Understanding Decibels

[TrickyBoy]

OK...

 

This might be a stupid question and sorry if it is, but I'm confused...

 

So, I've been a semi-professional guitarist, on and off, for 20 years, but I've never been much into understanding the technology. I've generally been a "sounds good enough" kind of guy. That has recently changed.....

 

Up until 2 months ago I was playing with a cheap Excaliber 12 Watt Amp (1x12 Combo) and a Line6 HDPOD500. Well I fell in love with the Z-Wreck and bought the head/2x12 cabinet 2 months ago, and I'm now in the process of finalizing an all analog boutique pedal board. And I have to admit, as much as I used to argue that tone wasn't that important, it's night and day how much better my tone is now...

 

Anyway, that's not the point of this post. I have a decibel meter, though if I can't pretend I understand what I'm measuring. I got it because I switch between two guitars and I wanted to make sure they were the same volume. And I've done a really good job at this. However, my quandary is this... I'd set the meter a couple feet from the speaker, and generally at "stage volume" it would read about 100 dB. Now that I've switched the the Z-Wreck, I got it out and when I got the tone I wanted, I expected it to be higher dB's. To my surprise, it's right about the same. But it sounds SO much louder. So I guess my question is "are dB's all equal?" Or does 2x12 vs 1x12 make the Z-Wreck seem louder? Or is there something else at play? Or is there more than just dB's that is involved with the overall volume that you hear?

[DeepEnd]

A decibel is a unit of acoustic energy. A difference of 10 dBs normally seems "twice as loud," all else being equal. I suspect the Z-Wreck cab is producing a fuller range of sound than your old combo amp. More low end energy especially tends to make music seem louder. If your new rig puts out more total energy it's going to seem louder in general. Your decibel meter is probably "A-Weighted," which means it measures sound around 2KHz or so preferentially (https://www.noisemeters.com/help/faq/frequency-weighting.asp). The two amps may indeed be putting out the same level at 2KHz but not across the board. If you can set your meter for C-Weighting you'll get a better picture.

[1001gear]

I'm not sure if this is an actual thing but projection might come into play?

[WRGKMC]

Decibel meters are not all the same. They are what you call weighted, which in simple terms, means some will detect its peak decibels at different frequencies. The categories are A,B,C,D & Z Your cheap meters have A weighting which ranges from 30~ 4000hz. The peak decibels will likely read on an A weighted meter most effectively between 500~2K. Effective Guitar frequencies range from around 100~5K.

 

If you use the meter to adjust overall loudness it should work fine. I'd likely keep it at about 1 meter from the source. The meter probably wont detect high frequencies very well. If you have allot of treble dialed up the amp may actually be louder then the meter can detect. Bass frequencies of course carry most of the power. Higher frequencies carry much less but our ears are most sensitive to our normal speaking voice which is in the 1~3K ranges

 

Using a DB meter can work somewhat well for getting your foot pedals set up. You can compare the pedals gain levels to them bypassed and get them somewhere in the ball park. You usually have to do some additional tweaking because "actual" loudness and "perceived" volume levels are something we have to deal with. Many guitarists like to goose their gain pedals up a Db or two so when they switch from playing 6 string chords to playing single strings the volume levels have a perceived match or maybe a bit higher so their solo's is boosted and matches the Vocalists volume level. Then when they switch back to chords their volume drops and "Backs" the vocalist.

 

If you have an exact Db match on lead vs chords this can be ideal for a sound man who mics the amp and uses a solo button for leads. A solo button boosts the mic gain up around 3 db so the player can be heard over the rest of the band. If you do your own sound and have fixed levels, or don't mic your amp, then giving your amp a little boost can work. Also the bigger the venue the more you may need to boost leads because the reflection can create a wash of reverb through the room.

 

Best you can do is use a really long cord or a wireless and stand out front and hear how you sound to the audience in comparison to the PA speakers. What the audience hears as even is what counts, not what the meter tells you.

[onelife]

. . .

Best you can do is use a really long cord or a wireless and stand out front and hear how you sound to the audience in comparison to the PA speakers. What the audience hears as even is what counts, not what the meter tells you.

 

Instead of turning up, why not have everyone else back off and get out of the way of the soloist? That way you don't get volume creep as the show goes on.

[Phil O'Keefe]

I know I've done this in other threads, but I'm just going to leave this link here...

 

http://www.harmonycentral.com/articles/wattage-speaker-efficiency-and-amplifier-quotloudnessquot

 

 

[WRGKMC]

You can do that too but I think you're just seeing the glass half empty instead of half full. It makes no difference so long as the levels are right for the music.

 

The thing is however, guitarists and bassists don't set the overall volume level, the Drummer does. Everyone else simply has to fall in line with his volume level sets.

 

Even an good drummer who knows his stuff can only back off so much before the character of the music changes and the energy levels drop. A medium rock song sounding tight and punchy can wind up sounding wimpy elevator music.

 

Lighter sticks, smaller drums, padded heads work sometimes but if you've worked with allot of drummers, you'll find you don't make friends trying to micro managing his playing. I've worked with at least 40 good drummers over the years and after the first few you learn most have fixed ideas on how they prefer to their instruments and if you don't like it you can take a hike and find someone else. Getting them to change their playing habits like asking them to play softer isn't like turning a knob down for a guitarist. When you tell a drummer to turn down, his energy level usually goes down and his bad attitude level goes up.

 

Cant blame them either, Drums are very physical and most players tie power and emotion together. I've played with a few who could make that separation, mostly Jazz drummers who have some formal training and understands the difference between pianississimo and a fortississimo when it comes to playing dynamically. Unfortunately those players are in demand and harder to come by.

 

Anyway, the people I play with have been playing as long as I have and volume creep hasn't been an issue since my high school days 40 years ago. Most of that was caused by us not knowing two instruments couldn't occupy the same frequency ranges. Once we knew we had to have separate frequency ranges to have equal volumes and still be heard, those volume wars ended.

[TrickyBoy]

That was really informative. Thanks.

[onelife]

Good drummers can groove without being overly loud.

 

I find getting out of the way of the other players is much more effective than trying to play over each other.

 

When I was young and starting out a retired clarinet player told me "if you can't hear the soloist then you are playing too loud."