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Incredible tube tones without speakers: why every guitar player needs a full range flat response (FRFR) amp!


Is the 4×12 cabinet going to die out? We don’t think guitar players would ever allow it, but there’s a new kid on the block promising to keep our tube tone awesome even without a speaker or cab. It’s called full range flat response, and it could just be the best thing to happen to guitar amps in ages…

There was a time when guitarists went to great lengths to avoid hearing the sound of their cabinet piped through a stage monitor.

And for good reason: more often than not, the tone was harsh, cold and on the brittle side of glassy. It was a clear case of direct, in-your-face sound taken to an unpleasant extreme.

When your tone turns out to be as cringe-inducing as a dental drill burrowing into a root canal, drastic measures are in order, and some guitarists’ revulsion bore strange fruit indeed: it wasn’t unusual to see wedges’ high-frequency drivers masked with duct tape.

For many of us, a bad monitor signal was just another item on that long list of annoying inevitabilities that starts with death, taxes and spam.

A wedge monitor covered in duct tape, yesterday. Just one of the many, many reasons you should have rolls of this stuff in your gig bag at all times!

A wedge monitor covered in duct tape, yesterday. Just one of the many, many reasons you should have rolls of this stuff in your gig bag at all times!

Even well-miked guitar cabinets sounded sorry over fullrange speakers, especially when your signal ventured into the distorted end of the spectrum.

Painting pictures with guitar tone

Although the rock gods seemed to cope well enough, the studio situation was even more frustrating for us mere mortals.

Inspiration is shy, elusive, and hard to capture when the cab is miked up in another room and you can only hear an alien version of yourself over stale-sounding studio monitors.

When guitarists paint musical pictures, taste, touch and tone are their tools of choice. Taking away that uplifting tone and ass-kicking attack is like forcing an old master to paint with a mop.

The reason we love guitar

Most of us who are drawn to this instrument find it so alluring precisely because those six strings can make such a soulful sound. Compelled to work with soulless, uninspiring tone, it takes a lot of discipline to nail a performance as inspired as some of our finer moments in the rehearsal room and on stage.

Fingers feel stiff, lines that usually flow effortlessly come out halting, and the anxious wait for the engineer to audition that last take against the backdrop of the mix is an excruciating exercise in patience.

Parallel but unequal signal chains and guitar sounds were an inauspicious pairing, and you couldn’t help but wonder how on earth one’s guitar heroes managed to sound so stellar on their albums. It was downright supernatural.

We recently achieved supernatural tube tones by miking up one of our TM212 cabs in a toilet. A girls' toilet, no less. But there has to be an easier way... right?

We recently achieved supernatural tube tones by miking up one of our TM212 cabs in a toilet. A girls’ toilet, no less. But there has to be an easier way… right?

And that element of mystery was a good thing, because what’s music without that inexplicable magic?

A Deluxe tube amp experience

In any event, things have changed with the arrival of modeling technology in the early noughties, especially when it comes to recording.

Many guitarists have a DAW (digital audio workstation) at home and, with nifty digital tools such as modelers and budget-friendly software solutions, you can come pretty close to capturing the guitar gods’ iconic tones.

Speaking of powerful tools, TubeMeister Deluxe certainly deserves more than passing mention. These rigs let you enjoy all the benefits of a tube amp on stage, at home or in the studio, even without actually connecting a speaker cabinet!

Is that even possible? Indeed it is.

This is the first breed of tube amp to treat users to a genuine FRFR experience, which comes courtesy of the groundbreaking Red Box AE (AE, by the way, stands for ambience emulation – more on that later!).

And FRFR means…?

OK, OK. I’d like to take the release of this game-changer as a welcome opportunity to elaborate on that cryptic abbreviation FRFR.

Short for ‘full range flat response’, the term FRFR is often bandied about when discussions in guitar circles turn to digital recording assets such as DAWs.

TubeMeister Deluxe 20 in a recording environment at H&K HQ in Germany. Not a cab in sight, as you'll notice...

TubeMeister Deluxe 20 in a recording environment at H&K HQ in Germany. Not a cab in sight, as you’ll notice…

But what does it actually mean? Let’s back up a bit to scan the big picture.

Are the days of the speaker cabinet over?

These days, more and more guitar sounds are being generated in the studio and on stage without the benefit of the time-tested guitar-to-amp-to-cab-to-microphone signal chain.

Many artists have forsaken amps altogether.

Modelers and even laptops running amp software are encroaching on a domain once dominated by the classic amp head and cab + FX board combo. These tools’ signals generally go straight to a mixing console without ever seeing a guitar speaker cab in the signal chain.

Goodbye 4×12, goodbye back pain

So the very component that is such a formative force in shaping guitar tone has been taken out of the loop.

That may come as a bit of shock, given the almost cultic veneration accorded certain 4×12 cabs, but it works. Don’t believe us? This video we shot at The NAMM Show 2016 proves you don’t need a cab to sound good:


However, it only works well enough when the FRFR signal is treated with impulse response (IR) filters whip that signal into the shape of a typical guitar sound.

Put simply, FRFR capability is the means to render of an audio signal on a fullrange system such as studio monitors, ideally with linear frequency response.

What are IR filters, and how do they help me?

So, what to do IR filters do? Well, we’ve enjoyed a rather good run with our cabinet simulations.

The H&K engineers succeeded in emulating the sound of a miked guitar cabinet. They did this by first decoding the DNA of the guitar-speaker-cab-and-microphone-combo’s frequency response and then coming up with filter circuits that EQ the direct signal in such a way as to imprint it with this genetic stamp.

Imposing the frequency response on signals yielded quite convincing results, as the countless users who invested in the platinum selling Hughes & Kettner Red Box would attest.

Speakers and cabinets

There was a minor catch, though. The signal sounded much more like a miked loudspeaker in isolation, and less like a speaker in its natural habit; that is, installed in an enclosure.

Of course, we guitarists generally prefer well-dressed speakers in a fetching housing to the naked option because of the tasty flavoring that the housing adds to the tone.

And as we all know, the same speakers can sound very different in dissimilar housings.

What’s more, finessing the distance of the microphone to the speaker cone is a science unto itself. Classic speaker simulations largely ignored this variable.

Just like they did it in the old days (although maybe not always with as many mics as this!). But FRFR and the Red Box AE mean you no longer have to worry about stuff like this...

Just like they did it in the old days (although maybe not always with as many mics as this!). But FRFR and the Red Box AE mean you no longer have to worry about stuff like this…

They factored the ‘hard’ parameters of the microphone and speaker into the equation, while neglecting the ‘soft’ stuff that comes down to good ears and lots of experience.

How IR filters make you sound more real

The answer to the question of what IR filters do is this: they factor those ‘ignored’ parameters – the natural sound of the cab, the distance between the microphone and speaker – into the sonic equation to inject a little more authenticity into the digital facsimile of a guitar cabinet’s acoustical behavior.

The point is, of course, to capture the cab’s sweet spot.

IR filters can even approximate the ambient sound of a room, which has a slight but tangible impact on the frequency response. After all, there’s a noticeable difference between the sound of your guitar cabinet in a tiled cellar and that same cab in a small studio cabin soundproofed with carpets and insulation materials.

An impulse response for every occasion

In principle, there can be as many IR variants as there are combinations of cabs, microphone placements and rooms. And if you’d rather not agonize over the many options, you can even create your own.

Yes, with just a few tools and a little patience, your personal cab setup can be distilled into a replicable data packet.

All this is great news for guitar players who are recording at home, but it's also perfect for gigging players out on the road. We imagine our friend Christian Kreutzer (guitarist for German hip-hop king SIDO) is not really in a position to crank a 4x12 on the band's tour bus!

All this is great news for guitar players who are recording at home, but it’s also perfect for gigging players out on the road. We imagine our friend Christian Kreutzer (guitarist for German hip-hop king SIDO) is not really in a position to crank a 4×12 on the band’s tour bus!

IR + FRFR = your sound, any time, anywhere

But that’s just us thinking out loud. The key thing here is that IR filtering and FRFR capability have presented us with such a versatile solution that the days of the classic cabinet miking technique may well be numbered.

The benefits of this novel form of EQ certainly far outweigh any perceived drawbacks.

For one, the sound of your guitar as delivered by the PA no longer hinges on the skills, patience and whims of stressed technicians tasked with setting up your microphones.

With FRFR capability added to your guitar setup, your sound over a PA will be exactly the same as the sound you worked out at home, in the rehearsal room or in a studio. Really!

In the standard gigging scenario, where time is tight and the pressure is on, most techs/players won’t bother fiddling with various microphone placements to pinpoint a given cab’s sweet spot.

Seen in that light, IR-based FRFR technology is a dream come true for the gigging guitarist.

And once you have the sound of your dreams dialed in, it’s no less an advantage to have that tone at your fingertips, always and everywhere, at home, in the studio and in the rehearsal room.

How we got FRFR into a tube amp

Many modelers already have all this capability built into their engines and there are plug-ins available for home DAWs that deliver satisfying results.

However, FRFR capability was not to be had in any conventional tube amp head.

For one, you would have to tap the power amp signal directly because the power stage plays such a key part in shaping tone.

More TubeMeister Deluxe studio action. If you're reading this and still wondering how much you can really benefit from the true FRFR tube experience, we sugggest you give the Deluxe amps a go when you next get the chance!

More TubeMeister Deluxe studio action. If you’re reading this and still wondering how much you can really benefit from the true FRFR tube experience, we sugggest you give the Deluxe amps a go when you next get the chance!

For the other, you’d definitely need a power soak to bring the signal down to a level suitable for processing without adversely affecting the power stage’s tone-shaping action.

The many benefits of Red Box AE

Add these features and subsequent IR filtering to a good amp, and you could conjure FRFR-enabled, all-tube-driven tone.

TubeMeister, for example, offers the exceedingly rare but certainly nifty combination of a tube-driven power amp with a very handy on-board power soak.

Then there’s this to consider: our experience with the Red Box has been so rewarding over the years that the idea of upgrading the TubeMeister Deluxe series with an IR filter practically suggested itself.

Our engineers dubbed this filter AE (Ambience Emulation, if this slipped your mind from last time!), and tweaked it to give the target device a ‘big picture’ view of the simulated source.

In other words, it delivers a realistic rendering of a true 4×12 in all its raging glory. And to top off what’s already a very good thing, Red Box AE even offers the novel option of bypassing the on-board filtering when you want to work with your own IR filters on your home DAW.

There are plenty of freeware plug-ins available to this end, so you can tune and tweak to your heart’s content.

Time to try out this new kid on the block…

TubeMeister Deluxe, with its practical on-board filters, sounds more than persuasive on a DAW. Watch this video we shot at NAMM 2016 for proof:


In fact, it sounds so very convincing that soon many home recordists may forgo a guitar speaker cabinet altogether.

Of course, it’s all a matter of taste, preference and habit.

However, if the day comes when the only difference between a speaker cabinet and the alternative is the former’s ability to set those trouser legs a-flappin’, then I believe you should seriously consider the benefits of FRFR, IR filters and Red Box AE.

Capturing great tone on stage and in the studio has never as easy and convenient as it is today.

What are your thoughts on the choice between FRFR and impulse responses or traditional speaker cabs? We’d love to hear your thoughts, so leave them in the comments section below…


First published: February 12 2016. Most recent update: December 22 2016.

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Leave a comment

Stephen Fell on January 5, 2018 Reply

Hi I think the concept is great just what Tom Schultz of Boston did 30+years ago. Linear Amp FRFR speakers Frequency 55 – 80 (I think) basically his own PA system then into the FOH Mixer then out to the PA system.( the 4×12 speaker cabs in stage for show were empty. Well I would like to order this amp from you for my music room and now small gig’s not recording yet as I tour working with a big band but I will need
FRFR speakers to go with it what can you suggest? 100 watts rms is enough regards Stephen F

    Hughes & Kettner Hughes & Kettner on February 20, 2018 Reply

    Yes! We love reading about the Tom Scholz setups – guy was/is legendary, and so ahead of the game in so many ways. An inspiration to gearheads everywhere 🙂

    Hmm, we recommend you actually try out a few speakers, once you’ve got the amp. Get to a store that has a bunch in and see which work for you. Technically, they should all sound the same 😉 But you’ll notice differences, and of course some will have extra features you’ll either want, or not! There’s a huge range in prices too, depending on your budget. Our speakers of choice are a pair from our sister company (HK Audio) in their LINEAR 5 range…

Jean-Yves on December 22, 2017 Reply

Good article. I had bunch of amps/cabs over the last 30 years. But rather trying to avoid using those since a few years. I’m using modelers mainly because of the simplicity, and lower cost.

But now that I learned about wet-dry-wet, that might bring some attention back to my forgotten combo.

    Hughes & Kettner Hughes & Kettner on February 20, 2018 Reply

    Yes Jean-Yves, dig that combo out and give it another try! A lot of the joy of guitar is about inspiration, and if you’re inspired to try it, you absolutely should 🙂

    Rock on!

    Team H&K

Christian on December 6, 2017 Reply

You can turn the ambience emulation off?? I see no such switch on my GM40 😉 But to be clear, the Red Box 5 standalone unit and the built in AE version are two different sounding devices, ie. no room/space/mic emulation on the former? If so, any plans on releasing official impulse responses of it, or maybe a standalone unit? The AE version is probably one of the (if not THE) best sounding cab emulations I’ve ever heard, and I’d love to use it on my other amps. I use several Two-Notes products, and by comparison the AE is practically mix ready at the flick of a switch. Kudos! 🙂

    Hughes & Kettner Hughes & Kettner on December 14, 2017 Reply

    Hi Christian. Sure, on the GM40 you can turn off the Ambience Emulation: there’s a switch on the Red Box (the bottom one) that says Off/On. That’s the one. Turn it to ‘off’ and you simply get the amp’s pure tube tone. It sounds strange on its own, of course 😉 But it’s perfect for playing with afterwards, adding your own favorite cab sims or other FX, etc.

    And yes, the Red Box 5 and the Red Box AE are different. The Red Box 5 also features speaker emulation – you can download the impulse responses on the Red Box 5 product page here:

    Sadly, the Red Box AE was built in a different way, so it’s not so simple to offer the Ambience Emulation files for other players to use. But maybe one day there will be a way! Because we agree, it’s an amazing sound. We actually compared it extensively to several Two Notes products at the GuitCon event in Germany this year, and it held its own amazingly well. What’s better? That’s a taste thing. But everyone agreed that having the AE built into our amps as standard is an amazing bonus 🙂

    Hope this helps a bit, even though there’s no solution on the AE front for you… yet!

    Team H&K

Phil on January 10, 2017 Reply

Hi, how do you switch to FRFR on the triamp mk3 if the switching isn’t physically there? MIDI?

I’ve only just got the amp so haven’t delved that deep yet.

    Hughes & Kettner Hughes & Kettner on January 27, 2017 Reply

    Hi Phil! FRFR doesn’t switch on and off – it’s just always there as an option if you need it…

Mark Robinson on July 26, 2016 Reply

I am looking to start a rig. I have a Line 6 Helix, just wondering what else I need to buy in order to enjoy an IR + FRFR experience? I don’t quite understand what this is actually doing. Do I need an amplifier as well, or will a powered modeler/profiler monitor do the trick?

    Hughes & Kettner Hughes & Kettner on August 8, 2016 Reply

    Hi Mark. Hmm, if you’ve got a Helix, it has all the IR stuff built in and you’ll just need to get started with learning how to use the unit to the full extent of its capabilities. Here’s a great Premier Guitar article all about Impulse Responses:

    When it comes to the FRFR side, it basically means you’ll need to get hold of a powered (or active, as they’re also called) PA speaker, or stage monitor, and hook the Helix up to that. And again we’re pointing you to an external link, but this video from Line 6 themselves explains the FRFR thing pretty simply:

    Finally though, what’s awesome about the TubeMeister Deluxe amps is that they give you awesome full-tube tone PLUS the IR and FRFR capabilities. So you’ve got the best of both worlds, really – much better basic tones than the digital Helix modelling can offer (of course tone is a matter of opinion, but we’re right on this 😉 ) and the tehcnology to enjoy the full FRFR/IR experience.

    Hope this helps, and that you’re on the way to building a rig that works for you. At the end of the day, FRFR is really starting to revolutionize the world of the guitar amp, so you’Ve got in at a great time! Enjoy 🙂

Tony on April 30, 2016 Reply

Hi guys, question regarding the difference between the original Tubemeister and the new Tubemeister Deluxe. It looks like the sound of the Deluxe is based on the Triamp Mark3? What is the original Tubemeister based on ? An earlier Triamp, a Puretone, or something else?

    Hughes & Kettner Hughes & Kettner on May 2, 2016 Reply

    Hi Tony, good question! And the answer is… TriAmp MKII. So you could say that once we got the TriAmp Mark 3 out, that was the perfect time to build a new TubeMeister too 😉

Carlo on March 23, 2016 Reply

Thanks for getting back to me so quickly. I am close to buying the Deluxe 40 and the 212 cab. I have tried your amps in the past liked them. I’ve narrowed my search down to your Deluxe 40 and a popular 50 watt amp on the market. I have three questions.
1) I take it there is no reverb on this amp as I understand the idea was to add it to the tone afterwards so as to not corrupt the signal? Am I correct on this?
2) If I have any troubles/questions what is the service/operational knowledge of Hughes and Kettner products in Canada? I understand it is Yorkville sound but they don’t have any of your products on your site.
3) I don’t like to many gadgets on my gear. Would you recommend buying two footswitches (one for the three channels and one for the FX) or should I start out with the 432? I’m the kind of guy who thinks simple is better. Your amp is definitely not simple but I am impressed with the total package.
Thanks in advance.

    Hughes & Kettner Hughes & Kettner on March 23, 2016 Reply

    No problem! 🙂 OK, so let’s have a look at those questions:

    1. The standard TubeMeister 36 head has built-in reverb, but the overwhelming feedback we get from guitarists is also that players who play heads prefer to bring their own pedals for FX, while combo players want reverb built in. So this was in our thinking. You’re also right on the tone front – TubeMeister is about keeping the tone pure and sweet, and players can add extra textures as they want. The GrandMeister is our amp with all the extra bells and whistles!

    2. Yes, Yorkville distribute our amps in the USA and Canada, and they would be your point of contact for any issues. Although of course you can contact us directly at any time too, on here, on Facebook, etc. We’re generally pretty easy to get in touch with 🙂 (Oh yes, and Yorkville keep their own site nice and simple, and let our website do the H&K talking!)

    3. TubeMeister Deluxe 40 doesn’t have any built-in FX as such. But if you get the FSM 432, you’ve got a footswitch that lets you switch between the three channels, and also program different MIDI presets (for example, choosing between power soak settings, channels, FX loop on/off, etc.). If you want to add other effects (echoes, delays, flangers, etc.) then you could consider single FX units, or a multi-FX unit, or the GrandMeister 36…

    We hope this helps, but again, just ask if you have any more questions! 🙂

Carlo on March 22, 2016 Reply

Does that Cabinet Emulator have any effect on your sound if you are plugged into a smaller cabinet like a 212, or does it only come into play when using the Red Box to plug into other equipment besides your cabinet?

    Hughes & Kettner Hughes & Kettner on March 22, 2016 Reply

    Hi Carlo. Good question, and the answer is this: the emulation is only there if you are actively using the Red Box. If you are playing the amp in a standard way through a cab, it’s not active at all. Hope this helps 🙂

Mete on February 29, 2016 Reply

Hi. I own a TM18 (30th anniversary) and I’m using it with a 12″ Celestion Greenback cabinet. While I’m happy with it, the new Deluxe series drew my attention. But I wonder if I can achieve the cabinet emulation for my existing TM18.
Many thanks.

    Hughes & Kettner Hughes & Kettner on February 29, 2016 Reply

    Hi Mete, and thanks for your message. The new Red Box AE on the TubeMeister Seluxe is an updated version of the standard TM18 Red Box, and it gives you many more options. However, there is an Impulse Response available for the TubeMeister 18 NOS – you can download it from the TM18 page here:

    In the download is a PDF that explains how to use it, but if you have any more questions about it you can ask us any time 🙂

Harald Braun on February 17, 2016 Reply

I can´t hear anything of the ambience !

    Hughes & Kettner Hughes & Kettner on February 18, 2016 Reply

    You’d need to watch some of the videos recorded under more formal conditionhs, Harald. Try the session muasic video for size, for example (it’s in German, but you’ll certainly hear the differences!

    Also, we think of the ambience in these videos as being like the secret ingredient of a great dish: it’s sort of subtle, and you don’t really consciously notice them while you’re experiencing them – but boy do you miss them when they’re not present! Try listening to the Red Box AE with the AE switched off and you’ll see exactly what we mean 😉

Joe Sanguedolce on February 17, 2016 Reply

Sounds awesome. I have been running Tubemeisters for a few years now (18, 36 and now my gig head is the Grandmeister).

When does this technology hit the Grandmeister or it’s next evolution???

    Hughes & Kettner Hughes & Kettner on February 18, 2016 Reply

    Thanks for the support Joe 🙂 Hmm, it would certainly be cool to see this technology in GrandMeister too, so let’s see what happens if/when we see another GM36 evolution! We certainly wouldn’t rule it out though 😉

Martin McVitty on February 17, 2016 Reply

Is this something similar to the Red Box AE that I have in my Triamp 3?

    Hughes & Kettner Hughes & Kettner on February 18, 2016 Reply

    Hi Martin. The Red Box AE in the TubeMeister Deluxe amps is indeed a newer incarnation of the Red Box AE on the TriAmp Mark 3. The TriAmp is actually also FRFR-ready – it just lacks the switching the TM Deluxe Red Boxes have 🙂

Tony vitale on February 14, 2016 Reply

Is this currently what I have in my grandmeister 36 or something new?

    Hughes & Kettner Hughes & Kettner on February 15, 2016 Reply

    Hi Tony, Red Box AE is something totally new 🙂

Huey T. on February 12, 2016 Reply

Finally! This is exactly what I want! I like the FRFR option and the great range of possibilities, but I don’t like to much f***n digital stuff. I prefer hotel bedrooms, not tents, I’m definitely not a camper (lol), especially not on the amp-side of tone. Some like it hot, and I do too! I will check out the new Deluxe series immediately und if it fits, which I hope it will, I will buy one! J

    Hughes & Kettner Hughes & Kettner on February 13, 2016 Reply

    Thanks for the kind words Huey! If you like it hot, you’ll love the Deluxe amps’ power soaks too 😉 We hope you get to try the new amps soon, and thanks for reading the blog 🙂

Ted Jones on February 12, 2016 Reply

Hey H&K, I was Googling FRFR and found this blog and didn’t realise the technology was available for tube amps! So this is cool news for me. Are there any more videos out there where I can see and hear these TubeMeister Deluxe amps with the Red Box? Because if it sounds as good as you make it, it’s my next amp! Thanks guys!

    Hughes & Kettner Hughes & Kettner on February 12, 2016 Reply

    Thanks for the feedback Ted, and we’re happy you found our blog! 🙂 As far as we know, we’re the first tube amps in the world ever to offer you guitar players the FRFR experience, and we’re happy to be in that position! There are plenty more demos of the amps from the NAMM Show where we just sent the Red Box AE signal straight into the camera equipment – made things very simple 😉

    You can just go to YouTube and search for TubeMeister Deluxe to see them, but three of the coolest ones are these ones:

    Premier Guitar:
    Guitar World:

    All done without a cab, not that you’d know unless we told you! Enjoy, just let us know if you have any more questions about the Red Box AE and FRFR, and we hope you get to try a Deluxe yourself soon 🙂