Since one of my (purported) skills is broadcasting, every so often a reader wonders “Why not do an STS article on how to have a super home sound system?
Well, OK, this can be really short (“do what sounds best to you”) or really long. Which begins like this:
Inputs & Speakers Matter
Long ago, in broadcasting days, my 1971 home stereo consisted of a good belt drive turntable and a high-end ($150) Empire cartridge and low-mass needle. It was head and shoulders above the QRK turntables and more robust gear we used in studios. Because DJ’s were (and still are) wild people and didn’t understand about delicate needles…
The other thing was about speakers. I had huge University Presidio’s, Made of teak and gorgeous. After a few years (and neighbor-pissing volume often enough) the cones were rebuilt with upgraded high flex cones.
People from the radio station would come over and comment on how dynamite the speakers sounded. Surely, I must be driving it with a big chrome plated Macintosh or Fisher tube amp?
Nope. But here is where today’s lesson in sound begins. Inputs and Outputs are most of the game.
Just like ham radio. It ain’t the light-dimming, power hungry 3-kilowatt afterburner amplifier that gives you a great signal. No sir. It’s the dead-flat, broad banded antenna perfectly matched and ground that can turn a mere 20-watts into a screamer. Sound has a few built-in Simple Truths like this. Speakers and inputs.
My (back then) amplifier was a simple Lafayette 40 watts RMS per channel. Again, many of the Amazon ads for 3,000 watts of *music power* don’t mean crap. Give me a 100-ohm resistor with a 4- or 8-ohm value, a signal generator, and let’s see how well a sine wave warms it up.
Best Speaker Configuration
Speakers are like blondes. Everyone has an opinion about ’em. Some people swear by one brand, or that one over there which just had a good write-up. Nonsense and poppycock, mostly.
In the two corners at the front of my little home studio are three (cheap) speakers on each side. These are in the tri-amped configuration. People who have single amped a serious sound room are not playing with a full deck, or a full budget,
When you have a speaker, we know a low-frequency A/C current comes out of the speaker terminals on whatever amp. With the volume up, this can approach the power handling capacity of the speakers and amps. Neighbors will begin calling you and threatening to call the cops.
When the cops arrive, you can explain you were just doing “due diligence” prior to either bi-amping (two amps) or “tri-amping” (3 amps) on each side for your front mains.
If you look at the three speakers above, you will see that a single audio line for the (R) front drives:
- A 10- or 12-inch Pyle self-powered sub-woofer.
- And a lovingly re-capped 60 watts (RMS which is God knows how much in phony “music power” these days)
- One channel of the (R) Crown amps drives a Bose Series II which I like the sound of for mid-range power.
- The second (R) Crown amp channel drives a surprisingly good four horn mobile tweeter stack.
- This is then mirrored on the (L) left front.
This is exceptionally clean sounding up in to the 105-110 dB range. The EPA hearing protection levels begin after an hour at 86 dB which is modest “loud” volume. 100 dB is powerful opening of a concert with occasional drum and horn passages to 105-110 db.
We’ve seen +120 dB here, but there may have been alkyhaul involved.
Tri-Amp Sounds Different?
Oh, you bet. Because when your source is pressing out two tones, say 100 HZ and the amp and speakers are near max, there is little support for an even higher sound level at perhaps 2000 Hz. The effect is to lose clarity somewhere along the line.
The best woofers I ever used were at the MusicMaster turned Pinnacle College sound studio that used to be in Burbank when I ran that shop. A legendary Quad-Eight analog mixing deck and each side of that room had 16-inch World War II speakers that were used to scare rodents out of English grain storage units during the war. And 200 watts per side for these sub/woofs.
With tri-amping, everything can sound as “present” and “bright” and powerful as you care to dial in. We’ll get to that in a sec. But first?
The Perfect Sound Room?
There is almost no limit to how far (and how utterly grand the speakers in a good room can sound. I remember going through one of the (was it Joiner-Rose designed?) studios in Portland, OR. There were not two parallel walls in the place. The “mains” in the mixing rooms were mounted on chromed 2″ pipes sunk 20-feet into the ground and buffered from the concrete pad under the room with rubber mats. Custom made, of course.
These purpose-built rooms “clapped out” great. Quietest room outside of Apple London at the time, because no two surfaces were parallel, the clap of hands anywhere would quickly fade off. Evenly, all over the room.
A good article on getting the room itself to sound good – regardless of equipment and speakers – is You Can DIY! An Introduction to Measuring Rooms.
Around here, we’ve resigned ourselves to having some big mid-room low frequency standing waves. To sniff these out, a simple dB meter, like this one, can be walked around the room while feeding tone into the room at a suitable (90 dB kind of) level. At very low frequencies. Long standing waves are at low frequency.
You can buy a simple meter like this one, off Amazon, for under $20. They have a high capture (max, hold) which is also out on the shooting range when you’re dialing in a…um…let’s not go there, shall we?
For really good studios? 30 dB is a nice noise floor target. When I adjust for recording, we get down into the 35-40 dB range. Not an anechoic chamber, lol. Down in these regions, even a computer fan you never noticed before will become a major PITA to silence.
Ultra-filtered power for condenser mics – we are on the upslope of complicated now. You know about phantom power, right?
For more serious room measurements, we still use tones but then walk the room with a Linux laptop, and the input to Audacity and a Behringer linear reference mic. They are not expensive.
So, that’s the basic geometry of the room. Now for the details. I will keep these brief and we’ll do more on gear, software, recording and developing work flows next week. Sound is a very complicated subject.
Remember, sound in my (crackpot) theories can bend space-time at the right frequencies.
Studio Construction Notes
These are just some of the basics – depending on how far you want to go with things.
- No parallel surfaces.
- Two sets of framing lumber. 2X4 and 2X3 with an air gap.
- Different thicknesses of sheetrock. 5/8 rock on one wall and one or two layers of 1/2 inch on the other.
- No single pane windows.
- Double or triple pane with all different thicknesses of glass (STC rated, of course) and never parallel. 15-degree difference between panes, please.
- Full gasketing of doors.
- All of which are solid core. On closers.
- All of which require an “air lock” arrangement so that there’s a whole sealed dead space. Two doors back-to-back.
- Walls are filled with sand. Cheap home builders can use double-batted fiberglass.
- This means after basic electrical wiring, some wires will show. We all need something to trip on, right?
- All walls will have some anti-bounce treatment. This is where glued on foam comes into play. Auralux.
- If you’re plagued with bass issues, baffles in corners, floor to ceiling.
- No resonances from the floor. If wood, underlay with solid foam. If concrete treat with throw rugs and moving mats (which are cheap and work great).
- Lighting must be silent.
- Air conditioning must use anti-tumbling mats and large low speed air outlets.
- Don’t forget to sound condition air returns, as well. You don’t want a pressurized studio.
- Extra overhead wiring for lighting, too, if you plan to shoot a video someday under something other than available or handheld lighting.
On the air outlets, you can feed a modest room with an 8-inch high-pressure air-conditioning line, but then come down into a 10–15-foot section of 12″ diameter sound “boot” – with a couple of right angle or greater turns if you can fit them in.
This slows the air, so it stops tumbling which is where rumbles down in the 5-30 Hz range come from.
Last but not least, the air gaps have to all be filled. Studios I put in had all of their floor and ceiling plates set in adhesive and then caulked to ensure air couldn’t transit. Air movement allows sound movement – and a serious recording room has no air exchange.
Few will have the time or resources to really build a sound room. I’ve taken the time here because, well, I’m partly crazy in case you missed it. But serially, if you have a room and you can even hang a few moving mats over walls and cheap carpet on the wall, it will pay off.
Or do what we did in broadcasting: Get some Sennheiser earphones (“cans”) and use them.
As a newbie to this studio stuff, there are three types of earphones. The “buds” that go in your ears. Not a fan.
There are the “on the ear” cans, but like an ill-fitting CPAP mask, if it leaks air (see construction notes above) it’s not perfect. You really want the old-school full over the ears and sealing well variety.
Sennheiser makes a very good foam, open-back, on the ear type, but the first time you get feedback from a monitor circuit being too hot and you blast your ears into next Tuesday, you’ll thank me for trying to save your ears in advance.
The profound truth of our “studio” here was it started off as a deck. Then we put up a half-roof so we could sit outside in the rain. Then the weather got cold. So, I framed it in and put in some windows.
Then asked Elaine “What should we do with this here new room?”
“Your toy – do whatever you want with it.” That’s one hell of a trusting woman. But now she likes mashing on drums, too.
Not a real studio…but a nice place to play and edit audio and video, do the odd Peoplenomics podcast back when and now even setting up for video editing…
P.S. if you put in a drum kit, be sure to get a bunch of small beanbags to put on the heads. If the drums are tuned and the sound levels up, the drumheads will resonate and piss you off when listening to longhair music.
Yes, of COURSE you loosen the snare brushes, too!
Next Sunday: DAWS, desks, software and workflows. After that, Radio automation software and low power FM transmitters for home.
Homework assignment #2: Get your (Windows) PC rolling with a good wipe of hard drive(s) for cookies and such. CCLeaner.com. And then – to repair and speed up old, sluggish machines. use a C prompt (as administrator) and run:
c://> (or whatever your prompt is) sfc /scannow
This will make sure all needed Windows files are in place. Use the System File Checker tool to repair missing or corrupted system files (microsoft.com).
A really good computer for serious listening and recordings will have an i-7 or better, at least 16 GB RAM and hopefully dual SSDs. If you have a computer with an old mechanical drive, seriously consider an SSD update.
Last, but not least as long as we’re on the topic of “computer readiness” for serious audio work (and intermediate video editing) consider a low-noise sound card if you are planning to go analog from the computer to speakers without an intermediate FireWire device. Something like an ASUS XONAR SE 5.1 Channel 192kHz/24-bit Hi-Res 116dB SNR PCIe Gaming Sound Card with Windows 10 compatibility will pnly set you back about $45-bucks.
We’ll be covering the “audio chain” for recording as well as playback as we go.
Write when you get rich,