
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 ā59 Fender Bassman cranked up through its internal 4x10ā speaker configuration sounds nothing like a Mesa Dual Rectifier through its oversized, closed-back 4x12ā cabinet with Celestion Vintage 30s. And the speakers and speaker cabinet are a huge part of the equationāif you were to run the Mesa Recto into the Bassman speakers, youād get a completely different tone, but one that leans in the classic Bassman direction.
The same thing goes for Vox tonesātry running almost any amp into an open back 2x12ā with Celestion Blues and youāll instantly see just how much of that classic Vox character is actually coming from the cabinet.
Itās 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 doesnāt replicate many of the complex factors that come into play when micāing a speakerāthe 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 technologyālike a micād 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 ampās 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 micāing combinations. You can mix and match and blend virtual cabinets to your heartās content. And when you land on a sound you really like, itās easy to store that sound within your DAW, so you can call it up again later.
Of course, you canāt 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 youāll 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, Iāve 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 micāing 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.
Letās 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 wonāt 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 ControlāMastering Fake Spaces ... āŗ
- The Recording Guitarist: Speakers? We Don't Need No Stinking ... āŗ
- Amp Mic'ing vs. Impulse Responses - Premier Guitar āŗ
Brent Mason is, of course, on of the most recorded guitarists in history, who helped define the sound of most ā90s country superstars. So, whether you know it or not, youāve likely heard Masonās playing.
Professional transcriber Levi Clay has done the deepest of dives into Brent Masonās hotshot licks. At one point, he undertook the massive project of transcribing and sharing one of Masonās solos every day for 85 or so days. Mason is, of course, on of the most recorded guitarists in history, who helped define the sound of most ā90s country superstars. So, whether you know it or not, youāve likely heard Masonās playing. Levi shares the insight he gleaned from digging deep, and he tells us what it was like when they shared a stage last year. Plus, Levi plays us some great examples of Masonās playing.
For the first time ever, two guitar greats, John 5 and Richie Kotzen will be heading out on the road this year. The tour will launch October 16 and run through November, hitting markets across the U.S.
Find the full tour itinerary right plus a link for tickets & VIP, including additional dates featuring John 5 only. Reserved seating tickets will go on sale Friday May 16 though a fan presale will begin today at noon local time and fans are strongly encouraged to buy early to get the best seats.
Meet and Greets for both artists will be available. For John 5 please go to: https://john5store.com/collections/vip.
Today, John 5 also announces more details of his anticipated new album. Called The Ghost, it will be released October 10 and is led by the new track āFiend,ā featuring Kenny Aronoff.
John 5 continues running public tours this month for his Knights In Satanās Service Museum of KISS Memorabilia in Los Angeles, California. Guided tours are open to the public for one month only (with a possible expansion). Current dates available are May 12-16, May 19-23 and May 27-30. Each will be led by John 5 himself who will provide tons of rich detail and answer any questions. Secure your place HERE.
JOHN 5 continues to tour with Mötley Crüe including an upcoming residency in Las Vegas in 2025.RICHIE KOTZEN &
JOHN 5 FALL 2025 TOUR
October 16 El Cajon, CA @ Magnolia
October 17 Riverside, CA @ Fox Performing Arts
October 18 Roseville, CA @ Goldfield Trading Post
October 19 San Jose, CA @ The Ritz
October 21 Phoenix, AZ @ Celebrity Theatre
October 22 Albuquerque, NM @ KiMo Theatre
October 24 Dallas, TX @ Granada Theater
October 25 Leander, TX @ The Haute Spot
October 27 New Orleans, LA @ House of Blues
October 28 Memphis, TN @ Minglewood Hall
October 29 Nashville, TN @ Fogg Street Lawn Club
October 30 Atlanta, GA @ Variety Playhouse
October 31 Orlando, FL @ House of Blues
November 1 Fort Lauderdale, FL @ Culture Room
November 2 Clearwater, FL @ Capitol Theatre
November 4 Richmond, VA @ The National
November 5 Leesburg, VA @ Tally Ho Theater
November 6 Patchogue, NY @ Patchogue Theatre
November 11 Glenside, PA @ Keswick Theatre
November 12 Derry, NH @ Tupelo Music Hall
November 13 Foxborough, MA @ Six String Grill & Stage
November 14 Stroudsburg, PA @ Sherman Theater
November 15 Lorain, OH @ Lorain Palace Theatre
November 16 Columbus, OH @ The King Of Clubs
November 17 Warrendale, PA @ Jergels
November 19 Wyandotte, MI @ District 142
November 20 Flint, MI @ The Machine Shop
November 21 Fort Wayne, IN @ Piereās
November 22 St. Charles, IL @ Arcada Theatre
November 23 Belvidere, IL @ Apollo Theatre
November 25 Denver, CO @ Oriental Theater
November 29 Pioneertown, CA @ Pappy & Harriet's*
*John 5 only
AEROSMITH guitarist and songwriter JOE PERRY is set to return to the road for a series of August performances with THE JOE PERRY PROJECT. The 8-date run kicks off August 13 in Tampa, FL and wraps August 23 in Port Chester, New York, with an August 19 performance in PERRYās Boston hometown (see the itinerary below). For the North American trekāwhich marks the first solo shows for PERRY this yearāthe legendary guitarist will be joined by his Aerosmith bandmates Brad Whitford (guitar) and Buck Johnson (keys), along with The Black Crowesā Chris Robinson (vocals), and Stone Temple Pilotsā Robert DeLeo (bass), and Eric Kretz (drums).
āWellā¦itās time to let the music do the talkin again,ā PERRY says. āIām really excited about the JPP line up this year!!!! Most of these guys played with me at The Roxy in L.A. at the debut event for my latest solo album [Sweetzerland Manifesto] in January 2018. Theyāre all busy as hell but thankfully theyāre able to carve out some time for this run. And Iām not only lucky enough to have Brad Whitford onstage with me but Chris Robinson of The Black Crowes! [who sang āFortunate Oneā on Sweetzerland Manifesto MKII], Robert DeLeo and Eric Kretz from STP!!! and Buck Johnson who plays keys and sings with Aerosmith, the Hollywood Vampires, and is also a solo artist in his own right.ā
For the shows, the Rock and Roll Hall of Fame inductee says āthe set list is gonna include my fav JPP cuts, STP, Black Crowes, and with Brad weāll be hitting the Aero hits and some deep cuts and then ya never know!!!! Gonna be a BLAST, and if youāve ever been to one of my shows you know the words GARAGE BAND on STEROIDS come to mind! See you there!!!!ā
DATE | LOCATION | VENUE |
Wednesday, August 13 | Tampa, FL | Seminole Hard Rock - Tampa |
Thursday, August 14 | Hollywood, FL | Seminole Hard Rock - Hollywood |
Saturday, August 16 | Toronto, ON | HISTORY |
Sunday, August 17 | Muskoka, ON | Kee to Bala |
Tuesday, August 19 | Boston, MA | Wang Theatre |
Wednesday, August 20 | Hampton Beach, NH | Hampton Beach Casino Ballroom |
Friday, August 22 | Mashantucket, CT | The Premier Theater at Foxwoods Resort Casino |
Saturday, August 23 | Port Chester, NY | Capitol Theatre |
A sample page from the authorās analog log.
Seasonal changes are tough on your acoustic. Hereās how you can take better care of your prized instrument.
As you read this, spring is in bloom in most of the US, or maybe it has been for some time. Iām timing this column specifically to ask acoustic guitarists, in this season of increasing humidity and comfortable conditions, to prepare for whatās coming. Itās never too soon, and time flies. Before you know it, weāll be back to the maintenance phase and you might be blowing up the phones of your local guitar shops, luthiers, and techs. Iām here to encourage a decidedly old-school approach to preventative guitar maintenance, and yes, it starts now.
Why, you ask? Well, as the lead luthier at Acoustic Music Works, I can tell you that in my nearly 15 years in this position, this was the worst winter ever for preventable repairs on acoustic guitars. Fret sprout, bridge lifts, top sink, soundboard cracks, back cracks, loose binding, general malaise⦠These hit us very hard in the winter that spanned 2024 and 2025. Am I complaining? On the one hand, no. This is part of how we make our money. On the other hand, yes! Repair schedules related to dryness and humidity issues can stretch into weeks and even months, and nobody wants to be without their favorite instruments for that amount of time. With a little thoughtfulness, however, you might get through next winter (and every one thereafter) without hefty repair bills or time apart from your musical companion.
Our preparation is going to start with an unlikely but very important guitar accessory: the humble notebook. Plain, lined, grid, day planner⦠it doesnāt matter. We all need to actively participate in our instrument maintenance, and in my experience, fancy apps that track humidity via Bluetooth breed a kind of laziness, a feeling of safety that might prevent us from actually physically looking in on conditions. Better we keep an analog, well, log, so that we know where things stand, and I suggest checking in daily.
āThis was the worst winter ever for preventable repairs on acoustic guitars.ā
Track your relative humidity, both in the case and in the room where your instruments mostly reside, but also take notes on your action height, top deflection (StewMac has some great tips for measuring this) and anything related to playability that you believe you can observe empirically.
Dryness is the root cause of most guitar issues that manifest in the fall and winter months. Symptoms of dryness include sharp fret ends, falling action and dead frets, sunken top around the sound hole, and cracks and bridge lifts. With your trusty notebook, youāll get a feel for the sensitivity level of your instrument, and that knowledge is power!
A few other basic implements will not only assist you in your observations, but may also satisfy your need to buy guitar-related things (at least for a minute). Getting quick and comfortable with a fret rocker is a great skill to have, and is invaluable in diagnosing buzzes due to high frets or frets that have come unseated due to dryness. A well-calibrated relief gauge might seem luxurious, but it can prevent you from making unnecessary or extreme truss rod adjustments. A string action gauge, or even a simple machinistās rule or set of feeler gauges, will help you keep track of your action. Get a three-pack of hygrometers so you can average their readings, rather than depending on one.
Lest we forget: A guitar can not only be too dry, it can also be too wet. By beginning your maintenance diligence in the spring/summer, youāll also be able to tell if your instrument is the victim of a too-humid environment. The signs of over-humidification are subtle: Your action may rise from a puffed-up top, and in extreme cases, glue joints could begin to fail. In my experience, an over-humidified guitar will suffer from dulled tone, almost like a sock in the sound hole. If youāre sensing a lack of clarity in your guitar all of a sudden, start with new strings. If it persists, it might be due to over-humidification, and you may want to introduce a desiccant to the case for a time. The more lightly built your guitar is, the more sensitive it will be to seasonal changes.
By getting into these habits early, youāll be empowered by knowing your instrument more intimately. Youāll understand when and why changes in tone and playability might have occurred, and youāll hopefully save on repair bills year-round. Feel free to reach out with any questions. Who knows? I might just send you a notebook with an AMW sticker on the cover!