"Little Angel" - Super Simple PT2399 Mini Chorus

[Unluckyfett]

Is it possible to voice this pedal for bass? I have some ideas but Im not really certain of anything. correct me if im wrong but following the revision 2 /earthscum mod schem i would have to increase the values of the .1 caps. Would I need to increase/adjust the value of the caps/resistors on pins 9-16 of the 2399?

[garcho]

The caps between those pins on the PT2399 are part of a complicated filter. Changing their values will do more than a simple RC would. I've had many hours of fun experimenting with those values. Do you have a breadboard?

[Unluckyfett]

Unfortunately i dont. I really should invest in one. when i buy the rest of the parts i do some experimenting myself. so what were your observations on changing those values?

[Unluckyfett]

I was reading through the thread some more and found this, which i believe tells me i should be ok following that schem and the delay mod.

Aye. I've used it at 2 shows. For bass, you want to increase the delay a little bit for sure. I like the 5k pot, but already had the 10k installed.

For bass, once you find that perfect setting for you, you go from flat to gigantic godly overtones!

I used a TL072, hence the 100k pot in place of the 470k. I haven't un-ductaped my pedal to pop in an NE yet, so can't report on that. I rode my bike to the store to buy parts, came home and had it boxed and working and ready in 5 hours, with only an hour to spare before we had to be at the bar. Used it in an outdoor setting at the last one, and it is awesome. If you are outdoors, you can increase the depth a bit more without busting through over the top of the guitars.

And, lastly... absolutely no bass cut! I breadboarded mine with .022's in the audio paths, but I built it with all stock parts plus my mods to box up. I have a "super-fat" DS-1 that is basically my big OD. It increases the bass without destroying too much of the punch, still has the DS-1 grit, but bigger. This goes in front of my LA, and I only get the most minor bass cut out of it, which actually just seems to add to the overall tonal qualities.

Of all the things I tried, the ONLY one necessary for bass is the delay mod. Just a 5k pot. I wired mine so I could (next build) use the stock jumper pads from the layout. I just used a DIP strip on this one, but kept mods simple to work with the stock PCB.

[BarBandit]

Hello everyone. I'm trying to get this layout working with the earthscum mods
http://www.diystompboxes.com/smfforum/index.php?topic=86297.560
bypass works, engaged I get a faint guitar signal with no effect and I have 100k in R1
I'm hoping someone can look at these voltages and know whats wrong
Thanks
Tim

NE5532
pin1 : 3.08-3.325v
pin2 : 3.151-3.170v
pin3 : 3.025-3.055v
pin4 : 0V
pin5 : .597v
pin6 : .877v
pin7 : 1.304v
pin8 : 9.5v

PT2399

pin1 : 5.02v
pin2 : 2.415-2.417vv
pin3 : 0V
pin4 : 0V
pin5 : 2.822v
pin6 : 2.396v
pin7 : .740v
pin8 : .812v
pin9 - 16 : 2.411-2.415v

[Perrow]

bypass works, engaged I get a faint guitar signal with no effect and I have 100k in R1
I'm hoping someone can look at these voltages and know whats wrong
Thanks
Tim

From my own dealings with this circuit I've learned that reversing the in and out has this effect 

[BarBandit]

bypass works, engaged I get a faint guitar signal with no effect and I have 100k in R1
I'm hoping someone can look at these voltages and know whats wrong
Thanks
Tim

From my own dealings with this circuit I've learned that reversing the in and out has this effect 

Double checked it and I have it wired correctly

[BarBandit]

Had a loose wire and reflowed some solder now
bypass works, engaged I get a faint guitar signal with effect and I have 100k in R1
and all controls seem to work except the level pot
I'm hoping someone can look at these voltages and know whats wrong
Thanks
Tim

NE5532
pin1 : 3.08-3.325v
pin2 : 3.151-3.170v
pin3 : 3.025-3.055v
pin4 : 0V
pin5 : .597v
pin6 : .877v
pin7 : 1.304v
pin8 : 9.5v

PT2399

pin1 : 5.02v
pin2 : 2.415-2.417vv
pin3 : 0V
pin4 : 0V
pin5 : 2.822v
pin6 : 2.396v
pin7 : .740v
pin8 : .812v
pin9 - 16 : 2.411-2.415v

[BarBandit]

Got it going.
I made the pcb with a cnc router and it didn't complete a couple traces
don't know how many times I stared right at it and didn't see it
Sounds very cool but is pretty noisy even with the delay turned down
is there a way to filter out most of the noise?
I've tried taking out the 2399 and the noise remains
It's pretty loud hissing thats not coming from my guitar(volume down on guitar)
Thanks
Tim

[azrael]

I'm not a particular fan of the parts placement in that layout. C8 should be closer to pin 1. I would put a 100nF cap in parallel with it, too.
Try lifting Pin 4 from ground, by bending the leg before placing it in the IC socket. I've had problems with it working like this, but other people report a slight improvement in noise when you allow digital ground to flow through the internal 10 ohm resistor between pin 3 and 4.
a 100nF cap in parallel with C11 wouldn't hurt either.
is it in an enclosure already? once it's in a grounded enclosure, that will help a lot.
maybe shielded wire would help, too.

[BarBandit]

I'm not a particular fan of the parts placement in that layout. C8 should be closer to pin 1. I would put a 100nF cap in parallel with it, too.
Try lifting Pin 4 from ground, by bending the leg before placing it in the IC socket. I've had problems with it working like this, but other people report a slight improvement in noise when you allow digital ground to flow through the internal 10 ohm resistor between pin 3 and 4.
a 100nF cap in parallel with C11 wouldn't hurt either.
is it in an enclosure already? once it's in a grounded enclosure, that will help a lot.
maybe shielded wire would help, too.

Awesome thanks I will try your suggestions and report back
it is in an enclosure already

[BarBandit]

Tried your suggestions and had no change
I guess this is just a noisy circuit. Too noisy for anything I would use it for
What would be a better choice for a chorus?
Is the zombie chorus quiet?

[azrael]

Oh, it sucks that it didn't improve. Have you tried a different PT2399? just wondering.
You could try building a discrete 5V regulator that's better than a 7805:
http://valvewizard2.webs.com/PT2399_Data_Notes.pdf
on page 2.
I forgot to mention, I usually use ceramic multilayer caps for the 100n decoupling, they have better qualities for this purpose, I've read.

No experience with the Zombie.

[Ark Angel HFB]

Recently I've been going way over board with my power filtering but the results of getting zero hum from what are crap but cheap wall warts has been a good thing.

no really here is the power filter that goes on the front of every pedal I build... Vin > polarity protection Diode(negative side faced toward V in) > 100 resistor > 1000uf cap to ground > 1nf cap to ground > V Out to circuit.

try the above if you can... sometimes I find the hiss from really bad power supplies doesn't drop till you get to like 220uf or even 470uf.

[garcho]

I guess this is just a noisy circuit. Too noisy for anything I would use it for.

It's not a noisy circuit, it's a basic op amp buffer/boost. The other half of the op amp is a standard LFO. Something is wrong with your layout or components.

[BarBandit]

Have you built this layout?
pretty noisy for me.

[garcho]

Have you built this layout?

I've built the circuit from the schematic a number of times, no noise. Sorry, I assumed you meant the circuit was faulty, not the layout you're using, my bad.

[BarBandit]

no worries, was just looking for confirmation that this layout was noisy
I can't seem to do anything to get rid of the hiss

[Ark Angel HFB]

no worries, was just looking for confirmation that this layout was noisy
I can't seem to do anything to get rid of the hiss

What kind of power filtering are you using?

[aballen]

Hey guys. I have a copy of the birthday edition layout on page 33 post 644,  but I cant find a pdf.  I'm having trouble figuring out the scaling.

Anyone have dimensions for the board, or a dpi I can set it to for proper printing?