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MAKE FRIENDS WITH YOUR AMP A HANDY E-GUIDE FOR UNDERSTANDING THE FEATURES ON MODERN BASS INSTRUMENT AMPLIFIERS BY BOB GOLLIHUR COURTESY OF Gollihur Music WWW.GOLLIHURMUSIC.COM All Material ©Copyright 2012 Bob Gollihur Page |2 W e 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, BLOBBYBLOBBY, THUD, THUD is not a good bass sound. FAMILIARIZE YOURSELF WITH WHAT TONE CONTROLS ACTUALLY DO The whole point of this exercise is this: 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 e-guide, but we’re going for general knowledge and results in these exercises, so pardon the “layman’s terms.” 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. For instance, turning the bass knob all the way up and the treble all the way down sounds like listening to a song being played in the next room with the door closed. Tone controls split the spectrum of sound into chunks, sort of like the piano keyboard splits in the image to the right (not precise, the drawing is only to illustrate the concept). The controls let you boost or cut those frequency bands. The other drawing is the frequencies of some notes on the upright (or electric) 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 (aka the fundamental). There are also overtones (aka harmonics) above that note that give it character and clarity. Severely cutting 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. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |3 TURN THEORY INTO PRACTICE AND ANALYTICALLY LISTEN TO THE EFFECT OF EACH KNOB 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, usually the right-most Graphic EQ slider or knob), 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! Remember: 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 GIGS LESS OF A HEADACHE I suggest that you consider developing what I call a Reference Sound. My 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 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 for easy, well… reference. Most of my on-gig adjustments then only involve tiny adjustment to bass, to suit the room’s inclination for boominess, and/or a boost in the midrange for clarity. One final suggestion on the subject of EQ. 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. Shorthand: The commonly seen “Smiley-Face” EQ might sound great with your head directly in front of the speaker, but in the audience it will be all “rumble and click.” Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |4 Now we move on to advanced features that you’ll find on many amplifiers and preamps and how they can further help your sound… Let’s cover 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. PREAMP (INPUT GAIN) AND MASTER VOLUME CONTROLS These 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… “Gain Staging” 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 signal. 1. 2. The Preamplifier takes the relatively low level signal of your instrument and pre-amplifies (multiplies) to a medium signal level that is at a high enough level to feed the power amp efficiently. The Amplifier then takes that stronger signal and multiplies it to an even higher level to power your speaker. 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. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |5 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 is not so “hot” that it overloads the input and causes distortion. You can draw an analogy to the limits of a person’s jumping height inside a room with a ceiling. Our friend on the left demonstrates the signal levels as you play bass; he’s a six foot tall guy in an eight foot tall room. As you play notes he leaps; the louder you play, the higher he jumps. If you play a note that makes him jump higher than the amplifier’s “ceiling” (maximum level)… well, let’s just say it’s going to get 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 experimentation 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 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 perceived overall volume. sounds like something brown. The bottom line is that an amplifier cannot get louder than it is designed to get, at least not in a “pretty” way. 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 the pre-amped, 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. 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 is certainly worthwhile. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |6 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 band mates. 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. 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 the EQ section of this e-guide and go back to the drawing board for some tweaks. A final word on “Too Much Bass Disease”: 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 all of their cool musical activities are obscured by the 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 Dark Side. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |7 MOVING ON: OPTIONAL SPECIAL FEATURES FOUND ON SOME BASS AMPS Earlier we talked about basic amp controls and specific methods for learning their effect on tone; we then moved on to the all important topic of “Gain Staging,” and discussed some of the tools relevant to that. Now let’s get to the real “toys” – the additional features on some more complex amps and external preamps that affect your sound, including parametric EQ’s, Notch Filters, Contour Settings, and more. As always, I encourage you to spend time with each one to analyze what they can do for you. The better we learn our amps, the more instinctive it will become to reach for the right knob to tweak when the need arises. A Parametric Equalizer (EQ) is form of tone control, like the “Bass/Mid/Treble” knobs covered in Part 1, but it can be a much more precise tool than a conventional tone control or even a graphic equalizer. Why? It allows you to choose the frequencies being boosted or cut, providing far more control over your tone than typical “fixed” tone controls. As illustrated in a piano image from part 1 of this series, an amplifier’s regular Bass tone control, for example, affects a wide swath of notes, or frequencies. Parametric EQs come in two flavors: Semi-Parametric and Full Parametric. A SEMI-Parametric Equalizer (at right, top) adds a knob (or multi-position switch) to choose the center frequency of the group of notes affected. YOU — not the amp designers — decide which notes are boosted or cut, as to better sculpt your tone. A “Full” Parametric Equalizer (at right, bottom) adds a third knob, which is used to adjust the bandwidth (this control is sometimes called “Q”). This lets you choose how many notes on each side of that center frequency are affected by the control – from a big wide “scoop” to a small slice. As with other tone controls, I’d suggest learning what these do by listening — but you can always reference actual bass note frequencies at our FAQ on “FREQUENCIES: What are the frequencies of bass notes?” I love these equalizers for the incredible flexibility they bring. They’re great for correcting flaws, such as frequencies that are louder in some performance spaces, as well as more precisely enhancing midrange presence and detail without sounding like you’re playing through a telephone. Notch Filter: A Notch Filter is similar to a 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 (like a “wolf tone,”) 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 all of the neighboring notes and the quality of 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. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |8 High Pass Filter – aka Low (Bass, Sub-Bass) Cut Filter, Subsonic Filter, Depth Control – The counterintuitively named “High Pass” Filter is so-called because it lets high frequencies pass. And, like the black knight, it 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 kill tone-robbing 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 may taste 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 (for instance, whether you’re stuck in a corner). Want to know more? Check out our FAQ about High-Pass Filters. Enhance, Shape, Contour… These 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 the 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 also 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 the beginning of this e-Guide. A FEW OTHER RELATED TOOLS 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 sound waves (we’ll visualize it as “air” for the sake of easy comprehension) from your bass into the room, and the vibration of your amp’s speaker also pushes similar “air” out into the room. A Phase Switch (also called a “Phase Reverse”, “Invert Switch,” etc.) reverses the signal’s phase, so when you play a note, the speaker more or less pushes air “in” while your bass is pushing out (and vice-versa). Reversing phase may or may not result in a big change to your sound. But since it is the opposite from your bass’ vibrations, it doesn’t “couple” with the bass and make your bass vibrate more. In practical use, the use of reverse phase may help you gain a little more volume before you get 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 or balanced tone. 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. Active noise-cancelling headphones use this principle of phase reversal by reproducing what they “hear” (on built-in microphones) in reverse phase, thus effectively “cancelling” the sound in your headset. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR Page |9 Effects Loop This is a feature for inserting various sound-changing “effects” devices, typically pedals (reverb, delay, chorus, etc.) 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 (“mixes it with”) the original signal. Usually you’ll have a control that lets you choose how much of the affected signal to “blend” with your original bass sound. If you don’t know which you have, plug an unused cable into the Send jack while playing; if you can no longer hear your amplified bass from the speaker, it is a series effects loop. Instead of using a loop, many players choose to put their effects boxes, or sometimes tuners, between the bass pickup output and the 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 (Direct Injection), is usually a XLR (microphone cable) 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; 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. I hope that you have found at least some of this information helpful. Just remember that the whole idea is not necessarily to become an expert on the technical aspects of how your amp works – it’s to become comfortable enough with the various features so that you can quickly know exactly what needs to be adjusted to accomplish the task at hand (whether it be to squelch feedback, improve your “cut” in the mix, get a better tone, etc.) As such, I’ve tended to oversimplify most of the topics for easy digestion, and write using common words rather than jargon – so that even if you’re a relative newbie to amplification, you won’t be overwhelmed by the information and “tune out.” In short: what's written here is by no means the authoritative absolute answer, I am not the world's greatest authority on bass (not even close), amps, or on anything else for that matter. I hope the information and opinions here are helpful to you; that's the point! As always, please feel free to contact me at Gollihur Music if you have questions not answered here – if I don’t know the answers, I’ll help you find them. People who are already associated with Gollihur Music will recognize that this e-Guide is a compilation of several “blogs” I published over several months in our free Gollihur Music Newsletter, which we send out to our friends and customers every couple of months or so. It also contains product reviews, special offers on upright bass gear, lessons, and more – why not stop by and sign up? (We won’t SPAM you or share your information.) Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR P a g e | 10 ABOUT THE AUTHOR Bob is a self-proclaimed Bassic Bassist, with no claim to fame or particular proficiency – although he has been playing and gigging upright and electric bass since the early 60's. He'll also wink, and tell you that he recognizes the fact that after so many years, he should be far better at it. Since shortly after his first paying gig in 1963, he's had one ear focused on his bass, and the other on amplified sound and electronics. Bob has always been the "Gear Guy" in the band, fond of designing and building custom speaker cabinets as well as amp and pedal kits. Over the years, he's also built his own pickup and mic systems, and has consulted with several of Gollihur Music’s gear manufacturers and other bass players over the years. In the early 80's, he wrote bass-oriented articles for Guitar Player magazine (before Bass Player existed), including one on custom Bass Bi-amplification. While he does not consider himself a tone guru, he is definitely a huge fan of chasing “The Sound,” and explains "It's taken me many years to learn about – and become conscious of – the many facets involved in getting my sound. I'm happy to share my experience to help other players achieve their goals." ABOUT GOLLIHUR MUSIC We are the Family Music Shop Dedicated to the Upright Bass. Since 1997, we've proudly offered a varied line of Pickups and Microphones, Preamps, and Amplifiers for Double Bass at very good prices. Over the years, we've added Upright and Electric Upright Basses, Parts, Strings, Cases and Stands, Bows, and many other useful, quality products for bass players. You benefit from shopping with us because our experience and focus means that you get real answers to your questions, from bassists! Our product descriptions are in-depth and detailed, because they are most often based on our own use of the gear, rather than the generic "manufacturer blurbs" you'll find on most other websites. We only carry gear that we would (and often DO) confidently use ourselves: anything we consider selling has to pass the "Bob & Mark Test" -- or you won't see it here. Our secure website is available 24 hours a day for your ordering ease. And we're committed to keeping products in stock; we ship most weekday orders within 24 hours of being placed, and provide you with tracking and post-purchase support. And our many "extras" - like installation guides, product-specific tips, and even cool BASS stickers for your car - are included at no charge! And We're More Than Just a Store. The Gollihur Music crew is happy to offer lots of useful, free resources on their website. You'll find answers to lots of Frequently Asked Upright Bass Questions in the FAQs section. Bob's Double Bass Links have been on the web since 1996, and include over 900 links to upright bass-oriented sites. Our Luthier Directory provides contact information for bass makers and repairpersons all over the world, so you can find someone in your area to work on your bass. Have a bass to sell? We also have FREE Upright Bass Classified Ads. Make Friends With Your Amp – by Bob Gollihur Courtesy of Gollihur Music • www.GollihurMusic.com • ALL MATERIAL ©COPYRIGHT 2012 BOB GOLLIHUR