Why I Quit Using Aux Fed Subs (And Do This Instead)

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I’m going to come right out and say it. I think aux fed subs are the wrong way to manage your low end. I’m not saying you should forego control of your subs, but an aux or a bus is the wrong tool for the job.

Today I’ve got four reasons why you shouldn’t use aux fed subs, then I’ll walk you through how I set up my console and system processor to handle my low end.

My name's Michael I love helping you level up your audio and business skills so you can build a career you love.

We’ll cover:

- Why the mono bus (as well as auxes/buses) set your low end up for failure
- What bad habits we’re borrowing from film world
- How your brain has to think twice as hard about mixing low end with an aux-driven setup

00:00 - Intro
01:20 - Clarification, Defining Aux Fed Subs
02:29 - Reason #1
07:01 - Reason #2
07:58 - Reason #3
09:24 - Reason #4
11:39 - How I Route and Control My Subwoofers
14:56 - Conclusion

[lfisher]

Great thoughts. Related to #4 I would also add that when designing systems for permanent installs like churches, schools, community theater and similar venues where you will have a wide range of mix engineers, including volunteers, using the matrix approach and a single fader will be much more user friendly and keep them from getting lost. You set the system up properly and turn over the system with confidence.

[steve]

It's like a lot of things in audio: it's one way of doing it. I've found over the years that it's better to stay away from holding an opinion that states someone should never do something. Some of the reasons I love using aux fed subs is that I don't have to HPF nearly everything. I don't want acoustic going to the subs and I don't want a HPF on it. I also love having the ability to give the subs more level at lower volume to compensate or giving them a bit of a boost to emphasize some moments. Yes, the acoustic crossover changes, but while system design is linear and analytical, running sound is not. There is room for some of the artistic opinions and if no one gets hurt, then go for it.

[inkrebel]

Sick theory. That comparison to surround sound was brilliant. Thanks for sharing!

[HAZZASIB]

For me I run aux fed subs. I set the subs up so they are roughly the same volume as my tops and so I can have as much of an even frequency response across my PA. Once i've done that I only send things to the sub at unity and then forget about it (and also link the PA master LR with aux/mono. I use the aux feed as more of an on / off switch rather than a 'how loud I want the bass' switch. I like this as it acts as an immediate high pass and saves more energy for things that are routed to the subs. I do agree you can get caught up in thinking about routing more than actually mixing the channel but for me its a 'set and forget'.

[jen]

this makes perfect sense to me. never stop challenging norms . it's how we grow. there will always be people who say outside ideas are invalid. even f they eventually are, trying new ideas is how we grow. i love this channel. one of the most eloquent educators out there. i wish i had your savvy at your age but i'm a late bloomer. by the time you are my age you will be top notch, no doubt.

[bendadams]

Question here.
I've been learning about aux subs and watched this to combat what I've been learning. Mixing at a smaller church. 50x80 room with overflow rooms open to main room (zone 2)
I have a external PA processor with only 2 inputs. How do I control different zones levels and subs on the console but still use the EV DC-one processor.
You use 1&2. Left/Right. 3. front fills (in my case overflow zone 2) 4. subs. with matrices, but i only have 2 inputs on my processor. Would I bypass the processor to do this and just go straight to amps? Or the processing on the matrices would output the stereo bus to the processor post fader with the sub fader affecting the stereo output? I have new gear on the way and i want to understand this stuff before i route the new console.

[aaronduesterhoeft]

I try to maintain an open mind. I do typically run my subs aux style. However, I do like the concept of this approach and the benefits that could come out of it with regard to tonality, TF translation and stream balance. I might have to try it out at my venue! Can't knock it till ya try it! If it doesn't seem to work, it's easy enough to switch back. Keeps ya fresh!

[Sound.Church]

I really don't think your tone was bad at all... thank you for the info. I really agree and enjoy your content, even when I disagree. Keep it up!

[JamesEatonMedia]

I’ve run subs in an aux for so long. I’m used to some of the “oddities” like walk in music and things that are hitting those subs differently. BUT. I have been watching your stuff and I am trying the LR to Matrix mixing for some clients to see how it works. I’ve got a room to test soon and I’m rebuilding their X32 for matrix feed and I will try the subs this way and A/B it to see how it works.

I also see the benefit from a mixing standpoint. You just mix faders at the end of the day. All those tweaks should represent a whole system that sounds good. Plus it cleans up your LR mix for reference and review.

When I think about training new people to mix, I can totally see this being a great choice. It’s more wholistic!

[mirarzaamplification]

This is what I'm thingking too. If a reference music can go to a PA without mudding the vocals that means we can do it in live also, its only the matter on how to use your eq on your channel.

[artmathias]

I have been a concert engineer for over 20 years now, so I live by the motto of not telling another engineer how he should do things, just like I wouldn't tell a musician how to play HIS instrument. That said, I feel that some of the things you mentioned were made for the wrong reasons. I am neither an electrical engineer nor a comp programmer, so I don't know the exact physics of what is going on under the hood. But, there is a stereo summation from Main LR, that gets decorrelated when moving to Matrics. When I was first shown the difference, I had to go back to my shop and experiment for myself. With a 2 tops over 2 subs a side, stacks, I wired 1 top to 1 sub on each side with one amp system, while hooking up the second speaker set to a like amp system. Being able to A/B the two set-ups with one being fed main bus and the other from matrics. There is a noticeable fidelity change from one output to the other.
As for the lack of full range on your main L/R bus, when using subs on an aux, your left/right outputs are still seeing full range, and anything that you matrix off of your L/R is still full range. Your sub is only affected after your system crosses over at its designed frequency, With that being said, your sub send will also send a full range signal to the sub channel of your amp, where at that point, your system will cross over, filtering all other frequencies from that full bandwidth signal.
With proper "system" gain structure, there should be no audible change from a full range system to a 'subs on aux' system with channel aux send at unity. You shouldn't have to treat your channel equing any differently than mixing in full range.
It isn't about having more steps to do. It is about having less to do! In most "Band" set-ups and sound, it is easier, and quicker to dial that sub aux when you only have a few instruments that you want to go to your subs vs. having to run a high-pass on 20 other channels to get them out of the sub bandwidth. This also has added benefit to your amps, being that they have to work less when you don't have all the summated noise floor that every channel ads to your outputs. The sub drivers will also become tighter if freed up from having to try to reproduce sounds from the entire mix, just like the example of the pre-fader aux send that is missed on your source music channel, you will still be able to recognize a song due to the whole stereo mix of the source channel. "if you send it there, it will try to produce it", best option is to only send what you want to exploit that frequency band, i.e. kick drum, floor tom/low tom, Bass guit, keys, and other instruments that live in that bandwidth, your overheads, for example, should be as far away from your sub bandwidth as possible, even if high-passed.
I also do that to front-fills when we are playing a smaller venue. It is only the channels that get lost over the stage volume, i.e. vocals, acoustic instruments, etc, that I feed into front fills.
This only a cursory explanation of why I use subs on aux and not matrix or mono. I am happy to get more in-depth on this, if interested, but this comment is already turning into a book.

[fitton]

I still just use a crossover lol. I will explore this method for sure. I've tried aux fed subs and just went back to an external crossover because I was constantly "balancing" the system. This would eliminate that👍 Oh, and I always MUTE the walk-in music channels right after I fade them out now. I had the same thing happen lol Great video! Cheers

[toddmoore]

When I first heard of the subs on aux idea, I had the same thoughts as you are expressing here. Thanks for confirming what I've been thinking about this for some time. Good video.

[QuicksilverSG]

Aux fed subs are appropriate for hiphop and DJ-centric venues. In those situations you often ride the gain on the subs to suit each particular track or performer, as well as punch up the energy in the room. For live bands, however, it's better to use FOH speaker management via well-tuned external crossovers. That way your master fader controls everything as it should, and there's no need to complicate things with a layer of matrix outputs.

[BERMANSOUND-nkfr]

08:30
Sure you can send group to an aux on x32:
1. take 2 free channels, link them to be stereo
2. choose the input of those channels - the buses of the group
3. send the channels to an aux as usual

[billschnake]

Michael, I have done this both ways. On very large shows I have done the Left/Right to 4 matrixes, Left/Right/Sub/Fill. We always do it in that order. We do get the request to set it up Left/Right/Sub/Fill for many of the artist we support where we are doing a Aux for sub and Matrix for fill. I myself prefer the way that you suggest and as you said if we need to do a live feed for recording, we can just simply pick another Matrix and send it to the live record feed. We did this at a corp show last week. As I said, I prefer to do my feeds as you suggest, however I have clients who prefer the aux method and when they are paying the bills we do as they wish. Nice video.

[ernietalks]

I use the main L/R output for my subs. I can take R for the tops and L for the subs after coming out of crossover with the high and low. I use the PAN knob on the channel strip to assign each things at channel level to the subs. For example, for kickdrum I PAN hard left and also compliment with the EQ low knob on the channel strip. For vocals, I PAN right and also use the EQ on the Channel strip to achieve a balance for the low ends and high properties of vocals . It works perfectly for me in house of worship and all applications

[nathanlively]

Makes sense to me. I think most people arrive at the same conclusion considering these questions. Any reason I can find to make things easier.

[MrRoberacer]

Thanks for your thoughts. I see one issue with sending a copy of your entire mix to the subs and that is that in the case of vocals you are right in that a recording doesn't have the big bottom on the vocals that many people seem to leave in them in live situations but I think we need to explore why that is a little more. Yes, some folks have not quite understood why we commonly don't use much bottom end in vocals on recordings. That is true but the thing that some people don't understand is that the best way to achieve any specific sound especially in a recording is at the source. In the best recordings the vocalists are a good distance from the mic thereby creating far less proximity effect than with mics on a stage. Heck more often than not even lectern mics are closer to the face of an orator than a common studio vocal set up. Also something to note is that lectern mics are commonly hyper or super cardioid designs because they need the off axis rejection but with that the trade off is that they suffer from excessive proximity effect. Some consoles offer a -24db/oct cut but with that if you look at the curve you will note that above the cut frequency they also ten to boost information which is most commonly not a desirable effect either. While using the crossover as a low cut is not going to fix your recording it can at least make the house mix more usable when using substandard quality mics (we commonly record with mics costing in excess of $5K. Stage vocal mics are commonly some of the cheapest mics in the box. While the cost of a given technology is not a direct correlation to sonic quality it does in fact factor in.) An alternate to correct for the record feed which I mostly do from stereo matrixes also is to run the vocal through a buss that is doing some of the global corrections for the vocals/ for example commonly engineers spec the same mic for all of the vocalists who are performing together. There are some good reasons for that for those who don't understand but that is another topic altogether. Suffice it to say that undoing the "58 curve" is something you can do as a global setting on a subgroup while using your channel eq to fix specific issues for the various singers as well as some consoles allow you to low cut in both sections or at least "low shelf" the bottom. Also inserted eq can be your friend there as well.

[jordanthurt]

For me, it boils down to several things:
1. What console am I working with?
2. How many outputs do I need and how many are left?
3. What type of event am I mixing for?
4. So I have any external processing control for the PA?

All of that is going to influence whether I use aux-fed subs or not.