Control of subwoofer or not?

[NHStech]

We recently renovated our sanctuary and had an install done where the subwoofer was tied into the lows on the new sound board, in other words, there is no independent control. It was set at what the installer thought was "reasonable."
The reasoning was that sound mixing is too subjective and there is the fear that too much (or too little) of the sub may be introduced into the mix. This is whether our sound techs know what they are doing or not. Needless to say, the worship team is not a fan of this. Neither is the worship director (this was done prior to him being hired).

So, do you folks think this is a good idea or not? The deacon in charge said this is not etched in stone, but has to be persuaded. What would be the best arguments to persuade independent control of the sub, such as tying it into an aux send or something? I realize some of you may want more technical information, but assuming accoustics are okay, as is equipment, I am speaking more about philospohical arguments. Thank you.

 

[jkowtko]

If you are just looking for good balanced frequency response and someone has done an acoustic analysis and "pinked" the room, then presumably the sub should be dialed in with crossovers and DSP to get the best sound out of the room. In which case it is theoretically better to leave it alone.

But ... if this acoustic levelling has not been done with the room, and/or you want to be able to use the sub to deliver special effects, then you need some level of manual control over it.

If you need all three, then maybe the "default" settings for the sub can be noted somehow such that it is easy to revert to them when you are not doing something special.

 

[themuzicman]

In a properly tuned audio system that has been tuned for both flat phase and flat frequency response, the subs are a natural extension of the rest of your speaker cabinets and all enclosures work as one to create sound. This assumes that you have speakers placed in proper locations and the tuning was done properly.

I only ever run subs on an aux when I need to split them out for sound effects in theater, otherwise I trust that I have tuned the room to my liking, and have fought for optimal speaker placements so everything is working together as a cohesive whole. When I have them on an aux, I send my signal to them at the same level I am sending to my other audience facing busses so everything is phase coherent.

 

[Footer]

You just stumbled onto one of the biggest arguments in modern sound re-reinforcement. In your case, it sounds like first you need a good DSP and have your room tuned. Without that, going the aux route is the only way to go.

Two schools of thought here though...

"Full Range"/Subs on L/R- If properly setup and tuned you don't have to think about it. If the source needs the subs, they'll be there. The subs work in phase with the rest of the system and help the entire system. Typical for theatre or set it and forget it installed PA's. However, you will find your high pass filter used a lot more in this situation.

Aux Fed-The engineer can decide how much and if any sub to give to each input. Usually used to lessen the impact erratic low frequencies in the mix. Basically serves as a built in high pass filter. Most often found in PA's built for music. Can lead to tighter low frequincies in the mix due to less EQ work. Can also cause massive problems with how the rooms sounds as a whole.

In my place all of my rooms are set up on aux fed subs. Most band engineers want it this way. We can switch our processing around to do it full range as well, but house standard is aux fed. When I mix rather prefer it that way. It allows be to have a bit tighter control of the low end of the room without cutting up my EQ's to keep stuff out of the subs.

 

[JMBrowne]

I strongly recommend aux-fed. Nothing will drive you nuts like your vocal mics feeding back at 80Hz. Remember that filters operate on a curved topology and are not hard stops. A channel with a 100Hz "low cut" will still pass 80Hz audio, just attenuated.

Those low end frequencies flow like water. Best to keep the unwanted channels out of the picture entirely.

 

[TJCornish]

There are two issues here - what the function of a subwoofer is, and attempting to keep content out of subs that shouldn't be there.

If you have a system where you are relying on your subs to produce all sound below 80Hz or even 100Hz, then IMO aux-fed subs are a mistake, as you're effectively turning a pretty big part of your system into an effect. If you have a main system that goes down to 50Hz and only use your subs for VLF work, then aux-fed subs can be useful.

10 years ago in the era of analog desks with fixed high-pass filters, aux-fed subs were a useful way to keep vocal mics out of the subs. These days, even very low-end digital desks have variable high-pass filters which give you a lot more ability to manage this without needing to set sub level on every channel.

A hybrid approach that I use is to put the subs on a group feed instead of an aux send. This gives me final level control of the subs but also a very clear reference point relative to the mains - if the sub fader is in line with the mains, the system is balanced (assuming I set it up correctly in the system DSP). If I want to add a little more for a short time I can, if I want to kill them entirely I can, and I can always get back to neutral by matching fader position to the main fader.

Are there a few situations where variable aux subs can make a material difference over just using the variable high-pass filter or group subs? Sure. Is there a lot of potential for screwing stuff up by having more levers to pull? Absolutely. Now you have to sound check the subs for every input, too.

I think a lot of times this comes down to ego on the part of engineers. I'm not necessarily saying this is the case in your situation, but you haven't told us what actual problem you're experiencing. Are you having trouble getting good mixes? Are you unhappy with your system tuning or the PA itself? What exactly are you hoping aux subs will fix for you?

 

[Aaron Becker]

Having worked on rigs where this was set up both ways (aux-fed vs full range), I think they both have benefits depending on the application. One question I'd ask in this environment (I think I read this is a house of worship setup) is what's the style/production type? Is this full orchestra reinforcement, theatrical within a house of worship, a "band" or just spoken word? This will probably influence the decision of how the system is set up, along with the capability of the end users and how much control you want them to have.

 

[Jay Ashworth]

I think the answer is probably 'yes', and that's his driver.

Sent from my SGH-M919 using Tapatalk

 

[Catwalker]

I've seen systems where control of subs is on the "mono" out, while the rest of the array is L/R. Am I correct in assuming that is different than the question of aux fed or not?

 

[Footer]

I've seen systems where control of subs is on the "mono" out, while the rest of the array is L/R. Am I correct in assuming that is different than the question of aux fed or not?

Yup, the aux solution is variable, on most consoles the mono out is simply another buss that gets the same signal as L/R.

 

[Dionysus]

Indeed, MONO send is a very different approach than AUX sending.

Personally I think it depends on the system, and the use of the system. Frankly when I am doing Folk music I almost always put subs on an AUX send, I want that control. When I am simply doing playback for theatre, no, generally I'll just send it off MONO or L/R or such, unless I REALLY want to push something though the subs perhaps.

 

[Aaron Becker]

Indeed, MONO send is a very different approach than AUX sending.

Personally I think it depends on the system, and the use of the system. Frankly when I am doing Folk music I almost always put subs on an AUX send, I want that control. When I am simply doing playback for theatre, no, generally I'll just send it off MONO or L/R or such, unless I REALLY want to push something though the subs perhaps.

This is generally my approach too. I only use aux fed if I need the control for some reason, generally I'll automate it too (depending on the show) and if I need to throw something that really needs to "thump" below 100 Hz.

 

[StradivariusBone]

This thread inspired me enough to finally re-patch our DSP and set up the subs at my church on a mono-send arrangement. The building is a repurposed house of worship, originally built to house a traditional service, so it's very live with lots of parallel surfaces and very wide when compared to its depth. We use a driverack PA for DSP and the crossover point was set around 80Hz, but I would still get enough pieces of vocals and other things muddying up the subs to make it difficult to bring vocals or certain instruments forward in the mix without bumping them up. Coupled that with a loud-ish drummer, we are forever fighting the battle of "it's too darn loud" vs. "all I hear are drums".

I need to spend a bit more time on the EQ, but initial reaction was that the vocal and solo instrument clarity was much improved. Correct me if I'm wrong, but I'm treating (at least mentally) the tops like its own system and using the subs to augment the low-end as necessary. Our tops are full range, biamped. With that in mind the only things I'm currently applying to the mono out are the bass, kick, synth, and tracks. The tops by themselves sound perfectly reasonable, but the subs add that chest-thump feel without overwhelming with mud.

I think I will switch over to aux fed next week since the first thing I noticed was the balance between the kick and bass was wrong and not easy to change with it using an out from the main bus. We use submasters to isolate certain instrument and vocal groups, but they also route to the LR for the tops (L specifically since it's now in mono). I don't want to change how I route that unless necesary.

I also see where an inexperienced tech at the console would hit some pitfalls in this arrangement, but for our application where they strongly encourage us to remain at or below 85db I feel this will help with clarity and make it easier to get a warm sound without a large increase in volume.

 

[Aaron Becker]

This thread inspired me enough to finally re-patch our DSP and set up the subs at my church on a mono-send arrangement. The building is a repurposed house of worship, originally built to house a traditional service, so it's very live with lots of parallel surfaces and very wide when compared to its depth. We use a driverack PA for DSP and the crossover point was set around 80Hz, but I would still get enough pieces of vocals and other things muddying up the subs to make it difficult to bring vocals or certain instruments forward in the mix without bumping them up. Coupled that with a loud-ish drummer, we are forever fighting the battle of "it's too darn loud" vs. "all I hear are drums".

I need to spend a bit more time on the EQ, but initial reaction was that the vocal and solo instrument clarity was much improved. Correct me if I'm wrong, but I'm treating (at least mentally) the tops like its own system and using the subs to augment the low-end as necessary. Our tops are full range, biamped. With that in mind the only things I'm currently applying to the mono out are the bass, kick, synth, and tracks. The tops by themselves sound perfectly reasonable, but the subs add that chest-thump feel without overwhelming with mud.

I think I will switch over to aux fed next week since the first thing I noticed was the balance between the kick and bass was wrong and not easy to change with it using an out from the main bus. We use submasters to isolate certain instrument and vocal groups, but they also route to the LR for the tops (L specifically since it's now in mono). I don't want to change how I route that unless necesary.

I also see where an inexperienced tech at the console would hit some pitfalls in this arrangement, but for our application where they strongly encourage us to remain at or below 85db I feel this will help with clarity and make it easier to get a warm sound without a large increase in volume.

I saw nearly this exact problem at one House of Worship I advised for a friend - of - a -friend situation... they ended up going with a hybrid setup, instead of just the subs being aux fed, they actually ran the music cluster (located over the music area) separately from the speech clusters (intelligibility in the room sucked), but I believe an aux was still set up individually for the subs. This gave them ultimate control over the music area volume vs a spoken area, and the sub (which was still controlled by the master of the "music" area master). I think they set it up using a mix/mix/matrix configuration on a Yamaha board. It's actually a really nice setup to give the end user some additional control without giving away ALL of it (most of the end users don't know how to adjust the balance between the mixes feeding into the matrix mix, nor do they need to know how to).

 

[Dionysus]

This thread inspired me enough to finally re-patch our DSP and set up the subs at my church on a mono-send arrangement. The building is a repurposed house of worship, originally built to house a traditional service, so it's very live with lots of parallel surfaces and very wide when compared to its depth. We use a driverack PA for DSP and the crossover point was set around 80Hz, but I would still get enough pieces of vocals and other things muddying up the subs to make it difficult to bring vocals or certain instruments forward in the mix without bumping them up. Coupled that with a loud-ish drummer, we are forever fighting the battle of "it's too darn loud" vs. "all I hear are drums".

I need to spend a bit more time on the EQ, but initial reaction was that the vocal and solo instrument clarity was much improved. Correct me if I'm wrong, but I'm treating (at least mentally) the tops like its own system and using the subs to augment the low-end as necessary. Our tops are full range, biamped. With that in mind the only things I'm currently applying to the mono out are the bass, kick, synth, and tracks. The tops by themselves sound perfectly reasonable, but the subs add that chest-thump feel without overwhelming with mud.

I think I will switch over to aux fed next week since the first thing I noticed was the balance between the kick and bass was wrong and not easy to change with it using an out from the main bus. We use submasters to isolate certain instrument and vocal groups, but they also route to the LR for the tops (L specifically since it's now in mono). I don't want to change how I route that unless necesary.

I also see where an inexperienced tech at the console would hit some pitfalls in this arrangement, but for our application where they strongly encourage us to remain at or below 85db I feel this will help with clarity and make it easier to get a warm sound without a large increase in volume.

Got it alright, use the rest of the PA as more or less "full range" (depending on the system & not the real low stuff, that's what subs are for ) and then route the stuff that needs it to the subs. Think of it as the ultimate high-pass filter, without need for as much of a high-pass filter. Also as mentioned allows you to really "pop" the stuff that could use it with the subs.

A good example is Harp music. The harp has an extremely broad range, and how I approach mixing it depends on what and how it is being played. For some Harp music I really DONT want the harp going to the subs at all, but I still want as much of the range of the harp as possible in the system, but don't want the subs make it sound like there is a bass guitar playing along. Don't route it to the subs. If for a song it would work, then you CAN route to the subs.

 

[Brentgi]

I have a few questions for the OP:

1. Is the console digital or analogue?
2. What kind of processing is at your disposal? Is it inboard or outboard gear?
3. What frequencies are being sent to the subs?

These would play a factor in my decision. I think there are pro's and con's to both....

If you are doing a L/R config, I would definitely recommend a good eq & crossover. I am a huge fan of the DBX Driverack. Although this is becoming less and less necessary with more people switching to digital consoles. So, if you are still on the analogue board, make sure that you have proper processing. But going this route means that EVERYTHING gets sent to the subs, vocal mics included.

Currently, I am using an aux fed sub. HOWEVER, this aux is eq'd separately. Something that you MUST do with an aux fed sub. This is easy to do with a digital console. There is a problem with this setup though when you are using volunteers to mix. I think that there is a great deal of control that is given to the engineer. I've had people add too much to the sub, and others not enough (AM radio, anyone?). If you are the only one mixing and you are willing to take responsibility for this, the do it. Otherwise, leave it as L/R, with a good crossover, and find out a way to just boost the signal to the subs. And do it over time. Perhaps 2 or 3 dBs a week, until you find it where you like it. You could even (at your own risk) bump up the amps on your subs a bit - but only if the crossover is set correctly, if you have it.

Church sound is a touchy subject. My best advice to you, become a student of frequency. You'll be able to do much more with the right eq than you will with just setting levels.