I wanted to do a video about the most difficult thing about soundproofing a home studio. We could call it “What’s That Noise?”  So, what’s the big deal about that? Well, oddly enough, this story starts on the roof of an apartment building. If that sounds weird, check out our “Kokomo Hum” video; then you will understand what I’m talking about.

The most challenging part with a home studio is low frequency control. You can get isolation for vocals and that type of thing somewhat easily. However, when you have base drum, bass guitar, any low frequency sounds that you don’t want seeping into the rest of the house — or low frequency noises from upstairs that you don’t want filtering into your studio (which you may not hear with your headset mic) — there is the challenge!  

For the backstory, listen to The Kokomo Hum.

You will notice in the soundproofing video that I am wearing headphones. Computer speakers typically do not pick up the elusive low frequency sounds that we are featuring so, when watching the video, you should put on a set of good headphones or in-ears to be able to hear the type of low frequencies.

Next, and unrelated to that, we were called to come to an apartment building. Residents were complaining about a humming noise that was occurring in several apartments in the same complex. It was a 3-story apartment building with dozens and dozens of apartments that were not hearing this noise. For those residents who were hearing it, though, the noise was annoying and impossible for them to track down.

So, we were called in to solve the mystery and tell them how to get it to stop. (You will want to go over to our soundproofing video now, wearing headphones, to get a much better perspective on this.)

 

And just so you know, we actually are going to get to why this has something to do with soundproofing a home studio and many other things. So, we arrived at the apartments where the hum was occurring, and we took a look at the roof above them. It was lined with air conditioning units — dozens and dozens and dozens of them. And they were all mounted the same way. They were mounted to a rail, sitting on another rail, sitting on a roof. They are just air conditioning units like you may have outside of your house. Now the ones outside of your house don’t do this into your house or you would probably leave your home.

So we discovered the air conditioning units were how the noise was getting there. The next step was to find what was causing it in the first place.  So when went into the apartments that were having the noise problem, we definitely heard the noise.

We went up on the roof and, when you’re walking around the roof you don’t really hear it, but you feel it in your feet. When you would get your ear up really close to one of these air conditioning units — really, really close – you could hear the noise.  When you would get your head down lower towards the bottom, it would go away. On the roof, you could hear it and feel it in the floor. Now what we got into is that we found that the units were mounted on rubber vibration isolators. They have a high enough deflection that typically 48 Hertz wave, which is what we were hearing, would be damped by them.

However, the problem was that they had them sitting on rubber vibration isolators. That seems pretty good, other than they could fall off the rail, which is a whole nother issue. The problem turned out to be this simple. They fastened them to the rail with an angle bracket that tied them to the rail.

So a single screw in four places on each unit was enough to put the unwanted low frequency noise into the apartment downstairs. We disconnected it from the rail and the result in the apartment downstairs was:  no noticeable noise.

When it comes to doing home studios, the likely challenge will be => vibration.

Note:  if you’re listening carefully to the video on good headphones, you can hear that it’s still there, but we had a 24 DB drop in level by simply disconnecting four screws. The takeaway is that when you get into doing home studios the challenge you are most likely to face is vibration.

When you try to do vibration isolation, no matter how you go about it, there are a lot of challenges. The first challenge is physical contact. If your walls are tied to your joists in the basement, you are going to have some issues. In this apartment scenario, there was other stuff going on that was kind of unusual and not easily understood. The entire roof here had many air conditioning units. They were all over the place. But there was only one apartment in the building that had the noise interference going on.  

So the question then is why, and it has to do with deflection and flexibility of the roof system. So, it was just the magic of math that in a particular spot up there in the roof, you ended up with this situation where all the right things came together, causing this frequency to show up in that apartment. And it was a little bit in the hallway outside it, but the neighboring apartments weren’t getting it. When we turned on all these other units, this was the unit that was for the apartment we were working on. When we turned on the other ones, it hardly changed at all. Uh, the other ones could activate it.

However, it didn’t matter which one on the rail did it. It was just this thing where this one place was a problem. So when people talk to us about designing a home studio with isolation or any kind of isolation, the challenge is always, how do you prevent isolation vibrant from occurring?

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This advice is primarily for theater folks who work in school districts. Are your auditoriums being renovated? It will be helpful for you to be aware of the design and bid process that you are entering into before things get too far along.  

First, there will be an architect on board and probably some engineering firms, as well. If part of the scope of the project includes stage rigging or lighting or audio or video or any of the technical parts of the auditorium, who will design that work? This is a very important consideration.

There are two paths you could take.

1. On one path, the architect hires a theater consultant for his team who stays with the job from get-go to the tail end, making sure everything is done properly.  That includes assuring that it is set up correctly and seeing to it that people are thoroughly trained on all the new equipment. The theater consultant is there, representing you the client, to make sure that everything goes the way you want it to.
2. The alternate path that they could take does not include a consultant and, instead, you get “vendor specs.” Now vendor specs are an interesting breed…this is how it works:

You hire an architectural firm which also has an engineering firm working for them. Typically, the electrical engineer on the team gets tasked with doing audio, video, and theatrical lighting. Admittedly, there are some electrical engineers who actually know something about this work but there are many who don’t.

 

So what exactly is a “Vendor?”

The electrical engineers who don’t have those skills set get a “vendor” involved. A vendor is a third party who often does have know-how, but they also sell equipment. That makes their role a little odd. Vendors will not be paid for their time in specifying the project. In a public bid market, they may or may not even win the job. It’s less than a 50/50 chance, depending on how many bidders are participating. So, they spend time specifying something that may make them no money at all. There is not a lot of incentive in that to follow up later.

As the client you should understand that the way a vendor spec works is the vendor, who actually does have some skill set, provides some information to the engineer who then transfers that to his drawings and specifications. Now, in some cases it may be done fairly well. In some cases, it may be very, very basic.

We’ve seen bids produced as simple as one drawing for an entire audio system with no information of how to actually connect things, where speakers should be located, how they should be mounted and aimed, etc. Video projection often is left with no indication of where the inputs and outputs are.  We have seen theatrical lighting systems labeled as an “LED par fixture”, and that’s as far as the description goes.  The whole spec can be generic. The chances of you getting what you truly want can be slim.

The complaint I have with vendor specs is two-fold:

1. It is wasting the time of someone who may never get paid for their participation which, as a consultant, I just object to. It is un-American.  As consultants we get paid for our involvement. And I think that is the way life should be. If, however, a vendor does get paid for their work, they are not supposed to bid that work.
2. If a vendor specifies a system the next issue becomes “if they lost the bid, who reviews his submittals after bid and someone else wants to substitute products?”  

I had this happen on a job recently, we created a design for a school district where we did all of the acoustical work for all of their auditoriums, and they wanted high quality acoustics in their auditorium. So, we made them pretty reactive meaning that anything that happens in the room is very audible.

A different designer did the theatrical lighting. Our design included the stage shell.  We asked the engineer to use a specific light in the stage shell because we were concerned about noise over the orchestra.

So, we had our fixture specified for the part of the job we cared about, the rest of it was handled by the engineer. Now to his credit, he worked with a manufacturer’s representative (ie. Vendor) who gave him good information and he specified some really good fixtures for the rest of the lighting system. The problem came in when the project was bid and the low bidder substituted everything, including the shell fixtures.

We chose these lights for a reason.

The LED lighting that was in our original design had been carefully selected for two aspects: one was color quality, and the other was fan noise. The substitute that ultimately was accepted by the electrical engineer was very noisy. This happened because he didn’t know any better, He was going by cut sheets, which don’t refer to noise.

After the lighting fixtures were installed, we were contacted by the owner since we had designed the acoustics. They wanted to know why the lights were so noisy. It was because no one ever showed us the submittal on what was being substituted. The engineer was dealing with us as if we were a vendor and they don’t contact vendors on substitutes.

When we found out what they had done, we had to explain “the rules of the road.” The LED lights that they had accepted could indeed be run quietly only if they were willing to accept 60% light output. With those particular lights, that is the only way to get the fan noise low enough.

Vendors are pretty much in it to make the sale. This is a real-life example of a vendor that made an alternate selection – his product – as a substitute in the bid so that he could do just that – make a sale. They made that sale based on lumen output, color rendering index, and other factors. There was nothing in the spec from the engineer about noise, so he didn’t consider that factor.

As consultants, all of our specs for LED lighting have specific requirements for noise, and we never would have agreed to the particular substitute that was accepted on this job.  We put our 2 cents in, and the owner is now trying to figure out how they’re going to resolve the problem.

The room was designed acoustically so that you could hear nuances and harmonics. To protect these excellent room acoustics, the client will now have to accept low light output or unwanted noise in the room.

In this particular case, using vendor specs was kind of awkward. There were 2 vendors involved: the original one and the one for the substituted product. If the engineer had gone back to the original vendor’s rep asking what he thought of the substitute, he obviously wasn’t going to like it as it cuts him out of a sale.

So, both sides of that road are kind of rough. You’ve got people who haven’t been paid and lost the job. You have other people who are interested in getting paid and that happens if they make a sale. This is a scenario where lots of things can go wrong, and the client suffers.

Consultants work for YOU!

In our opinion if a customer, such as a school district, cares about the performance of all their systems in their auditorium, they need to have consultants on board that work for them, or work for the architect, and are not part of any sales organization. 

That was an example of a problem with lighting. In audio, we have seen even worse situations. We have seen people take a design from a vendor which might have been somewhat well done, but then allowed substitutions of everything, including where the speakers would be located.

“Which way does it go?”

Most recently we were in an auditorium where they substituted a speaker that was completely inappropriate. Then they decided that positioning a pair in the front of the auditorium in the corners, a pair halfway down the auditorium against the sidewalls and a pair in the rear corner of the auditorium firing forward would be a really good idea. Mind you, the particular loudspeaker they had specified has its own a wacky coverage pattern to begin with.

No, this was not surround sound. These speakers were not processed, independently tuned, delayed in any manner. They were all just running in unison.

It was like an audio “hall of mirrors”!

So, it was kind of like a “hall of mirrors” effect when you got into the room. It was just bad. So, we were called in to figure out why they were hearing all these echoes in the room and we had to give them the grim news.

The problem was multi-faceted. It was not just where all the speakers had been located but what they were and how they interacted with the room. By the time we got involved, they already owned it all, had accepted it and now were stuck with it.

A word to the wise in public bid situations is that someone must specify clearly what you, as the end user, want and that person should never be one who is also selling product. They should be someone knowledgeable whose sole interest is what you, the customer, wants and not what they would like to sell to you.

Consultants do have preferences. We might like a particular audio console or lighting console but if you like a different one, as an end-user, our job as a consultant is to get you what you want, not to get you what we want.

Please Get Qualified Consultants

So be sure to have the architect get qualified consultants on board.  Better architectural firms automatically do this because they know the benefit of having us on their team.  With some architectural firms, you will have to force the issue. (their engineers insist to them that they know what to do…..)

There have been times that we have kind of been thrown at some architects. They didn’t want to hire a consultant, but the end user was savvy enough to insist on it. They knew from experience that they did not want to leave this part of the project to the engineer, or to a vendor.

In defense of engineers, there are some who really do have more than a hobby-interest in audio, video and lighting and that is awesome – but they are rare.

 

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Copyright AVLDesignsInc. 2021+

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This first segment is “how to mix front of house” when you also have control live stage monitors, are feeding IEMS (in-ear monitors) and maybe a sub feed out to a streaming mix. When  mixing all of these different things from the same console, it  forces you into a mode where your gain structure and certain other parameters have to be driven by the other feeds you are mixing, not just the PA. Truly, it isn’t perfect, but it can work.

*In an ideal world you have a monitor engineer, streaming engineer and two more consoles. Lots of $$$$$$$ Good Luck!

So, the first thing you have to look at is how much gain is required to feed the IEM direct outs to get good signal-to-noise. Inadequate levels with whatever types of headphones/in-ears the individual musicians are using leads to excessive IEM Noise.

Tip=> everyone’s IEM’s needs to have high sensitivity at least 107 dB. If that’s not the case, you may have to have enough gain to handle the lower output devices that people might be using.. 

So your Gain structure is initially driven by what needs to go to the IEM and direct outs. Busses will also be used for IEM feeds so  you’ve also got to look at things that need to be grouped into the IEM.  Also determine which feeds are pre EQ, compressor etc.…. and which aren’t. People always say give me a pre everything feed, but that is not always the best choice for live or IEM. (Ear Damage i.e. accidents)

You may not want to have EQ applied  to certain aspects. The last thing you want to do is have any EQ you’re doing at front of house affect, let’s say a bass player and what they’re hearing in their in hears. On most consoles  there’s a variety of feed options with direct outs, buss outs, other ways of getting signal to an IEM with or  without mute with or without EQ with or without gain adjustment.

Vocals vs. Godzilla

When you deal with a group of vocals however, it’s very important that what you’re doing at front of house does translate into the in IEM ears and floor wedges. For example, you have six vocalists and one of them goes “Godzilla” on you and is much louder than the other five.   

At front of house you have to pull that one singer down to save the mix. (It’s a rescue operation!) You want that change to translate to the IEM mix (and floor wedges). So they get  fed off of a post fader group buss. (On most  consoles it’s not called a “group.”  It’s called a “buss.”)  On a buss, send every EQ change and every gain change that you make on the vocals does translate to the in-ears and it also translates to the floor monitors.

Similar issues anyone else using live wedges.

Note – do not let these people have stage IEM control boxes to mix their own mix. This basically becomes a second sound system, being run by a musician. You need control of all wedges or your mix will be destroyed by your other “sound people” on stage.

Floor Wedges  

You’ve got another anomaly you have to look at when you have floor wedges that are primarily giving keyboard and in some cases click cues to the musicians that aren’t using any ears, which most often  are the vocalists.

The question is do you make these pre fader or do you make these post fader? Now the prevailing wisdom would be make that pre fader because you wouldn’t want front of house changes to make it disappear. 

The reality, however, is that when you do that, the tonality in the front of house is constantly changing due to the unchanging monitor mix. If you pull a fader down on the keyboard FOH, the monitor bleed, which is a completely different frequency set and is out of phase and creating comb filtering is at a higher level than what’s coming out of the PA. Can sound pretty bad.

So the best solution is to actually keep a set of in-ears handy at front of house or a really good set of headphones, mix everything post fader – keyboards, guitars, everything else that’s going into the monitors.

You have to check the monitor mix  levels by soloing up that bus to see what the blend is and make sure that with vocals there’s enough keyboards and other instruments  there that they can get all of their frequency cues and all of their timing cues from the click track.  So you want that to be there but not overbearing. 

Streaming

The feed to streaming is a similar scenario. Drums in the live mix do not need to be that loud in the house. Kick drum does, but unless they are in a separate room, most everything else does not. However, what needs to go to the streaming mix is all of it.

So you need to create  a buss mix  that allows you to get a better mix to streaming than you would get if you just left it alone.  This has to be post EQ fader etc….. so your FOH changes affect that feed. And, you have to listen to it once in a while. Okay, so that kind of ends the basic session there about big gain structure, etc…

Also assign a good gain limiting device to that bus overall, and set it so on quiet songs it is barely set on working, on RMS. Use one that simulates a vintage comp/limiter.

It’s still not a good choice compared to mixing on a separate console, but if you pay attention it can work.

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