Aux Fed Subs | Pros, Cons, & Finding Common Ground With Dave Rat

The event that finally made me switch to aux subs was a show I did for comedians. Subs were required because of walk-in / walk-out music and different intros..etc. I was getting a low rumble / roaring sound on a particular comedian and I couldn't understand because my High Pass Filter was high..... cranked to 250 - 280Hz yet the frequency was around 120Hz. How can this be? It is only speech from a person. So it hit me that High Pass Filters don't filter out everything below a certain point after all. 24dB slope and still getting through. So after making ridiculous cuts on the EQ channel, I decided to figure out how to properly do the aux sub thing. Aux Sub totally fixed this issue. So here are my thoughts: High Pass Filters do NOT filter everything out like we think & not necessarily their fault either. The reason High Pass Filters don't filter out the frequencies we think may be because we are asking them to do something not designed to do.... for example... a 10 -15dB boost on the low end that many are accustomed to for a Rock Show or even a Rap Show (20dB boost), and we want them to filter all of that out. If the system was set up with minimal low end boost, the HPF would work better or so it seems. The problem comes down to how much low end boost you have on your PA. Strong low end, no way you can high pass your way out of that. Don't believe me, shut off your tops and speak into the vocal mic while you listen to your subs, you will hear all kinds of muffled up mud it will blow your mind. By the time you High Pass it, you will be at 500Hz but then your sound coming out of the TOPS will be horrifying. The ONLY way to get that out of there is to keep the vocal from going to the subs in the first place. Aux Subs fixes this. Same thing applies to guitar players who think Low End is best leaving no room for the Bass player.... Its a personal thing for me now and I don't always stick to aux subs. I'm open for correction but I just keep going back to aux subs. Final Observation: I worked at a 1500 capacity venue and 99.9% of the touring bands that came through.... their engineers want the subs on an Aux.

Hey Michael, love how you decorated this room as a comlete mirror image to your usual recording room. 🥳 Really appreciate all your videos!

I go back and forth. Today, I used aux fed instead of matrix fed because the rig I was using was two dual 12” Yorkville subs (which really impressed me) and even with aggressive high pass filters on the vocals, and a third order crossover on the subs, I was still getting them in the subs.

I used to prefer aux fed subs, and I HATE hearing vocals in the subs, but after using properly constructed and balanced PAs I'm now fine to mix LR (though I often want control of front fill and delay mixes). I don't mind aux fed though, it's just a modestly different workflow. I have a better time thinking of the sub mix as LFE, there for when the epic video plays or when the band wants to shake the earth. I think the ideal system is one where half the subs are integrated into the LR mix to make it balanced full range, and the other half are on a separate LFE mix (assuming these mixes are processed to play nice together).

Vocals, guitars, and other non-sub instruments still have low-end that is part of their sound. Too much can get in the way, but too little (or nothing, as some people like) might be pretty bad too. The subwoofers are there to reproduce low frequencies, not specific instruments. I don't get the logic of aux-fed subs. To be really consistent with that mindset, we should also mix the midrange separately from the hi-end, but that doesn't make sense at all! I get there are certain situations when aux-fed subs are a good thing, but for me, that's the exception, not the rule. Thanks for the video!

He wasn't concerned with if it can be heard or not - he was talking about getting rid of even the slightest unwanted 1-80Hz content driving the multi-kilowatt sub arrays. Even if you cant hear it, and the highpass filters do have some roll-off per octave, it will inevetably bring some voltage to the subs no matter how slight or inpercievable it is. He also thinks of it as a ON or OFF sub switch

This is probably the best and most thorough comparison I have found, and has answered so many questions and put to bed a lot of the concerns I've been spinning around in my brain as to how I am going to set up my room. I am now certain that I want to do aux fed, but will be heavily relying on your explanation of the pros and cons to guide me in my pursuit of the perfect sound! Thank you!

Appreciate you revisiting this! Was watching your previous video thinking about Dave Rat's take the whole time! lol Then saw you update link. So, if time, complexity and ability were not an issue, and you we're just running a basic PA for a rock band. 2 subs 2 Tops, with two stage monitors, what method would you choose? Knowing that once it's all setup, you will NOT have a dedicated Sound Engineer, and can only make adjustments between songs or a break. Does that have you leaning either way?

kudos for being open to new things and changing your mind.

Different strokes for different folks. Comes down to most how you are able to control and manage your system, but I do believe you can achieve more consistent and more accurate results by using The plethora of processing available and a straight LR mix.

The musical ability to fade subs up and down 5db throughout the show is the most effective way to keep people interested. Hands down.

I'm glad that you mentioned the corporate situation, because I come from both Corporate and Rock N Roll. I never understand why people would want lavs/headsets to go to subs, so in most corporate gigs I'll always have aux-fed subs. Still finding my stance with this on live music, though I do think that aux-fed gives more manageable quality to low-end. I don't for example want my rack tom to drive the same weight as my kick drum, but I do like a proportionate amount that feels appropriate for the instrument. I am always happy to be wrong, but haven't personally experienced the same sense of balance/separation on a L/R system (yet).

I did a unique show where the band was performing aboard a century-old sailing schooner, and the audience was paddle-boarders on the water. I rigged my EV ETX-12P speakers from the ship's rigging. This speaker produces an impressive amount of bass for its size, but covering this kind of distance outdoors, I wanted the 18s to handle more of the upper bass range. So I crossed it at 100 Hz (ordinarily I cross at 80 or below). Problem: I was high-passing guitar and vocals, etc., at 80 Hz, but had subs on an aux. So, if I'm high-passing mics at 80 Hz, it means that there's content at or above 80 Hz that I want, and that was getting tossed since it wasn't going to any speakers set to produce that 80-100 Hz range. But I also didn't want a lot of wind rumble in my mics to go through the subs. In this case, it probably would have been better to just feed the subs from a matrix fed from LR, since the subs were in effect acting as a system WOOFER, and not just as a sub. There's a video on my channel that I took while mixing from a separate boat, if you're interested.

Just a question for my smallish rig using a dbx PA2 to provide crossover, room eq and feedback supression. If I take my subs out of there and run through a Matrix with a low pass shelf, I lose some functionality of the dbx unit, especially for the room eq wizards and live feedback supression. I'm not likely to get sub feedback I know, but then that crossover is just doing mids and tops. This could also affect time alignment of the subs if they're taken out of the PA2.

I have a few rules about how I approach aux-fed subs: 1. There isn't any input channel that I ONLY send to the subs 2. I do NOT use aux-fed subs without ALSO having a crossover, I do not use aux-fed subs as a substitution for a crossover 3. I do not vary the levels of the instruments going to the subs, they are on or off

I always prefer mixing aux fed, but after watching this I'd say the biggest merit against it is the introduction of latency, thus misaligning subs, when using any master bus processing. I hadn't ever really thought of it for some reason. I've never really been a victim of obvious issues when doing so either. But it's something to think about for sure.

I toured with a Grammy award-winning mix engineer and i picked up some habits along the way. One of those being put the Kick In only in the tops and the Kick Out only in the subs for tone control. Same thing with bass DI/mic. Can't do this with matrix subs

I love the way your presentation on this video

I was about to make a comment on your previous video two years ago, since you've made a follow up here's my take on this. We should be open to different perspectives and approaches but I'd stick running my Subs via aux as I have more control which channel I want route to use subs specially on a Church setup. This get's sure to prevent bleeds specially from headworn and lapel mics. I only use subs to supplement the low's of the FOH speakers. I have no problem with this setup on our livestream as I have live mastering mix.

I have always been a subs on an aux guy in the old analog world but have switched mono bus via the matrix due to the fact that delay compensation is often just applied to the mains busses on digital desks. I still use an aux with certain bands where I want more control for creative effect. Boosting the sub on certain floor Tom hits etc.