thing is you can use REW’s room simulator to predict the response of the room based on speaker, sub and listening position. There’s a lot it can’t account for but it’s definitely helped me predict what to look out for or find good starting points (that correlate to how things sound and measure in the room).
 
not the best pictures but just to get an idea of how much difference the subs/position/phase can make:

27A09CBB-2FA1-49AE-98BE-CF674928C917.jpeg
F8BA44A1-FDB4-418C-9D35-61F291382DA8.jpeg
206835F4-B3CF-4133-8C2C-6A25265B1961.jpeg



Think I have all these saved in my REW project, I tidied it up quite a lot as there ends up being a lot of measurements (especially doing L and R separately, and doing it for 3 sets of monitors+subs).
 
Carl explains it better, but the biggest dips are from axial modes and many of the dimensions being multiples of themselves.
No, in the article Carl Tatz attributes the biggest culprit as SBIR from the floor.

Going off of his tweeter & listener height of ~49 inches and supposing a speaker-to-listener distance of 5 feet, floor reflection arrives after ~4ms of direct sound. 1 / (4ms * 2) = 125 Hz. Seems to check out.
This guy has designed and built some of the best studios on the planet, and the approach to use subs in this way is pretty common from lots of speaker manufacturers.

I can’t claim to know more about it or try to explain it better, but through experimenting with the position of my sub and speakers and adjusting phase on the sub, I was able to reduce my biggest null to within -3dB on sonarworks (using a sub with the crossover set to 85hz).

I’m definitely a bit stretched for space for a 2nd sub, but when I change my desk it’s definitely what i’ll do next.

Another cool thing is you can use REW’s room simulator to predict the response of the room based on speaker, sub and listening position. There’s a lot it can’t account for but it’s definitely helped me predict what to look out for or find good starting points (that correlate to how things sound and measure in the room).
Yeah, using subs is cool. Just wanted to point out some other factors that go into it.

I can't make sense of your graphs cus the y-axis isn't shown, but glad you're getting better results! And REW is a great tool.
 
No, in the article Carl Tatz attributes the biggest culprit as SBIR from the floor.

Going off of his tweeter & listener height of ~49 inches and supposing a speaker-to-listener distance of 5 feet, floor reflection arrives after ~4ms of direct sound. 1 / (4ms * 2) = 125 Hz. Seems to check out.

Yeah, using subs is cool. Just wanted to point out some other factors that go into it.

I can't make sense of your graphs cus the y-axis isn't shown, but glad you're getting better results! And REW is a great tool.
was a few weeks ago, pretty sure the line where the deep null there is 100hz but I’d need to check the REW file to check the Y axis, but either way, was cool to see how much the low end could be smoothed out (or made worse) simply by moving and adjusting the subs. Some of those measurements are simply rotating the phase or crossover.

Was able to get my main monitors within +/- 3dB in sonarworks, and improved the other 2 sets of monitors a good amount. Hard with only so much space but a huge improvement over what I’ve been able to achieve with monitor placement alone.
 
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was a few weeks ago, pretty sure the line where the deep null there is 100hz. I’d need to check the REW file to check the Y axis, but either way, was cool to see how much the low end could be smoothed out (or made worse) simply by moving and adjusting the subs. Some of those measurements are simply rotating the phase or crossover.

Was able to get my main monitors within +/- 3dB in sonarworks, and improved the other 2 sets of monitors a good amount. Hard with only so much space.
+/- 3dB within what frequency range? Does REW show the same +/- 3dB result? (When I've seen Sonarworks review videos, their graphs don't quite look realistic, perhaps smoothed out a lot... but dunno, haven't used it.)
 
+/- 3dB within what frequency range? Does REW show the same +/- 3dB result? (When I've seen Sonarworks review videos, their graphs don't quite look realistic, perhaps smoothed out a lot... but dunno, haven't used it.)
Sonarworks is definitely smoothed out, you measure around 40 positions around your listening spot and it kind of averages things out (I guess with some weighting towards where you intend to listen from).

I’m not in my studio atm (just gone midnight) - this was a curve made before I did some other changes (I tried swapping brands of subs around and then changed back). Also some other small tweaks that smoothed things a bit. General shape is like this though.

074E26E9-18C6-46DC-8DD8-2C4D0B8784FB.png


Short of getting a Trinnov system, I think Sonarworks is an excellent investment. Can absolutely vouch for it improving the translation of my mixes and mastering, and offers a nice familiarity when working on different systems. I was quite skeptical of it before trying but I really would recommend trying it. If you have a measurement mic you can just demo the software.
 
I don't recommend Sonarworks. The software is just so damn buggy. When it works, it's great, but for me it crashed so often I requested a refund after they couldn't get it fixed on either Windows or MacOS. It would crash from nothing more than another audio device becoming online - didn't matter if it was an audio interface, my Axe-Fx 3 etc. If you don't use the systemwide software and just the plugin then it might be fine.

One workaround I used was to create left/right IRs of the correction curves and use them in the IR player block of the Axe-Fx 3. To be fair the global EQ works almost as well but I had the processing power so why not.

As for subwoofers, I tried the old BK XLS200 I have with my Genelec M040s only to find it largely unnecessary. In my previous space there wasn't a huge dip but instead a huge boost at around 130 Hz. Sonarworks worked well to correct that. In my current apartment there's surprisingly far less correction needed.
 


Cool video from Carl Tatz about monitor and sub placement, especially from 13 minutes or so onwards. recommends going up to around 120hz to deal with the SBIR null
 
So I've been planning on a pair of subs to go with my ATC's. Because of space and other considerations, the best spot for the ATC's gives a response at my listening position like this:
ATC Start.png


which overall, isn't TOO bad but obviously that dip at 100hz is a bit of a concern.

I tried my existing subs with the ATC's (Adam Sub 10 and Genelec 7050C) but I wasn't really happy with the tradeoff. I thought if I'm going to try these with a sub, I'll need to go another step up (without going to ATC levels of £).

The only issue really was space, a pair of KH750's is still quite an investment before you've tested the results. My plan was/is, buy one sub, get a feel for space and where I can position it in my room for the best results and then decide if a second one is beneficial. Its really hard to gauge a lot of this stuff until you're able to move things around and measure for yourself.

So a pair of Neumann sub's came for sale (one new in box, which I went for). By the time I ordered, the other one sold so for the time being I'll be using one.

Arrived today, I placed it where I had the most free space and at every possible phase position, I got worse results than no sub at all (red=no sub, the others are with the various phase postiions):
1699963509762.png


Not the best start, but this is why I wanted to test for myself in my own room. There's some iPhone app I've used before that gives sub placement suggestions based on room measurements which I'd used with some success before, so I used that as a guide for placing the sub in its next position.

At another (better) position in my room I was able to get this response (red=before, purple=after):

1699963608318.png


Which is clearly MUCH better in the low end. I need to measure/calibratae with Sonarworks, but the resulting EQ curve should now be doing much less work, and that hole around 100hz is much smoother.

The next step from there is to see if I can source a demo unit to test with 2 subs - this should provide a more even low end around the room, as well as smoothing the gaps a little more. It'll also give a better stereo image of the low end as it gets to the higher frequency range of the sub.

Im also curious to test Neumann's calibration software - its not really optimised for use with other monitors but I'd be interested to see if there is much to be gained with time aligning subs, as well as potentially managing crossovers.

All in all, a nice improvement and its verified by my nuts shaking about 40% more with each kick drum
 
FWIW, I remember getting in a big argument with someone years ago about subwoofers in small rooms - the multi-sub approach just wouldn't make sense to me.

I was wrong.

The home theater world is years ahead of most studio people in this regard, with the exception of a few people (Ethan Winer is aother).

Yes, adding 2 subs to my room (and figuring out how to integrate them) was a night & day difference, even after several thousand dollars worth of treatment and room correction. The three approaches together are the solution, IMHO, unless your room is huge (think US classroom sized).

One key point to understand is that it literally is not possible to fit enough bass trapping in a small room to completely even out the low end. The volume of the bass traps required is greater than the volume of the room. Another is that for small rooms, sound actually "moves" in two different ways. Above some critical frequency (Schroeder frequency), sound moves like it does in the diagrams. Below it, the room acts more like the inside of a subwoofer, and what the speaker is doing is actually changing the air pressure in the room. And it does it inconsistently. That frequency, for small rooms, can be upwards of 200Hz.

It is not enough to use speakers that play really low. The ideal position for sub-bass response has nothing to do with correct placement for stereo. Fortunately, sub-bass also doesn't contribute to stereo localization, so it doesn't matter. That one probably takes even longer to accept.

The easier ways to integrate them are to use a MiniDSP or a Trinnov, but if you do your research and take the time to experiment, you can do it with plugins for crossovers and delay compensation (and 4 mono outs from your audio interface).

So...yes, I'm a believer. Even with big floorstanders that measure well (anechoic) to the low 30s. The difference now is that my room is reasonably flat (plus the tilt I like in the high end) all the way into the 20s at my listening position. Even if I upgrade to bigger & better speakers, I'll still be using subwoofers and DSP.
 
FWIW, I remember getting in a big argument with someone years ago about subwoofers in small rooms - the multi-sub approach just wouldn't make sense to me.

I was wrong.

The home theater world is years ahead of most studio people in this regard, with the exception of a few people (Ethan Winer is aother).

Yes, adding 2 subs to my room (and figuring out how to integrate them) was a night & day difference, even after several thousand dollars worth of treatment and room correction. The three approaches together are the solution, IMHO, unless your room is huge (think US classroom sized).

One key point to understand is that it literally is not possible to fit enough bass trapping in a small room to completely even out the low end. The volume of the bass traps required is greater than the volume of the room. Another is that for small rooms, sound actually "moves" in two different ways. Above some critical frequency (Schroeder frequency), sound moves like it does in the diagrams. Below it, the room acts more like the inside of a subwoofer, and what the speaker is doing is actually changing the air pressure in the room. And it does it inconsistently. That frequency, for small rooms, can be upwards of 200Hz.

It is not enough to use speakers that play really low. The ideal position for sub-bass response has nothing to do with correct placement for stereo. Fortunately, sub-bass also doesn't contribute to stereo localization, so it doesn't matter. That one probably takes even longer to accept.

The easier ways to integrate them are to use a MiniDSP or a Trinnov, but if you do your research and take the time to experiment, you can do it with plugins for crossovers and delay compensation (and 4 mono outs from your audio interface).

So...yes, I'm a believer. Even with big floorstanders that measure well (anechoic) to the low 30s. The difference now is that my room is reasonably flat (plus the tilt I like in the high end) all the way into the 20s at my listening position. Even if I upgrade to bigger & better speakers, I'll still be using subwoofers and DSP.
great post!
 
I have a KRK sub and honestly could never get low end right in my mixes until the slate VSX cans. It’s fun for playback or composition though.
 
I have a KRK sub and honestly could never get low end right in my mixes until the slate VSX cans. It’s fun for playback or composition though.

You and someone else mentioned it, but....one sub will probably make the problem worse. It actually takes at least two to make it better. Depending on the room 3-8 can be even better....but diminishing returns kicks in at some point.

But, yes, if you have headphones that go low enough, they also completely solve the problem. I'm not sold on Slate VSX, but I didn't demo them for that long. I just can't figure out why you'd want to incorporate someone else's room into your monitoring. To me, the whole point of headphones or IEMs is that you can listen "without the room" but with HRTF cross-feed so that the phantom center is actually in front of you instead of in the middle of your head.

It's a much more cost-effective option that can be great.
 
You and someone else mentioned it, but....one sub will probably make the problem worse. It actually takes at least two to make it better. Depending on the room 3-8 can be even better....but diminishing returns kicks in at some point.

But, yes, if you have headphones that go low enough, they also completely solve the problem. I'm not sold on Slate VSX, but I didn't demo them for that long. I just can't figure out why you'd want to incorporate someone else's room into your monitoring. To me, the whole point of headphones or IEMs is that you can listen "without the room" but with HRTF cross-feed so that the phantom center is actually in front of you instead of in the middle of your head.

It's a much more cost-effective option that can be great.
Why would why would I want to incorporate someone else’s room into my monitoring?

Very simple. My room sucks, and the modeling mimics professionally treated rooms and other acoustically relevant situations. The point of these headphones is to listen with someone else’s room. For me, the proof is in the results.
 
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