
Compared to traditional speaker simulators, IRs offer much greater realism and depth.
I find the evolution of rock guitar tone to be a fascinating subject. A ‘59 Fender Bassman cranked up through its internal 4x10” speaker configuration sounds nothing like a Mesa Dual Rectifier through its oversized, closed-back 4x12” cabinet with Celestion Vintage 30s. And the speakers and speaker cabinet are a huge part of the equation—if you were to run the Mesa Recto into the Bassman speakers, you’d get a completely different tone, but one that leans in the classic Bassman direction.
The same thing goes for Vox tones—try running almost any amp into an open back 2x12” with Celestion Blues and you’ll instantly see just how much of that classic Vox character is actually coming from the cabinet.
It’s not always easy to do this kind of research. A lot of these differences become more apparent at volume, and cranking tube amps is just not an option for many guitarists. Assembling a large speaker cabinet collection is even more impractical. But because of these factors, guitarists have long been using speaker simulation devices to simulate the characteristic sound of different cabinets. Devices such as the Palmer PDI-09 apply a filter or EQ curve that mimics the sound of a guitar speaker to the full range output coming off your amp speaker out. This processed signal can then be sent to a PA or recording setup. Devices like this can work well, but you are usually stuck with one or two preset EQ curves, and the filter doesn’t replicate many of the complex factors that come into play when mic’ing a speaker—the thump of the cabinet, the airiness, or early reflections.
Recently, a whole new technology has surfaced called Impulse Responses (IRs). The first time I encountered Impulse Responses was in reading about Altiverb, the popular convolution reverb plug in. In lay terms, Altiverb gives you the power to sample any acoustic space you can think of, load it as an IR into the plug in, and voila, you have the characteristic reverb of say, the Sydney Opera House available to you in your DAW. But IRs are not just used for reverbs. You can effectively capture the sonic fingerprint of just about anything you can pass a sound through using IR technology—like a mic’d speaker cabinet.
Compared to traditional speaker simulators, I find that IRs offer much greater realism and depth. When you apply an IR to a line out signal from your amp, you are not just applying a preset EQ curve to your amp’s signal, you are essentially applying the distinct sonic characteristics of a certain speaker, cabinet, mic, mic preamp, and any early reflections that also make it into the mic during the recording process. There are libraries of IRs available to you at your fingertips, an almost endless variety of cabinet and mic’ing combinations. You can mix and match and blend virtual cabinets to your heart’s content. And when you land on a sound you really like, it’s easy to store that sound within your DAW, so you can call it up again later.
Of course, you can’t just plug a line out from your tube amp into your recording console or computer interface. Tube amps need to see a load (either a speaker or a dummy load of some sort). And you’ll need a good DAW and a convolution plug in that allows you to load IRs as well. To help us get a handle on what IRs mean for us guitarists, and how we can use them both live and in the studio, I’ve asked Mike Grabinski from Red Wirez Impulse Responses a number of questions.
Thanks for being a part of this, Mike! First off, what is an impulse Response, and how can guitarists incorporate them into their rigs?
Technically, an Impulse Response, or IR for short, refers to a system's output when presented with a very short input signal called an impulse. Basically, you can send any device or chain of devices a specially crafted audio signal and the system will spit out a digital picture of its linear characteristics. For speaker cabs, that means frequency and phase response, phase cancellation between multiple speakers, edge reflections, and other audible signatures wrapped up in the gnarly, old pieces of wood, paper, and glue that guitarists find so endearing. IRs will not capture non-linear stuff like distortion and compression.
When you're capturing an IR from a speaker cab, by necessity you are also sampling your D/A converter, power amp, the mic, mic preamp, your A/D converter, the cables you're using, and the room you are in. Basically, everything that comes in contact with the impulse as it makes it round-trip from your DAW and back again. So, it's important to use high quality gear and have a good recording environment. There's really no cheating physics.
Once you've captured a speaker cabinet IR, you process the signal coming from your amp by convolving it with the IR, imprinting the signal with the sound of your speaker cabinet. There are quite a few plug-ins and a few devices these days that will do the convolution part.
What are the benefits of using impulse Responses versus traditional mic’ing of speaker cabinets? IRs give you access to gear and acoustic spaces that might be too expensive or otherwise unattainable. The ability to run totally silent can be a real plus, too. Especially when cranking even a 30-watt amp can make your ears bleed, your dog run for the hills, or make your neighbors call the SWAT team.
IRs are a boon in a live situation, as well. Because you are essentially going straight from your rig into the house system, a setup using IRs is mostly immune to bleed and feedback from other instruments. You have more control over your tone. You are no longer at the mercy of the overworked sound guy, who would probably love to spend 10 minutes finding just the right mic position, but just doesn't have the time. And because you are eliminating a lot of the variables from the process, you can more easily reproduce your tone from venue to venue.
In your opinion, how close does an impulse response come to replicating the tone and overall coloration that that the typical cabinet/mic/mic preamp chain creates?
Early on I did double blind tests to convince myself it was worth the effort and expense to sample all these cabs. When levels are matched and you are comparing an IR and a mic in exactly the same position it is very hard to hear any difference at all. With dynamic mics, at least, I can sometimes pick out the IR, because a mic like the SM57 exhibits some distortion and I know what to listen for, and more importantly I actually know one of them is a real mic and one is an IR. With condenser mics, which are generally more linear, they sound pretty much identical. If you gave someone a recording and didn't tell them you were using IRs, they would never know, or even think to ask.
What's the best way to get your guitar amp signal into an Impulse Response that's loaded up in a typical computer host?Well, if making noise is an option, the best way, in my opinion, is to tap your amp's speaker out with a DI that can handle the power and then pass the signal through to a real speaker. That way, you are capturing preamp and power tube distortion and your amp still gets a reactive load. You don't really care what the speaker sounds like because you are going to be using IRs for the tone. You can shove it in a closet in the basement and as long as it can move some air, it's shouldn't negatively impact the DI signal. Some amps have the DI function built into the amp. Some even tap the signal coming from the power tubes, so a separate DI is not always necessary.
If you have to run silent, then you need a dummy load to take the place of the speaker, otherwise you can damage your amp's output transformer. There are lots of attenuators that also function as dummy loads out there. It is important to understand that your tube amp will probably react differently to a dummy load and you may find that your tone is missing the low-end bump and upper-mid rise you are accustomed to when using a speaker.
There can be several reasons for this, but one major factor is that speakers do not present a uniform load to your amp. If you look at a typical guitar speaker's impedance curve, which is a plot of the speaker's impedance across the frequency spectrum, you will see a big low-end bump and a steady upper-mid rise. This can also be described as a midrange scoop, depending on your perspective.
The load, or impedance, measured in ohms, will differ based on the frequency of the your amp's output. Solid-state amps have low output impedance, so their power output is not jerked around very much by the speaker's varying load. Tube amps have relatively high output impedance and as a result they deliver more power as the impedance of the speaker rises. And for a typical guitar speaker, that means you hear more bass and upper-mids.
Because a lot of dummy loads and attenuators present a uniform load to the amp, your amp's output will remain constant across the frequency spectrum. If you're accustomed to a low-end bump and upper-mid rise, you will probably hear this as the dreaded attenuator tone suck. To alleviate tone suck, you can use EQ. An alternative would be to use the sampled impedance curve of a real speaker to adjust the highs and lows in an authentic way.
What equipment does a musician need in order to use Impulse Responses with amplifiers, both live and in the recording studio?
You need a load for your amp, either a speaker or dummy load and a DI capable of tapping the speaker out of your amp. You also need a means to convolve the IR with your amps' output. In the studio, you can use a convolution plug-in. There are quite a few, including our own mixIR2 (wink, wink, nudge, nudge).
Live, the options are fewer and generally more expensive because you need a reliable device with enough horsepower to do the convolution with minimal latency. Not an easy task on a stage.
Let’s look at that for a minute. It's relatively easy to load an IR into a host on a computer in the studio, but what about boxes that allow you to do this easily live, in a road-worthy portable package? Say, with a built in load for your amp, and with multiple memory locations for IRs so you can load them up and take them to the gig? What's out there now, and do you see a market for more boxes like this down the road?
There aren't too many that I know of. There's the Fractal Audio Axe-Fx and Axe-Fx II, the Torpedo VB-101, and apparently you can load IRs into the Digitech GSP 1101 with some unofficial firmware mods. It is my understanding that the GSP 1101 truncates the IRs to 128 samples, which would limit your low and low-mid resolution. I suppose you could rig up a laptop, but I'm not sure how reliable and road-worthy that would be.
There seems to be increasing interest in these kinds of devices, so I'm sure more will pop up in the future.
Right. Also, we should mention, the Axe-FX and the GSP 1101 won’t provide a load for a tube amp but they do work great as hosts for IRs. I use the Axe FX this way live. Anything else you'd like to share?
San Dimas High School Football rules!
[Updated 12/12/21]
- The Recording Guitarist: Impulse Control—Mastering Fake Spaces ... ›
- The Recording Guitarist: Speakers? We Don't Need No Stinking ... ›
- Amp Mic'ing vs. Impulse Responses - Premier Guitar ›
After decades of 250 road dates a year, Tab Benoit has earned a reputation for high-energy performances at clubs and festivals around the world.
After a 14-year break in making solo recordings, the Louisiana guitar hero returns to the bayou and re-emerges with a new album, the rock, soul, and Cajun-flavoredI Hear Thunder.
The words “honesty” and “authenticity” recur often during conversation with Tab Benoit, the Houma, Louisiana-born blues vocalist, guitarist, and songwriter. They are the driving factors in the projects he chooses, and in his playing, singing, and compositions. Despite being acclaimed as a blues-guitar hero since his ’80s days as a teen prodigy playing at Tabby Thomas’ legendary, downhome Blues Box club in Baton Rouge, Benoit shuns the notion of stardom. Indeed, one might also add simplicity and consistency as other qualities he values, reflected in the roughly 250 shows a year he’s performed with his hard-driving trio for over two decades, except for the Covid shutdown.
On his new I Hear Thunder, Benoit still proudly plays the Fender Thinline Telecaster he purchased for $400 when he was making his debut album in Texas, 1992’s Nice & Warm. After that heralded release, his eclectic guitar work—which often echoes between classic blues-rock rumble-and-howl, the street-sweetened funk of New Orleans, and Memphis-fueled soul—helped Benoit win a long-term deal with Justice Records. But when the company folded in the late ’90s, his contract and catalog bounced from label to label.
Tab Benoit - "I Hear Thunder"
This bucked against Benoit’s strong desire to fully control his music—one reason he settled on the trio format early in his career. And although his 2011 album, Medicine, won three Blues Music Awards—the genre’s equivalent of Grammys—he stopped recording as a leader because he was bound by the stipulations of a record deal, now over, that he deemed untenable.
“I wanted to make records that reflected exactly how I sounded live and that were done as though we were playing a live concert,” Benoit says. “So, I formed my own label [Whiskey Bayou Records, with partner Reuben Williams] and signed artists whose music was, to me, the real deal, honest and straightforward. I couldn’t do anything on my own, but I could still continue putting out music that had a positive impact on the audience.”
Benoit’s new album, which includes Anders Osborne and George Porter Jr., was recorded in the studio at the guitarist’s home near the bayou in Houma, Louisiana.
Those artists include fellow rootsers Eric McFadden, Damon Fowler, Eric Johanson, Jeff McCarty, and Dash Rip Rock. Benoit also spent plenty of time pursuing his other passion: advocating for issues affecting Louisiana’s wetlands, including those around his native Houma. His 2004 album was titled Wetlands, and shortly after it was issued he founded the Voice of the Wetlands non-profit organization, and later assembled an all-star band that featured New Orleans-music MVPs Cyril Neville, Anders Osborne, George Porter Jr., Big Chief Monk Boudreaux, Johnny Vidacovich, Johnny Sansone, and Waylon Thibodeaux. This ensemble, the Voice of the Wetlands All-Stars, has released multiple CDs and toured.
Essentially, Benoit comes from the bayous, and when it’s time to record, he goes back to them, and to the studio he has in Houma, which he refers to as “the camp.” That’s where I Hear Thunder came to life. “George and Anders came to me and said, ‘Let’s go make some music,” Benoit offers. “So, we went out to the camp. They had some songs—and George and Anders and I go back so many years it was really a treat to put everything together. It only took us a couple of days to do everything we needed to do.”
“George Porter and Anders Osborne and I saw this alligator sitting around the boat where we were writing the entire time. I guess he really liked the song.”
I Hear Thunder has become his first number one on Billboard’s blues chart. Besides the fiery-yet-tight and disciplined guitar work of Benoit and Osborne, the latter also an esteemed songwriter, the album features his longtime rhythm section of bassist Corey Duplechin and drummer Terence Higgins. Bass legend Porter appears on two tracks, “Little Queenie” and “I’m a Write That Down.” Throughout the album, Benoit sings and plays with soul and tremendous energy, plus he handled engineering, mixing, and production.
Once again, that ascribed to his aesthetic. “My main reason for taking on those extra duties was I wanted to make sure that this recording gives the audience kind of a preview of how we’re going to sound live,” he declares. “That’s one of the things that I truly don’t like about a lot of current recordings. I listen to them and then see those guys live and it’s like, ‘Hey, that doesn't sound like what was on the album.’ Play it once or twice and let’s run with it. Don’t overdo it to the point you kill the honesty. All the guys that I love—Lightnin’ Hopkins, Albert King—they played it once, and you better have the tape machine running because they’re only going to give it to you that one time. That’s the spontaneity that you want and need.
“One of the reasons I don’t use a lot of pedals and effects is because I hate gimmicks,” he continues. “ I’m playing for the audience the way that I feel, and my attitude is ‘Let’s plug into the guitar and let it rip. If I make a mistake, so be it. I’m not using Auto-Tune to try and get somebody’s vocal to seem perfect. You think John Lee Hooker cared about Auto-Tune? You’re cheating the audience when you do that stuff.”
Tab Benoit’s Gear
Benoit in 2024 with his trusty 1972 Fender Thinline Telecaster, purchased in 1992 for $400. Note that Benoit is a fingerstyle player.
Photo by Doug Hardesty
Guitar
- 1972 Fender Telecaster Thinline
Amp
- Category 5 Tab Benoit 50-watt combo
Strings
- GHS Boomers (.011–.050)
The I Hear Thunder songs that particularly resonate include the explosive title track, the soulful “Why, Why” and the rollicking “Watching the Gators Roll In,” a song that directly reflected the album’s writing experience and environment. “George and Anders and I saw this alligator sitting around the boat where we were writing the entire time. I guess he really liked the song. He’d be swimming along and responding. That gave it some added punch.” As does Benoit and Osborne’s consistently dynamic guitar work. “I’m not one of these people who want to just run off a string of notes or do a lot of fast playing,” Benoit says. “It has to fit the song, the pace, and most of all, really express what I’m feeling at that particular moment. I think when the audience comes to a show and you play the songs off that album, you’ve got to make it real and make it honest.”
When asked whether he ever tires of touring, Benoit laughs and says, “Absolutely not. At every stop now I see a great mix of people who’ve been with us since the beginning, and then their children or sometimes even their grandchildren. When people come up to you and say how much they enjoy your music, it really does make you feel great. I’ve always seen the live concerts as a way of bringing some joy and happiness to people over a period of time, of helping them forget about whatever problems or issues they might have had coming in, and just to enjoy themselves. At the same time, I get a real thrill and joy from playing for them, and it’s something that I always want the band’s music to do—help bring some happiness and joy to everyone who hears our music.”
YouTube It
Hear Tab Benoit practice the art of slow, soulful, simmering blues on his new I Hear Thunder song “Overdue,” also featuring his well-worn 1972 Telecaster Thinline.
The two-in-one “sonic refractor” takes tremolo and wavefolding to radical new depths.
Pros: Huge range of usable sounds. Delicious distortion tones. Broadens your conception of what guitar can be.
Build quirks will turn some users off.
$279
Cosmodio Gravity Well
cosmod.io
Know what a wavefolder does to your guitar signal? If you don’t, that’s okay. I didn’t either until I started messing around with the all-analog Cosmodio Instruments Gravity Well. It’s a dual-effect pedal with a tremolo and wavefolder, the latter more widely used in synthesis that , at a certain threshold, shifts or inverts the direction the wave is traveling—in essence, folding it upon itself. Used together here, they make up what Cosmodio calls a sonic refractor.
Two Plus One
Gravity Well’s design and control set make it a charm to use. Two footswitches engage tremolo and wavefolder independently, and one of three toggle switches swaps the order of the effects. The two 3-way switches toggle different tone and voice options, from darker and thicker to brighter and more aggressive. (Mixing and matching with these two toggles yields great results).
The wavefolder, which has an all-analog signal path bit a digitally controlled LFO, is controlled by knobs for both gain and volume, which provide enormous dynamic range. The LFO tremolo gets three knobs: speed, depth, and waveform. The first two are self-explanatory, but the latter offers switching between eight different tremolo waveforms. You’ll find standard sawtooth, triangle, square, and sine waves, but Cosmodio also included some wacko shapes: asymmetric swoop, ramp, sample and hold, and random. These weirder forms force truly weird relationships with the pedal, forcing your playing into increasingly unpredictable and bizarre territories.
This is all housed in a trippy, beautifully decorated Hammond 1590BB-sized enclosure, with in/out, expression pedal, and power jacks. I had concerns about the durability of the expression jack because it’s not sealed to its opening with an outer nut and washer, making it feel more susceptible to damage if a cable gets stepped on or jostled near the connection, as well as from moisture. After a look at the interior, though, the build seems sturdy as any I’ve seen.
Splatterhouse Audio
Cosmodio’s claim that the refractor is a “first-of-its-kind” modulation effect is pretty grand, but they have a point in that the wavefolder is rare-ish in the guitar domain and pairing it with tremolo creates some pretty foreign sounds. Barton McGuire, the Massachusetts-based builder behind Cosmodio, released a few videos that demonstrate, visually, how a wavefolder impacts your guitar’s signal—I highly suggest checking them out to understand some of the principles behind the effect (and to see an ’80s Muppet Babies-branded keyboard in action.)
By folding a waveform back on itself, rather than clipping it as a conventional distortion would, the wavefolder section produces colliding, reflecting overtones and harmonics. The resulting distortion is unique: It can sound lo-fi and broken in the low- to mid-gain range, or synthy and extraterrestrial when the gain is dimed. Add in the tremolo, and you’ve got a lot of sonic variables to play with.
Used independently, the tremolo effect is great, but the wavefolder is where the real fun is. With the gain at 12 o’clock, it mimics a vintage 1x10 tube amp cranked to the breaking point by a splatty germanium OD. A soft touch cleans up the signal really nicely, while maintaining the weirdness the wavefolder imparts to its signal. With forceful pick strokes at high gain, it functions like a unique fuzz-distortion hybrid with bizarre alien artifacts punching through the synthy goop.
One forum commenter suggested that the Gravity Well effect is often in charge as much the guitar itself, and that’s spot on at the peda’t extremes. Whatever you expect from your usual playing techniques tends to go out the window —generating instead crumbling, sputtering bursts of blubbering sound. Learning to respond to the pedal in these environments can redefine the guitar as an instrument, and that’s a big part of Gravity Well’s magic.
The Verdict
Gravity Well is the most fun I’ve had with a modulation pedal in a while. It strikes a brilliant balance between adventurous and useful, with a broad range of LFO modulations and a totally excellent oddball distortion. The combination of the two effects yields some of the coolest sounds I’ve heard from an electric guitar, and at $279, it’s a very reasonably priced journey to deeply inspiring corners you probably never expected your 6-string (or bass, or drums, or Muppet Babies Casio EP-10) to lead you to.
The ’60s Were Weird and So Were the ’90s—Thanks, Santana
Was Supernatural his ultimate gift to the world?
Carlos Santana’s career arc has been a journey. From blowing minds at the far edges of psychedelia at Woodstock to incendiary jazz experimentalism with the likes of John McLaughlin and Alice Coltrane to later becoming a chart-topping star with some of the biggest collaborators in pop and rock, his guitar playing has covered a lot of ground.
On this episode of 100 Guitarists, we’re covering everything about Santana’s playing we can fit in one neat package: How did Santana’s sound evolve? Has any other rock star mentioned John Coltrane’s A Love Supreme on morning network television? Was Supernatural his ultimate gift to the world?
In our new current listening segment, we’re talking about a Bruce Hornsby live record and a recent release from guitarist Stash Wyslouch.
This episode is sponsored by PRS Guitars.
Learn more: https://prsguitars.com.
Lollar Pickups introduces the Deluxe Foil humbucker, a medium-output pickup with a bright, punchy tone and wide frequency range. Featuring a unique retro design and 4-conductor lead wires for versatile wiring options, the Deluxe Foil is a drop-in replacement for Wide Range Humbuckers.
Based on Lollar’s popular single-coil Gold Foil design, the new Deluxe Foil has the same footprint as Lollar’s Regal humbucker - as well as the Fender Wide Range Humbucker – and it’s a drop-in replacement for any guitar routed for Wide Range Humbuckers such as the Telecaster Deluxe/Custom, ’72-style Tele Thinline and Starcaster.
Lollar’s Deluxe Foil is a medium-output humbucker that delivers a bright and punchy tone, with a glassy top end, plenty of shimmer, rich harmonic content, and expressive dynamic touch-sensitivity. Its larger dual-coil design allows the Deluxe Foil to capture a wider frequency range than many other pickup types, giving the pickup a full yet well-balanced voice with plenty of clarity and articulation.
The pickup comes with 4-conductor lead wires, so you can utilize split-coil wiring in addition to humbucker configuration. Its split-coil sound is a true representation of Lollar’s single-coil Gold Foil, giving players a huge variety of inspiring and musical sounds.
The Deluxe Foil’s great tone is mirrored by its evocative retro look: the cover design is based around mirror images of the “L” in the Lollar logo. Since the gold foil pickup design doesn’t require visible polepieces, Lollartook advantage of the opportunity to create a humbucker that looks as memorable as it sounds.
Deluxe Foil humbucker features include:
- 4-conductor lead wire for maximum flexibility in wiring/switching
- Medium output suited to a vast range of music styles
- Average DC resistance: Bridge 11.9k, Neck 10.5k
- Recommended Potentiometers: 500k
- Recommended Capacitor: 0.022μF
The Lollar Deluxe Foil is available for bridge and neck positions, in nickel, chrome, or gold cover finishes. Pricing is $225 per pickup ($235 for gold cover option).
For more information visit lollarguitars.com.