EQD acapulco gold clone

[oip]

hey folks

played this pedal in a guitar shop and really enjoyed it, plus the one knob design is hilarious.  saw the vero design on tagboard, super small circuit and already had some LM386 ICs around so built it on vero a few weeks ago.  finally got around to etching and boxing over the weekend.  few errors in the etch and layout and not the cleanest soldering/wiring ever but hey i like it and it sounds ludicrous.  lots of fun. 

also had two madbean PCBs arrive last night so many thanks brian and on to the next ones!

cheers!

[beneharris]

Great build. How does it sound? I've done that tagboard layout, and made my own on a board, and I just can't get rid of the high pitched squeal it has without grounding an extra pin on the first IC (can't remember which off the top of my head). I know it is going to be noisey, but it is quite unruly. How do you feel about it?

[AntKnee]

I like it, but I gotta tell you, I could use a little more knob. 

[oip]

aha not even joking it's meant to have a bigger knob (...) but that has yet to arrive from hong kong after a month and i've lost all hope.  i think this size is probably as big as it needs to be, i already had to dremel down the pot so it wasn't mysteriously floating above the enclosure.

about the noise, i haven't cranked it since boxing but it's not noticeably noisy under 11 o'clock.  i only have a gibson with humbuckers, it gets slightly muddy on neck pickup but on all settings sounds 'rockier' and less creamy than the big muff clone i did couple weeks ago.  there is a sticky plasticky undertone as well which gives it the doom vibes i think.

when i was testing, past about 3 o'clock it just squeals out and is unusable, though i did pick up some radio stations (?!)

a weird thing about it that i need to test is, i have a LM386 amp which can power a decent sized speaker on its own at 9V, but this doesn't seem to be able to.  i'd also love to a/b with a real version and might buy even one at some point to do so then trade.

[bluescage]

Very nice build!

[beneharris]

aha not even joking it's meant to have a bigger knob (...) but that has yet to arrive from hong kong after a month and i've lost all hope.  i think this size is probably as big as it needs to be, i already had to dremel down the pot so it wasn't mysteriously floating above the enclosure.

about the noise, i haven't cranked it since boxing but it's not noticeably noisy under 11 o'clock.  i only have a gibson with humbuckers, it gets slightly muddy on neck pickup but on all settings sounds 'rockier' and less creamy than the big muff clone i did couple weeks ago.  there is a sticky plasticky undertone as well which gives it the doom vibes i think.

when i was testing, past about 3 o'clock it just squeals out and is unusable, though i did pick up some radio stations (?!)

a weird thing about it that i need to test is, i have a LM386 amp which can power a decent sized speaker on its own at 9V, but this doesn't seem to be able to.  i'd also love to a/b with a real version and might buy even one at some point to do so then trade.

See, that is the exact problem I have with mine, too. I can ground out that pin - again, I forget which one, if you'd like to know, I'll open the box and tell you - but the high pitch squealing goes away on higher volume and gain settings. It loses a slight bit of hairyness and loses some gain, but it is totally worth having an almost fully useable gain range.

[oip]

interesting, i'm going to test it some more.  tbh i'm pretty ok with it turning to angry noise past 3 o'clock as i feel like most of the effect lives in a pretty small range of output.  i'm also going to look at some mods, and go back to some earlier LM386 projects to see if i can find anything worth tweaking.  if you ever do feel like cracking it open i'd be interested to see what changes can be made.

according to the datasheet (http://www.ti.com/lit/ds/symlink/lm386.pdf) it's also possible to adjust the overall gain by adding a resistor to the capacitor between pin 1 and 8 on the first IC - this may be what you have changed if you grounded pin 1?  or it could be pin 7 grounded which is recommended in the datasheet but not on the vero as far as i can see.  bypasses the unused input.

i wonder what happens if you play with the gain on the second IC.

[beneharris]

Yes, I've noticed that, too. I haven't gone through the work of trying that quite yet though. I'll be back home Monday, and I'll report which one I've got grounded.

Mainly I'm just curious with the EQD layout, how they managed to make it a useable pedal, but I've not played a real one.