Acapulco Gold.. All the kids are doing it

[Ben Lyman]

This pedal is all the rage these days and I wanted to see what all the hype is about.
Someone posted this schematic on Facebook, I'm not sure where it came from or if it's right.
That R1 seems like it's in a weird spot to me, but I breadboarded it the way I thought it might go.


I wasn't too impressed so I started adding stuff and I like it better now.
I added a gain control to the first IC but it still needed cleaning up, especially with humbuckers, so I added a Pre-Gain control to the input.
Of course, it was too muddy for use as a light OD, so I added a high pass filter in between the IC's, then a low pass "presence" pot at the end.

[Plexi]

You're right... noticed it time ago
I think because it seems to be easy.
PGS sell it as a great distortion pedal that will turn your poor amp into a full throttle Sunn beast stack. They don't tell that they use isolated cabs/amps in another room at inhuman decibels 
I've only read guys asking: "how can I made it to sound lower?", "why it sound's horrible and fizzy?", "why mines have a constant fried sound?"...etc.

LM386 seems to be an "easy" goes IC...but it's not.

I've recommended to going back to the classics: if you whant a simple LM386 beast, go for Krank Distortus Maximus or D*A*M Sonic Titan.

About the designs and mods you made: what IC suffix are you using?
Remember that every one has more / less output.
In this case, I would go for N-1 (325 mW)

Here's another ways to tame the gain:


I think your schem is great: a lot to do with Pre and Post gain controls.
I would used a simple A100K voltage divider at Pre: lug 1 to ground (5/10k resistor in between), lug 2 to circuit in and guitar in to lug 3.
I would try the classic Rat Filter at the end.

[Kennt82]

I also prefer my Sonic Titan and Distortus to my Acapulco.  They are both a boost stage into a single 386.   A pedal to check out with with dual 386's is the Peachfuzz.

[Plexi]

I also prefer my Sonic Titan and Distortus to my Acapulco.  They are both a boost stage into a single 386.   A pedal to check out with with dual 386's is the Peachfuzz.

And a TL072 as a.. preamp? I suppose.
It's on my wish-list now 

I notice that the 386's aren't linked to get gain (pins 1 to 8: gain to 20), so it seems that the 1st are 'gently' pushing the 2nd one to break.

[Ben Lyman]

Muchas gracias amigos! I'll check out the Titan and Distortus. I think my IC's just say LM386N, I might have some others that say LM386L

[Plexi]

De nada! 

Oh.. that's confusing...
Check about that: if they're the higher one's (N-4, 1w output), you can feed them with 18v...
Remember to have >18v rated caps, and permissive neighbors 

[duck_arse]

check out the beavis "tufnel". looks quite like the aca gold. and ben - your presence control - is it missing a cap?

[Plexi]

check out the beavis "tufnel". looks quite like the aca gold. and ben - your presence control - is it missing a cap?

Wow... another one:


Seems interesting that they add gain to both LM's

[duck_arse]

I have a different vershun .....



.... mine's louder.

[Plexi]

The V1.1 goes to 11 
Which would be the difference that C5 and C9 made?

[anotherjim]

Y O Y, Why oh why.... are those zobel networks in there? That is C6 & R3. 4n7 too small to do anything and if it did, it's only a slight load on the 386 output, which has no inductive load so don't need a zobel anyhow.

[Ben Lyman]

check out the beavis "tufnel". looks quite like the aca gold. and ben - your presence control - is it missing a cap?

oopsy 
Thanks Duck, I just took a close look at the bread board to make sure I didn't forget anything else and updated my schematic above.
If I have time later, I'll try to make a short demo to show how versatile it is. 5 knobs is a bit much in my opinion, but oh well..

[Ben Lyman]

I changed it around a little bit, here's a sample

[Plexi]

Niiice! Love that nasty mids at the beggining!
Really usefull the 3 gain pots.

[Ben Lyman]

It's getting better but I don't think it's perfect yet.
The pre and post gain controls are great but I want to work on the tone controls some more.
Thinking about maybe trying a BMP tone control next.
Here's the current version on the board:

[Plexi]

I think a normal roll off highs controll at the end would work well (see Sonic Titan).
Or maybe the Rat Filter in between.
For the BMTS, I would try to bump mids there... the design is very scooped.
A good similar 'variant', is the Zvex Box of Rock tonestack.

Which software you use for the schematic? Looks great

[Ben Lyman]

I think a normal roll off highs controll at the end would work well (see Sonic Titan).
Or maybe the Rat Filter in between.
For the BMTS, I would try to bump mids there... the design is very scooped.
A good similar 'variant', is the Zvex Box of Rock tonestack.

Which software you use for the schematic? Looks great

Agree, BMP is too scooped, it needs a switch to bring back mids, or change values so it isn't always scooped. Gus shared a cool BMP component change that I remember liking a lot. It's very elegant too, in that it has values of "Forty-Seven" and "One" all around.

My presence control at the end rolls off highs, it's basically a stripped down version of the Rat Filter. I will have a look at the ZVEX BOR, thanks.

Schematics.com is a free site, all your work is stored on the site and available for the public to view. Some people might not like that but I don't care. There may also be ways to keep your work private but I'm not savvy enough figure it out. I just make something, take a screen shot, then save it on my computer

[Ben Lyman]

Here's how I had it last night, I like it like this too. It has a BMP tone knob with values recommended to me by Gus, it has a very nice midrange snarl to it.
Plenty of beefy low end when the gain is cranked up and nice jangle to the high end when playing lower gain tones.
Also, a very helpful friend suggested a treble bleed (560p C4) across the pre-gain control and it works like a charm.
All this seems to eliminate the need for the variable cap tone control.

Here's an update to last night's schematic, today it's about the same but I have added a buffer. Jim and Antonis, if you're out there you must think I'm very dense but I'm trying hard to understand everything you've taught me. Any opinions on my BJT output buffer? Does it look like I've learned anything at all?

Anyway, the Pre-Gain is now a C1M and I might call this knob the "Bass Boost" control.
I can still achieve the original flavor of the Acapulco gold but there are lots of other tones to be had.

[Plexi]

Thanks for the schematic site.. I'll try 

A few movements there... no gain to the 2nd LM, just to amplify?

The most mid configuration I used on a BMTS was 10nf/22k on high pass, and 6.8nf/39k on low pass.
But...still scooped...almost flat.

I'll try that values!

I asume, due the huge amount of volumen, it's unnecesary a recovery stage after the tone stack volume sucking...did you try to place after the 2nd LM?

The BOR:
http://3.bp.blogspot.com/-kq989pNrtME/TxQ5v0UVl8I/AAAAAAAAAkQ/tQV0VA6M2QQ/s1600/zvex_boxofrock_schematics.jpg

[Ben Lyman]

Plexi, yes I believe the IC2 is just for volume and there is tons of extra volume, so no need for make up stage after tone stack.
With all gains off and tone maxed low is the quietest it can be and it still boosts well above unity volume.
Sometimes I feel reluctant to use the BMP tone stack but in the case of the Acapulco Gold it's just what the doctor ordered!