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The Gollihur Music Blog
Learn How To Play Your Amp!! (Part 3, continued)
Notch Filter: A Notch Filter
is similar to a Semi-Parametric Equalizer, but it's usually a tool that
is mostly used to "cut" the response of a very narrow band, like a single note. While
the parametric EQ is designed specifically to alter your tone, the notch filter
allows you instead to fix problems without making a dramatic change in your tone. So, if
your bass "favors" a particular frequency with extra response, or
there is a specific frequency that excites your bass into feedback,
you can dial in a reduction on just that frequency (note) to tame its response -- without
screwing up the neighboring notes and your overall tone. There are
some units that have more than one filter, so if you identify more
than one problem frequency, you can address them as well. Most units will also allow you to boost that narrow band to help out with a note or range of notes that are weak. In
most cases a Parametric Equalizer can be utilized as a Notch Filter,
by simply specifying a very narrow bandwidth of frequency, and cutting it.
High Pass Filter - aka Low (Bass, Sub-Bass)
Cut Filter, Subsonic Filter, Depth Control - The counter-intuitively named "High
Pass" Filter is so-called because it lets high frequencies
pass and, like the black knight, stops undesirables (in this case, boomy and muddy low frequencies) from passing,
starting at the frequency where you adjust the knob or slider.
This feature is a popular and very useful one,
particularly for upright bass players, as it can get rid of low frequency
rumble, and surprisingly, even subsonic sounds beneath the range of
notes your bass can play. While
we know a low E is 41.2Hz and a low B is 30Hz, it's best to set this
control by ear, because it isn't a sharp cutoff but gradual
reduction at the frequency you select. Using this control properly
can reduce "mud" and power-robbing, bass vibrating lows that make
your sound flabby... and encourage feedback. That satisfying thickness
on stage may mean your audience is just hearing rumble, and while that rich maple syrup tastes good, it's no fun to swim in it. Whether you need
to use one -- and where you'd set it -- will depend on your instrument and
pickup, as well as the stage and setup (like whether you're stuck in a corner).
Want to know more? Check out our FAQ about High-Pass Filters.
Enhance, Shape, Contour are
a sample of labels you'll find on some amp knobs, most of which
change the tonal character of your signal by boosting high and low
frequencies and cutting midrange. In my experience they seldom help
the sound of upright bass -- which in my opinion needs those midrange
frequencies to help define its character in a live performance mix --
and they often impart an "electric bass" or otherwise
generic tone. Switches or buttons like
Deep, Bright, etc. will also apply a specific tone
shape, which can sometimes be kind of radical for upright. Learn these tools by
setting all of the amp's tone controls at neutral, and try each of
them using the techniques discussed in Part 1 of this series.
These last few common amp features are not specifically involved in tone, but it's
good to know what they do:
Phase Switch: When a signal
is "in phase", a note you play pushes air from your bass into the
room, and the vibration of your amp's speaker also pushes air out into the
room. A Phase Switch (also called an "Phase Reverse", "Invert
Switch," etc.) reverses the signal's phase, so when you play a note the
speaker is "sucked in." Reversing phase may or may
not result in a big change to your sound. But since it it is
opposite from your bass' vibrations, it doesn't make your bass
vibrate more, because it more or less pushes air "in" while your
bass is pushing out. In practical use, the use of reverse phase may
help you gain a little more volume before feedback, but don't expect
a miracle. Another use for a phase switch is when one is using
two pickups, or a microphone with a pickup. Different devices can be
inadvertently wired in or out of phase, and if the phase is not the
same it will usually rob you of bass response. Noise-cancelling
headphones use this principle by reproducing what they hear (on
built-in microphones) in reverse phase, thus cancelling the sound in your headset.
If you suspect this condition, switch the phase on one
channel and listen to the result. The Euphonic
Audio Doubler has a Phase Knob,
which changes phase gradually from one extreme to the other, for
more precise adjustments.
Effects Loops are a feature
for inserting various devices, typically pedals, into your bass
signal. They come in two flavors, series
and parallel. Series interrupts the entire bass
signal and sends it through the device, so none of the original,
unaffected bass sound remains. Parallel gives you a signal to affect
but places it alongside the original signal. Usually you'll have a
control that lets you choose how much of the affected signal to mix
in with your original bass sound. If you don't know which you have,
plug an unused cable into the Send jack while you're playing; if you
can no longer hear your amplified bass from the speaker, it is a
series effects loop. Many players choose to put their effects boxes,
or sometimes tuners, between the instrument and amplifier input,
where it acts as a series loop might. It's best to experiment to see
which method works best for your specific purposes.
Direct Out, or DI is usually
a XLR jack that is designed for sending your bass signal to a PA
system or recording board. There can be various controls and
switches associated with this, such as the ability to send the raw,
unprocessed signal (often labeled Pre-EQ) or sending it after it is
filtered by your tone settings (Post-EQ). If you tend to fiddle with
your on-stage tone and volume settings it will be best to send the
Pre-EQ signal to the board, because your sound engineer may throw a
rock at you because they will have to make adjustments at the board
to compensate for your changes. For help with these settings if you
are in a performance or recording session requiring the use of the
Direct Out jack, talk with the person running the system — always
make friends with these people because they can make you sound
really good... or really bad.
Learn How To Play Your Amp!! (Part 2)
In Part 1 of this
series, we talked about basic amp controls and specific methods
for learning their effects. This article, Part 2 (of 3) covers the
tools (and concepts) for managing preamp gain, as well as some of the features which
can have an effect on preamp gain, like compression and alternate inputs.
gain) and Master Volume controls are two different controls
entirely, and how you use them can have a big effect
on your sound. This brings us to the important topic of...
Instrument amplifiers have separate preamplifier and
power amplifier circuits, and most have a volume
(gain) knob to adjust the levels of each. The way these knobs are adjusted can help -- or hurt -- your sound. What the preamplifier and
power amplifier do is pretty simple; they each multiply the bass
Generally speaking, if your instrument and/or preamp signals
(volumes) are too low and your Master (power amplifier) level is too
high, you're likely to have extra noise (usually "hiss" or "static.")
This is because the
percentage of good bass signal is low, so the preamp increases
general background noise in the signal along with the bass. On the
other hand, if your instrument level and/or preamp signal (volumes)
are too high, they can cause distortion, and other ugly sounds, as
they overwhelm the input capacity of the power amp.
- The Preamplifier takes the relatively low level signal of your instrument and preamplifies (multiplies) to a medium signal level that is at a high enough level to feed the power amp.
- The Amplifier then takes that stronger signal and multiplies it to an even higher level to power your speaker.
The trick to setting these controls properly is to find the "window" where the incoming signal has sufficient level to provide adequate volume without excess noise, but not so "hot" that it overloads the input and causes distortion. Our friend on the left demonstrates the signal levels as you play bass; he's a 6'4" foot guy in an eight foot room. Just as you play notes, he jumps, but if you play a note that makes him jump higher than the amplifier's ceiling (maximum level)... well, it's bloody.
Some amplifiers provide assistance: Peak, Overload, or similarly labeled lights, or a meter, are designed to tell you when you have reached the preamp's or amp's design limit. There is no "standard" (or if there is, nobody abides by it), so experience or experimenting should tell you just how ugly things get if that light flashes too much or stays on. To set my amp's input gain/volume control,
I will play my lowest note at the loudest instrument preamp and/or volume control level (play hard and continually) and adjust all the knobs to a point (all the way up on my bass guitar) and adjust the input gain control on my amp so that little light only flashes a tiny bit. That way you'll know you shouldn't distort, but still have a strong signal that will have a full sound. Listen carefully for distortion, because those lights and meters are calibrated differently depending on each amp's design, so you will know what works best for your particular amplifier.
The Straight Dope: if an amp has a power rating of 300 watts, even if you add more
preamplification (gain) to try to make it louder -- well, that's like
trying to put 400 gallons in a 300 gallon septic tank. The brown
seeping over the 300 watt limit represents the brown sound; let's say it sounds like something
The bottom line is that an amplifier cannot get
louder than it is designed to get, at least not in a "pretty" way.
Note: Depending on the amp, turning up any tone controls (bass, in particular) may also increase the effective preamp volume and can put you back into that distortion place, so compensate by reducing the amp's input volume/gain control if necessary. You can also use this to your benefit: if you are at the limit and still need more volume, roll off some bass and
then turn up a little; lower notes take more amplifier
power to reproduce than the highs and mids, and while you won't have
quite the "bottom," it may increase your percieved overall volume.
High/Low and Passive/Active are just two examples of labels you may find next to input jacks. Usually, the two different jacks allow for two different fixed levels of gain (see above) - one for the higher level of output for instruments with active preamplifiers or other electronics, and the other for lower-gain "passive" pickup arrangements. Unfortunately, there are no industry standards, but you'll find when you plug into one of them your bass will be quieter. That is the jack to use if you use an external preamp, or if one is built into your bass, meaning it is "active." The other is for basses with passive (no preamp) instruments, so it is "louder", offering more gain (volume). It is important when considering Gain Staging, above, so that your preamped, and therefore usually louder, signal does not overload the preamp inside your amplifier. Some amplifiers have only one input jack but may have a switch or button to decrease the input sensitivity; like with the jacks, your ears should tell you which to use.
(this blog continued on the Gollihur Music Blog page)
Learn How To Play Your Amp!! (Part 2, continued)
(continuation of part 2)
Drive, if included, is
usually a knob alongside the input gain control. The design goal is
to add character to the sound, such
as a tube saturation or mild to wild intentional overdrive, which can add
thickness and/or distortion to your bass sound. Some amps
include preamp tubes (aka "valves") or tube emulators,
and in that case a gentle dose of drive can add
heft to your notes. Off is
usually a good position for these controls if you want a pure
upright bass tone, but as with these other controls, experimentation
Compression, Limiter: An Upright Bass, when we pluck it
enthusiastically, can put out a huge burst of sound. Compressors and
Limiters soften and minimize that peak so it doesn't
overload the amp and/or annoy your bandmates. A Compressor can
usually do it more gracefully than a simple Limiter (depending on its
design), but a compressor's primary role is to squeeze the dynamic
range of the notes you play, so the quietest are a little louder, and the
loudest are a little quieter. You'll notice compression being used
when you watch a TV show -- where if the whispers were at their
original, actual volume, they would be hard to hear, and an
explosion in an action scene would make you jump out of your chair.
Amp makers may include simple single knob compressors, or less
often, a more comprehensive unit with up to four knobs for precise
control. Compression is not something generally needed for upright
bass gigs, except in special situations, such as for taming the
impact of rockabilly slap. Using compression well would take up
an entire article on its own -- so Study
user manuals, and experiment extensively before using. Rule
#1: If you can "hear" the compressor working (a "pumping" sound) it isn't set right.
Subtle = good.
A final word on Too Much
Yes, I know you are playing a bass, but don't automatically turn up
the bass or push the deep switch! If you've read my other writings,
you know this is a pet peeve of mine. This is due to the many
upright and electric bass players I've heard, or tried to hear, only
because they are so far down in the bassment
that their all their cool musical
activities are buried in rumble. And dammit, so many can't take the
constructive criticism or objective advice from their band members
or another bass player. "This is the way I play," or some similar
justification makes for the ugly status quo. And yes, I am like one
of those reformed smokers, because I remember my own past
self-defeating leanings towards the Deep
So check out these features (if available) on your amplifiers, perhaps it's time to adjust these controls and carefully listen to the results, so you are familiar with the tools at your disposal. All of these are potential ingredients in creating your Reference Sound. It may be
time to revisit
Part 1 and go back to the drawing board for some tweaks.
Part 3 - Parametric EQ, Notch Filters and other useful features!
One might ask...
...after over ten years with just
two amplifier companies, why have you added Genz•Benz
to the mix? As usual, it comes down to the same reason I first began
to use, and then sell Acoustic
Image and Euphonic
Audio's stuff. My never-ending "in search of" philosophy
brought me to another amplifier company, one that has some gear
unlike what we currently have, as well as some options for lower
priced amplification solutions for you, our customers.
I don’t know about you, but my pattern for gear adoption has usually
been driven by gig needs. Lately, electric bass gigs have been
mostly the blues on electric five string, leading me to look for a
more "tubey" sort of sound, not unlike the legendary Kern IP-777
tube preamp I used to pair with a power amp a dozen years ago... but
lighter and more compact. I should mention that its replacement, the
Euphonic Audio iAMP800, was to meet the need for a more articulate
yet still warm sound that could better cut through a dense mix, the
primary gigging needs at that time, and something I still admire and
Streamliner 900 will sit atop my new Euphonic
Audio NL-210 (coming out in late October 2011) 2x10 speaker
cabinets, as my electric bass guitar (and very loud URB/EUB) rig. The Acoustic
Image Contra (now Coda Series 4) remains my favorite for low
to medium volume upright bass gigs, and my compact EA
Doubler (or Streamliner)/EA Wizzy 10 rig will also still see
service for small electric gigs and some URB/EUB stuff. Just like
having two upright basses set up for different sorts of gigging
duties, having multiple rigs is also a good thing if you have the
resources to do so.(Yes, there are advantages to owning a music
store as well as having kids that are well past their college years.)
But back to the Genz•Benz gear...
Streamliner amps have three 12AX7 preamp tubes utilizing six
gain stages, so it is definitely very Old School Tone Land. Their
other amps, and most other “tube preamp” rigs on the market, have
but one tube in the preamp section, so the result can be far less
“tubey.” In fact, many of those amps seem to use their single 12AX7
tube more effectively in the marketing of the amp than in the actual
circuitry, but the Genz•Benz are not in that category. I should also
mention that all the Genz•Benz amps have tube preamps with solid
state power amp sections, and some even have circuitry to lend a
tubey tone to the power amp's limiter, so doesn't go splat when you
hit the wall.
Amps with tubes can have characteristics that can make them
desirable... or unacceptable. You have to decide what you want your
amp to do for, or to, your bass tone, and also recognize that all do
not offer the same characteristics. The perceived benefit of a tube
in the preamp section is a desired coloration of the sound, and
varying the level of tube involvement and gain level of the circuit
can take it from mildly warm, somewhat fat, or all the way to
overdriven nastiness... if the amp maker includes that ability. My
personal goal was more “heft,” with more body in the higher
register, with a subtle smoothness and softening of the overall bass
signal. The price you pay by going in this pillow-ish tonal
direction can be the loss of some of those edges to the note that
help it overcome a dense mix, as well as some jagged overtones that
exhibit the distinctive character of your bass.
Of the Genz•Benz lineup, the Streamliner’s three-tube
preamp definitely can deliver more of the pillowy, rich sort of old
school goodness, but can also get pretty intense and driven as you
advance the tube gain control. The Shuttle
and ShuttleMax single-tube preamp offers a slightly less intense
tube experience, not as thick or dense, but still pretty satisfying,
and is probably a better choice for players who want to play on both
sides of the fence. The Genz•Benz
ShuttleMax 9.2 is in a class by itself, offering both a tube
and FET (solid state) channel that you can mix for a little
sharpness in your cream, or move between tube and clean channels
depending on the gig or song. I have been swaying back and forth
between the Streamliner and ShuttleMax, as the surgical fine tuning
ability of the latter is quite attractive, similar to the Euphonic
Audio iAMP800 (now
iAMP Pro) I have used for the past several years.
In any case, one does have to step back and evaluate their personal
amplification goals. None are wrong, all are valid, and admittedly,
the differences can be quite subtle... especially in the mix.
We are indeed fortunate to have the variety of such highly capable
and precise bass amps and cabs from which to choose.
I should also say how thankful I am that Class D amps and Neo speaker cabs arrived just in time for the
decline of my ability to carry the heavy stuff. What a wonderful
This blog preempted "Making Friends
With Your Amp (Part 2)
", but it will be published shortly.
Making Friends With Your Amp (Part 1)
We spend hours learning and practicing bass, not to mention fussing for hours over strings and accessories, and agonizing over pickup and/or mic choices. However, the amplifier is often overlooked; we plug it in, twiddle the knobs a little bit, and that's often the end of it. It's important to understand every component of the sound you project. I've heard a lot of amplified basses; and sounding "bassy" = sounding "muddy." Mumble, rumble, blobby-blobby, thud, thud is not a good bass sound.
The whole point of the following exercise is: when you are playing and something just doesn't sound quite right, you will instinctively know which knob to adjust. This is a valuable talent well worth learning. I could use more technical jargon and scientific precision in this article, but we're going for general knowledge and results in these exercises.
Familiarize Yourself with what tone controls actually do
Most amps feature "tone" controls labeled Bass, Middle, and Treble; each control a band of frequencies. "EQ" (equalization) is a common way to refer to these tone controls. You are probably quite aware of the effect twisting those knobs has when you've adjusted a radio or stereo unit. Turning the bass knob all the way up and the treble all the way down has the effect of listening to a song that's playing in the next room with the door closed!
Tone controls split the spectrum of sound into chunks, sort of like the piano keyboard approximations in the image to the right (not precise, the drawing is only to illustrate the concept). Those controls let you boost or cut those frequency bands. The other drawing is the frequencies of some notes on the upright bass fingerboard. Speaking generally, the lowest (bass) control usually affects the frequencies around the fundamental of the notes we play on our basses. But, for example, when you play the open A string on your bass, you hear a lot more than just that original note (the fundamental). There are overtones (also known as harmonics) above that note that give it character and clarity. Severely cutting down the middle and high frequencies down (by turning down the midrange, treble or whatever your amp has) reduces your amp's delivery of those harmonics and can hurt clarity. Note: If you have a graphic equalizer with more than just "low-mid-high," those sliders are just further splitting the frequencies into finer slices - low lows, middle lows, high lows, low mids, middle mids, etc., so you have even more precise control over the total sound.
Turn Theory Into Practice and analytically listen to the effect each knobs has
If the acoustic sound of the bass is louder than the amp, you won't be able to evaluate the amplified sound, so let's get the amp up in the air so the speaker is close to ear level. Put it on a couple milk crates on top of a table, a wooden file cabinet -- anything that is a solid base for the speaker, but won't make distracting sounds when it vibrates. Turn the amp up to "Goldilocks Volume" -- not too loud, not too soft... just right. Too loud, and you'll overwhelm your senses and screw up your perception.
My recommendation for learning your amp is to play the same series of notes up and down the fingerboard, repeating as you make adjustments to the amp's controls, studying the differences. Before you start, set the amp to "flat" -- turning all the tone knobs to the middle, and locating any graphic equalizer sliders in the middle, too, so there are no boosts or cuts to any frequencies.
You can start with the highest frequency control (Treble, Highs, the right-most Graphic EQ slider), turning it all the way down, then perhaps to 9 o'clock, straight up, 3 o'clock, then all the way up. Listen carefully to the resulting changes in your sound (good and bad), and take your time! Let me repeat: the whole point of this exercise is, when you are playing and something just doesn't sound quite right, you will instinctively know which knob(s) to adjust.
Throughout this exercise, pay particular attention to midrange, low midrange, and upper bass controls. That's where acoustic bass lives, and the midrange frequencies can provide desirable texture and character. It's those controls that help to define the notes and tone of your particular bass. Don't try to do this all at once. You need to take breaks from this activity for the best results, as we all can suffer ear fatigue. However, once you spend significant time with your amp, you'll have a better feel for its capabilities, and the experience may also give you some new perspective on "your sound."
Create Your Own "Reference Sound" to make gig sound adjustments less of a headache
I suggest that you consider developing what I call a Reference Sound. My own definition of Reference Sound is where I set my preamp and amp controls when I first walk into a new situation. I know how it should sound from past experience, and it's a lot easier to start from a sound that you know "works" most of the time. Once onstage, you can then make minor tweaks, to adjust for unique room and stage acoustics. That's where learning your amp pays off -- you will instinctively know which knob to twist to quickly and easily fine-tune your sound to the stage and room. The controls of my Euphonic Audio iAMP (mostly used for bass guitar in my case) are far more extensive, so I actually took a photo of my Reference Sound settings and taped it to the inside of my rack case. Most of my on-gig adjustments then only involve tiny adjustment to bass and/or boosting midrange for clarity.
Let me make one final suggestion. Recognize that, like your bass, the exact sound coming from the speaker down there on the floor is not going to reach your audience over one hundred feet away intact. Someone standing right in front of your acoustic instrument would hear much more "detail", such as string sound, which is combined with and complements the sound from the body. By the time that gets across and bounces around the room, the higher frequencies can get "lost in the sauce." So, when you develop your reference sound, please give consideration to keeping some of that midrange detail that helps define the character of your own bass.
Next time, we'll talk about learning advanced features that you'll find on many amplifiers and preamps and how they can further help your sound...
Note: Bob's Blog (and additional blog posts) can now also be found on our Wordpress Blog Page.
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