Earthquaker Devices - Acapulco Gold

beneharris · Post by **beneharris** » 27 Dec 2015, 23:58

I built this today, and it sounds good, but boy, the decay is really hard to deal with. Has anybody else noticed that?

rullywowr · Post by **rullywowr** » 31 Dec 2015, 17:15

I made a build doc/single sided etching layout (attached in PDF below). Enjoy!

My results...Perhaps it's my layout or my LM386 IC however when testing with my bench amp I get some squealing when turning the knob up past say 10%. I am using a Tayda LM386L (can't rule that out) and also a 1n5817 for reverse protection. Perhaps the 1N4001 voltage drop is putting series resistance to the supply which helps combat squeal? Also the grounding may be incorrect?

If you have any ideas or some time to etch this bad boy up and test it I'd appreciate it.

Hexjibber · Post by **Hexjibber** » 05 Jan 2016, 10:08

I've just populated a board from OSH that I laid out using the schem I posted earlier in this thread but I'm just getting a horrendous loud buzzing noise. I suspect it's a grounding issue perhaps but can't see anything obvious after checking parts orientation etc. Had a quick go with an audio probe and the signal seems to be fine (albeit crackly) up until around C2 or R2 then it's just the buzzing, is there anything else anyone can think of that might be the problem that I'm overlooking?

I've attached my Eagle files in case anyone can see something obvious.

Would appreciate any assistance at this point!

Hexjibber · Post by **Hexjibber** » 05 Jan 2016, 18:24

So had some progress, realised one ground pad on the board wasn't actually connected to ground! I've not got signal coming through but there's no distortion, just a loud clean sound. I'm using LM386N-3 ICs, wondering whether that could have anything to do with it?

EBRAddict · Post by **EBRAddict** » 05 Jan 2016, 19:25

Hexjibber wrote:So had some progress, realised one ground pad on the board wasn't actually connected to ground! I've not got signal coming through but there's no distortion, just a loud clean sound. I'm using LM386N-3 ICs, wondering whether that could have anything to do with it?

I tried -1, -3 and -4. You should see/hear clipping on the output from the first IC and the second IC in each case. Theoretical gain on stage 1 is 200 so anything over 45mVpp--an open power chord will do that--at the input should cause it to clip noticeably at the output. Did you add a current limiting resistor to the IC supply voltage?

Hexjibber · Post by **Hexjibber** » 05 Jan 2016, 20:21

EBRAddict wrote: I tried -1, -3 and -4. You should see/hear clipping on the output from the first IC and the second IC in each case. Theoretical gain on stage 1 is 200 so anything over 45mVpp--an open power chord will do that--at the input should cause it to clip noticeably at the output. Did you add a current limiting resistor to the IC supply voltage?

Just looked at my schem from earlier in the thread and yes there is a CLR on the same supply line that feeds the ICs, had no idea this might affect them although it seems obvious now! Shall I remove the resistor and jumper it?

EBRAddict · Post by **EBRAddict** » 06 Jan 2016, 00:07

Hexjibber wrote:
EBRAddict wrote: I tried -1, -3 and -4. You should see/hear clipping on the output from the first IC and the second IC in each case. Theoretical gain on stage 1 is 200 so anything over 45mVpp--an open power chord will do that--at the input should cause it to clip noticeably at the output. Did you add a current limiting resistor to the IC supply voltage?
Just looked at my schem from earlier in the thread and yes there is a CLR on the same supply line that feeds the ICs, had no idea this might affect them although it seems obvious now! Shall I remove the resistor and jumper it?

Just looked at your Eagle, the LED CLR resistor in your schematic is not affecting the IC voltage. Some 386 circuits use a CLR to the IC supply which is why I asked.

I guess the first thing is to verify you have 9V at the IC power, then use an audio probe down the signal path. With the input pot turned fully CW you should get a distorted output from IC1.

EBRAddict · Post by **EBRAddict** » 06 Jan 2016, 00:11

Also pins 2 and 4 on IC1 are not connected to ground but a different "net" in your Eagle schem, and are not grounded on the board. Both should be grounded.

Hexjibber · Post by **Hexjibber** » 06 Jan 2016, 09:06

EBRAddict wrote:Also pins 2 and 4 on IC1 are not connected to ground but a different "net" in your Eagle schem, and are not grounded on the board. Both should be grounded.

Ah amazing, great spot! I've done a really duff job with this layout it would seem!

It's only my third attempt at laying out in Eagle and my first two worked great first time so I suppose I had it coming!

Will try grounding those IC pins and see what comes out, thanks again, really appreciate you having a look for me as I probably wouldn't have spotted that for a while!

Hexjibber · Post by **Hexjibber** » 06 Jan 2016, 14:40

EBRAddict wrote:Also pins 2 and 4 on IC1 are not connected to ground but a different "net" in your Eagle schem, and are not grounded on the board. Both should be grounded.

Just managed to nip home and after a quick hack to link those IC pins to earth its working like a charm! Thanks so much, again!

I had LM386-1 and LM386-3 available and the -3 seemed to provide a better sound, the -1's had a bit of decaying going on. I might try some -4's at some point out of curiosity. It certainly puts out some serious volume and I personally love the big slab of distortion it provides! It is a bit of a one trick pony but it's great for that one thing!

Just also wanted to say thanks to everyone on this thread whose assisted getting to this point with the pics, circuit insight and suggestions, cheers!

EBRAddict · Post by **EBRAddict** » 10 Jan 2016, 18:22

There was a question above about decay. The LM386 and JRC386 chips seem to like ample, clean power and a clean ground.

If you have sputtering or motorboating try hooking the chip up directly to a quality power source and power source ground with a short connection. No resistors in series, no jumpers, no breadboard rails, no diodes in series, no dying or cheap battery, and no coiled 50' 28awg ribbon cable from the supply.

chubfresh · Post by **chubfresh** » 29 Apr 2016, 05:50

could anyone tell me what the green dot on this vero layout indicates? thanks!!

http://tagboardeffects.blogspot.com/201 ... 7256704011

induction · Post by **induction** » 29 Apr 2016, 12:58

That's a double-link. The upper and lower jumpers both connect to that row.

Udonitron · Post by **Udonitron** » 01 Aug 2016, 03:33

johnk wrote:I just finished mine. it's in a 1590A & I added a gain control. IMO, it's 1000X better with it and it sounds MASSIVE!:

[ Image ]

[ Image ]

Sorry to dredge this up but I am building this...1st build ever so be gentle.
I am getting some weird stuff happening.
I made the 2 knob version from this schematic here:

but I only connected volume 1 out of the 2 and when I actuate the pedal my volume drops big time...it becomes quite fuzzy for sure but very quiet.
If I touch the wire to the additional volume pot that is supposed to have a 1M pot on it, the volume bumps up a bit but nothing significant.
I am just not sure where to connect the second volume pot to on the foot switch and also I had no 68k resistors so I used a 100k.
I suppose I should use a rule of thumb lower resistance vs more?

I used the offboard wiring from here:

https://tagboardeffects.blogspot.ca/201 ... iring.html

But your FSW is wired up quite differently so perhaps that is where to start lol?
Cheers for the help!

Intripped · Post by **Intripped** » 01 Aug 2016, 11:28

for the 68k res you could connect a 220k resistor, in parallel to the already soldered 100k: the equivalent resistor is 68.75k.

regarding the pots i'm not sure i understand correctly how you soldered them.

being G1, G2, G3 the lugs of 1M gain pot, and V1, V2, V3 the lugs of volume
i would make these connections:

G3 is the new input of the effect, so connect here the wire that goes to PCB "IN" in the 1 pot version
G1 connected to ground
G2 connected to PCB "IN"

Volume pot should be connected as in the 1pot version, so:
V1 to ground (you already have a place on the PCB, named accordingly)
V3 to the PCB
V2 is the OUT of the effect, so you should connect it to the 3PDT switch, as illustrated in the tagboardeffects link

Udonitron · Post by **Udonitron** » 02 Aug 2016, 02:05

OK...here is how the mess stands now.
My pots of course need grounding on a chassis.
I coupled another 100k on the initial one in parallel to get 50k but perhaps I should use a 220k as you suggest since I do have those.
Does anything look bokred with my switch wiring?
Cheers for the reply man.

Udonitron · Post by **Udonitron** » 02 Aug 2016, 02:07

I cannot see the edit function here lol...link to the photo

https://goo.gl/photos/6G614aGQRCDZt7mN9

Intripped · Post by **Intripped** » 02 Aug 2016, 08:30

the wiring on switch and jacks looks ok, but you've definitely messed up with the pots.
try and follow the connections of my previous post and let's see how it goes.

for grounding the pots you could connect lug1 to the shell of each pot, like in guitars, but you have to be VERY sure that there is a good connection between the chassis and the pots, and also between the jacks and the chassis, since the chassis is grounded through them.
in terms of reliability this type of grounding is not (very) used in pedals, though: if for any reason a pot or a jack becomes loose, or oxidated, you will experiment issues.

in your case there is a very easy and reliable solution: just connect G1 to V1 (and V1 to the PCB)

...if you're looking for the optimal grounding, try and google "star ground"

Udonitron · Post by **Udonitron** » 02 Aug 2016, 19:10

OK I connected the grounds from the pots to the main ground on the board last night.
I used an old 1982 Telephone box, which looks cool but is a little cramped..I will need to order some boxes off ebay.
Regarding the 1M pot, G3 has the white wire attached to it that comes off the 1uf cap.
Would G2 connect to where the input comes off the board still as well or to the center pin on the foot switch?

You mentioned:

G3 is the new input of the effect, so connect here the wire that goes to PCB "IN" in the 1 pot version
G1 connected to ground
G2 connected to PCB "IN"

So where would that Vol 3 white wire go to then if both the G3 AND G2 are connected to the green PCB "In"?
THanks again for the help man, appreciate it!

Intripped · Post by **Intripped** » 02 Aug 2016, 23:12

start from version 1 of the pedal, imagine to have it all wired up in front of you
see the wire that comes from 3PDT switch and goes to PCB "IN"?
desolder it from the PCB
solder it to G3
run a new wire from G2 to PCB "IN"
connect G1 to ground (well, ok, to V1)

now the Volume
it's connected exactly as in version 1, so:
V3 to PCB "Volume 3"
V1 to PCB "Volume 1"
V2 to the 3PDT switch

hope it's clear now

Earthquaker Devices - Acapulco Gold [traced]