Got the Afterlife on my breadboard with the Ghost Note mod, and I'm getting clipping that sounds like a starved voltage fuzz/OD of sorts, and the sustain and sensitivity controls don't seem to work properly. I'm a bit puzzled about this one as I've double checked the circuit, connections, and component values several times. Any possible leads or tips are greatly appreciated. Cheers!
Post pictures and voltages please.
probably want to link to the mod, too, even I don't remember exactly where that post is ... :)
Here you go. Thanks for the help!
https://drive.google.com/file/d/1jJo9mGtU8UiblM5ofhBwo4obNSCsGC2R/view?usp=sharing
My IC voltage readings
1 7.53
2 8.90
3 4.37
4 0
5 8.93
6 6.77
7 7.62
8 9.04
Mod is R7 (47k) swapped for 24k in series with B50k pot as you've described. Here's how I hooked it up
Quote from: thesameage on January 09, 2015, 03:03:21 PM
For anyone wondering, here's how you do the Ghost Note mod:
Connect lugs 2 and 3 of the pot. Solder one side of the resistor to lugs 2/3, and the other side goes to the PCB. A wire from lug 1 of the pot goes to the other resistor hole on the PCB. Order doesn't matter. You could use a 100K pot without the limiting resistor (or even larger) instead if you like, but I found the 50K + 24K gave plenty of range.
I used a linear so that noon was the original value, but feel free to deviate!
pin 5 is connected directly to Vb in the schematic, which should put 4.5V on that pin -- you have it almost at 9v. Trace all your power connections starting with the 9V.
Ah yeah I had R9 going to VB instead of to IC 4. Thanks a bunch!
There still seems to be a fair bit of breakup (much nicer sounding now though) at higher sustain levels, but I've been using a guitar with pretty hot humbuckers. For now I've just turned the sensitivity knob all the way down and backed off the sustain until it cleans up a bit. The compression sounds quite nice!
Just in case anyone ends up following this, I addressed the clipping primarily by using a different optocoupler. The cleanest ones I have seem to reduce overall volume a fair bit. Unity is basically max on the A100k pot, but it's ok imo because I'm never really looking for a compressor to boost my signal. Though if anyone has tips on how to increase the make up volume available I'm all ears.
I also stumbled across this write up which I found very useful to make the circuit a little friendlier to different opamps, among other things.
https://atomiumamps.tumblr.com/post/158891400886/hollis-flatline-compressor-modsupdates-ive-built
Lowest noise I have is a NE5532 which is dead silent even with everything exposed on a breadboard. The LM833 has lower noise than the TL072 as well, and it seems to be the squishiest of the bunch so far. I'm not sure which I prefer yet. I've also swapped the bridge diodes to 1N5817 as I have a few extra, and I want to save the germaniums for another project.