dap9 wrote:
Overall I'm pretty pleased. When compared to my original DLS MkIII, it sounds pretty close. I only need to do two things in order to get my build 100% to my liking:
1. Decrease the overall gain - mine has a little too much at the minimum setting
2. Decrease the Bass - the original pedal is pretty bassy, and I think my build is similar, but I'd like it to be a little more useable.
Any tips are greatly appreciated
1. Decrease the limiting resistor on the gain control (47K to ground) to 33K or maybe lower, and it should bleed more signal to ground and give less gain/volume. Or you can take it out completely, it's basically a volume control of the first gain stage being fed to the second. If you turn it all the way down, it's the same as turning the output volume control all the way down- it sends all the signal to ground.
2. Decrease the value of coupling caps, the 220n on the input and output could be halved(100n~120n) and that will kill some bass. It is usually more noticeable on the input.
That's what I was thinking - thanks for the confirmation!
I actually finished the board layout already. Six controls on the top of a 125C enclosure.
I was planning to use the presence trimmer as an off board control but couldn't find a good place for the 4PDT toggle switch. They're kind of large. So I made the Presence control a trimmer again and fit the S Lead/S Bass switch in it's place.
I think I'd rather stick with a switch so that I can switch in between the two original Marshall tone stacks. After all...there is a lot of variation already with the full range of tone controls.
The user manual states that you can "mess" with the presence trimmer but...the factory setting is about 50%.
I'm sure that this is a "sweet spot" for this circuit. It's probably not something I would mess with much.
I'll post build docs after I'm finished with my build. I ordered 4393s from a trusted seller on Ebay, but don't expect them for a few weeks.
Maybe I'll bread board the circuit after the JFETs arrive and check out the tonal difference with the different switching options.
I also went through the pictures of the MK3 that were uploaded earlier in this thread. I compared them to the schematic and found a few mistakes with the pot wiring.
The Treble, Mid, and Master are wrong on the schematic marked V1.1.
I'll upload a corrected schematic after my build is verified.
armdnrdy1 wrote:There did not seem to be an updated schematic of the DLS MK3 with the corrected values of R3 (1K) and R9 (680R) so...here it is.
Question...does anyone know which position the switching depicts? With all of the switches on the lug 1 side...is this "super lead" or Super bass"?
Thanks so much if you put work into that.
But it's always good to somehow not the version information, a date, or something to distinguish it.
But great work
In general, threads like these need cleaning up, it's becoming an unreadable mess...
Can a JFET based overdrive circuit be powered at 3.3V?
I took the Catalinbread DirtyLittleSecret overdrive pedal that emulates a Marshall super-lead / super bass amp and tried to see if I could clone it using 3.3V instead of 9V.
I have to say that it's a bit of a challenge, JFETs in general don't work very well at low voltages, it's difficult to bias them and it's difficult to make them work in the active region.
But I think I found the "dirtylittlesecret" to make them work.
The answer can be found on this blog post I published: DirtyLittleSecret 3v3 clone: LTSpice analysis
Spoiler: Pinch-off voltage
Some jfet's won't work because Vgs will be close to 3.3V, and for the dirtylittlesecret, the top Jfet's source will be at ~ (0.5*3.3V)+Vgs. As you can see, Vgs actually must be lower than1.15V. That's why I offered you some very low Vgs jfets.
bmxguitarsbmx wrote:I know. That's what the wink is for.
Some jfet's won't work because Vgs will be close to 3.3V, and for the dirtylittlesecret, the top Jfet's source will be at ~ (0.5*3.3V)+Vgs. As you can see, Vgs actually must be lower than1.15V. That's why I offered you some very low Vgs jfets.
Ah OK, sorry I got confused.
Yes, J201 Vgs(th) can be as low as -0.3V and as high as -1.5V
I think it's not a DLS anymore but does it sound similar?
Here are some guitar samples sound tests made with the simulations output form the original effect circuit, the JFET 3.3V version and the 3.3V MOSFET version:
Hello!
Presence pot characteristics A or B? The manufacturer says that the Presence initially stands in the middle. In the middle - a 5 K or not, if the characteristic of A?
mganzer wrote:After some ajustments (of spacement) here it go. Working and verified.
I really dig your layout and it fits a 1590B! Would it be possible to add spaces for the 1M in series with the 2n2 cap needed for the Super Bass mode? That way both versions could be built on the same board. I'm not looking for features like mode switching or voltage doubling, just the ability to build it in SB mode without "offboard wiring" lol. Thanks!
