Fig. 1
Hello, and welcome to another Dojo. Last month, I focused on the history and development of the VU meter, and then defined some of the more confusing terms regarding decibels (dB, dBu, dBA, and dBSPL), as well as various ways to measure loudness and amplitude. I also asked: “Is a 100-watt amp twice as loud as a 50-watt amp?”—the answer shall be revealed presently. But first, I’m going to focus on a relative newcomer to the scene: dBFS. Tighten up your belts, the Dojo is now open.
More dB Terms?
What is dBFS? It is relegated to the digital realm, and whenever you hear this term, I want you to remember the following joke: “What sounds better than digital distortion? Everything!”
You see, dBFS (decibels full scale), is the unit of measurement for amplitude within a digital system (such as your DAW), and all digital systems have a maximum peak level before clipping (overload) occurs. A reading of 0 dBFS is the highest signal level achievable for a digital audio. Unlike the analog world, where brief moments of being “in the red” of the VU meter won’t adversely affect the audio, dBFS digital “overs” are squared off (or, mercilessly guillotined), and clipping occurs. It sucks, and is to be avoided at all times. The audio irony is that, when or if you see those two teeny-tiny rectangles above your master fader turn red (Fig.1), you’ve got big problems, and need to turn everything down in order to avoid clipping when you bounce/render your mix.
Is a 100-watt amp twice as loud as a 50-watt amp?
I’m going to answer this by helping you learn some more about how we perceive loudness, and I’ll be using dBA as our mode of measurement. Because, as you’ll recall from last month, using dBFS treats all frequencies equally, and that’s not how the human ear works. In other words, our sensitivity to frequency, sound level, and duration vary across our general range of hearing (20 Hz to 20 kHz). Specifically, our hearing has evolved to be most sensitive between the approximate ranges of 2 kHz and 5 kHz.
Using this range as a yardstick, audiologists agree that 3 dB (up or down) is the minimal detectable change the average person can hear. In my experience, in a critical listening environment, I—and anyone else in the studio—can easily hear 1 dB changes—this especially happens when mixing and mastering.
“The audio irony is that, when or if you see those two teeny-tiny rectangles above your master fader turn red, you’ve got big problems.”
However, to increase the sound, 3 dB requires twice the power (intensity). An increase of 6 dB requires twice the amplitude (voltage), and an increase of 10 dB sounds to the human ear twice as loud. Stated another way: +3 dB is 2x the acoustic power, +6 dB is 4x the acoustic power, and +10 dB is 10x the acoustic power. For those who are mathematically inclined (I am not), here is the decibel formula: dB = 10log10 (S1/S2), where S1 and S2 are the intensity of the two sounds.
Remember when I said last month that decibels are based on a ratio, and they are logarithmic? Now we want to look at the relationship of decibels and power. What is the international unit of measurement for power? It’s the watt (W), named after Scottish inventor James Watt (1736–1819). Check out these relationships:
| Number of Decibels | Relative Increase of Power |
| 0 dB | 1x |
| 3 dB | 2x |
| 10 dB | 10x |
| 20 dB | 100x |
| 30 dB | 1,000x |
| 50 dB | 100,000x |
| 100 dB | 10,000,000,000x |
So, let’s say we have a lovely vintage 4x12 cabinet, and we have two amps that we are going to run through it—a 50-watt head and a 100-watt head (both with matching impedance). Using this relationship, we can answer our previous question! Our 50-watt head is the starting point and baseline for measurement.
Let’s say that, as we play our latest epic jam through our dimed 50-watt head, our drummer comes over and says, “It’s not loud enough! They can’t hear it in the parking lot of the Waffle House across from the stadium!” So, we switch to the 100-watt head thinking it will be twice as loud. Wrong! Go back and look at the chart above. We’ve doubled the power (2x) and that only gained us a paltry increase of 3 dB! That’s right, a 100-watt amp is only 3 dB louder than a 50-watt amp. So, what would be twice as loud? Do the math—we’d need a 10x increase in watts (50 W × 10), so a 500-watt amplifier (or 10 dimed 50-watt amps, simultaneously) would be needed! (Yes, but do they go to 11?)
Until next time, namaste.
- How to Record Like the Beatles ›
- Two Mics. One Cab. Infinite Tones. ›
- Why You Should Record An Album ›
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Peterson StroboStomp Mini Pedal Tuner
| The StroboStomp Mini delivers the unmatched 0.1 cent tuning accuracy of all authentic Peterson Strobe Tuners in a mini pedal tuner format. We designed StroboStomp Mini around the most requested features from our customers: a mini form factor, and top mounted jacks. |
But by gosh, if delay—and its sister effect, reverb—haven’t always been perfect for the music I like to write and play. Which brings us to the Fishman EchoBack Mini Delay. The EchoBack, along with the standard delay controls of level, time, and repeats—as well as a tap tempo—has a toggle to alternate between analog, tape, and digital-delay voices.
I hooked up my Washburn Bella Tono Elegante to my Blues Junior to give the EchoBack a test run. We love a medium delay—my usual preference for delay settings is to have both level and repeats at 1 o’clock, and time at 11 o’clock. With the analog voice switched on, I heard some pillowy warmth in the processed signal, as well as a familiar degradation with each repeat—until their wake gave way to a gentle, distant, crinkly ticking. Staying on analog and adjusting delay time down to 8 o’clock and repeats to about 11:30, some cozy slapback enveloped my rendition of Johnny Marr’s part to “Back to the Old House,” conjuring up thoughts of Elvis trapped in a small chamber, but in a good way. It sounded indubitably authentic. The one drawback of analog delay for me, generally, is that its roundness can feel a bit under water at times.
Switching over to tape, that pillowy warmth evaporated, and in its place came a very clear replication of my tone—but with just a bit of the highs shaved off the top. With the settings at the medium-length mode listed above, I could see the empty, glass hall the pedal sent my sound bouncing down. I heard several pronounced pings of repeats before the signal fully faded out. On slapback settings (time at 8 o’clock, repeats at 11:30), rather than Elvis, I heard something more along the lines of a honky-tonk mic in a glass bottle. Still relatively crystalline, which actually was not my favorite. I like a bit more crinkle—so maybe analog is my bag....“That pillowy warmth evaporated, and in its place came a very clear, pristine replication of my tone—but with just a bit of the highs shaved off the top.”
Next up, digital. Here we have the brightest voice, and as expected, the most faithful repeats. They ping just a few times before shifting to a smooth, single undulating wave. When putting its slapback hat on, I found that the effect was a bit less alluring than I’d observed for the analog and tape voices. This is where the digital delay felt a little too sterile, with the cleanly preserved signal feeling a bit unnatural.
All in all, I dig the EchoBack for its replications of analog and tape voices, and ultimately, lean towards tape. While it’s nice having the digital delay there as an option, it feels a bit too clean when meddling with time of any given length. Nonetheless, this is surely a handy stomp for any acoustic player looking to venture into the land of live effects, or for those who are already there.
