Amp Recording Tip #4,567,882

[László]

Most folks like to put their amps and cabs flat up against/parallel to walls, and pile 'em all up next to each other.

But for recording, I don't think that's a great idea, and the smaller the room, the worse it will sound. This is because the speakers will be aimed flat at the opposite parallel wall, and sound will simply bounce back and forth between the two walls, exciting various unwanted room modes, causing phase cancellations at several frequencies, and generally generating mud and inaccuracy.

The best location to record an amp is to have it elevated off the floor, and away from walls and corners just for the purpose of getting accurate bass. Floors and nearby walls/corners cause artificial bass reinforcement. In home studios, that's a recipe for mud.

Having done that, it's also a good idea to place the amp or cab at an angle in the room. Experimentation will tell you what sounds best, but allowing the sound to bank a little can prevent the buildup of the most audible room modes by scattering the sound energy a bit.

In addition, if the room is in a typical home studio, unless you have plenty of bass trapping, keep the door to the room open if it's at all possible. This can relieve low frequency sound pressure levels in the room that can again muddy the sound. If you have adequate bass trapping, you can get away with a closed door and still get some accuracy without mud.

Foam on the walls is not bass trapping; it does almost nothing for low frequencies, and is meant for high frequency reflections. Real bass traps are pricy, but most home studios need them, and the smaller the room, the more they're needed. So it's good to know these tricks if you don't have the real deal stuff.

P.S. - Yes I know your mic is only an inch or two from the speaker grille. But it will still reproduce enough mud in a room if there is any to cause mixing problems later.

 

[andy474x]

Geez, this guy again?

Thanks for the tip Les, gonna be setting up a new jam room with a small recording setup in a few weeks. Moving to a new house (back in MI!!!), was thinking about some kind of shelf to put my cab on, maybe I'll take a page out of your playbook and get a cart with wheels.

Going for one of the Focusrite Scarlet units, with a SM57 and e906 to start. That rig and your pointers should help capture the many nuances of my extremely average tone and playing

 

[László]

Geez, this guy again?

Thanks for the tip Les, gonna be setting up a new jam room with a small recording setup in a few weeks. Moving to a new house (back in MI!!!), was thinking about some kind of shelf to put my cab on, maybe I'll take a page out of your playbook and get a cart with wheels.

Going for one of the Focusrite Scarlet units, with a SM57 and e906 to start. That rig and your pointers should help capture the many nuances of my extremely average tone and playing

I put the cab on an Isoacoustics stand, and put the stand on an Auralex Great Gramma decoupler. This puts the cab about 6 inches from the floor, give or take. This is still a little low, but Isoacoustics is coming out with a larger stand that can be custom sized, so I'll be migrating to that.

A shelf has to be attached to something that can resonate and interfere with the natural sound of the cab. What you need to do is isolate the cab from furniture and from the structure of the house.

I use a wheeled cart just for the head, which I separate from the cab for several reasons: First, I keep the head in my workstation area, so I can tweak it while recording. That allows me to put the cab wherever in the room it sounds best, or even stick it in my storage room when I don't want to hear it so loud (the storage room is very large so there's plenty of space for the sound to dissipate and I can close it off).

The reason I posted this thread is that I love yakking about this stuff. I'm really more of a sound/texture guy than a real guitar player. This lets me talk about audio and amps, both of which I love, without having to demonstrate my lack of skill on guitar!

 

[Boogie]

Another excellent lesson from Les! So, it seems the old school audiophile techniques of the '80s still hold true...isolation spikes on amp stand to be deployed. If I were doing anything - recording-wise - for real, I'd pull the cab away from my wall-o-cabs. Since my music area is so small, I have to be frugal.

Any suggestions in bass trap designs? Once I finalize my wall treatment and start on acoustic control, I'll want to do it right.

 

[veinbuster]

Thanks Les.

 

[László]

Any suggestions in bass trap designs? Once I finalize my wall treatment and start on acoustic control, I'll want to do it right.

Every room is going to present its own issues. If your room is small (not aware of the size of the one you're working with) bass trapping takes on more significance, as do high frequency reflections.

As sound bounces back and forth, you get phase cancellations, these are more likely to occur in a smaller room because sound tends to build up as it bounces off walls, and in a small room, the sound waves don't have to travel far. So the sound doesn't dissipate the way it does in larger rooms. Everything seems louder (this is why I recommend smaller studio monitors in smaller rooms, large ones not only sound too loud, but their low frequency energy often causes problems unless the room is acoustically very well treated).

This means that smaller rooms need more acoustic treatment than larger ones.

Another problem is that basement exterior walls are concrete or cinder block put up against earth. They're not going to absorb or pass through sound, they're going to bounce it back. On the other hand, interior basement walls (drywall and stud construction) are going to act as diaphragms, and allow certain frequencies to pass (mostly low frequencies). So that imbalance in the audio has to be accounted for with acoustic treatment as well, and truly mandates more bass trapping than one might ordinarily consider for an upstairs room.

One idea I've seen done in conjunction with good bass traps on the side walls is to load a basement ceiling with acoustical fiberglass, and instead of using ceiling tiles and such, stretch acoustically transparent cloth and tack it up as a ceiling material. I've also seen a closet used as a bass trap, where the doors are removed, layers of insulation are loaded into the closet space, and then acoustically transparent cloth is stretched over where the doors would be located.

The old "roll up a bunch of acoustical insulation and stick it in plastic garbage cans and cover with grille cloth" idea in the corners of the room actually works, but not as well as commercially available bass traps that are properly designed and built. The problem I find with circular solutions like this is that while they will do trapping, they don't cover wall surfaces or the upper part of corners. You really need taller traps with frontal surface area to notice improvement.

Thing is, these days you can buy fantastic bass traps from a company like RealTraps (there are others) for under $250 each for a real-deal 2x4 membrane trap with high frequency absorption and diffusion. Put one in each corner, and you've gone a long way toward solving the problem of bass buildup. Another trap mounted horizontally on the concrete basement side walls will not only handle low end, but do a nice job with absorbing and diffusing high frequencies.

These commercially available traps do a better job than one can do building one with some acoustic fiberglass and a framed board backing, but do-it-yourself are still better than nothing. My thinking is that by the time you've got enough materials to do the job properly, and factoring in the time, my time is better spent working for the money than building bass traps, because those guys do it better than I could, since they test their traps in anechoic chambers, and they're designed by acousticians. YMMV.

The recording booth in my old studio was a 16 x 12 room, and sounded awful. Ringy, overly bassy, with weird treble resonances. Before I discovered proper stuff I tried everything on the market. Foam made the room too dead; you need diffusion, absorption, and bass trapping. I was able to solve the problem with ASC products combined with foam glued to the ceiling, but it looked terrible. Still, it was just a recording booth.

On the other hand, my control room was very large, and it sounded great without much acoustical treatment. I was able to get away with ASC tube traps in the corners, and that was it!

Having moved, I still have a nice sized control room - 33 x 14. But the ASC stuff no longer worked - as I said, each room presents its own problems. This room isn't as wide as my old one, and has higher ceilings. Instead of drywall, these are drop ceilings. I expected them to work better since they're designed for sound absorption, but the room still needed more treatment than the old one. So a certain amount of experimentation is needed unless you know what you're doing.

 

[Deleted member 5962]

Good tips Les. I've seen everything from people actually putting some form of insulation between the stud and the drywall (like packaging foam or even neoprine) to not putting drywall up at all, but using insulation between the studs, then covering them with a cloth type cover. Used to be one of those crazy audiophiles, so I've seen it all. LOL

The only problem is, I missed tips #1 through 4,567,881. Could you please provide a link?

 

[László]

Good tips Les. I've seen everything from people actually putting some form of insulation between the stud and the drywall (like packaging foam or even neoprine) to not putting drywall up at all, but using insulation between the studs, then covering them with a cloth type cover. Used to be one of those crazy audiophiles, so I've seen it all. LOL

The only problem is, I missed tips #1 through 4,567,881. Could you please provide a link?

Hah! I guess I'll have to find a link.

I occasionally consult with a very successful audio post facility that uses acoustical insulation with cloth covered walls, that was designed by the famed acoustician and architect Russ Berger. Both the A and B rooms sound great and are very nice looking. On the other hand, each room cost a cool 1 million dollars to construct back in 1992, not including equipment.

So there's no limit on what you can spend on a room if you want to do things right, and today those rooms would cost even more.

 

[Deleted member 5962]

Les,

Hey look, I like you and all, but I don't think my wife is going to go for a cool mil to redo my music room! At least not if I ask her. Can you call and ask her for me? LOL

The ones I saw were done by audiophiles and were apparently not that elaborate. I've seen all sorts of non-parallel walls, alternative wall coverings, etc. Personally, all I will get away with is some insulation here and there and every once in a while when she's not there I leave the door open and drive the poor dog crazy.

 

[László]

Les,

Hey look, I like you and all, but I don't think my wife is going to go for a cool mil to redo my music room! At least not if I ask her. Can you call and ask her for me? LOL

The ones I saw were done by audiophiles and were apparently not that elaborate. I've seen all sorts of non-parallel walls, alternative wall coverings, etc. Personally, all I will get away with is some insulation here and there and every once in a while when she's not there I leave the door open and drive the poor dog crazy.

Heh. I don't have a dog to drive crazy, so I drive my wife crazy.

Someone's gotta go crazy, right?

 

[Deleted member 5962]

That is what the rock and roll is all about, my man! (And I drive my wife crazy too!)

 

[László]

That is what the rock and roll is all about, my man! (And I drive my wife crazy too!)

Exactly. I drove my parents crazy in the late 60s, drove my roommates crazy in college, and have driven my wife crazy ever since.

Rock and roll only counts if someone is annoyed.

 

[Deleted member 5962]

My parents built a new home when I was 17. All the bedrooms were at one end of the house except mine, which was at the completely opposite end. Any guesses why? LOL I really don't play THAT loud at home, but last night when I turned my amp off the TV (3 rooms away) was loud enough to hear in my music room. But, my lovely wife didn't complain, she just turned it up so she could hear it. I guess after 27 years she's finally learned to tolerate it. :dontknow:

 

[László]

I guess after 27 years she's finally learned to tolerate it. :dontknow:

My wife hasn't even learned to tolerate me, let alone my noise!