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Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups

What is a "Modeling" Amp?

Discussion in 'Modeling Amps, Plugins and Apps' started by JayFreddy, Mar 1, 2013.

  1. Gnobuddy

    Gnobuddy Friend of Leo's

    Sep 15, 2010
    British Columbia
    I actually got to try one of these out a few days ago. It was amazingly small. I've seen women's handbags that were bigger! The one I saw was finished in expensive-looking real wood, and sold for over a grand. And it was amazingly loud, you could definitely gig with one of these.

    As for the amps tone - well, it wasn't harsh like so many SS amps, but to me the treble was a little muffled (probably rolled off to avoid that typical SS harshness). It certainly didn't sound as sweet as a good tube amp set for clean tone. But it was light, loud, and the sound was usable enough.

    Last edited: Mar 6, 2013

  2. BigDaddyLH

    BigDaddyLH Telefied Ad Free Member

    Acoustic Image are also class D amps. They're used quite a bit by jazz guitarists: a super clean "acoustic-sounding" amp.

  3. Abu Twangy

    Abu Twangy Friend of Leo's

    Mar 16, 2012
    Rocky Mount, NC
    That's what I use for bigger venues for jazz guitar, bass and acoustic guitar--an 800watt Ten2 combo with two 10" speakers which weighs under 30 lbs. Unfortunately it is not voiced like a conventional guitar amp so to get a Twin Reverb-type clean I boost the EQ with a Boss GE-7.

    So for smaller gigs and grab 'n go it is a modeling amp with a class AB SS power amp for me.

  4. boredguy6060

    boredguy6060 Friend of Leo's

    Mar 28, 2012
    Sou Cal
    The Ipad has a dozen or more modeling amps which I doubt anyone could argue, are purely computer generated. There are Fender amps of all sorts, Marshall, Vox, Orange, Peavey, all offering several different models. There are also a hundred effects pedal models as well.
    I an old school amp guy, in fact 99 percent of my post are in the Shock Bros. I build some, own some, so I'm familiar with old tube amps.
    Got laid up for a while, so I got a Ipad to keep me from going nuts and after a bit discovered these different apps. I started with the free stuff and was impressed enough to buy a bunch of different ones.
    So laying around jamming with headphones on I got to tell you it's suprisingly good.
    So here's my question,
    I know my guitar signal is passing this 30 pin connector and turned right into ones and zeros, no doubt about it. So why if I use a totally clean setting, I can tell which guitar is which, meaning, my LP sounds like my LP. My strat sounds just like a strat. My tele is just as twangy, and my jazz guitars all sound like jazz guitars,.
    If none if my guitar signal makes it thru, why don't they all sound the same, on the same amp settings?
    Just asking?

  5. Jefe

    Jefe Tele-Afflicted

    Jun 17, 2004
    Wallingford, CT
    I'll attempt to answer that - it's because today's modeling amps are pretty good! Set clean or dirty, the various amps are being simulated fairly accurately, or accurately enough to fool our ears. Yes, your signal is being converted to "ones and zeros", but it's being done in such a way that most of us have a very hard time telling the differece between the moderler and the real thing. This applies just as much to the clean amp settings as a dirty ones. So your LP playing through a model of, say, a clean Fender amp is still going to sound pretty much like a LP playing through a clean Fender amp.

  6. LarsOS

    LarsOS Tele-Holic

    Oct 24, 2011
    It seems you have modelling or AD/DA confused with synthesizing?

    On a clean setting, your guitar signal is simply turned into a digital signal, goes through some hoops in the iPad, and is then turned back to an analog signal that is almost indistinguishable from the original signal. So you can actually say that all of your guitar signal makes it through.

    When you apply a modelling filter, it's just that - a filter. It doesn't replace the original signal, it just modifies it. Mostly EQ, some compression, and some harmonic distortion, I would guess.

    I'm pretty impressed with modern modelling myself. I've got a Trace Elliot bass combo at the place where I practice. At home I've got a multi-effect-board where I model this exact amp - with the same knob settings as on the physical amp. It even models the 15" speaker. Now I can tweak my sound at home, and have a reasonable idea of how it will sound through my amp when I go to the studio. That is something I couldn't do before.

  7. Gnobuddy

    Gnobuddy Friend of Leo's

    Sep 15, 2010
    British Columbia
    Actually all of your signal makes it through that digital conversion - it's just converted from analog to digital format at that point.

    A truly "totally clean" setting would be like a CD recording - the signal is all ones and zeros, but nothing is lost in the process. In fact it's the most accurate way to make a recording that we humans have figured out since Edison's first tin-foil gramophone in the 1870's.

    A genius named Claude Shannon was the first to figure out that you can convert a signal into a string of ones and zeros and lose *nothing* in the process (provided certain conditions are met). He published his work in 1948 - before Leo Fender sold his first Broadcaster guitar!

    So truth be told, all-digital is old-school too: as old as those vintage Fender tube amps! It was all understood that long ago, but it was so expensive that only research institutions could afford to actually build digital hardware.

    It took over 30 years before Shannon's work arrived in the hands of the general public in the form of the audio CD - all your music is stored as ones and zeros on a CD, as I'm sure we all know. Just as you can tell what guitar is on a CD recording, you can tell what guitar is sending its signal - transformed into ones and zeros - into your iPad.

    So there's not much mystery as to how your clean guitar signal makes into onto your digital recording device. The mystery starts after that, in the amp sim - the process used to actually digitally distort your clean signal, ideally to distort it the same way, say, that a Fender Princeton would.

    That part - the amp modelling - is still proprietary and secret. All the companies doing this keep their methods to themselves, and as far as I know no researcher has come forward and published a scientific paper telling the world how to do this, as Claude Shannon did with his world-changing research in 1948.

    So everybody is constantly re-inventing the wheel, or stealing each other's engineers, or trying to reverse-engineer each other's software or hardware. Line 6 makes modelling amps that sound like fifty different kazoos in one box, someone else tries to do a little better - groping in the dark, without the benefit of knowing how Line 6 made their digital kazoo sounds - and this has been going on for some decades now.

    I believe Roland was selling digital guitar stuff - their earliest guitar synth hardware - in the late 1970's, so the history of digitally tinkering with guitar sounds in a commercial product goes back at least that far, i.e. some forty-five years!


    Edit: Oops. LarsOS posted while I was composing and typing this up. He said some of the same things, but I'm leaving this post because I also said some diferent things than he did.

  8. Willie D

    Willie D Friend of Leo's

    Nov 19, 2004
    So. Illinois
    I've said it before,

    One time my son was using his Vox AD15vt and my '71 VibroChamp with my Telecaster. He set the Vox on the Blackface setting, turned off all the effects, adjusted the gain, and I couldn't tell the difference.

    I was in the kitchen, he was in the living room. He kept switching between the amps. I could tell when he was switching! Then he settled in to play. I was absolutely certain he was on the Champ. I walked into the room and saw the cable plugged into the Vox.

    He told me he was trying to make it sound as much like the VC as possible. He succeeded. Made a believer out of me. The digital model was that good.

  9. Gnobuddy

    Gnobuddy Friend of Leo's

    Sep 15, 2010
    British Columbia
    Could you tell which was which once you were in the same room as the amp?

    Not being snarky - I want to know if the modelling amp was good enough to fool your ears once you were in the same room and could hear all the detail that was lost when you were in the kitchen.

    Most of the time I hear a difference in terms of harshness when I compare digital sims (hardware, I have no experience with software sims) with analog amps. Usually the bass end of the spectrum sounds fine to my ears - in fact bass guitar amp sims like my Zoom B3 multi-FX pedal are quite convincing to my ears.

    But when it comes to regular guitars and the much higher frequencies they put out, I always seem to hear that harshness to the mids. I also have a Zoom G3 guitar multi-FX, and it doesn't convince my ears the way the Zoom B3 does. The G3 has that harshness to its guitar amp models.

    That harshness is carried by the higher frequencies in the sound, which is very apparent if you turn down the treble - the harshness is reduced, but of course the guitar sounds muffled as well.

    Because you were listening from another room, there was probably a lot of treble attenuation going on because of the nature of sound itself. High frequencies have short wavelengths and do not carry as well around corners and through obstacles as lower frequencies do. Even walking away from directly in front of the speaker diminishes the highs, as most of us have discovered if we tried an amp-stand that pointed our guitar amp speaker at our ears instead of our knees.

    That's why I'm curious if the Vox still sounded as good as the real thing to you once you were in the same room as the amps.

    When Zoom corp. came out with their G3 multi-FX pedal, they did something pretty brave: they made a demo video featuring an actual Marshall guitar amp back to back with the digital Marshall amp model in the G3. Here it is:

    What do your ears tell you in this case? (And this is for everybody reading this thread - as long as nobody objects and we keep the discussion civil even if we don't all agree!)


  10. brookdalebill

    brookdalebill Telefied Ad Free Member

    Nov 15, 2009
    Austin, Tx
    I can't find anything that beats my Roland Cube 80XL.
    I'm beginning to wonder what Roland can do to "improve" it.
    Light, loud, cheap, small, versatile, dependable, (almost) bulletproof,
    and replaceable.
    I rarely use (switching/control) pedals with it, anymore.

  11. Willie D

    Willie D Friend of Leo's

    Nov 19, 2004
    So. Illinois
    I still couldn't tell the diff in the room. The house was an open design, huge opening between living room and kitchen. My guitar still sounded like my guitar through the model. It really sounded good.

  12. LarsOS

    LarsOS Tele-Holic

    Oct 24, 2011
    They tell me what they've always told me: YouTube sounds like ****. ;)

  13. Willie D

    Willie D Friend of Leo's

    Nov 19, 2004
    So. Illinois
    And I agree with your observations about treble attenuation. Obviously why mic placement is so critical when recording a guitar amplifier.

    Personally, I'm a big fan of placing the mic farther from the amp for that sort of Jimmie Vaughan recorded sound.

  14. Gnobuddy

    Gnobuddy Friend of Leo's

    Sep 15, 2010
    British Columbia
    Yeah, but do the two sections of the same video sound like the same **** to you, or do you hear differences, and if so, are they significant to you? :)


  15. KevinB

    KevinB Doctor of Teleocity

    Mar 4, 2007
    New Jersey
    I listen thru a decent pair of studio monitors, and to me the Marshall has a bit more fullness and is a little smoother in the trebles. And I say this as a big fan of modeling amps (my go to setup is a Line 6 Pod XTL into a Tech 21 Power Engine).

    How old was that demo?

  16. Gnobuddy

    Gnobuddy Friend of Leo's

    Sep 15, 2010
    British Columbia
    I agree about the mic placement, moving the mic an inch (away from the soundhole and towards the bridge, say) when micing an acoustic guitar can make a huge difference in tone. Things aren't quite as dramatic with an electric guitar going through a speaker, but even so a couple inches mic movement can make an audible change in the sound.

    I was talking about something a little different, though. Take all the distortion pedals using clipping diodes as an example. There are tons of these on the market. If you listen to the signal right after it's clipped by the diodes, it is very harsh and truly awful. Most pedals will put this horribly harsh sound through some sort of treble-cut filtering (removing the higher frequency harmonics which sound harshest) before the signal leaves the box. It still sounds nasty, but less obnoxiously nasty. As TDPRI member 11 Gauge said, it's like putting a Bandaid on a shotgun wound, but I guess even a Bandaid is better than nothing.

    Many - almost all, in fact - of the digitally modelled amps I've heard first-hand have traces of the same sort of harshness. It's not usually anywhere near as extreme as a raw diode-clipper sound, but it's the same sort of gritty, buzzy, sand-between-your-teeth harshness, just at a lower level.

    I recently heard two SS modelling amps that didn't sound particularly harsh; one was a second-generation Fender Cyber Twin, the other a brand spanking new $1200 Quilter Micropro 200 Studio ( Neither sounded harsh on the two or three settings I tried out - but both sounded muffled. If I believe my ears, both had a fair bit of high frequency filtering going on, almost certainly to try and tame that SS harshness - but at a cost in brightness and clarity compared to a tube amp.

    In your case, being in a different room would probably muffle the treble from the Vox enough to remove some of that gritty distortion even if you could hear it when you were directly in front of it. So that's why I was asking.

    I have never actually heard the Vox amp in question, by the way, so I'm not saying it sounds harsh to me. I have no idea how it sounds.


  17. Gnobuddy

    Gnobuddy Friend of Leo's

    Sep 15, 2010
    British Columbia
    I hear the same thing even through my lousy sounding little Creative computer speakers. Except where you say the Marshall is smoother, I would instead say the Zoom is harsher.

    The interesting thing is that if I start with fresh ears and listen to that demo video, when the Zoom first appears it sounds quite good. Thinner and raspier than the Marshall, yes, but still good. But the longer I listen to the Zoom the harsher it sounds to me. It becomes - literally - painfully harsh after a few minutes of steady listening.

    It's like ear fatigue - the longer I listen to it, the worse it sounds, and after a while it's physically uncomfortable, like sand between my teeth and nails scratching on a blackboard at the same time.

    And I say this as an owner and user of the Zoom G3. I'm not randomly criticising something just for jollies. In fact I like many of the FX pedals in the G3, and those sound fine to me. It's just the amp models that leave me with gritted teeth and cringing ears after a few minutes exposure.

    Years ago at a birthday party for my big sister, we found out that the decorative icing roses on the cake tasted sweet to two members of my family (my mom and eldest sister). No surprise there - the surprise was that the same roses tasted bitter to the other two people - myself and my other sister.

    Whatever red dye the baker had used on those icing roses was undetectable to the two people who tasted only the icing. But other two of us could taste it - and it tasted nasty to us. I assume this is down to some minor genetic difference that showed up in the taste receptors on our tongues.

    I bring that exerience up because I think exactly the same thing is going on with modelling amps. To some people they sound indistinguishable to the original, or at least indistinguishable for all practical purposes. To some others they sound harsh and unpleasant. I suspect it may actually come down to some genetic component that affects the way we hear things - either that, or something in the way our brains first learn to process sounds when we're babies.

    When the cake incident occurred, we were all intrigued, and kept repeatedly tasting bits of icing roses to verify our experiences. The results were consistent - sweet for two of us, nasty and bitter for the other two. There was no way for the people who found it bitter to experience any sweetness there - all we got was a foul bitter taste. There was no way for the people who found it sweet to taste the bitterness - it continued to taste sweet to them. The divide was impassable, because it was wired into our senses.

    I think we are in the same situation with modelling amps. Those of us who hear (sometimes ear-cringing) harshness can't understand why others say they sound exactly like the real thing. Those who hear them sound exactly like the real thing don't understand why anyone would claim they sound harsh.

    This is probably a big part of the reason why this debate has raged for years and years without coming any closer to any sort of resolution.

    So I don't think we'll all have a consensus any time soon. That would only happen if the models get good enough for nobody to hear the harshness - and that might not happen any time soon.

    Fortunately, we don't actually have to have a consensus. We can simply agree that we experience these devices differently, and go get the ones that make us happy.

    For the record, I would very much like to have a modelling amp that doesn't have that harsh sound (to my ears). They have so many other advantages - size, weight, cost, flexibility. If I found an SS amp that sounded as good as a tube amp to my ears, I'd quite happily buy it and stop fussing about with century-old technology.

    I'll also add that if I take the harsh-sounding Zoom amp models and feed them through slatherings of reverb and/or delay and/or a tiny bit of chorus, the harshness gets sanded off by all those subsequent effects, and then it can sound quite good to my ears. Lately I've been chaining the Rack Comp, Big Muff, and Tape Delay in the G3, and feeding it into my guitar amp set for lots of reverb. Under those conditions the Zoom is quite listenable.
    Not sure exactly. The G3 is a pretty new product. I believe the G3 was launched late in 2011, and I don't think that video was uploaded until long after the launch. So maybe a year old.

    Zoom did release a firmware update for the G3 a while ago. I've read claims that the models are better after the update. I don't know if there is any validity to those claims - I haven't updated my G3, which is still running the original version 1 firmware. (No mystery why, I don't have any computers running Windows, and the Zoom software only runs on Windows.)


  18. TieDyedDevil

    TieDyedDevil Tele-Holic

    Sep 8, 2006
    Portland, OR
    The code may be proprietary, but the methods are well-known. You just have to know where to look.

    You can find all manner of technical papers related to modeling techniques if you use Google Scholar.

    Here's a search on "guitar amplifier simulation modeling", just for starters:

    The first hit is an excellent survey of techniques, published in Computer Music Journal in 2009:

    The full article is available as a PDF:

    And that's just the first hit of hundreds... :)

    My point is: this stuff is not rocket science. Yes, it's more difficult than building a tube amp. Yes, there is math involved. But anyone with the appropriate tools, knowledge and skills *could* contribute to the art.

    The people already in the business of building modelers may be adding their own unique spin to existing techniques (in a manner somewhat analogous to the way that a programmer imparts a particular look and feel to yet another spreadsheet or e-commerce implementation), but they're not doing basic research.

    Maybe in another twenty or thirty years these things will become common enough and standardized enough that we'll be able to search the `net for collections of favorite DSP code snippets for amp modeling. :lol:

  19. Willie D

    Willie D Friend of Leo's

    Nov 19, 2004
    So. Illinois
    Oh, I'm not offended at all by discussion. I'm aware that attenuation of the harshness you're talking about could happen by being in a separate room, having the amp pointed toward padded furniture, or simply by having carpet on the floors.

    I'm simply expressing my amazement at how far digital modeling has come, how much more realistic digital amp models are than they were 10 years ago, and how - in particular situations - the vast majority of people would be hard pressed to hear any difference.

    I'm enjoying the discussion.

  20. KevinB

    KevinB Doctor of Teleocity

    Mar 4, 2007
    New Jersey
    Now you mention it, I noticed this too. The first time I listened I thought the Zoom sounded quite good. Not quite as good as the Marshall but still very acceptable. But the more I re-ran the clip the more I could detect, and started to dislike, the harshness of the Zoom.

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