Another Amp In A Box

[POTL]

Hello.
Amplifiers in the box are my favorite type of effector, I've tried many circuits and have come up with and continue to come up with new ones.
But I have always avoided operational amplifiers.
The reason was that many of the popular circuits of the last century sounded boring and unpleasant (to my taste), all these classic numerous effects of distortion and overdrive.
Not so long ago I came across BAJAMAN projects and got acquainted with Dave Friedman's products, which interested me.

I noticed that besides Friedman and REVV, no one else makes commercial amps in the box (maybe tech 21, but I didn't like them).
Operational amplifiers allow you to simulate the frequency response of a tube amplifier in full, frequencies are easier to pick up than on a MOSFet, and they do not need to be tuned like in a JFET, and they do not turn into history like a JFET.
Why do you think there are no successful commercial op amp products?
Has anyone tried such effects?
I only have 2 thoughts on this
1) Op amps may sound rougher than transistors due to a different form of clipping (but this can be corrected with diodes)
2) This is a tribute to trends and the reluctance of manufacturers to come up with something else while being able to use ready-made solutions.

[ElectricDruid]

Why do you think there are no successful commercial op amp products?

I think your first premise is deeply flawed.

Tom

[marcelomd]

I noticed that besides Friedman and REVV, no one else makes commercial amps in the box (maybe tech 21, but I didn't like them).

The first Marshall In a Box that I know of is the Marshall (!!!) Guv'nor. To me, all of it's descendents, JHS Angry Charlie, Suhr Riot, Mi Audio Crunch Box count as MIABs to me. They are based on clipping opamps plus some additional diode clippers.

Anyway. The thing about tube amps is "feeling". They "feel" different while you are playing. Solid state can an does sound nice, but doesn't have that same feeling.

For the tone, the magic sauce is the eq. Pre- and post-distortion/overdrive/etc eq. The device that does it is not so important, I think.

[iainpunk]

first off, it think the term ''amp in a box'' is mainly a malicious marketing term. better, more honest terms to use would be pre-amp or overdrive. pre-amp if you design it to put in to the effects return, and overdrive if you put it in front of the amp's existing pre-amp (sorry for the rant)

Why do you think there are no successful commercial op amp products?
Has anyone tried such effects?

there are enough tho, but they are generally called overdrive or distortion. the boss MT-2 sounds really good in to the effects loop, but is labeled distortion.
boutique builders like the marketing term ''amp in a box'' because it sounds fancy and special. there are enough pedals that actually are designed to sound like an existing amplifier, without having to go in the effect loop, like the boss HM-2 which is designed to sound like a Marshall JTM.

cheers, Iain

[Vivek]

Hello.
Why do you think there are no successful commercial op amp products?

I know nothing.

Anyway, here are my thoughts.

The only question in the original post is regarding commercial success of a product.

That has to do with many aspects besides technology

Even the choice of knobs on the pedal has an effect on the commercial success !!!!


However from what little I have read about the technology :

First, What really differentiates a distortion pedal ( run into effects loop) from an AIAB Amp in a Box ?

Is it that the distortion pedal makes no marketing claims to sound similar to an existing preamp/amp ?

or that the distortion pedal has more primitive tone controls ?

or the distortion pedal has less gain stages, normally just the one ?


Second, since last 25 years, everyone will tell you that the magic sauce is Pre-distortion EQ, Clipping, Post-distortion EQ.

Maybe all distortion pedals implement that formula in a simple way, but it seems that a tube amp has a bit more up its sleeve, like

multiple gain stages that make more complex total transfer function

Interstage EQ

volume dependent harmonics,

harmonics and volume dependent on integration of signal envelope.

Do the self-proclaimed AIAB do that ? Normally they have multiple gain stages but dont do the signal envelope dependent stuff.  So what gives them the right to call themselves AIAB rather than Distortion boxes with better tone controls ?

[Fancy Lime]

To be fair, not all tube amps do all of the things Vivek mentioned, either. Some particularly revered amps specifically try to avoid things like sag and non-linearity by having oversized power supplies and global negative feedback.

To me, an AIAB is any pedal I use as an always-on preamp replacement. That may be something as simple as a DOD-250.

Cheers,
Andy

[Vivek]

Some particularly revered amps specifically try to avoid things like sag and non-linearity by having oversized power supplies and global negative feedback.
Andy

But I guess they have moving DC bias due to asymmetrical clipping / Coupling caps anyway.

[Fancy Lime]

Some particularly revered amps specifically try to avoid things like sag and non-linearity by having oversized power supplies and global negative feedback.
Andy

But I guess they have moving DC bias due to asymmetrical clipping / Coupling caps anyway.

Not sure what you mean. How would asymmetrical clipping or coupling caps move the DC bias? Do you mean the effect that happens when you have "asymmetrical" clipping diodes to ground after a coupling cap? That moves the DC bias of the clipper so that it becomes symmetrical. But that is a thing in pedals, not so much in tube amps (although some tube amps actually produce their clipping with diodes rather than overdriven tube stages).

Andy

[POTL]

In my understanding, the amplifier in the box and the distortion / overdrive pedal are two different things.
What is the difference? There are quite a few of them.
1) The amps in the box simulate the preamble of a specific amp model, the overdrive pedal does not emphasize simulating a specific amp.
2) The amp in the box quite often has a passive tone stack that works in a completely different way than the usual tone control or active EQ in the overdrive pedal.
3) The amplifier in the box is almost always made with field effect transistors, of course we know the exceptions like the JHS Angry Charlie or Tech 21 character series, the overdrive pedals are mostly op amps, very old designs with bipolar transistors.
4) Sounds different, the amps in the box seem less distorted and squeezed than conventional pedals such as the BOSS HM-2 / MT-2 or RAT, etc.
It seems to me that the high frequencies are more open, and the response to the volume knob is better.

[iainpunk]

well, amp in a box is still just a pedal that makes distortion. its just a marketing term, just like ''transparent overdrives'' that aren't transparent what so ever. (fuzz face is one of the most transparent pedals i have ever measured, haha)
almost all amp in a box pedals don't actually sound like the amp they claim to clone, especially when A/B tested in the fx loop.
there are enough just as expensive overdrives that are as ''touch sensitive'', ''respondent to vol control'' and ''open sounding''.

ever plugged in to a reall 100W marshall with overdriven power tubes?
not much of those aforementioned artifacts were in it. if you want touch sensitive, respondent to volume control and open sounding, get a fuzz pedal.

, Iain

[11-90-an]

For me I think that AIABs should have the sound of the amps they're emulating, same knobs/controls, same tone... basically when plug it straight into a soundcard you SHOULD be able to get the amp-that-was-emulated tone..

For example we have a "fender twin-reverb" AIAB... it should probably have the bass, mid, treble volume controls and some switches to activate "vibrato" and reverb or something...

However I see this isn't the case with most of the AIABs now...

[iainpunk]

For me I think that AIABs should have the sound of the amps they're emulating, same knobs/controls, same tone... basically when plug it straight into a soundcard you SHOULD be able to get the amp-that-was-emulated tone..

For example we have a "fender twin-reverb" AIAB... it should probably have the bass, mid, treble volume controls and some switches to activate "vibrato" and reverb or something...

However I see this isn't the case with most of the AIABs now...

i fully agree, most AIAB sound nothing alike the real amp they claim to clone.
hence, i call the word a malicious marketing term.

cheers, Iain

[niektb]

Origin Effects Magma 57 seems to be a proper 'AIAB'! Full tone stack and switches to compensate for amp eq types or for running straight into the power amp, and an excellent vibrato channel!

[Ben N]

Anyway. The thing about tube amps is "feeling". They "feel" different while you are playing. Solid state can an does sound nice, but doesn't have that same feeling.

first off, it think the term ''amp in a box'' is mainly a malicious marketing term. better, more honest terms to use would be pre-amp or overdrive. pre-amp if you design it to put in to the effects return, and overdrive if you put it in front of the amp's existing pre-amp (sorry for the rant)

These issues are connected. The loss of "feel" is AFAIAC an issue when the the AIAB is functioning as a preamp--i.e. all voltage gain and tone shaping pre-power amp. When a pedal is meant to interact with a tube preamp, i.e. is run above unity, there is no loss of feel.

[iainpunk]

Origin Effects Magma 57 seems to be a proper 'AIAB'! Full tone stack and switches to compensate for amp eq types or for running straight into the power amp, and an excellent vibrato channel!

funny that they don't even use the words amp in a box, but call it a 'vibrato and overdrive' pedal

when it comes to feel, an opamp big muff feels more like an (old school) tube amp than most modern (mid 90s and later) high gain tube amps. want even more ''feel''? get yourself a compressor. the "feel" argument for tube amps is fickle at best, and straight up false if we're honest.

cheers, Iain

[Fancy Lime]

Well, standing in front of a 100W no-master Marshall full stack fully cranked has quite some "feel" that you cannot reproduce with any amount of analog or digital modelling in you bedroom through headphones. So I say: feel is real! It's just something that cannot be imitated at low volume because humans experience loud sounds with.more than just their ears. A good AIAB run through a powerful enough PA may not sound exactly like the amp it tries to emulate but it can sound damn good with all the feel you can ask for, nonetheless.

Cheers,
Andy

[rutgerv]

Some particularly revered amps specifically try to avoid things like sag and non-linearity by having oversized power supplies and global negative feedback.
Andy

But I guess they have moving DC bias due to asymmetrical clipping / Coupling caps anyway.

That is a good point, but by no means dependent on tube technology. It might as well be implemented with an asymmetric opamp driven clipper, and a coupling capacitors.

By the wat, a very recent insight I had due to a Spice simulation: in cascaded and overdriven gain stages, the coupling capacitor not only affects frequency response around the corner frequency, but also higher up in the spectrum, due to its phase response. Effectively it makes higher harmonics slightly out of phase with lower harmonics, affecting how they are clipped. When all harmonics are in phase, the low end dominates the clipping response, but this is suddenly changes by a slight phase shift.

Rutger

[ThermionicScott]

first off, it think the term ''amp in a box'' is mainly a malicious marketing term. better, more honest terms to use would be pre-amp or overdrive. pre-amp if you design it to put in to the effects return, and overdrive if you put it in front of the amp's existing pre-amp (sorry for the rant)

Why do you think there are no successful commercial op amp products?
Has anyone tried such effects?

there are enough tho, but they are generally called overdrive or distortion. the boss MT-2 sounds really good in to the effects loop, but is labeled distortion.

After reading ElectricDruid's analysis of the MT-2, I think it tries to be more of an "amp in a box" (type, not "malicious marketing" designation) than most realize.  Check out the post-distortion EQ:  that gentle high-end rolloff and then the slight peaks at 100Hz and 4kHz -- can you say "cabinet simulator"? 

I'm pretty sure most of the bad rap this pedal gets is due to people setting their amp EQ scooped, which intensifies the loss of low midrange and excess of harsh high-end.  And that's if they don't go completely stupid and turn all the knobs all the way up!  Putting the pedal in the effects loop obviates the "two sets of EQ" problem.  Dialing in more of a neutral amp EQ or counteracting the pedal's bass/treble boost via its controls will also help, although the pedal still won't be everyone's cup of tea.

I'm invested in this line of thought because I still haven't given up the quest to mod my MT-2 into more of a "neutral" crunchy distortion!   

[Vivek]

If the post dist EQ on MT2 was meant to be Cab Sim, they would have made it switchable, to avoid 2 cabs in the chain (mt2 with cab sim - effects return- power amp-cab)


Unless you meant it was meant to be used direct into a PA system, not effects loop.

[teemuk]

We can't tell with certainty what Roland engineers thought with that design but...

1) Overall pre/post distortion voicing and response of that pedal definitely follow the "tried and approved" configuration one would find from many "high gain" amps and which is product of several years of design evolution favouring certain type of distortion tone.
In such the "cab sim" and "underdamped amp" responses - whether real or modeled - just happen to be important ingredients.
2) The low and high frequencies of the controls are unsurprisingly about the same frequency ranges commonly implemented to "resonance" and "presence" controls, which alike mostly control post-distortion response and magnitude of response introduced by the amp-speaker combination.
3) Tone controls unsurprisingly work to de-emphasize the heavy mid-range (pre distortion) emphasis, or alternatively emphasize it even further.