Tone/EQ Question

[doc540]

Although bass rig related, I think it's a general "live sound" question and, therefore, pertinent to this forum.

If not, well, I'm a dumbass and you can kiss my ass anyway cause I don't know where to ask.

(ahem)...Now, to the question.

I have my new bass rig wired up in the garage, and I'm messing around with the knobs (highly technical phrase), experimenting with different tones.

Why am I getting more gain and a louder low end output when playing the low "B" note on my standard tuned 4 string? I can play a chromatic, descending scale from the "D" position on my second (A) string down to the low "G" or "F" on my E string, and it really booms when I play the low "C", "B", and "Bflat".

I'm guessing there's a well known (but unknown to me) formula which explains the correllation between certain notes and frequencies.

[Tele-Bob]

Bass is a frequency nightmare for a live player. How many times have you finished a set thinking "man, my tone just isn't happening tonight" only to find that everyone else really digs your sound.

The reason for this is that a bass emits extremely long sine waves for it's low frequencies. Did you know that low E on a bass guitar emits a wave 28 ft long? So basically what this boils down to is that, if you're standing any closer than 30 ft to your rig than, you are not getting the full spectrum of sound from your rig when playing a 4 string bass. That said, if you're playing in a room that is 14 ft wide, and you're facing the wall, all the frequecies you can evenly divide by 2 relative to that 28 ft wave length, will be affected or even partially cancelled to a certain extent. Try setting up the amp in a different room and see if any of this changes. There are of course several other reasons for the conditions you state, but this is one example that not many people think of.

Secondly, do you have boost and cut knobs for each frequency knob? Very often, once you isolate a particularly boomey frequency, you can tame it by cutting the frequecy insted of changing it and sacrificing that part of the spectrum.

[doc540]

Ya know, for a dumbass you sure talk smart.




Thanks, TB, I knew about that sine wave thing and remember playing my Acoustic 360 with its bigmutha, folded horn 18" cab.
It wouldn't sound loud standing in front of it, but if I walked forward a ways, it would compress my diaphram like I was deep water diving. (Don't even think about making a diaphram joke.)

And, yes, I have a plethora of tone control from the treb/mid/bass knobs on the Yamaha PB-1, to the parameter eq, to a dual crossover if I decided to biamp. And, last but not least, each cab has a horn and adjustable pot.

But what I don't understand is why, for instance, with the bass tone control flat at 12 o'clock does the bass BOOM at the "C/B" position on the E string, yet the "G" and "F" notes don't BOOM with equal gain. What is it about the "C/B" positions that cause them to get low, fat, and louder?

[Tele-Bob]

If there is a "gain" or volume ring around each frequency knob on your amp you can control that problem. The cause is "sypathetic harmonics". This is a situation where things in motion tend to create actual harmonies with other animat or inanimate objects. One example is a car with a slightly imbalanced wheel that at certain engine rpm's causes great vibration when the wheel and engine become harmonized. The action of the two vibrating becomes greater than the whole of the two parts and a sympathetic harmonic is created.

Could be the cabinet having a sensitivity to the wavelength of B or C creating a sympathetic harmonic with the bass itself that almost acts like feedback. It could also be the specific frequency where the wood construction of your bass becomes most resonant and actually causes a low volume feedback with the amp. Whatever it is. it's tunable and can be resolved with the gain control on a given frequency knob. If you work at it a little, you should be able to create the same problem with almost any note on you bass.