Flex SmartAmp takes a best-of-both-worlds approach to guitar amplification


February 3, 2013

Michael Ibrahim, creator of the Flex SmartAmp

Michael Ibrahim, creator of the Flex SmartAmp

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In an effort to bridge the divide between tube and digital guitar amplifiers, MI Audio has created the Flex SmartAmp, a tube-driven, analog guitar amplifier that can be controlled using an iDevice.

Ever since its inception, the digital or "modeling" guitar amplifier has caused a great deal of debate amongst players. On one hand, a digital amp gives you versatility, with a multitude of emulated amp "models" and tones that can be dialed up within seconds. A regular vacuum tube amp is far less versatile, but purists will argue that the warm tube-sound it produces can never be replicated by digital modeling.

The Flex SmartAmp is not a digital modeling amp. Instead, it uses pure analog circuitry that can be controlled digitally by the user.

“Instead of thinking
 of Flex SmartAmp as an amplifier, think of it as a library of all of the different components needed to build an amplifier," explains Michael Ibrahim, the amp’s inventor. "Inside the amplifier there are banks of resistors, capacitors, switches, potentiometers and most importantly vacuum tubes. It is all sitting there waiting to be used; you just need to tell it HOW they are to be used.”

By using an iPad or other iOS device, the user can control all of these components through a multi-touch platform that is replicated on the 22-inch front screen of the SmartAmp.

“When choosing an amplifier via the iPad, or similar device, it sends a series of instructions to Flex SmartAmp telling it how to build the required circuit, be it a single ended push-pull amplifier, cathode, fixed-biased, or even mixed-biased,” says Ibrahim.

Essentially what this gives you is access to almost every type of amplifier ever created – and the ability to "build" your own unique amp through the iOS platform. Every minute detail right down to the power supply and how hot or cold you run your vacuum tubes can be saved to your handheld device, and then dialed up again at a moment’s notice.

All data is stored on the iOS device rather than in the amp, an aspect likely to appeal to guitarists both on tour and in the studio. The idea is that a touring guitarist can keep all of their presets stored in their portable device and simply hire a Flex SmartAmp for the show. The same principal applies when recording. Instead of lugging several amps to the studio, players can "build" the desired settings into the iOS platform and then use the SmartAmp on each track.

The Flex SmartAmp is currently in prototype form and according to Michael Ibrahim, is likely to undergo some radical changes before being released to the public.

“Imagine the front of the amplifier being completely taken up by the screen, or integrating the amplifier design tools into the amplifier itself as a Schematics Editor," says Ibrahim. "Our plan for the Schematics Editor gives users the internal workings of the amplifier on the screen with the ability to edit, modify or create from scratch your own dream amplifier.”

There is no word yet on how much the Flex SmartAmp will cost when it hits the market, but considering the craftsmanship that has gone into the prototype it probably won’t be cheap. The good news is that the company is also working on the Mini Flex, a scaled-down (and cheaper) version of the SmartAmp that utilizes hybrid digital-analog technology while still retaining a valve signal path.

The Flex SmartAmp was due to premiere in January at the Winter NAMM (National Association of Music Merchants) show. Unfortunately for MI Audio and those wanting to take a closer look, the SmartAmp prototype was held up at U.S. customs and didn't make it to the show.

Source: Flex SmartAmp


When will these people realize that there's no way to accurately simulate an all-tube guitar amp? Power tubes are fundamentally different from transistors in the way they shape the sound and interact with the guitar, and are an actual part of the musical instrument. You can simulate the sound they make and play back that sound, but on stage, in a live performance, solid state amps don't feedback the way tube amps do, they don't distort the way tube amps do, and they don't interact magnetically with the guitar. Most rock and metal musicians need that as a part of their setup.

Only if you don't need those exact characteristics of an all-tube amp, then you can recreate the sound digitally and have that flexibility.

Joris van den Heuvel


You seem to have missed the whole point of this article, and the objective of the guy's design. This is an all-tube amp. It is not a "solid-state amp". It uses tubes for amplification and rectification, not transistors.

The solid-state and computer bits allow you to re-configure the amp to different tube-amp circuits. The solid state stuff is not involved in the actual sound-processing at all.


it's a shame the amp didn't make it through the customs in time for the show. They probably thought it was some terrorist equipment designed to blow up America.

it's also disappointing not to have a video with a demonstration.

So it's likely to undergo some radical changes before it's released. Presumably that means it doesn't work very well at the moment. I always feel it's better to try and perfect something before you announce it.

As far as using it for gigs, you've got to lug around the pad, as well as the amp. It still seems strange that you cannot replicate the sound of valves.

David Clarke

I think this is a intriguing amp to say the least. I do hope the inventor's vision is realized and the amp lives up to all who play guitar. After all this is the 21st century and technology is changing by leaps and bounds.

Mike Anderson

@Dmoy: yea I seem to have missed that part... That's what happens when you scan through an article on "yet another digital tube amp". But this one is really different.

Joris van den Heuvel

The "tube sound" has been debunked by an article in Electronic Design. Yes, they sound different, but it's due to damping factor and filtering through a transformer. If you feel like lugging them around, fine.

Captain Obvious

@Captain Obvious: the sound has indeed been debunked, but the use of a tube amp as part of the musical instrument setup is not. Tube amps really are different. See my first comment.

Joris van den Heuvel

@Joris van den Heuvel: It's really no more different than the difference between two tube amps or the difference between two transistor amps. It is entirely, both in theory and realistically, possible for a digital circuit or a computer program to simulate everything tube amps did. In fact, one can do more with transistor logic than with vacuum tubes, with significantly less power and space usage.

The problem is how complicated the circuit or software has to be. As for being part of the instrument and interacting magnetically with the guitar, that can be done digitally too. Would you like to stick a gyroscope in your guitar and pair it to a computer too? Could dedicate that to some weird effects.

TL;DR: This amp is a nice proof of concept of a digitally controlled tube amp, and would be a nice point at which the amp war just... Ends. It's annoying, guys. The answer to your search for the best amp is "preference". Not "tubes", not "transistors", nor "large", nor "small". Just, "Preference".

Loki Scarlet

Yes it is. The way a tube amp couples with a guitar pickup differs from how a transistor amp does it. There's no denying in that: it's a simple fact. You can't simulate the stray magnetic fields and saturation effects of the output transformers, nor can you simulate a high output impedance and how all that affects the speaker resonance and feedback with the guitar, and even the magnetic and acoustic coupling with the speaker cabinet.

Joris van den Heuvel

"You can't" is not the words you are looking for, my friend. "It is not feasible to" would be more appropriate. The amount of processing power and memory that would take would make the amp too power hungry. But yes, it is, in fact, all entirely possible. One must think outside the box. Noise can be heard, as well as interpreted. In addition, sensors can be added, and anything that can't be accommodated by those two, can be simulated entirely in software. If one were to go that far, it may be easier to get a tube amp.

But that is only useful if you specifically want or need that tube amp sound. Otherwise it is cheaper to get a transistor amp, which would also be lighter.

As for output transformers, one could go through two identical transformers, one to bring it up and one to bring it down, with the same combined impedance that they would want from one transformer in their tube amp, and may get close. Possibly. I wouldn't hold my breath, but it would be cheaper than the hardware and the man-hours for the software to simulate that.

Really, if we did more research, we might be able to reproduce the sound. But to what end? If we did come up with the solution, who would even buy the resulting product? Firstly, everyone would doubt it. If they don't dismiss it outright, they'd be uncertain, and any tube amp users who are attracted to it at all, would fear "converting". This is an example of FUD, which keeps Microsoft and Apple afloat in the software market. Welcome to humanity, bro.

Loki Scarlet

I have the MI Audio Revelation Mk II, and it is one astonishing amplifier, plus a number of Michael Ibrahim's pedals, all great. This fellow and his employees have designed and manufactured some brilliant bits of kit and I would easily compare my Revelation Head with my Mesa Stiletto,THD Univalve and Bi Valve, Lab Systems Cage,Rivera Suprema, various Fenders, Hughes and Kettners, My Ulbrick ,Ampeg and Laney.

As a matter of fact, it is my preference over any of them with 4 channels, each channel totally different, and each channel different withing itself by using the pre amp 3 mode switch. I would rate the Revelation in the top 5 amps I have ever played.

So, barring a Meteor strike or the end of the the Tube amp industry, the amp will be made. The capability of any owner to safely redesign the amplifier circuitry and save the results for usage , or indeed sending the saved file to another Flex Amp owner, is revolutionary.

When Michael sorts out the appearance and sells them, I will line up to try and probably buy one.

Simon Vanderzeil

BTW, did not get through U.S Customs for what reason?, A renowned amp designer, his own company and his own design going to NAMM?

Me thinks some other Company will release their own version in the next 12 months....I wonder how that happened.

Simon Vanderzeil
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