Why does the Acapulco Gold sound good ?

[Vivek]

Why does the Acapulco Gold sound good ?

It has non-traditional ICs

Low input impedance

It has no pre-distortion filter (except it's loading of Guitar Pickup), no final LPF to control fuzzies

No tone controls,

Not even a gain control !!!!

No real reason to claim that it emulates a particular named Amp

Yet it sells, and DIYers love building it

What is it's secret ?

[Steben]

There is something about the 386 chip. It kind of clips like we want it to do. that's my 5 cents.

[FiveseveN]

It has non-traditional ICs

Fran Blanche used it in the Hep Cat in 1995 and Peachfuzz a couple of years later. Bruce Zinky's Smokey Amp had come a bit earlier but I couldn't tell you how many were using it as a distortion at the time.

No real reason to claim that it emulates a particular named Amp

But they do it anyway:

The Acapulco Gold is a dirt-simple distortion Device modeled after the sound of a cranked vintage Model T amplifier

386-based distortions have also been marketed as sounding like a Krank, Plexi or Jubilee.
And yes, these dirt-simple distortions have sold more than any complex AIAB developed with care for authenticity. Except the SansAmps if you consider them as such.

[teemuk]

Why does the Acapulco Gold sound good ?

Good in a context. If you like fuzzy stoner rock tones with low end flub and "mushy" response to chords and fast-picked leads, then yes, good. There are many fans of such tone, if nothing else it's very "thick". Would you ask opinion of guys liking traditional bright and gnarly crunch, and clarity on fast picked solo work or complex chording, or you might get another opinion though.

IMO, as long as a distortion box makes any kind of distorted sounds there are bound to be at least few people who like what it does... like there are bound to ne at least few people who hate it.

"Good" is a matter of subjective preferences. As such there are no universal rules to define what characteristics make a certain thing "good".   

It has non-traditional ICs

...But not with an extremely non-traditional circuit architecture. Inside a LM386 you find a generic opamp circuit with few tweaks and decent overload characteristics.

Low input impedance

It has no pre-distortion filter (except it's loading of Guitar Pickup), no final LPF to control fuzzies

Like several old fuzz pedals it still introduces a pre-distortion LPF that limits intermodulation distortion. One can definitely hear the lack of hi-pass filter as poor note separation, and flubby and mushy low end.

...And under usual circumstances there is a LPF: Your amp amp speaker cabinet.

No real reason to claim that it emulates a particular named Amp

One should take all advertisements with a grain of salt, but similarly to old Model T' s there is very little low end attenuation prior to distortion, which effectively captures the flubby characteristic of the said amp. IMO, resemblence to Model T tone is very evident.

Yet it sells, and DIYers love building it

Looks great, sounds decent, is extremely easy to build.

[Shoeman]

Pardon my ignorance, but what's a model T amp?    Traynor? 

[aleks_tedstone]

Sometimes simplicity is a wonderful thing... It does one very specific thing very well, and as I reacquainted myself with simply thrashing out sustained power chords through this thing, I remembered why I started playing guitar all those years ago, before I entered the rabbit hole of effect pedals.

I'd say its commercial success is more a feat of marketing than the circuits inherent qualities. Its DIY success, as teemuk says, in how easy it is to build, put in a small enclosure, and feel the 'I built this' satisfaction at high volume.

Shoeman - the Model T is a Sunn amplifier with an interesting history and a cult status that has spawned loads of pedal emulations and even a band simply named Sunn O)))

[teemuk]

Pardon my ignorance, but what's a model T amp?    Traynor?

Sunn Model T.

...although there are actually at least three Sunn amps all bearing the same model name. Initially the Model T was a Fender 5F6 clone with a beefed up 150-watt ultralinear power amp section that was basically a Dynaco circuit. The design was then revised a few times and rev C, or Model T Super, is already a quite different design with, for example, different (Baxandall) tone controls, different gain staging and a new feature of variable mid-range control. You can basically say it's a different amp.

Guitarists generally prefer the initial A revision, bass guitarists the C revision.

Fender Musical Instruments Corp. (who acquired Sunn from Hartzel in the 1980's) introduced yet another Model T amp in the late 1990's (IIRC), which, however, was a modern channel switching amp having nothing in common to old Sunn amp design.

[Steben]

Some 386 mini amps sound much better than 386 overdrive circuits. Perhaps its just my brain.