Had an unverified layout in the library that I was quite unhappy with so I decidied to give it another go with a new one from scratch. This is a soft clipping overdrive with a bass boost and cut filter. The eq / filter section are pretty unique with an OTA LM13700. With the Depth switch you can select between a simple one pole filer, a two pole filter and a resonant two pole filter. The Initial control lets you blend the clean overdive signal with the filtered signal.
Schematic from the wizards at Deadend Fx
Mmmh, interesting.
ReplyDeleteWith an OTA LM13700, the filter section might be inspired from the Korg MS20 Sallen-Key filter?
Yes, maybe. I also see some similarities with OTA phasers...
DeleteThe mosfet (VP3203/Q1 in Deadend FX schematic)?...
ReplyDelete... is replaced with a 1N5817. Sorry, should have mentioned that. It is the protection diode. I prefer a more stable rectifier shottky for in that spot.
DeleteAh, ok.
ReplyDeleteBuild it, just for curiosity. It works, but I don't have the beans, neither the on/on/on switch type 2. So, improvised with slide switch (8 pin), and zero resistors. It´s not the sound at 100%. Far from it. But all the pots do their stuff (with a boost before we can hear much better). I also suspect from the 7660S... Or bad ground somewere...
I'll tell you more, as soon I improve and debug all this.
Found an "oopsie". 1K resistor at pin 3 of IC1 should be 1M...:-S
DeleteCorrected. Louder but still fuzzy. It's starving somewere...
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteWere is Drive 1 should be Drive 2/3; and Drive 2/3 were is Drive 1...
ReplyDeletehmmm...according to the schematic lug 1 should be connected to pin 1 and lug 2 and to 10k?
DeleteBeen over the the layout a few times now, couldn't sput any mistake other than 1k/1m at IC1.
Is it the overdrive itself that sounds wrong? Filter control and Depth switch works as it should?
DeleteYes, the lug 1 should ne connected to pin 1. The lug 2/3 should connect to 10k - pin 2. If I'm seeing properly...
Delete1K resistor on U16 should go to T16 (ground).
ReplyDelete1k resistor on U17 should go to T17 (ground).
Double link on S27 should be on R27.
Thanks for taking a look. 1k resistor is tied to ground already. Are you sure about the doublelink? Pin 9 is the output of the OTA and is connected to 4,7k, 22k and 1uF. Pin 10 in only connected to pin 12 and 4,7nF?
DeleteYou're right! Doublelink is in proper place. Alucination of mine (after hours looking at the picture you become allucinating :O))...
DeleteNow we have, at last, perfect overdrive.
ReplyDeleteSorry, man. Confusion on my arquives and I ended building your old layout. And spoting corrections You've already made in the new/actual one. Typical mess of mine!...
ReplyDeleteBack to the beginning: I'm gonna build the new from root. The old is almost there, with all the corrections, and sounding pretty damn good (awesome overdrive), but still some annoying rf noise on background.
Works perfect for me ;)
ReplyDeleteThank you!
DeleteTagged.
First of all, thank you for your effort. I am looking forward to build this.
ReplyDeleteI was wondering, how could I wire a possible expression pedal to this layout?
Hello, you would need one of these: http://smallbear-electronics.mybigcommerce.com/1-4-in-stereo-nys212/
DeleteNotice that the pins you first see when clicking that link are called shorting pins (or that is what I call them). When you insert a jack the metal bands, that contact those pins to the opposite side lugs, will lift, effectively shorting whatever is connected to said pins.
So using the FILTER pot as an example of what you may want to control. Connect Filter 2 and Filter 3 from the board to the NON-shorting Tip and Ring connections on the jack, respectively. THEN, connect the POTENTIOMETER Filter 2 and Filter 3 to the shorting Tip and Ring connections on the jack. Connect both Lug 1s to ground on the jack.
Now, with no expression pedal plugged in the FILTER POT will work as expected. Plug in an expression pedal and you short out the FILTER POT, using the expression pedal in its place.